Photo via Pixabay
March 5, 2019
Science Daily/North Carolina State University
To get older adults to pay attention to important health information, preface it with the good news about their health. That's one takeaway from a study that found older adults are more willing to engage with negative health information when they have a positive attitude about their health.
"There's a lot of research showing that older adults prefer positive information, often avoiding or ignoring negative information," says Tom Hess, a professor of psychology at North Carolina State University and co-author of a paper on the new findings. "That can have consequences for older adults, particularly when it comes to information regarding their health. We wanted to see if there was a way to overcome this positivity bias when it comes to health news."
To that end, the researchers conducted a study of 196 adults between the ages of 65 and 80. A quarter of the study participants were shown images to put them in a negative mood. A quarter were shown images to put them in a positive mood. A quarter were asked to complete a health checklist designed to make them feel bad about the healthiness of their lifestyle choices. And a quarter were asked to complete a checklist designed to make them feel good about their lifestyle choices.
Study participants were then shown the headlines of six articles about health. Three of the headlines were negative, but offered information relevant to the health of the study participants. The other three headlines were positive, but were less likely to provide participants with useful information. Participants were asked to pick any three of the six articles to read.
Study participants who completed the "positive" health checklist read more than 50 percent more of the articles that had negative headlines, as compared to participants who completed the "negative" checklist.
"Specifically, study participants who completed the checklist giving them a positive attitude toward their health chose to read, on average, about 60 percent of the negative articles, whereas participants who completed the negative checklist chose only 37 percent of the negative articles," says Claire Growney, a Ph.D. student at NC State and lead author of the paper. "There was no effect for participants who did not complete the health checklist and whose moods were only influenced by images. We also ran the same study with a group of 201 younger adults, and there was no effect with any of the groups there. This tells us that having a positive attitude toward health may primarily affect the willingness of older adults to engage with negative health news.
"We also asked the study participants what their motivations were before reviewing the health articles, and found that older adults with positive attitudes toward their health were more likely to seek out health-related news that was relevant to their own lives."
To confirm the finding, the researchers repeated the study with 199 adults between the ages of 65 and 85. This time they focused solely on the negative and positive health checklists. One difference with this second study was that the health article headlines were split into four categories: positive and informative; negative and informative; positive and not informative; and negative and not informative.
"In this second study, we found participants who completed the positive checklist were over 30 percent more likely to select articles with negative headlines to read -- but only if the headlines were also informative," Growney says. "Specifically, the group with positive attitudes toward their health again chose to read about 60 percent of the negative/informative articles, while the group with negative attitudes toward their health chose only about 40 percent of the negative/informative articles."
"These findings have practical value in terms of how we share negative information with older adults regarding their health," Hess says. "For example, it may be useful for a health care provider to say 'here's what looks good' before talking to a patient about recommendations regarding diet or exercise."
Physical and mental health issues, hearing problems, and poor diet, exercise and sleep all linked to feeling isolated
March 4, 2019
Science Daily/Michigan Medicine - University of Michigan
One in four older adults say they feel isolated from other people at least some of the time, and one in three say they lack regular companionship, according to a new national poll. Those feelings of loneliness showed up most in people aged 50 to 80 who also reported they had health issues and unhealthy habits. The findings amplify research showing links between chronic loneliness and health issues ranging from memory loss to shorter lives.
Those feelings of loneliness showed up most in people aged 50 to 80 who also reported they had health issues and unhealthy habits, the poll shows. The new findings amplify research that has shown links between chronic loneliness and health issues ranging from memory loss to shorter lives.
In the new poll, people who said they had fair or poor physical health, mental health, or hearing loss were more likely to report that they felt isolated or lacked companions.
Meanwhile, people who said they ate healthy diets, exercised, got enough sleep or didn't use tobacco were less likely to report feelings of loneliness.
The new findings come from the National Poll on Healthy Aging, conducted by the University of Michigan Institute for Healthcare Policy and Innovation, and sponsored by AARP and Michigan Medicine, U-M's academic medical center.
"More than a quarter of poll respondents said they only had social contact once a week, or less, with family members they don't live with, or with friends and neighbors," says Erica Solway, Ph.D., the co-director of the poll and a social science researcher. "These results indicate the importance of proactively reaching out to those in your community who may be at risk of feeling isolated and disconnected, especially those with or at risk of health issues."
Poll director Preeti Malani, M.D., who has training in caring for older adults, notes that a growing body of research points to strong connections between health and loneliness -- and to positive effects on health from increased social contact through volunteering, taking part in religious or community groups, and other activities.
"As we grow older, and mobility or hearing becomes more of a barrier, these poll data show the importance of maintaining and strengthening our ties to other people," says Malani. "It also suggests that caregivers, spouses and partners, adult children and others involved in older adults' lives have a role to play in encouraging and facilitating these connections."
"We know that social isolation and loneliness are as bad for our health as obesity and smoking," says Alison Bryant, Ph.D., senior vice president of research for AARP. "AARP's own research shows that older adults who are unpaid caregivers, are low-income, or that identify as LGBT are at an increased risk for chronic loneliness. This is such an important public health issue that AARP Foundation launched Connect2Affect to help combat isolation and loneliness among older adults."
Other key findings
The poll explored many aspects of social connection and health and asked about feelings of companionship, feelings of social isolation, and social contact among people age 50 to 80. It found:
· Those who were unemployed, lived in lower-income households, lived alone and/or had one or more children living with them were more likely to say they lacked companionship
· Living alone was highly associated with feeling lonely; 60 percent of those who lived alone reported feeling a lack of companionship, and 41 percent felt isolated
· 36 percent of women said they lacked companionship often or some of the time, compared with 31 percent of men
· 26 percent of adults who said they lacked companionship also said they were in fair or poor physical health, while 13 percent of people who said they hardly ever lacked companionship reported fair or poor physical health
· Of those who reported feeling isolated, 17 percent had fair/poor mental health, compared to only 2 percent of those who hardly ever felt isolated.
· One in five respondents who reported feeling socially isolated said they had fair or poor hearing compared to about one in 10 of those who said they hardly ever feel isolated.
But study suggests higher education might counter effects of milder hearing impairment
February 12, 2019
Science Daily/University of California - San Diego
In a new study, researchers report that hearing impairment is associated with accelerated cognitive decline with age, though the impact of mild hearing loss may be lessened by higher education
Hearing impairment is a common consequence of advancing age. Almost three-quarters of U.S. adults age 70 and older suffer from some degree of hearing loss. One unanswered question has been to what degree hearing impairment intersects with and influences age-related cognitive decline.
In a new study, researchers at University of California San Diego School of Medicine report that hearing impairment is associated with accelerated cognitive decline with age, though the impact of mild hearing loss may be lessened by higher education.
The findings are published in the February 12, 2019 issue of the Journal of Gerontology: Series A Medical Sciences.
A team of scientists, led by senior author Linda K. McEvoy, PhD, professor in the departments of Radiology and Family Medicine and Public Health, tracked 1,164 participants (mean age 73.5 years, 64 percent women) in the longitudinal Rancho Bernardo Study of Healthy Aging for up to 24 years. All had undergone assessments for hearing acuity and cognitive function between the years 1992 to 1996 and had up to five subsequent cognitive assessments at approximately four-year intervals. None used a hearing aid.
The researchers found that almost half of the participants had mild hearing impairment, with 16.8 percent suffering moderate-to-severe hearing loss. Those with more serious hearing impairment showed worse performance at the initial visit on a pair of commonly used cognitive assessment tests: the Mini-Mental State Exam (MMSE) and the Trail-Making Test, Part B. Hearing impairment was associated with greater decline in performance on these tests over time, both for those with mild hearing impairment and those with more severe hearing impairment.
However, the association of mild hearing impairment with rate of cognitive decline was modified by education. Mild hearing impairment was associated with steeper decline among study participants without a college education, but not among those with higher education. Moderate-to-severe hearing impairment was associated with steeper MMSE decline regardless of education level.
"We surmise that higher education may provide sufficient cognitive reserve to counter the effects of mild hearing loss, but not enough to overcome effects of more severe hearing impairment," said McEvoy.
Degree of social engagement did not affect the association of hearing impairment with cognitive decline. "This was a somewhat unexpected finding" said first author Ali Alattar. "Others have postulated that cognitive deficits related to hearing impairment may arise from social isolation, but in our study, participants who had hearing impairment were as socially engaged as those without hearing loss."
The findings, said the authors, emphasize the need for physicians to be aware that older patients with hearing impairments are at greater risk for cognitive decline. They also emphasized the importance of preventing hearing loss at all ages, since hearing impairment is rarely reversible. One important way to protect hearing, they said, is to minimize loud noise exposure since this is the largest modifiable risk factor for hearing impairment.
May explain why women more likely to stay mentally sharp in later years
February 4, 2019
Science Daily/Washington University School of Medicine
Women's brains appear to be three years younger than men's of the same age, according to a new study on brain metabolism. The findings could explain why women maintain their cognitive skills longer than men.
A new study from Washington University School of Medicine in St. Louis finds that women's brains appear to be about three years younger than men's of the same chronological age, metabolically speaking. The findings, available online the week of Feb. 4 in Proceedings of the National Academy of Sciences, could be one clue to why women tend to stay mentally sharp longer than men.
"We're just starting to understand how various sex-related factors might affect the trajectory of brain aging and how that might influence the vulnerability of the brain to neurodegenerative diseases," said senior author Manu Goyal, MD, an assistant professor of radiology at the university's Mallinckrodt Institute of Radiology. "Brain metabolism might help us understand some of the differences we see between men and women as they age."
The brain runs on sugar, but how the brain uses sugar changes as people grow and age. Babies and children use some of their brain fuel in a process called aerobic glycolysis that sustains brain development and maturation. The rest of the sugar is burned to power the day-to-day tasks of thinking and doing. In adolescents and young adults, a considerable portion of brain sugar also is devoted to aerobic glycolysis, but the fraction drops steadily with age, leveling off at very low amounts by the time people are in their 60s.
But researchers have understood little about how brain metabolism differs between men and women. So Goyal and colleagues, including Marcus Raichle, MD, the Alan A. and Edith L. Wolff Distinguished Professor of Medicine and a professor of radiology, and Andrei Vlassenko, MD, PhD, an associate professor of radiology, studied 205 people to figure out how their brains use sugar.
The study participants -- 121 women and 84 men, ranging in age from 20 to 82 years -- underwent PET scans to measure the flow of oxygen and glucose in their brains. For each person, the researchers determined the fraction of sugar committed to aerobic glycolysis in various regions of the brain. They trained a machine-learning algorithm to find a relationship between age and brain metabolism by feeding it the men's ages and brain metabolism data. Then, the researchers entered women's brain metabolism data into the algorithm and directed the program to calculate each woman's brain age from its metabolism. The algorithm yielded brain ages an average of 3.8 years younger than the women's chronological ages.
The researchers also performed the analysis in reverse: They trained the algorithm on women's data and applied it to men's. This time, the algorithm reported that men's brains were 2.4 years older than their true ages.
"The average difference in calculated brain age between men and women is significant and reproducible, but it is only a fraction of the difference between any two individuals," Goyal said. "It is stronger than many sex differences that have been reported, but it's nowhere near as big a difference as some sex differences, such as height."
The relative youthfulness of women's brains was detectable even among the youngest participants, who were in their 20s.
"It's not that men's brains age faster -- they start adulthood about three years older than women, and that persists throughout life," said Goyal, who is also an assistant professor of neurology and of neuroscience. "What we don't know is what it means. I think this could mean that the reason women don't experience as much cognitive decline in later years is because their brains are effectively younger, and we're currently working on a study to confirm that."
Older women tend to score better than men of the same age on tests of reason, memory and problem solving. Goyal, Raichle, Vlassenko and colleagues are now following a cohort of adults over time to see whether people with younger-looking brains are less likely to develop cognitive problems.
October 3, 2018
Science Daily/University of British Columbia
Exercising at least three times a week for six months reduced stress in a group of family caregivers and even appeared to lengthen a small section of their chromosomes that is believed to slow cellular aging.
"I am hoping that a new focus on the family caregiver will emerge out of this research," said Eli Puterman, a professor in the University of British Columbia's school of kinesiology and lead author of the study. "We need to design interventions that help caregivers take care of their bodies and their minds, and provide the type of support that's needed to maintain that long-term."
The population of seniors in the U.S., where Puterman and colleagues from the University of California conducted the study, is expected to nearly double by 2050. Younger family members will increasingly be providing this type of care and it can take a toll on their health.
"What caregivers need is support for healthy behaviours, because that is one of the first things to drop when you become a family caregiver," said Puterman. "The time to take care of yourself just goes out the window."
The researchers recruited physically inactive people who care for family members with Alzheimer's disease and dementia, and who reported feeling high levels of stress. The 68 participants were divided randomly into two groups. One group undertook 40 minutes of aerobic exercise three to five times per week, while the others were asked not to alter their level of activity. Those in the exercise group had free access to a gym, and a fitness coach for weekly conversations. Eighty-one per cent of them adhered to at least 120 minutes of exercise per week for the duration of the study.
At the end of the study, not only had the caregivers improved their cardiorespiratory fitness, reduced their body mass index and trimmed their waistlines, they also reported lower levels of perceived stress.
At the cellular level, the researchers observed longer telomeres in the participants' white blood cells after the program. Telomeres protect the ends of chromosomes, much like the aglets that protect the ends of shoelaces. Without them, chromosomes shorten to the point where they either die or enter a state called "senescence," in which they stop replicating. Senescent cells have been shown to be predictive of future health problems such as cardiovascular disease.
The study's findings suggest that in addition to reducing stress, exercise can slow or even reverse telomeric aging in a highly stressed, at-risk group.
October 25, 2018
Science Daily/University of Texas Health Science Center at San Antonio
Stress may be causing impaired memory and brain shrinkage in middle-age adults, even before symptoms of Alzheimer's or other dementia begin, according to a new study.
Adults in their 40s and 50s with higher levels of cortisol -- a hormone linked to stress -- performed worse on memory and other cognitive tasks than peers of the same age with average cortisol levels, research found. Higher cortisol in the blood also was associated with smaller brain volumes, according to the study, published Oct. 24 in Neurology, the medical journal of the American Academy of Neurology.
"In our quest to understand cognitive aging, one of the factors attracting significant interest and concern is the increasing stress of modern life," said study senior author Sudha Seshadri, M.D., professor of neurology at UT Health San Antonio and founding director of the university's Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases. "One of the things we know in animals is that stress can lead to cognitive decline. In this study, higher morning cortisol levels in a large sample of people were associated with worse brain structure and cognition."
The cognitive data are from 2,231 participants in the Framingham Heart Study, for which Dr. Seshadri is a senior investigator; 2,018 participants also underwent magnetic resonance imaging (MRI) to measure brain volume. The team included Framingham collaborators at Harvard Medical School; the National Heart, Lung, and Blood Institute; Boston University School of Medicine; the University of California, Davis, at Sacramento; and UT Health San Antonio.
Blood serum cortisol, which varies in level throughout the day, was measured in early morning (between 7:30 and 9 a.m.) in each fasting participant. The study featured a relatively young sample of male and female participants (mean age 48.5).
"Cortisol affects many different functions, so it is important to fully investigate how high levels of the hormone may affect the brain," said study lead author Justin B. Echouffo-Tcheugui, M.D., Ph.D., of Harvard Medical School. "While other studies have examined cortisol and memory, we believe our large, community-based study is the first to explore, in middle-aged people, fasting blood cortisol levels and brain volume, as well as memory and thinking skills."
Memory loss and brain shrinkage were found in the study's middle-age participants before the onset of any symptoms, Dr. Echouffo-Tcheugui noted. He said it is important for physicians to counsel people with higher cortisol levels on ways to reduce stress, such as getting enough sleep and engaging in moderate exercise.
"The faster pace of life today probably means more stress, and when we are stressed, cortisol levels increase because that is our fight-or-flight response," Dr. Seshadri said. "When we are afraid, when we are threatened in any way, our cortisol levels go up. This study adds to the prevailing wisdom that it's never too early to be mindful of reducing stress."
Findings were adjusted for factors including age, sex, smoking and body mass index. The team asked whether having APOE4, a genetic risk factor for cardiovascular disease and Alzheimer's disease, might be associated with higher cortisol level. This did not prove to be the case.
Preventive strategies could, in theory, more than halve lifetime risk for those aged 85-plus, say researchers
Science Daily/October 1, 2018
One in two women and one in three men will likely be diagnosed with dementia, Parkinson's disease, or stroke in their lifetime, estimate Dutch researchers in an observational study.
But preventive strategies, which delay the onset of these common diseases by even a few years, could, in theory, cut this lifetime risk by between 20 and more than 50 per cent, they say.
The global costs of dementia, stroke, and parkinsonism are thought to amount to more than 2 per cent of the world's annual economic productivity (GDP), a figure that is set to rise steeply as life expectancy continues to increase.
But while the lifetime risks of other serious illnesses, such as breast cancer and heart disease are well known and used to raise public awareness, the same can't be said of dementia, stroke, parkinsonism, say the researchers.
To try and redress this, they tracked the neurological health of more than 12,000 people taking part in the Rotterdam Study between 1990 and 2016. This study has been looking at the incidence of, and influential factors behind, diseases of ageing in the general population.
All the participants were aged at least 45 years old when they were recruited, and more than half (just under 58 per cent) were women.
When they joined, participants were given a thorough health check, which was repeated every four years. Family doctor health records were also scrutinised for signs of disease or diagnoses arising between the four yearly check-ups.
Monitoring for dementia, parkinsonism, and stroke continued until death, or January 1 2016, whichever came first.
Between 1990 and 2016, 5291 people died, 3260 of whom had not been diagnosed with any neurological disease. But 1489 people were diagnosed with dementia, mostly Alzheimer's disease (just under 80%); 1285 had a stroke, nearly two thirds of which (65%) was caused by a blood clot (ischaemic); and 263 were diagnosed with parkinsonism.
A higher prevalence of high blood pressure, abnormal heart rhythm (atrial fibrillation), high cholesterol and type 2 diabetes was evident at the start of the monitoring period among those subsequently diagnosed with any of the three conditions.
Unsurprisingly, the risk of developing any of them rose steeply with age, but based on the data, the overall lifetime risk of a 45 year-old developing dementia, parkinsonism, or having a stroke was one in two for a woman (48%) and one in three for a man (36%).
This gender difference was largely driven by women being at heightened risk of developing dementia before men. But there were other gender differences in risk.
While 45 year-olds of both sexes had a similar lifetime risk of stroke, men were at substantially higher risk of having a stroke at younger ages than women.
And women were twice as likely as men to be diagnosed with both dementia and stroke during their lifetime.
The researchers calculated that if the onset of dementia, stroke, and parkinsonism were delayed by 1 to 3 years, the remaining lifetime risk could, in theory, be reduced by 20 per cent in 45 year-olds, and by more than 50 per cent in those aged 85+.
A delay of only a few years for one disease could also have a significant impact on combined lifetime risk, suggest the researchers.
"For instance, delaying dementia onset by 3 years has the potential to reduce lifetime risk of any disease by 15 per cent for men and women aged 45, and by up to 30 per cent for those aged 85 and older," they write.
The researchers point out that their study included only people of European ancestry with a relatively long life expectancy, so might not be applicable to other ethnicities/populations, and that they weren't able to measure the severity of any of the diagnosed conditions.
This research is observational, so no definitive conclusions can be drawn. But the researchers nevertheless conclude: "These findings strengthen the call for prioritising the focus on preventive interventions at population level which could substantially reduce the burden of common neurological diseases in the ageing population."
Eight-year study reveals association that may indicate early stage changes in cognition
January 29, 2019
Science Daily/Brigham and Women's Hospital
Hearing loss affects tens of millions of Americans and its global prevalence is expected to grow as the world's population ages. A new study led by investigators at Brigham and Women's Hospital adds to a growing body of evidence that hearing loss is associated with higher risk of cognitive decline. These findings suggest that hearing loss may help identify individuals at greater risk of cognitive decline and could provide insights for earlier intervention and prevention.
"Dementia is a substantial public health challenge that continues to grow. There is no cure, and effective treatments to prevent progression or reverse the course of dementia are lacking," said lead author Sharon Curhan, MD, MSc, a physician and epidemiologist in the Channing Division for Network Medicine at the Brigham. "Our findings show that hearing loss is associated with new onset of subjective cognitive concerns which may be indicative of early stage changes in cognition. These findings may help identify individuals at greater risk of cognitive decline."
Curhan and colleagues conducted an eight-year longitudinal study among 10,107 men aged ?62 years in the Health Professionals Follow-up Study (HFPS). They assessed subjective cognitive function (SCF) scores based on responses to a six-item questionnaire administered in 2008, 2012 and 2016. SCF decline was defined as a new report of at least one SCF concern during follow-up.
The team found that hearing loss was associated with higher risk of subjective cognitive decline. Compared with men with no hearing loss, the relative risk of cognitive decline was 30 percent higher among men with mild hearing loss, 42 percent higher among men with moderate hearing loss, and 54 percent higher among men with severe hearing loss but who did not use hearing aids.
Researchers were interested to see if hearing aids might modify risk. Although the found that among men with severe hearing loss who used hearing aids, the risk of cognitive decline was somewhat less (37 percent higher), it was not statistically significantly different from the risk among those who did not use hearing aids. The authors note that this may have been due to limited power or could suggest that if a difference truly exists, the magnitude of the effect may be modest.
The authors also note that the study was limited to predominantly older white male health professionals. This allowed for greater control of variability but further studies in additional populations would be helpful. In addition, the study relies on self-reported hearing loss and subjective measures of cognitive function. In the future, the team plans to investigate the relationships between self-reported hearing loss, change in audiometric hearing thresholds, and changes in cognition in women using several different assessment measures.
"Whether there is a temporal association between hearing loss and cognitive decline and whether this relation is causal remains unclear," said Curhan. "We plan to conduct further longitudinal studies of the relation of hearing loss and cognition in women and in younger populations, which will be informative."
'Brain Soup' research connects number of neurons to longevity
October 30, 2018
Science Daily/Vanderbilt University
New research finds how long humans and other warm-blooded animals live -- and when they reach sexual maturity -- may have more to do with their brain than their body. More specifically, it is not animals with larger bodies or slower metabolic rates that live longer; it is animals with more neurons in the cerebral cortex, whatever the size of the body.
"Whether you're looking at birds or primates or humans, the number of neurons that you find in the cortex of a species predicts around 75 percent of all of the variation in longevity across species," said study author associate professor of psychology and biological sciences Suzana Herculano-Houzel.
Body size and metabolism, in comparison, to usual standards for comparing animals, only predicted between 20-30 percent of longevity depending on species, and left many inconsistencies, like birds that live ten times longer than mammals of same size.
Most importantly, humans were considered to be a "special" evolutionary oddity, with long childhood and postmenopausal periods. But this research, published in the Journal of Comparative Neurology, finds that's not accurate. Humans take just as long to mature as expected of their number of cortical neurons -- and live just as long as expected thereafter.
In the study, Herculano-Houzel examined more than 700 warm-blooded animal species from the AnAge database which collects comprehensive longevity records. She then compared these records with her extensive data on the number of neurons in the brains of different species of animals.
Herculano-Houzel color-coded the data for hundreds of species and found that parrots and songbirds, including corvids, live systematically longer than primates of similar body mass, which in turn live longer than non-primate mammals of similar body mass.
"Likewise, for similar specific basal metabolic rates, parrots and songbirds live longer and take longer to reach sexual maturity than many mammalian species, especially non-primates," said Herculano-Houzel.
She had seen that pattern before: her previous studies determining what brains are made of showed that parrots and songbirds have more cortical neurons than similar-sized primates, which have more cortical neurons than any other mammal of comparable body size.
Her new analysis confirmed her suspicion: that longevity increases uniformly across warm-blooded species together with the absolute number of neurons in the cerebral cortex.
"The more cortical neurons a species has, the longer it lives -- doesn't matter if it is a bird, a primate or some other mammal, how large it is, and how fast it burns energy," says Herculano-Houzel.
ARE HUMANS UNIQUE? ASK GRANDMA
Anthropologists and researchers interested in evolution and human behavior have been working under the assumption that one of the ways the human species is unique is that humans have an uncommonly long childhood and adolescent period to allow for learning and social interactions. If larger animals live longer, then gorillas should live longer than humans -- but they don't: humans outlive them. One favored hypothesis is that being cared for by grandmothers could have led humans to delayed sexual maturity and increased postmenopausal longevity beyond the expected.
But Herculano-Houzel's new data show that humans are not an exception from other mammalian species. Given the number of neurons in our cortex, humans take as long as they should to reach sexual maturity -- and live just as long as expected for their number of neurons. Body size, it turns out, is irrelevant in matters of longevity.
"Now we can say that humans spend just as long in childhood and live exactly as long after reaching maturity as you would expect for the number of neurons in our cerebral cortex," said Herculano-Houzel.
Which is longer, compared to other species -- gorillas included -simply because humans have the most neurons in the cerebral cortex.
"It makes sense that the more neurons you have in the cortex, the longer it should take a species to reach that point where it's not only physiologically mature, but also mentally capable of being independent," says Herculano-Houzel. "The delay also gives those species with more cortical neurons more time to learn from experience, as they interact with the environment."
And if longer lives also accompany more cortical neurons, those species will also enjoy a greater overlap between generations, and so more opportunities to pass along what they learned.
"Which means that grandma is still fundamental in the lives of those with plenty of cortical neurons; she's just probably not the reason why our species is long-lived," argues Herculano-Houzel.
FUNCTION OF THE CORTEX
What is the link between having more neurons in the cortex and living longer lives? Herculano-Houzel says that's the new big question researchers need to tackle.
"The data suggest that warm-blooded species accumulate damages at the same rate as they age. But what curtails life are damages to the cerebral cortex, not the rest of the body; the more cortical neurons you have, the longer you will still have enough to keep your body functional," she says.
Contrary to the rest of the body, which gets new cells that replenish old ones, cortical neurons are thought to have to last a lifetime.
While the cortex is usually associated with cognition, Herculano-Houzel believes a much more basic function of the cortex is key to longevity.
"The cortex is the part of your brain that is capable of making our behavior complex and flexible, yes, but that extends well beyond cognition and doing mental math and logic reasoning," said Herculano-Houzel. "The cerebral cortex also gives your body adaptability, as it adjusts and learns how to react to stresses and predict them. That includes keeping your physiological functions running smoothly and making sure your heart rate, your respiratory rate, and your metabolism are on track with what you're doing, with how you feel, and with what you expect to happen next. And that, apparently, is a key factor that impacts longevity," she adds.
Herculano-Houzel pioneered the method for rapidly and accurately measuring the number of neurons in brains. She creates "brain soup" by taking brain tissue and breaking down the cells, then applying fluorescent tags to the nuclei floating in the "brain soup" and counting them.
In collaboration with Vanderbilt Distinguished Professor of Psychology Jon Kaas, she studied how many neurons compose different primate brains, including great apes. With colleagues in Brazil, she produced the first accurate count of the number of neurons in the human brain -- an average 86 billion, which makes it simply an enlarged primate brain.
TAKE CARE OF YOUR BRAIN!
Aging starts once humans and other species reach adolescence, and there's no way to gain back neurons. In fact, research shows humans can lose neurons in the prefrontal cortex. So Herculano-Houzel says taking good care of your mind, and keeping those cortical neurons healthy and busy, is the best bet to live long and well.
September 21, 2018
Science Daily/American Geriatrics Society
Researchers learn more about the relationship between sexual behavior, function, and cognition (people's ability to think and make decisions).
Experts agree that we know very little about sexuality among people living at home with AD or other cognitive problems. Older adults who have cognitive problems that impact the way they think and make decisions may ask physicians to help managing sexual problems. And caregivers may ask physicians about sexuality in the older adults for whom they provide care.
One frequently asked question is: Do older adults always have the capacity to consent to sexual activity?
Researchers have previously shown that the majority of people aged 57 to 85 have a spouse or other intimate partner and, among those with a partner, most are sexually active. Having an active sexual life is linked to better physical and mental health, higher quality of life, and lower rates of loneliness.
To learn more about the connection between sexuality and cognitive status, researchers designed a new study. They analyzed data from the National Social Life, Health, and Aging Project to learn more about the relationship between sexual behavior, function, and cognition (people's ability to think and make decisions). Their study was published in the Journal of the American Geriatrics Society.
Based on their study, the researchers reported that:
- 83 percent of men and 57 percent of women had an intimate partner. The more impaired participants' abilities to think and make decisions were, the less likely they were to have an intimate partner.
- Women with lower cognitive scores were less likely than men with lower cognitive scores to have intimate partners.
- Nearly half of all men with dementia were sexually active, as were 18 percent of women.
- Among people with an intimate partner, the majority of men (59 percent) and women (51 percent) with dementia were sexually active. More than 40 percent of partnered men and women ages 80 to 91 living with dementia were sexually active.
- More than 1 in 10 people living with a partner reported feeling threatened or frightened by a partner. This finding was similar among women and men and across different levels of cognitive problems. Experts and guidelines call on physicians to screen for elder abuse (the mistreatment of older people, which can take many forms, including physical, emotional, and sexual abuse, financial exploitation, and neglect), including sexual abuse, but definitions of abuse and standards of consent for sex vary widely.
The researchers estimate that, among people living at home who are aged 62 and older, at least 1.8 million men and 1.4 million women with suspected or diagnosed dementia are sexually active. This number will more than double by 2050. However, rarely do these people (especially women) receive a physician's counseling about sexual changes that may occur with dementia or other medical conditions.
The researchers suggested that these findings can inform improved counseling, treatment, and person-centered decision-making by physicians and other healthcare providers caring for people with dementia or Alzheimer's disease.
Sexual activity is an important aspect of human function throughout your lifetime, said the researchers. They added that respectful care for older adults, including people with cognitive impairments, requires an understanding of sexual norms and problems -- and effective strategies to manage sexual concerns with dignity.
Plasticity is enhanced but dysregulated in the aging brain
September 19, 2018
Science Daily/McGill University
Researchers examined the effects of aging on neuroplasticity in the primary auditory cortex, the part of the brain that processes auditory information. Neuroplasticity refers to the brain's ability to modify its connections and function in response to environmental demands, an important process in learning.
They say you can't teach old dogs new tricks, but new research shows you can teach an old rat new sounds, even if the lesson doesn't stick very long.
Researchers at the Montreal Neurological Institute and Hospital (The Neuro) of McGill University examined the effects of aging on neuroplasticity in the primary auditory cortex, the part of the brain that processes auditory information. Neuroplasticity refers to the brain's ability to modify its connections and function in response to environmental demands, an important process in learning.
Plasticity in the young brain is very strong as we learn to map our surroundings using the senses. As we grow older, plasticity decreases to stabilize what we have already learned. This stabilization is partly controlled by a neurotransmitter called gamma-Aminobutyric acid (GABA), which inhibits neuronal activity. This role of GABA was discovered by K.A.C. Elliot and Ernst Florey at The Neuro in 1956.
First author Dr. Mike Cisneros-Franco and lab director Dr. Étienne de Villers-Sidani wanted to test the hypothesis that plasticity stabilization processes become dysregulated as we age. They ran an experiment where rats were exposed to audio tones of a specific frequency to measure how neurons in the primary auditory cortex adapt their responses to the tones.
They found that tone exposure caused neurons in older adult rats to become increasingly sensitized to the frequency, but this did not happen in younger adult rats. The effect in the older adult rats quickly disappeared after exposure, showing that plasticity was indeed dysregulated. However, by increasing the levels of the GABA neurotransmitter in another group of older rats, the exposure-induced plastic changes in the auditory cortex lasted longer.
These findings suggest the brain's ability to adapt its functional properties does not disappear as we age. Rather, they provide evidence that plasticity is, in fact, increased but dysregulated in the aged brain because of reduced GABA levels. Overall, the findings suggest that increasing GABA levels may improve the retention of learning in the aging brain.
"Our work showed that the aging brain is, contrary to a widely-held notion, more plastic than the young adult brain," says Cisneros-Franco. "On the flip side, this increased plasticity meant that any changes achieved through stimulation or training were unstable: both easy to achieve and easy to reverse."
"However, we also showed that it is possible to reduce this instability using clinically available drugs. Researchers and clinicians may build upon this knowledge to develop rehabilitation strategies to harness the full plastic potential of the aging brain."
September 14, 2018
Science Daily/University of Illinois College of Agricultural, Consumer and Environmental Sciences
As mammals age, immune cells in the brain known as microglia become chronically inflamed. In this state, they produce chemicals known to impair cognitive and motor function. That's one explanation for why memory fades and other brain functions decline during old age. But, according to a new study, there may be a remedy to delay the inevitable: dietary fiber.
Dietary fiber promotes the growth of good bacteria in the gut. When these bacteria digest fiber, they produce short-chain-fatty-acids (SCFAs), including butyrate, as byproducts.
"Butyrate is of interest because it has been shown to have anti-inflammatory properties on microglia and improve memory in mice when administered pharmacologically," says Rodney Johnson, professor and head of the Department of Animal Sciences at U of I, and corresponding author on the Frontiers in Immunology study.
Although positive outcomes of sodium butyrate -- the drug form -- were seen in previous studies, the mechanism wasn't clear. The new study reveals, in old mice, that butyrate inhibits production of damaging chemicals by inflamed microglia. One of those chemicals is interleukin-1?, which has been associated with Alzheimer's disease in humans.
Understanding how sodium butyrate works is a step forward, but the researchers were more interested in knowing whether the same effects could be obtained simply by feeding the mice more fiber.
"People are not likely to consume sodium butyrate directly, due to its noxious odor," Johnson says. "A practical way to get elevated butyrate is to consume a diet high in soluble fiber."
The concept takes advantage of the fact that gut bacteria convert fiber into butyrate naturally.
"We know that diet has a major influence on the composition and function of microbes in the gut and that diets high in fiber benefit good microbes, while diets high in fat and protein can have a negative influence on microbial composition and function. Diet, through altering gut microbes, is one way in which it affects disease," says Jeff Woods, professor in the Department of Kinesiology and Community Health at U of I, and co-author on the study.
Butyrate derived from dietary fiber should have the same benefits in the brain as the drug form, but no one had tested it before. The researchers fed low- and high-fiber diets to groups of young and old mice, then measured the levels of butyrate and other SCFAs in the blood, as well as inflammatory chemicals in the intestine.
"The high-fiber diet elevated butyrate and other SCFAs in the blood both for young and old mice. But only the old mice showed intestinal inflammation on the low-fiber diet," Johnson says. "It's interesting that young adults didn't have that inflammatory response on the same diet. It clearly highlights the vulnerability of being old."
On the other hand, when old mice consumed the high-fiber diet, their intestinal inflammation was reduced dramatically, showing no difference between the age groups. Johnson concludes, "Dietary fiber can really manipulate the inflammatory environment in the gut."
The next step was looking at signs of inflammation in the brain. The researchers examined about 50 unique genes in microglia and found the high-fiber diet reduced the inflammatory profile in aged animals.
The researchers did not examine the effects of the diets on cognition and behavior or the precise mechanisms in the gut-brain axis, but they plan to tackle that work in the future as part of a new, almost-$2 million grant from the National Institute on Aging, part of the National Institutes of Health.
Although the study was conducted in mice, Johnson is comfortable extending his findings to humans, if only in a general sense. "What you eat matters. We know that older adults consume 40 percent less dietary fiber than is recommended. Not getting enough fiber could have negative consequences for things you don't even think about, such as connections to brain health and inflammation in general."
August 28, 2018
Science Daily/American Heart Association
A new study links anxiety, depression and other mental distress to an increased risk of heart attack and stroke among adults ages 45 or older, even after factoring for lifestyle behaviors and disease history. The associations were slightly stronger for stroke among women than men.
In a study of 221,677 participants from Australia, researchers found that:
· among women, high/very high psychological distress was associated with a 44 percent increased risk of stroke; and
· in men ages 45 to 79, high/very high versus low psychological distress was associated with a 30 percent increased risk of heart attack, with weaker estimates in those 80 years old or older.
The association between psychological distress and increased cardiovascular disease risk was present even after accounting for lifestyle behaviors (smoking, alcohol intake, dietary habits, etc.) and disease history.
"While these factors might explain some of the observed increased risk, they do not appear to account for all of it, indicating that other mechanisms are likely to be important," said Caroline Jackson, Ph.D., the study's senior author and a Chancellor's Fellow at the University of Edinburgh in Edinburgh, Scotland.
The research involved participants who had not experienced a heart attack or stroke at the start of the study and who were part of the New South Wales 45 and Up Study that recruited adults ages 45 or older between 2006 and 2009.
Researchers categorized psychological distress as low, medium and high/very high using a standard psychological distress scale which asks people to self-assess the level.
The 10-question survey asks questions such as: "How often do you feel tired out for no good reason?" How often do you feel so sad that nothing could cheer you up?" How often do you feel restless or fidgety?"
Of the participants -- 102,039 men (average age 62) and 119,638 women (average age 60) -- 16.2 percent reported having moderate psychological distress and 7.3 percent had high/very high psychological distress.
During follow-up of more than four years, 4,573 heart attacks and 2,421 strokes occurred. The absolute risk -- overall risk of developing a disease in a certain time period -- of heart attack and stroke rose with each level of psychological distress.
The findings add to the existing evidence that there may be an association between psychological distress and increased risk of heart attack and stroke, she said. But they also support the need for future studies focused on the underlying mechanisms connecting psychological distress and cardiovascular disease and stroke risk and look to replicate the differences between men and women.
Mental disorders and their symptoms are thought to be associated with increased risk of heart disease and stroke, but previous studies have produced inconsistent findings and the interplay between mental and physical health is poorly understood.
People with symptoms of psychological distress should be encouraged to seek medical help because, aside from the impact on their mental health, symptoms of psychological distress appear to also impact physical health, Jackson said. "We encourage more proactive screening for symptoms of psychological distress. Clinicians should actively screen for cardiovascular risk factors in people with these mental health symptoms."
All factors analyzed in this research, apart from the outcomes of heart attack and stroke, were identified at the same point in time, which made it difficult for researchers to understand the relationship between psychological distress and variables such as unhealthy behaviors like smoking and poor diet. With that analysis approach, they may have underestimated the effect psychological distress has on the risk of heart attack and stroke.
New study among senior Singaporeans suggests happiness may be key to longevity
August 27, 2018
Science Daily/Duke-NUS Medical School
In a new study, researchers have found that increase in happiness is directly proportional with a reduction in mortality. The study, which focused on Singaporeans aged 60 years and older, found that even small increments in happiness may be beneficial, suggesting individual activities as well as government policies and programs that maintain or improve psychological well-being may contribute to longer life.
The study utilised data for 4,478 participants of a nationally-representative survey to look at the association between happiness, assessed in the year 2009, and subsequent likelihood of dying due to any cause, until 31 December 2015. The survey was focused on individuals' aged 60 years and older living in Singapore.
Happiness was assessed by asking the survey participants how often in the past week they experienced the following: 'I felt happy', 'I enjoyed life' and 'I felt hope about the future'. Their responses were considered in two distinct ways; a 'happiness score', and a 'binary happiness variable -- Happy/Unhappy'. A wide range of demographics, lifestyle choices, health and social factors were accounted for in the analysis.
The researchers found that among happy older people, 15% passed away until 31 December 2015. In contrast, the corresponding proportion was higher, at 20%, among unhappy older people. Every increase of one point on the happiness score lowered the chance of dying due to any cause among participants by an additional nine percent. The likelihood of dying due to any cause was 19 percent lower for happy older people. Further, the inverse association of happiness with mortality was consistently present among men and women, and among the young-old (aged 60-79 years) and the old-old (aged 75 years or older).
"The findings indicate that even small increments in happiness may be beneficial to older people's longevity," explained Assistant Professor Rahul Malhotra, Head of Research at Duke-NUS' Centre for Ageing Research and Education and senior author of the paper. "Therefore individual-level activities as well as government policies and programs that maintain or improve happiness or psychological well-being may contribute to a longer life among older people."
June May-Ling Lee, a co-author, added: "The consistency of the inverse association of happiness with mortality across age groups and gender is insightful -- men and women, the young-old and the old-old, all are likely to benefit from an increase in happiness."
Interest in the pursuit of happiness to improve the health of older people has been growing. While previous studies have linked happiness or positive emotions with a range of better health outcomes, the evidence on the effect of happiness on living longer has been inconclusive. Many of these studies do initially observe a greater extent of happiness to be associated with a lower likelihood of dying, but this link disappears once differences in demographic, lifestyle and health factors between those less and more happy are accounted for.
This is one of the few Asian studies to have assessed the association between happiness and mortality among older people, while accounting for several social factors, such as loneliness and social network, therefore extending the generalisability of the findings to non-Western populations.