People who think positively about aging are more likely to recover memory

April 12, 2023

Science Daily/Yale School of Public Health

A Yale School of Public Health study has found that older persons with mild cognitive impairment (MCI), a common type of memory loss, were 30% more likely to regain normal cognition if they had taken in positive beliefs about aging from their culture, compared to those who had taken in negative beliefs.

Researchers also found that these positive beliefs also enabled participants to recover their cognition up to two years earlier than those with negative age beliefs.This cognitive recovery advantage was found regardless of baseline MCI severity.

"Most people assume there is no recovery from MCI, but in fact half of those who have it do recover. Little is known about why some recover while others don't. That's why we looked at positive age beliefs, to see if they would help provide an answer," said Becca Levy, professor of public health and of psychology and lead author of the study.

Levy predicted that positive age beliefs could play an important role in cognitive recovery because her previous experimental studies with older persons found that positive age beliefs reduced the stress caused by cognitive challenges, increased self-confidence about cognition, and improved cognitive performance.

The new study is the first to find evidence that a culture-based factor -- positive age beliefs -- contributes to MCI recovery. The study appeared in JAMA Network Open. Martin Slade, a biostatistician and lecturer in internal medicine at Yale, is co-author of the study.

Older persons in the positive age-belief group who started the study with normal cognition were less likely to develop MCI over the next 12 years than those in the negative age-belief group, regardless of their baseline age and physical health.

The National Institute on Aging funded this study. It had 1,716 participants aged 65 and above who were drawn from the Health and Retirement Study, a national longitudinal study.

"Our previous research has demonstrated that age beliefs can be modified; therefore, age-belief interventions at the individual and societal levels could increase the number of people who experience cognitive recovery," Levy said.

https://www.sciencedaily.com/releases/2023/04/230412131116.htm

Whether physical exertion feels 'easy' or 'hard' may be due to dopamine levels

April 12, 2023

Science Daily/Johns Hopkins Medicine

Dopamine, a brain chemical long associated with pleasure, motivation and reward-seeking, also appears to play an important role in why exercise and other physical efforts feel "easy" to some people and exhausting to others, according to results of a study of people with Parkinson's disease led by Johns Hopkins Medicine researchers. Parkinson's disease is marked by a loss of dopamine-producing cells in the brain over time.

The findings, published online April 1 in NPG Parkinson's Disease, could, the researchers say, eventually lead to more effective ways to help people establish and stick with exercise regimens, new treatments for fatigue associated with depression and many other conditions, and a better understanding of Parkinson's disease.

"Researchers have long been trying to understand why some people find physical effort easier than others," says study leader Vikram Chib, Ph.D., associate professor in the Department of Biomedical Engineering at the Johns Hopkins University School of Medicine and research scientist at the Kennedy Krieger Institute. "This study's results suggest that the amount of dopamine availability in the brain is a key factor."

Chib explains that after a bout of physical activity, people's perception and self-reports of the effort they expended varies, and also guides their decisions about undertaking future exertions. Previous studies have shown that people with increased dopamine are more willing to exert physical effort for rewards, but the current study focuses on dopamine's role in people's self-assessment of effort needed for a physical task, without the promise of a reward.

For the study, Chib and his colleagues from Johns Hopkins Medicine and the Kennedy Krieger Institute recruited 19 adults diagnosed with Parkinson's disease, a condition in which neurons in the brain that produce dopamine gradually die off, causing unintended and uncontrollable movements such as tremors, fatigue, stiffness and trouble with balance or coordination.

In Chib's lab, 10 male volunteers and nine female volunteers with an average age of 67 were asked to perform the same physical task -- squeezing a hand grip equipped with a sensor -- on two different days within four weeks of each other. On one of the days, the patients were asked to take their standard, daily synthetic dopamine medication as they normally would. On the other, they were asked not to take their medication for at least 12 hours prior to performing the squeeze test.

On both days, the patients were initially taught to squeeze a grip sensor at various levels of defined effort, and then were asked to squeeze and report how many units of effort they put forth.

When the participants had taken their regular synthetic dopamine medication, their self-assessments of units of effort expended were more accurate than when they hadn't taken the drug. They also had less variability in their efforts, showing accurate squeezes when the researchers cued them to squeeze at different levels of effort.

In contrast, when the patients hadn't taken the medication, they consistently over-reported their efforts -- meaning they perceived the task to be physically harder -- and had significantly more variability among grips after being cued.

In another experiment, the patients were given a choice between a sure option of squeezing with a relatively low amount of effort on the grip sensor or flipping a coin and taking a chance on having to perform either no effort or a very high level of effort. When these volunteers had taken their medication, they were more willing to take a chance on having to perform a higher amount of effort than when they didn't take their medication.

A third experiment offered participants the choice between getting a small amount of guaranteed money or, with the flip of a coin, getting either nothing or a higher amount of money. Results showed no difference in the subjects on days when they took their medication and when they did not. This result, researchers say, suggests that dopamine's influence on risk-taking preferences is specific to physical effort-based decision-making.

Together, Chib says, these findings suggest that dopamine level is a critical factor in helping people accurately assess how much effort a physical task requires, which can significantly affect how much effort they're willing to put forth for future tasks. For example, if someone perceives that a physical task will take an extraordinary amount of effort, they may be less motivated to do it.

Understanding more about the chemistry and biology of motivation could advance ways to motivate exercise and physical therapy regimens, Chib says. In addition, inefficient dopamine signaling could help explain the pervasive fatigue present in conditions such as depression and long COVID, and during cancer treatments. Currently, he and his colleagues are studying dopamine's role in clinical fatigue.

https://www.sciencedaily.com/releases/2023/04/230412131051.htm

The brain's cannabinoid system protects against addiction following childhood maltreatment

April 12, 2023

Science Daily/Linköping University

High levels of the body's own cannabinoid substances protect against developing addiction in individuals previously exposed to childhood maltreatment, according to a new study from Linköping University in Sweden. The brains of those who had not developed an addiction following childhood maltreatment seem to process emotion-related social signals better.

Childhood maltreatment has long been suspected to increase the risk of developing a drug or alcohol addiction later in life. Researchers at Linköping University have previously shown that this risk is three times higher if you have been exposed to childhood maltreatment compared with if you have not, even when accounting for confounds from genetics and other familial factors.

"There's been a lot of focus on addiction as a disease driven by a search for pleasure effects and euphoria, but for many it has more to do with the drugs' ability to suppress negative feelings, stress sensitivity, anxiety and low mood. Based on this, we and other researchers have had a theory that if affected in childhood, the function of the brain's distress systems is altered, and that this may contribute to addiction risk in adulthood," says Markus Heilig, professor and director of the Center for Social and Affective Neuroscience, CSAN, at Linköping University and consultant at the Psychiatric Clinic of the University Hospital in Linköping.

Endocannabinoids, i.e. the body's own cannabis-like substances, are an interesting player in this context. The endocannabinoid system plays an important part in regulating reactions to stress and discomfort. Recent research suggests that this endogenous system may function as a stress buffer.

The researchers behind the study, published in Molecular Psychiatry, aimed to investigate possible mechanisms behind susceptibility or resilience to developing substance use disorder later in life after exposure to childhood maltreatment. One difficulty in research is that people who develop problems later in life tend to overreport negative life experiences when questioned about earlier events. The researchers therefore used psychiatric care registers of children and young people having been treated for traumatic childhood experiences to find study participants with objectively and prospectively documented exposure. The study included about 100 young adults divided into four equal sized groups: individuals that had been exposed to childhood maltreatment and had developed an addiction, individuals that had been exposed but had not, individuals that had not been exposed but had developed an addiction, and individuals who had neither been exposed nor developed an addiction. The researchers measured endocannabinoid levels in participants' blood and carried out several experiments to test stress reactions. The participants' brains were also scanned using magnetic resonance imaging, MRI, while their reactions to social stimuli were tested.

It turned out that one group stood out compared to the other three: the group that had experienced childhood maltreatment but had not later developed an addiction. The researchers refer to this group as ?resilient'. In comparison with the other groups, this group showed increased function of the endocannabinoid system as well as different brain activity. Surprisingly, the resilient group differed most from the control group, which had not been exposed to childhood maltreatment, nor had any addictions.

Faced with emotional social stimuli, the resilient group showed higher activity in three areas of the brain. Two of these areas are part of a brain network that focuses attention and cognitive abilities on what is important at the moment and modifies individuals' behaviour according to the situation at hand. The third area of the brain is in the frontal lobe and is associated with regulating emotions. This area communicates extensively with other areas in the brain that process emotions. In comparison with other animals, humans have a well-developed frontal lobe that regulates impulses and emotions, for instance by suppressing fear impulses in situations where fear is not relevant.

"Increased activity in certain areas of the brain in the resilient group, which had not developed an addiction despite childhood maltreatment, may be linked to a more adaptive way of reacting to emotional social information. We can see that also in a resting state they show increased communication between the frontal lobes and other parts of the brain, which could indicate that this group has better emotional regulation," says Irene Perini, staff scientist at CSAN at Linköping University.

A question this discovery raises is whether the resilient group had a high endocannabinoid system function from the outset, or whether they were better able to activate the system in response to stress, thereby avoiding long-term consequences of childhood maltreatment. Because of its cross-section nature, this is not possible to determine from the present study.

https://www.sciencedaily.com/releases/2023/04/230412131025.htm

Greater fat stores and cholesterol increase with brain volume, but beyond a certain point they are associated with faster brain aging

April 11, 2023

Science Daily/University of California - Santa Barbara

Among Indigenous, rural non-industrial populations inhabiting the tropical forests of lowland Bolivia, researchers report, there appears to be an optimal balance between levels of food consumption and exercise that maximizes healthy brain aging and reduces the risk of disease.

"We hypothesize that energy gain from food intake was positively associated with late life brain health in the physically active, food-limited world of our ancestors, but that obesity and other manifestations of a Western lifestyle now lead to greater cognitive aging and dementia in middle and older ages," said UC Santa Barbara professor of anthropology Michael Gurven, a senior co-author on a study that published in the Proceedings of the National Academy of Sciences.

For this paper, the researchers collaborated with the Tsimané and Mosetén tribes, two Indigenous populations that live along tributaries of the Amazon River that flow through lowland Bolivia. In comparison to urban post-industrialized populations, these groups have less reliable access to food and have to exert a lot of effort to get it. They also have less access to modern health care. Meanwhile, people in wealthy countries have largely grown accustomed to eating more and exercising less -- habits that are associated with decreased brain volumes and faster cognitive decline.

"We set out to compare rates of brain aging between U.S. and European populations, and two Indigenous Bolivian populations: the Tsimané, who have very low rates of heart disease and minimal dementia, and the Mosetén, who are culturally similar to the Tsimané but whose lifestyle has shifted away from subsistence," said Gurven, who co-directs the Tsimané Health and Life History Project, a two-decade NIH-funded longitudinal study of health and aging.

The researchers enrolled 1,165 Tsimané and Mosetén adults, aged 40-94 years, and provided them transportation from their remote villages to the closest hospital with a CT scanner. They then used methods developed by study co-author Andrei Irimia, an assistant professor in the USC Leonard Davis School of Gerontology, to accurately measure brain volume from the CT scans. They also measured the participants' body mass index, blood pressure, total blood cholesterol and other biomarkers of cardiometabolic health.

"We found the fastest brain aging in the U.S. and European cohorts," Gurven said. "It was slowest in Tsimané and intermediate in Mosetén." Rates of brain atrophy, or brain shrinking, are correlated with cognitive decline and risks of neurodegenerative diseases such as dementia and Alzheimer's. In addition to less brain atrophy, the researchers found improved cardiovascular health in the Indigenous groups compared to industrialized populations in the U.S. and Europe.

The environment of limited food availability plays a role in the brain and cardiovascular fitness of nonindustrial societies, according to Irimia, in that "humans historically spent a lot of time exercising out of necessity to find food and their brain aging profiles reflected this lifestyle."

Studying the Mosetén population illuminated key findings: as a "sister" population to the Tsimané, they share similar languages, ancestral history and agrarian lifestyle. However, the Mosetén have more exposure to modern technology, medicine, infrastructure and education. Based on the researchers' results, according to Gurven, "the Mosetén's lifestyle is more vulnerable to the chronic diseases of aging than among the Tsimane, but less so than in post-industrialized countries."

Among the Tsimané, BMI, adiposity and higher levels of "bad" cholesterol were associated with bigger brain volumes for age. This, however, may be due to individuals being more muscular, on average, than individuals in industrialized countries who have comparable BMIs. Only at the highest levels of BMI, adiposity and cholesterol -- closer to the levels more typically observed in the U.S. -- was brain volume compromised.

"Our analyses suggest that 'too much of a good thing,' or what we call the 'embarrassment of riches,' seems to be what's going on," Gurven explained. "Greater adiposity, blood cholesterol and other indicators of nutrient intake increase with brain volume, but only up to a point -- a 'sweet spot.' Not too little and not too much. Beyond the sweet spot, higher levels of adiposity and cholesterol are associated with a smaller brain volume -- faster brain aging. That's consistent with our current environment being mismatched to our evolved biology."

Co-author Hillard Kaplan, an anthropologist at Chapman University and a co-director of the Tsimané Health and Life History Project, agrees. "During our evolutionary past, more food and less calories spent in getting it resulted in improved health, well-being and ultimately higher reproductive success," he said. "This evolutionary history selected for psychological and physiological traits that made us desire extra food and less physical work, and with industrialization, those traits led us to overshoot the mark."

According to Gurven, the study implications carry a hint of optimism. "The same active lifestyle that leads to a healthy heart seems to also lead to a healthy brain, and well into your 70s," he said. "If people like the Tsimané and Mosetén have found a manageable life-long balance to stave off dementia, then there's hope for the rest of us."

https://www.sciencedaily.com/releases/2023/04/230411150510.htm

Teachers who struggle to cope with stress report far lower job satisfaction

Findings can help identify coping mechanisms that alleviate teacher stress, which has implications for teacher shortages.

April 10, 2023

Science Daily/University of Missouri-Columbia

As teacher shortages continue to worsen across the United States, a new study at the University of Missouri gives insight into why so many stressed and burnt-out teachers are leaving the profession. The study found teachers who struggle to cope with the stress of their job report far lower job satisfaction compared to teachers who find ways to manage the pressure.

Seth Woods, a former doctoral student at MU, collaborated with Keith Herman, a Curators' Distinguished Professor in the MU College of Education and Human Development, and others to analyze survey data of 2,300 teachers from Missouri and Oklahoma who were asked to rate how stressed they were at work, if they found ways to cope with work stress and how satisfied they were with their jobs.

Woods said while the findings were not particularly surprising, the study highlights how the ability -- or inability -- to cope with work stress can be a significant factor contributing to teacher burnout, which ultimately leads many teachers to leave the profession.

"In my 20 years as an educator, I've seen many great people leave the profession unfortunately, and this research confirms that we need to start devoting more time and resources into helping teachers identify and adopt healthy coping mechanisms," said Woods, who is now principal at Beulah Ralph Elementary School in Columbia, Missouri. "Finding ways to mitigate teacher stress and investing in ways to help them cope with stress in positive manners will pay us back in not having to constantly hire and train new teachers all the time. In addition, retaining experienced teachers will likely benefit student achievement as well."

The researchers explained that positive, healthy coping mechanisms can be quick, easy and free. One healthy coping mechanism Woods suggests for stressed teachers is writing and delivering a short letter of gratitude to a colleague they enjoy working with. Herman, who authored a book titled, "Stress Management for Teachers: A Proactive Guide," said simple things like increasing positive interactions with students and peers, improving classroom management skills, and avoiding gossip at work can also help.

Herman added that while systematic issues, such as low teacher pay and overburdened teacher workloads remain critical topics to address, school principals, district superintendents and school administrators can all play in a role in supporting stressed teachers who may be struggling to cope.

"Communicating with teachers about their concerns, demonstrating empathy and checking in on their health and well-being shows that you care," Herman said. "Our overall goal is to create school environments that allow teachers to thrive and give them the tools they need to be successful."

"The relationship between teacher stress and job satisfaction as moderated by coping" was published in Psychology in the Schools. Funding for the study was provided by the U.S. Department of Education and the National Institute of Justice.

https://www.sciencedaily.com/releases/2023/04/230410111623.htm

High blood pressure in your 30s is associated with worse brain health in your 70s

April 7, 2023

Science Daily/University of California - Davis Health

Having high blood pressure in your 30s is associated with worse brain health around age 75, especially for men, according to a new UC Davis study.

The research, published this week in JAMA Network Open, compared magnetic resonance imaging (MRI) brain scans of older adults who had high blood pressure between the ages of 30 to 40 with older adults who had normal blood pressure.

The researchers found that the high blood pressure group had significantly lower regional brain volumes and worse white matter integrity. Both factors are associated with dementia.

The research also showed that the negative brain changes in some regions -- such as decreased grey matter volume and frontal cortex volume -- were stronger in men. They note the differences may be related to the protective benefits of estrogen before menopause.

"Treatment for dementia is extremely limited, so identifying modifiable risk and protective factors over the life course is key to reducing disease burden," said first author Kristen M. George, an assistant professor in the Department of Public Health Sciences.

"High blood pressure is an incredibly common and treatable risk factor associated with dementia. This study indicates hypertension status in early adulthood is important for brain health decades later," George said.

High blood pressure prevalent in U.S.

High blood pressure, also known as hypertension, is blood pressure that is higher than normal. A normal blood pressure level is less than 130/80 mmHg. The Centers for Disease Control and Prevention estimates that 47% of adults in the United States have hypertension.

The rate of high blood pressure varies by sex and race. About 50% of men have high blood pressure compared to 44% of women. The rate of hypertension is about 56% in Black adults, 48% in white adults, 46% in Asian adults and 39% in Hispanic adults. African Americans ages 35 to 64 years are 50% more likely to have high blood pressure than whites.

Data from healthy aging studies

The researchers looked at data from 427 participants from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) study and the Study of Healthy Aging in African Americans (STAR). This provided them with health data from 1964 to 1985 for a diverse cohort of older Asian, Black, Latino and white adults.

They obtained two blood pressure readings from when the participants were between the ages of 30 to 40. This allowed them to determine if they had been hypertensive, transitioning to hypertensive or had normal blood pressure in young adulthood.

MRI scans of the participants conducted between 2017 and 2022 allowed them to look for late-life neuroimaging biomarkers of neurodegeneration and white matter integrity.

A significant reduction in cerebral gray matter volume is seen in both men and women with hypertension but is stronger in men.

Brain scans reveal differences

Compared to participants with normal blood pressure, the brain scans of those transitioning to high blood pressure or with high blood pressure showed lower cerebral gray matter volume, frontal cortex volume and fractional anisotropy (a measure of brain connectivity). The scores for men with high blood pressure were lower than those for women.

The study joins a growing body of evidence that cardiovascular risk factors in young adulthood are detrimental to late-life brain health.

The researchers note that due to the sample size, they could not examine racial and ethnic differences and recommended interpreting results regarding sex differences with caution. They also note that the MRI data was only available from one time-point late in life. This can only determine physical properties like volumetric differences, not specific evidence of neurodegeneration over time.

"This study truly demonstrates the importance of early life risk factors, and that to age well, you need to take care of yourself throughout life -- heart health is brain health," said Rachel Whitmer, senior author of the study. Whitmer is a professor in the departments of Public Health Sciences and Neurology and chief of the Division of Epidemiology. She's also the associate director of the UC Davis Alzheimer's Disease Center.

"We are excited to be able to continue following these participants and to uncover more about what one can do in early life to set yourself up for healthy brain aging in late life," Whitmer said.

https://www.sciencedaily.com/releases/2023/04/230407110728.htm

Air pollution may increase risk for dementia

April 5, 2023

Science Daily/Harvard T.H. Chan School of Public Health

Exposure to fine particulate air pollutants (PM2.5) may increase the risk of developing dementia, according to a new meta-analysis from Harvard T.H. Chan School of Public Health.

"This is a big step in providing actionable data for regulatory agencies and clinicians in terms of making sense of the state of the literature on this hugely important health topic. The results can be used by organizations like the Environmental Protection Agency, which is currently considering strengthening limits on PM2.5 exposure," said lead author Marc Weisskopf, Cecil K. and Philip Drinker Professor of Environmental Epidemiology and Physiology. "Our findings support the public health importance of such a measure."

The study is the first systematic review and meta-analysis to use the new Risk of Bias In Non-Randomized Studies of Exposure (ROBINS-E) tool, which addresses bias in environmental studies in greater detail than other assessment approaches. It also is the first to include newer studies that used "active case ascertainment," a method that involved screening of entire study populations followed by in-person evaluation for dementia among individuals who did not have dementia at baseline.

The study will be published online April 5, 2023, in The BMJ.

More than 57 million people worldwide are currently living with dementia, and estimates suggest that number will increase to 153 million by 2050. Up to 40% of these cases are thought to be linked to potentially modifiable risk factors, such as exposure to air pollutants.

Weisskopf and his co-authors, Elissa Wilker, researcher in the Harvard Chan-NIEHS Center for Environmental Health, and Marwa Osman, a doctoral student in the Biological Science in Public Health program, scanned more than 2,000 studies and identified 51 that evaluated an association between ambient air pollution and clinical dementia, all published within the last 10 years. Those studies were assessed for bias using ROBINS-E, and 16 of them met the criteria for the meta-analysis. The majority of the research was about PM2.5, with nitrogen dioxide and nitrogen oxide being the next most common pollutants studied. Of the studies used in the meta-analysis, nine used active case ascertainment.

The researchers found consistent evidence of an association between PM2.5 and dementia, even when annual exposure was less than the current EPA annual standard of 12 micrograms per cubic meter of air (μg/m3). In particular, among the studies using active case ascertainment, the researchers found a 17% increase in risk for developing dementia for every 2 μg/m3 increase in average annual exposure to PM2.5. They also found evidence suggesting associations between dementia and nitrogen oxide (5% increase in risk for every 10 μg/m3 increase in annual exposure) and nitrogen dioxide (2% increase in risk for every 10 μg/m3 increase in annual exposure), though the data was more limited.

The researchers noted that air pollution's estimated association with risk of dementia is smaller than that of other risk factors, such as education and smoking. However, because of the number of people exposed to air pollution, the population-level health implications could be substantial.

"Given the massive numbers of dementia cases, identifying actionable modifiable risk factors to reduce the burden of disease would have tremendous personal and societal impact," Weisskopf said. "Exposure to PM2.5 and other air pollutants is modifiable to some extent by personal behaviors -- but more importantly through regulation."

https://www.sciencedaily.com/releases/2023/04/230405214852.htm

Jet lag's harmful health impacts found to be caused by biological clock misalignment

Effects of circadian disruption on adult neurogenesis

April 3, 2023

Science Daily/University of Massachusetts Amherst

New research at the University of Massachusetts Amherst zeroes in on the root cause of adverse health effects from disruption of the body's circadian rhythms, which typically occurs from jet lag and rotating work shifts.

The research, published in the journal eNeuro, also shows that the circadian clock gene Cryptochrome 1 (Cry 1) regulates adult neurogenesis -- the ongoing formation of neurons in the brain's hippocampus. Adult neurogenesis supports learning and memory, and its disruption has been linked to dementia and mental illness.

"Circadian disruption impacts a lot of things," says lead author Michael Seifu Bahiru, a Ph.D. candidate in the lab of Eric Bittman, Professor Emeritus of Biology. "There are links to cancer, diabetes and hypertension, as well as adverse impacts on neurogenesis."

Cell birth and survival in the adult hippocampus are regulated by a circadian clock, so its disruption may throw off the process of neurogenesis. In the U.S. alone, some 30 million people experience phase shifts in their circadian rhythms as they work rotating schedules.

Until recently, the researchers have faced a sort of chicken-or-egg question. "We always wondered what actually is the root cause of the ailments from circadian disruption?" Bahiru says. "Does the problem come from the act of shifting or the shift itself?"

Bittman explains further, "It's possible it's just changing the light cycle that affects neurogenesis, that jerking your clock around is bad for you, as opposed to the jet lag, which is the time delay that it takes for all circadian-dependent systems in your body to adjust to this change in daylight."

Their findings support the hypothesis that it's this internal misalignment, this state of desynchrony between and within organs that occurs during jet lag, that is responsible for the adverse impact on neurogenesis -- and, they suspect, other adverse health effects from circadian disruption.

To test their hypothesis, they studied cell birth and differentiation in Syrian hamsters with a recessive mutation in the Cry 1 gene that speeds up the clock in constant conditions and dramatically accelerates its ability to shift in response to light. Bittman named the mutation, discovered in previous research, duper. The research team also tested a control group of hamsters without the duper mutation. Both underwent the same sequence of changes in the light cycle.

They simulated jet lag in the form of eight-hour advances and delays at eight 16-day intervals. A cell birth marker was given in the middle of the experiment. Results showed that jet lag has little effect on cell birth but steers the fate of newborn cells away from becoming neurons. Dupers are immune to this effect of phase shifts. "As predicted, the duper animals re-entrained quicker, but also were resistant to the negative effects of the jet lag protocol, whereas the control -- the wild type hamsters -- had reduced neurogenesis," Bahiju says.

"The findings indicate that circadian misalignment is critical in jet lag," the paper concludes.

The ultimate goal of Bittman's lab is to advance understanding of the pathways involved in human biological clocks, which could lead to the prevention of or treatment for the effects of jet lag, shift work and circadian rhythm disorders. This latest research is a next step toward that goal.

Now the team will turn to "a big unanswered question," Bittman says -- "whether it's the operation of circadian clocks in the hippocampus that is being directly regulated by shifts of the light:dark cycle, or whether neurogenesis is controlled by biological clocks running in cells elsewhere in the body."

Another possibility, which Bittman thinks is more likely, is that the master pacemaker in the suprachiasmatic nucleus of the hypothalamus in the brain detects the light shift and then relays it to the stem cell population that has to divide and differentiate in the hippocampus.

https://www.sciencedaily.com/releases/2023/04/230403100325.htm

Harsh discipline increases risk of children developing lasting mental health problems

March 30, 2023

Science Daily/University of Cambridge

Parents who frequently exercise harsh discipline with young children are putting them at significantly greater risk of developing lasting mental health problems, new evidence shows.

In a study of over 7,500 Irish children, researchers at the University of Cambridge and University College Dublin found that children exposed to 'hostile' parenting at age three were 1.5 times likelier than their peers to have mental health symptoms which qualified as 'high risk' by age nine.

Hostile parenting involves frequent harsh treatment and discipline and can be physical or psychological. It may, for example, involve shouting at children regularly, routine physical punishment, isolating children when they misbehave, damaging their self-esteem, or punishing children unpredictably depending on the parent's mood.

The researchers charted children's mental health symptoms at ages three, five and nine. They studied both internalising mental health symptoms (such as anxiety and social withdrawal) and externalising symptoms (such as impulsive and aggressive behaviour, and hyperactivity).

About 10% of the children were found to be in a high-risk band for poor mental health. Children who experienced hostile parenting were much more likely to fall into this group.

Importantly, the study makes clear that parenting style does not completely determine mental health outcomes. Children's mental health is shaped by multiple risk factors, including gender, physical health, and socio-economic status.

The researchers do argue, however, that mental health professionals, teachers and other practitioners should be alert to the potential influence of parenting on a child who shows signs of having poor mental health. They add that extra support for the parents of children who are already considered to be at risk could help to prevent these problems from developing.

The study was undertaken by Ioannis Katsantonis, a doctoral researcher at the Faculty of Education, University of Cambridge, and Jennifer Symonds, Associate Professor in the UCD School of Education. It is reported in the journal, Epidemiology and Psychiatric Sciences.

"The fact that one in 10 children were in the high-risk category for mental health problems is a concern and we ought to be aware of the part parenting may play in that," Katsantonis said. "We are not for a moment suggesting that parents should not set firm boundaries for their children's behaviour, but it is difficult to justify frequent harsh discipline, given the implications for mental health."

Symonds said: "Our findings underline the importance of doing everything possible to ensure that parents are supported to give their children a warm and positive upbringing, especially if wider circumstances put those children at risk of poor mental health outcomes. Avoiding a hostile emotional climate at home won't necessarily prevent poor mental health outcomes from occurring, but it will probably help."

While parenting is widely acknowledged as a factor influencing children's mental health, most studies have not investigated how it affects their mental health over time, or how it relates to both internalising and externalising symptoms together.

The researchers used data from 7,507 participants in the 'Growing up in Ireland' longitudinal study of children and young people. Mental health data was captured using a standard assessment tool called the Strengths and Difficulties Questionnaire. Each child was given a composite score out of 10 for their externalising and internalising symptoms at ages three, five and nine.

A second standard assessment was used to measure the parenting style children experienced at age three. Parents were profiled based on how far they inclined towards each of three styles: warm parenting (supportive and attentive to their child's needs); consistent (setting clear expectations and rules); and hostile.

The researchers found that, based on the trajectories along which their mental health symptoms developed between ages three and nine, the children fell into three broad categories. Most (83.5%) were low risk, with low internalising and externalising symptom scores at age three which then fell or remained stable. A few (6.43%) were mild risk, with high initial scores that decreased over time, but remained higher than the first group. The remaining 10.07% were high risk, with high initial scores that increased by age nine.

Hostile parenting raised a child's chances of being in the high-risk category by 1.5 times, and the mild-risk category by 1.6 times, by age nine. Consistent parenting was found to have a limited protective role, but only against children falling into the 'mild-risk' category. To the researchers' surprise, however, warm parenting did not increase the likelihood of children being in the low-risk group, possibly due to the influence of other factors on mental health outcomes.

Previous research has highlighted the importance of these other factors, many of which the new study also confirmed. Girls, for example, were more likely to be in the high-risk category than boys; children with single parents were 1.4 times more likely to be high-risk, and those from wealthier backgrounds were less likely to exhibit worrying mental health symptoms by middle childhood.

Katsantonis said that the findings underscored the importance of early intervention and support for children who are at risk of mental health difficulties, and that this should involve tailored support, guidance and training for new parents.

"Appropriate support could be something as simple as giving new parents clear, up-to-date information about how best to manage young children's behaviour in different situations," he said. "There is clearly a danger that parenting style can exacerbate mental health risks. This is something we can easily take steps to address."

https://www.sciencedaily.com/releases/2023/03/230330210742.htm

Positive experiences in close relationships are associated with better physical health

March 27, 2023

Science Daily/Society for Personality and Social Psychology

Social relationships influence physical health, but questions remain about the nature of this connection. New research in Social Psychological and Personality Science suggests that the way you feel about your close relationships may be affecting the way your body functions.

Previous smaller-scale studies have examined the connection between relationship conflict or satisfaction with stress levels and blood pressure. The new research examines the effects of positive and negative relationship experiences on the body, as well as how these experiences and health outcomes change from day to day.

"Both positive and negative experiences in our relationships contribute to our daily stress, coping, and physiology, like blood pressure and heart rate reactivity," says lead author Brian Don of the University of Auckland. "Additionally, it's not just how we feel about our relationships overall that matters; the up's and downs are important too."

Over the course of three weeks, 4,005 participants completed daily check-ins via their smartphone or smartwatch, providing assessments of their blood pressure, heart rate, stress, coping. Every three days, participants also shared reflections on their closest relationship, detailing their positive and negative experiences.

Researchers found that, on average, people with more positive experiences and fewer negative experiences reported lower stress, better coping, and lower systolic blood pressure reactivity leading to better physiological functioning in daily life. By contrast, variability -- or daily ups and downs -- in negative relationship experiences like conflict were especially predictive of outcomes like stress, coping, and overall systolic blood pressure.

Dr. Don notes that one broader implication of this study is that it is important to consider how outside stressors -- such as the COVID-19 pandemic -- can affect people's relationships, and therefore their physical health.

"Since the COVID-19 pandemic, relationships have been facing unprecedented challenges, turbulence, and change," says Dr. Don. "What this means is that the COVID pandemic may have health implications not just because of the virus itself, but also indirectly as a result of the impact it has on people's relationships. That is, because the COVID-19 pandemic has created considerable strain, turbulence, and variability in people's relationships, it may indirectly alter stress, coping, and physiology in daily life, all of which have important implications for physical well-being."

Researchers cautioned against interpreting the study as proof that relationship experiences have physiological effects. Instead, the findings contain associations from daily life that illustrate how relationships and physical health are often intertwined. Causal conclusions, Dr. Don says, must be reserved for experimental studies.

In the future, Dr. Don suggests that researchers look beyond outcomes like blood pressure and heart rate reactivity to gain a fuller understanding of how relationships may affect health.

"It would be useful to examine other physiological states, such as neuroendocrine or sympathetic nervous system responses as outcomes of daily positive and negative relationship experiences, which may reveal different patterns of associations."

https://www.sciencedaily.com/releases/2023/03/230327114815.htm

A higher dose of magnesium each day keeps dementia at bay

March 23, 2023

Science Daily/Australian National University

More magnesium in our daily diet leads to better brain health as we age, according to scientists from the Neuroimaging and Brain Lab at The Australian National University (ANU).

The researchers say increased intake of magnesium-rich foods such as spinach and nuts could also help reduce the risk of dementia, which is the second leading cause of death in Australia and the seventh biggest killer globally.

The study of more than 6,000 cognitively healthy participants in the United Kingdom aged 40 to 73 found people who consume more than 550 milligrams of magnesium each day have a brain age that is approximately one year younger by the time they reach 55 compared with someone with a normal magnesium intake of about 350 milligrams a day.

"Our study shows a 41 per cent increase in magnesium intake could lead to less age-related brain shrinkage, which is associated with better cognitive function and lower risk or delayed onset of dementia in later life," lead author and PhD researcher Khawlah Alateeq, from the ANU National Centre for Epidemiology and Population Health, said.

"This research highlights the potential benefits of a diet high in magnesium and the role it plays in promoting good brain health."

It's believed the number of people worldwide who will be diagnosed with dementia is expected to more than double from 57.4 million in 2019 to 152.8 million in 2050, placing a greater strain on health and social services and the global economy.

"Since there is no cure for dementia and the development of pharmacological treatments have been unsuccessful for the past 30 years, it's been suggested that greater attention should be directed towards prevention," study co-author Dr Erin Walsh, who is also from ANU, said.

"Our research could inform the development of public health interventions aimed at promoting healthy brain ageing through dietary strategies."

The researchers say a higher intake of magnesium in our diets from a younger age may safeguard against neurodegenerative diseases and cognitive decline by the time we reach our 40s.

"The study shows higher dietary magnesium intake may contribute to neuroprotection earlier in the ageing process and preventative effects may begin in our 40s or even earlier," Ms Alateeq said.

"This means people of all ages should be paying closer attention to their magnesium intake.

"We also found the neuroprotective effects of more dietary magnesium appears to benefit women more than men and more so in post-menopausal than pre-menopausal women, although this may be due to the anti-inflammatory effect of magnesium."

Participants completed an online questionnaire five times over a period of 16 months. The responses provided were used to calculate the daily magnesium intake of participants and were based on 200 different foods with varying portion sizes. The ANU team focused on magnesium-rich foods such as leafy green vegetables, legumes, nuts, seeds and wholegrains to provide an average estimation of magnesium intake from the participants' diets.

https://www.sciencedaily.com/releases/2023/03/230323103415.htm

Road noise makes your blood pressure rise -- literally

Study shows the sound of traffic is associated with increased risk of hypertension, calls for public health measures to reduce noise exposure

March 22, 2023

Science Daily/American College of Cardiology

If you live near a busy road you might feel like the constant sound of roaring engines, honking horns and wailing sirens makes your blood pressure rise. Now a new study published today in JACC: Advances confirms it can do exactly that.

Previous studies have shown a connection between noisy road traffic and increased risk of hypertension. However, strong evidence was lacking, and it was unclear whether noise or air pollution played a bigger role. The new research shows that it is exposure to road traffic noise itself that can elevate hypertension risk.

"We were a little surprised that the association between road traffic noise and hypertension was robust even after adjustment for air pollution," said Jing Huang, assistant professor in the Department of Occupational and Environmental Health Sciences in the School of Public Health at Peking University in Beijing, China, and lead author of the study.

Previous studies of the issue were cross-sectional, meaning they showed that traffic noise and hypertension were linked, but failed to show a causal relationship. For the new paper, researchers conducted a prospective study using UK Biobank data that looked at health outcomes over time.

Researchers analyzed data from more than 240,000 people (aged 40 to 69 years) who started out without hypertension. They estimated road traffic noise based on residential address and the Common Noise Assessment Method, a European modeling tool.

Using follow-up data over a median 8.1 years, they looked at how many people developed hypertension. Not only did they find that people living near road traffic noise were more likely to develop hypertension, they also found that risk increased in tandem with the noise "dose."

These associations held true even when researchers adjusted for exposure to fine particles and nitrogen dioxide. However, people who had high exposure to both traffic noise and air pollution had the highest hypertension risk, showing that air pollution plays a role as well.

"Road traffic noise and traffic-related air pollution coexist around us," Huang said. "It is essential to explore the independent effects of road traffic noise, rather than the total environment."

The findings can support public health measures because they confirm that exposure to road traffic noise is harmful to our blood pressure, she said. Policymaking may alleviate the adverse impacts of road traffic noise as a societal effort, such as setting stricter noise guideline and enforcement, improving road conditions and urban design, and investing advanced technology on quieter vehicles.

"To date, this is the first large-sized prospective study directly addressing the effect of road traffic noise on the incidence of newly-diagnosed hypertension," said Jiandong Zhang, cardiovascular disease fellow in the division of cardiology at the University of North Carolina at Chapel Hill, and author of the accompanying editorial comment. "The data demonstrated in this article provides a higher quality of evidence to justify the potential to modify road traffic noise and air pollution from both individual and societal levels in improving cardiovascular health."

As a follow-up, Huang said field studies are underway to better understand the pathophysiological mechanisms through which road noise affects hypertension.

https://www.sciencedaily.com/releases/2023/03/230322190921.htm

Sweets change our brain

Why we can't keep our hands off chocolate bars and co.

March 22, 2023

Science Daily/Max-Planck-Gesellschaft

Chocolate bars, crisps and fries -- why can't we just ignore them in the supermarket? Researchers at the Max Planck Institute for Metabolism Research in Cologne, in collaboration with Yale University, have now shown that foods with a high fat and sugar content change our brain: If we regularly eat even small amounts of them, the brain learns to consume precisely these foods in the future.

Why do we like unhealthy and fattening foods so much? How does this preference develop in the brain? "Our tendency to eat high-fat and high-sugar foods, the so-called Western diet, could be innate or develop as a result of being overweight. But we think that the brain learns this preference," explains Sharmili Edwin Thanarajah, lead author of the study.

To test this hypothesis, the researchers gave one group of volunteers a small pudding containing a lot of fat and sugar per day for eight weeks in addition to their normal diet. The other group received a pudding that contained the same number of calories but less fat. The volunteer's brain activity was measured before and during the eight weeks.

Our brain unconsciously learns to prefer high-fat snacks

The brain's response to high-fat and high-sugar foods was greatly increased in the group that ate the high-sugar and high-fat pudding after eight weeks. This particularly activated the dopaminergic system, the region in the brain responsible for motivation and reward. "Our measurements of brain activity showed that the brain rewires itself through the consumption of chips and co. It subconsciously learns to prefer rewarding food. Through these changes in the brain, we will unconsciously always prefer the foods that contain a lot of fat and sugar," explains Marc Tittgemeyer, who led the study.

During the study period, the test persons did not gain more weight than the test persons in the control group and their blood values, such as blood sugar or cholesterol, did not change either. However, the researchers assume that the preference for sugary foods will continue after the end of the study. "New connections are made in the brain, and they don't dissolve so quickly. After all, the whole point of learning is that once you learn something, you don't forget it so quickly," explains Marc Tittgemeyer.

https://www.sciencedaily.com/releases/2023/03/230322140934.htm

Immune system cells in the gut linked to stress-induced depression

March 20, 2023

Science Daily/Johns Hopkins Medicine

In experiments with mice and humans, a team led by Johns Hopkins Medicine researchers says it has identified a particular intestinal immune cell that impacts the gut microbiome, which in turn may affect brain functions linked to stress-induced disorders such as depression. Targeting changes mediated by these immune cells in the gut, with drugs or other therapies, could potentially bring about new ways to treat depression.

The findings of the study were published March 20, 2023 in the journal Nature Immunology.

"The results of our study highlight the previously unrecognized role of intestinal gamma delta T cells (γδ T cells) in modifying psychological stress responses, and the importance of a protein receptor known as dectin-1, found on the surface of immune cells, as a potential therapeutic target for the treatment of stress-induced behaviors," says Atsushi Kamiya, M.D., Ph.D., professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study's senior author.

Dectin-1 binds to certain antigens, or proteins, to signal immune cells to activate in specific ways. This receptor, the researchers say, may be involved in the microbiome alteration and immune-inflammatory responses in the colon of mice, which suggests that it may be involved in stress responses via γδ T cells in the intestinal immune system.

On the basis of previous studies suggesting that immune inflammatory responses in the gut are related to depression, Kamiya and his team designed experiments to focus on understanding stress-induced behaviors produced by an imbalance in the gut microbiota -- types of microorganisms found in a specific environment, such as bacteria, fungi and viruses.

To this end, the team examined the effects of chronic social defeat stress (CSDS) on the gut microbiota in mice. CSDS is a standard rodent test to study stress-induced disorders such as depression. In a series of experiments, the researchers simulated potential stress inducing environments that could mimic similar responses in human environments. After each exposure, the mice were assessed and classified as stress-resilient (stress did not diminish social interactions) or stress-susceptible (stress increased social avoidance).

Fecal samples were then collected and put through genetic analysis to identify the diversity of bacteria in the gut microbiota of the mice. The analysis showed that the intestinal organisms were less diverse in stress-susceptible mice than in stress-resilient mice. It specifically revealed that there were less Lactobacillus johnsonii (L. johnsonii) -- a type of probiotic, or "good" bacteria -- in stress-susceptible mice compared to stress-resilient mice.

"We found that stress increased the γδ T cells, which in turn increased social avoidance," says Xiaolei Zhu, M.D., Ph.D., assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study's lead author. "However, when the stressed mice were given L. johnsonii, social avoidance decreased and the γδ T cells went to normal levels, suggesting that CSDS-induced social avoidance behavior may be the result of lower levels of the bacteria and γδ T cell changes."

Looking for potential natural approaches for prevention of depression rooted somehow in the gut, the researchers explored how changes in dectin-1 on CSDS-induced elevation of γδ T cells responded to pachyman. A compound extracted from wild mushrooms, pachyman is used as a natural anti-inflammatory agent and for treating depression in Eastern medicine. For this experiment, mice were fed a dose of pachyman, which was shown in previous research to affect immune function. Data from flow cytometry analysis -- a technology used to measure the physical and chemical characteristics of a population of cells -- provided evidence that dectin-1 binds to pachyman, inhibiting CSDS-induced γδ17 T cell activity and easing social avoidance behavior.

To gain insight into how the alterations in the gut microbiota could impact the human brain, the researchers investigated the makeup of gut organisms in people with major depressive disorder (MDD) compared to people without MDD. From June 2017 to September 2020, 66 participants, ages 20 or older, were recruited at Showa University Karasuyama Hospital, Keio University Hospital and Komagino Hospital in Tokyo, Japan. Of the study participants, 32 had MDD (17 women and 15 men). The other 34 participants (18 women and 16 men) who did not have MDD formed the control group.

Stool samples were collected from all study participants, who had comprehensive evaluations including psychiatric history and standard screening assessments for depression and anxiety. In these assessments, higher scores indicate greater depressive symptoms. Genetic analysis of the stool samples showed no difference in the diversity of intestinal bacteria between the subjects with MDD and the control group. However, the relative abundance of Lactobacillus was inversely related to higher depression and anxiety scores in the MDD group, meaning that the more Lactobacillusfound in the gut, the lower the potential for depression and anxiety, the researchers say.

"Despite the differences of intestinal microbiota between mice and humans, the results of our study indicate that the amount of Lactobacillus in the gut may potentially influence stress responses and the onset of depression and anxiety," says Kamiya.

The investigators say more research is needed to further understand how γδ T cells in the intestinal immune system may impact the neurological functions in the brain and the role of dectin-1 in other cell types along the gut-brain connection under stress conditions.

"These early-stage findings show that, in addition to probiotic supplements, targeting drugs to such types of receptors in the gut immune system may potentially yield novel approaches to prevent and treat stress-induced psychiatric symptoms such as depression," says Kamiya.

https://www.sciencedaily.com/releases/2023/03/230320143713.htm

Attending live sport improves wellbeing

Research is first to demonstrate major benefits across large adult population

March 17, 2023

Science Daily/Anglia Ruskin University

New scientific research has found that attending live sporting events improves levels of wellbeing and reduces feelings of loneliness.

Published in the journal Frontiers in Public Health, the research is the first large-scale study to examine the benefits of attending any type of live sporting event.

The study, carried out by academics from Anglia Ruskin University's School of Psychology and Sport Science, used data from 7,209 adults, aged 16-85, living in England who participated in the Taking Part Survey, which was commissioned by the British Government's Department for Digital, Culture, Media and Sport.

It found that attending live sporting events results in higher scores of two major measurements of subjective wellbeing -- life satisfaction and a sense of "life being worthwhile" -- as well as lower levels of loneliness.

These results are significant as previous studies have shown that higher life satisfaction scores are associated with fewer life-limiting conditions and better physical health, successful ageing, and lower mortality rates.

The new study also found that attending live sporting events leads to an increase in people's sense that "life is worthwhile," and the size of this increase is comparable to that of gaining employment.

Many initiatives currently promote the benefits of physical participation in sport, but the researchers believe that watching live sporting events can also offer an accessible and effective public health tool for improving wellbeing and reducing loneliness.

Lead author Dr Helen Keyes, Head of the School of Psychology and Sport Science at Anglia Ruskin University (ARU), said: "Previous research has focused on specific sports or small population samples, such as college students in the United States. Ours is the first study to look at the benefits of attending any sporting event across an adult population, and therefore our findings could be useful for shaping future public health strategies, such as offering reduced ticket prices for certain groups.

"The live events covered by the survey ranged from free amateur events, such as watching village sports teams, right through to Premier League football matches. Therefore, further research needs to be carried out to see if these benefits are more pronounced for elite level sport, or are more closely linked to supporting a specific team.

"However, we do know that watching live sport of all types provides many opportunities for social interaction and this helps to forge group identity and belonging, which in turn mitigates loneliness and boosts levels of wellbeing."

https://www.sciencedaily.com/releases/2023/03/230317145019.htm

Employees tend to avoid taking breaks despite high levels of stress

March 16, 2023

Science Daily/University of Waterloo

Heavy workloads make employees feel a greater need for a break, but new research finds they may actually discourage employees from taking breaks at work despite causing high levels of stress, fatigue, and poor performance.

Researchers from the University of Waterloo found employees often kept working despite wanting to pause. One potential reason is employees may have felt pressure to continue working to get everything done on time.

"Our research provides a comprehensive account of the processes involved in the decision to take a break and provides insights into how employees and managers can make more effective use of breaks at work, potentially improving both well-being and performance," said James Beck, professor of industrial and organizational psychology at Waterloo.

To conduct the study, researchers asked 107 employees about their reasons for taking a break and not taking one. They then surveyed another 287 employees twice daily over five days about their sleep quality, fatigue, performance concerns, workload, and the number of breaks they take each day.

The researchers also found that although previous research has shown that breaks can benefit employee well-being and performance, they may resist taking breaks if they feel supervisors discourage breaks in their workplace. Although there may be a misconception that breaks are unproductive, Phan notes that many employees take breaks because they are committed to staying focused and maintaining high levels of performance.

"We recognize that it may not always be possible for employees to take more breaks, but if employers can promote employee well-being by addressing the conditions that can make work unpleasant, they may be able to reduce the number of breaks needed," said Dr. Vincent Phan, first author of the study, which he led as part of his doctoral thesis in industrial and organizational psychology at Waterloo.

The researchers hope that their findings will aid in promoting employee well-being and that future research will explore broader structural and contextual factors that influence break-taking.

https://www.sciencedaily.com/releases/2023/03/230316114118.htm

Short night-time sleep linked with nearly doubled risk of clogged leg arteries

March 16, 2023

Science Daily/European Society of Cardiology

Sleeping less than five hours a night is associated with a 74% raised likelihood of developing peripheral artery disease (PAD) compared with seven to eight hours. That's the finding of a study published today in European Heart Journal -- Open, a journal of the ESC.1

"Our study suggests that sleeping for seven to eight hours a night is a good habit for lowering the risk of PAD," said study author Dr. Shuai Yuan of the Karolinska Institute, Stockholm, Sweden.

More than 200 million people globally have peripheral artery disease (PAD),2 where arteries in the legs are clogged, restricting blood flow and increasing the risk of stroke and heart attack. Dr. Yuan said: "Insufficient night-time sleep and daytime napping have previously been associated with a raised risk of coronary artery disease which, like PAD, is caused by clogged arteries. In addition, sleeping problems are among the top ranked complaints in PAD patients. There are limited data on the impact of sleep habits on PAD and vice versa, and our study aimed to fill that gap."

The study included more than 650,000 participants and was conducted in two parts.3 First, the researchers analysed the associations of sleep duration and daytime napping with the risk of PAD. In the second part, the investigators used genetic data to perform naturally randomised controlled trials -- called Mendelian randomisation -- to examine causality of the associations.

Dr. Yuan said: "Observational analyses are limited by reverse causality -- meaning that if an association between sleep habits and PAD is found, we cannot be certain if sleep habits caused PAD or having PAD caused the sleep habits. Mendelian randomisation is a robust method for evaluating causality and provides more certainty about the results."

Taken together, the strongest evidence was for short sleep, where the relationship with PAD went both ways. In an observational analysis of 53,416 adults, sleeping less than five hours a night was associated with a nearly doubled risk of PAD compared with seven to eight hours (hazard ratio [HR] 1.74; 95% confidence interval [CI] 1.31-2.31). This finding was supported by further analyses in 156,582 and 452,028 individuals. In the causal studies, short sleep was associated with an increased risk of PAD and, in addition, PAD was associated with an increased likelihood of short sleep. Dr. Yuan said: "The results indicate that brief night-time sleep can raise the chance of developing PAD, and that having PAD increases the risk of getting insufficient sleep."

Regarding long sleep, in an observational analysis of 53,416 adults, sleeping eight hours or more per night was linked with a 24% higher risk of PAD compared with seven to eight hours (HR 1.24; 95% CI 1.08-1.43). This finding was supported by analyses in two larger populations of 156,582 and 452,028 individuals. However, no causal relationships were found between long sleep and PAD. Similar results were reported for napping, where daytime nappers had a 32% higher risk of PAD compared to those who did not nap (HR 1.32; 95% CI 1.18-1.49) but no causal links were found. "More studies are needed on the relationships between lengthy night-time sleep, daytime napping and PAD," said Dr. Yuan. "Although we found associations in the observational studies, we could not confirm causality."

He concluded: "More research is needed on how to interrupt the bidirectional link between short sleep and PAD. Lifestyle changes that help people get more sleep, such as being physically active, may lower the risk of developing PAD. For patients with PAD, optimising pain management could enable them to have a good night's sleep."

https://www.sciencedaily.com/releases/2023/03/230316114126.htm

Sleep quality is significantly associated with quality of life indicators over time

March 15, 2023

Science Daily/PLOS

Sleep quality is much more significantly linked to quality of life over time than sleep duration or "social jetlag," according to a study published March 15, 2023 in the open-access journal PLOS ONE by Michaela Kudrnáčová from Faculty of Social Sciences, Charles University, and Aleš Kudrnáč from the Institute of Sociology, Czech Academy of Sciences.

Though many studies link sleep quality to one's overall quality of life, there's little research on the relative impact of changes in sleep duration, quality, and timing on an individual's quality of life over the long term.

To investigate this further, the authors used data from the annual Czech Household Panel Survey 2018-2020. Different adults in the same household each completed the survey, and later iterations of the survey approached the same individuals to participate again: 5,132 Czech adults responded to the survey in 2018, 2,046 in 2019, and 2,161 in 2020. The authors analyzed responses to questions covering life satisfaction, wellbeing, happiness, subjective health, and work stress alongside responses on self-reported sleep duration, sleep quality, and sleep timing or "social jetlag" (when someone's socially directed sleep rhythms and innate biological sleep rhythms are mismatched). Their model analyzed results within the same person's responses across the years of the survey, and also compared results between respondents. This is also the first study which has tested the longitudinal effect of social jetlag on quality of life.

At the individual level, reported sleep quality was significantly correlated with all five quality of life measures except work stress. Sleep quality was also significantly positively correlated with all quality of life measures when comparing between people. Comparing between respondents, sleep duration was significantly correlated with subjective health and happiness, and social jetlag was significantly correlated with life satisfaction and work stress. However, neither sleep duration nor social jetlag showed any significant correlations over time at the individual level.

The authors note that causes of social jetlag (e.g., a new job with different hours) change infrequently, and the current study's three-year time period studied may not have been long enough to capture any potential effect. Furthermore, the final wave of data captured the experience of the pandemic in the spring of 2020, albeit during periods of eased restrictions. This study, therefore, might not be representative of the behavior under normal circumstances. However, these results suggest that sleep duration or timing may not be as important to quality of life as high-quality sleep.

The authors add: "Better sleep means a better quality of life. While when we sleep and how long we sleep is important, individuals who have better quality sleep also have a better quality of life, regardless of the time and length of sleep. In addition, by following 4,253 people for three years, we found that those whose sleep improved also had an improved quality of life."

https://www.sciencedaily.com/releases/2023/03/230315143829.htm

Getting a good night's sleep could boost your response to vaccination

March 13, 2023

Science Daily/Cell Press

We all know how important sleep is for mental health, but a meta-analysis publishing in the journal Current Biology on March 13 found that getting good shut-eye also helps our immune systems respond to vaccination. The authors found that people who slept less than six hours per night produced significantly fewer antibodies than people who slept seven hours or more, and the deficit was equivalent to two months of antibody waning.

"Good sleep not only amplifies but may also extend the duration of protection of the vaccine," says senior author Eve Van Cauter, professor emeritus at the University of Chicago who, along with lead author Karine Spiegel at the French National Institute of Health and Medicine, published a landmark study on the effects of sleep on vaccination in 2002.

When the COVID-19 pandemic hit, and mass-vaccination became an international priority, Spiegel and Van Cauter set out to summarize our current knowledge about the effect of sleep duration on vaccine response.

To do this, they combed the literature and then combined and re-analyzed the results of seven studies that vaccinated for viral infections (influenza and hepatitis A and B). In their analysis, the team compared the antibody response for individuals who slept a "normal" amount (7-9 hours, as per the National Sleep Foundation's recommendation for healthy adults) with "short sleepers" who slept less than 6 hours per night. They compared the effect for men versus women and adults over the age of 65 years versus younger adults.

Overall, they found strong evidence that sleeping less than 6 hours per night reduces the immune response to vaccination. When they analyzed men and women separately, though, the result was only significant in men, and the effect of sleep duration on antibody production was much more variable in women. This difference is probably due to fluctuating sex hormone levels in women, the authors say.

"We know from immunology studies that sex hormones influence the immune system," says Spiegel. "In women, immunity is influenced by the state of the menstrual cycle, the use of contraceptives, and by menopause and post-menopausal status, but unfortunately, none of the studies that we summarized had any data about sex hormone levels."

The negative effect of insufficient sleep on antibody levels was also greater for adults aged 18-60 compared with people over the age of 65. This was not surprising because older adults tend to sleep less in general; going from seven hours of sleep per night to less than six hours is not as big of a change as going from eight hours to less than six per night.

Some of the studies measured sleep duration directly, either via motion-detecting wristwatches or in a sleep lab, while others relied on self-reported sleep duration. In both cases, short sleep duration was associated with lower levels of antibodies, but the effect was stronger for the studies that used objective measures of sleep, likely because people are notoriously bad at estimating the amount of sleep they have had.

Knowing that sleep duration impacts vaccination might give people some degree of control over their immunity, the authors say. "When you see the variability in protection provided by the COVID-19 vaccines -- people who have pre-existing conditions are less protected, men are less protected than women, and obese people are less protected than people who don't have obesity. Those are all factors that an individual person has no control over, but you can modify your sleep," says Van Cauter.

However, there's a lot more to be known about sleep and vaccination, the authors say. "We need to understand the sex differences, which days around the time of vaccination are most important, and exactly how much sleep is needed so that we can give guidance to people," says Spiegel. "We are going to be vaccinating millions and millions of people in the next few years, and this is an aspect that can help maximize protection."

https://www.sciencedaily.com/releases/2023/03/230313121003.htm

MIND and Mediterranean diets associated with fewer Alzheimer's plaques and tangles

March 8, 2023

Science Daily/American Academy of Neurology

People who eat diets rich in green leafy vegetables as well as other vegetables, fruits, whole grains, olive oil, beans, nuts and fish may have fewer amyloid plaques and tau tangles in their brain -- signs of Alzheimer's disease -- than people who do not consume such diets, according to a study published in the March 8, 2023, online issue of Neurology®, the medical journal of the American Academy of Neurology.

The study examined how closely people followed the MIND and Mediterranean diets. While similar, the Mediterranean diet recommends vegetables, fruit, and three or more servings of fish per week while the MIND diet prioritizes green leafy vegetables like spinach, kale and collard greens along with other vegetables. The MIND diet also prioritizes berries over other fruit and recommends one or more servings of fish per week. Both the MIND and Mediterranean diet recommend small amounts of wine.

While this study shows an association of regularly consuming these diets with fewer Alzheimer's disease plaques and tangles, it does not establish a cause and effect relationship.

"These results are exciting -- improvement in people's diets in just one area -- such as eating more than six servings of green leafy vegetables per week, or not eating fried foods -- was associated with fewer amyloid plaques in the brain similar to being about four years younger," said study author Puja Agarwal, PhD, of RUSH University in Chicago. "While our research doesn't prove that a healthy diet resulted in fewer brain deposits of amyloid plaques, also known as an indicator of Alzheimer's disease, we know there is a relationship and following the MIND and Mediterranean diets may be one way that people can improve their brain health and protect cognition as they age."

The study involved 581 people with an average age of 84 at the time of diet assessment who agreed to donate their brains at death to advance research on dementia. Participants completed annual questionnaires asking how much they ate of food items in various categories.

The participants died an average of seven years after the start of the study. Right before death, 39% of participants had been diagnosed with dementia. When examined after death, 66% met the criteria for Alzheimer's disease.

At autopsy, researchers examined participants' brains to determine the amounts of amyloid plaques and tau tangles. Both are found in the brains of people with Alzheimer's disease but may also be found in the brains of older people with normal cognition. Researchers then looked back at the food questionnaires which were collected during follow-up and ranked the quality of diet for each person.

For the Mediterranean diet, there were 11 food categories. Participants were given a score of zero to 55, with higher scores if they adhered to the diet in these categories: whole grain cereals, fruits, vegetables, legumes, olive oil, fish and potatoes. They were given lower scores if they ate red meat, poultry and full-fat dairy products.

For the MIND diet, there were 15 categories. Participants were given a score of zero to 15, with one point each for 10 brain-healthy food groups including green leafy vegetables, other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil, and wine. They lost a point if they ate foods more than recommended in five unhealthy food groups, including red meats, butter and margarine, cheese, pastries and sweets, and fried and fast food.

Researchers then divided participants into three groups for each diet and compared those in the highest groups to those in the lowest groups. For the Mediterranean diet, people in the highest group had an average score of 35 while those in the lowest group had an average score of 26. For the MIND diet, the highest group had an average score of 9 while the lowest group had an average score of 6.

After adjusting for age at death, sex, education, total calorie intake and whether people had a gene linked to a greater risk of Alzheimer's disease, researchers found people who scored highest for adhering to the Mediterranean diet had average plaque and tangle amounts in their brains similar to being 18 years younger than people who scored lowest. Researchers also found people who scored highest for adhering to the MIND diet had average plaque and tangle amounts similar to being 12 years younger than those who scored lowest.

A MIND diet score one point higher corresponded to typical plaque amounts of participants who were 4.25 years younger in age.

When looking at single diet components, researchers found people who ate the highest amounts of green leafy vegetables, or seven or more servings per week, had plaque amounts in their brains corresponding to being almost 19 years younger than people who ate the fewest, with one or fewer servings per week.

"Our finding that eating more green leafy vegetables is in itself associated with fewer signs of Alzheimer's disease in the brain is intriguing enough for people to consider adding more of these vegetables to their diet," said Agarwal. "Future studies are needed to establish our findings further."

A limitation of the study was that participants were mostly white, non-Hispanic, and older so the results cannot be generalized to other populations.

https://www.sciencedaily.com/releases/2023/03/230308201051.htm