Deep-brain stimulation during sleep strengthens memory
Researchers also report first direct evidence supporting main theory for how human memory is consolidated during sleep
June 1, 2023
Science Daily/University of California - Los Angeles Health Sciences
While it's known that sleep plays a crucial role in strengthening memory, scientists are still trying to decode how this process plays out in the brain overnight.
New research led by scientists at UCLA Health and Tel Aviv University provides the first physiological evidence from inside the human brain supporting the dominant scientific theory on how the brain consolidates memory during sleep. Further, the researchers found that targeted deep-brain stimulation during a critical time in the sleep cycle appeared to improve memory consolidation.
The research, published June 1 in Nature Neuroscience, could offer new clues for how deep-brain stimulation during sleep could one day help patients with memory disorders like Alzheimer's disease, said study co-author Itzhak Fried, MD, PhD. This was achieved by a novel "closed-loop" system that delivered electrical pulses in one brain region precisely synchronized to brain activity recorded from another region.
According to the dominant theory for how the brain converts new information into long-term memories during shuteye, there's an overnight dialogue between the hippocampus -- the brain's memory hub -- and the cerebral cortex, which is associated with higher brain functions like reasoning and planning. This occurs during a phase of deep sleep, when brain waves are especially slow and neurons across brain regions alternate between rapidly firing in sync and silence.
"This provides the first major evidence down to the level of single neurons that there is indeed this mechanism of interaction between the memory hub and the entire cortex," said Fried, the director of epilepsy surgery at UCLA Health and professor of neurosurgery, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at UCLA. "It has both scientific value in terms of understanding how memory works in humans and using that knowledge to really boost memory."
The researchers had a unique opportunity to test this theory of memory consolidation via electrodes in the brains of 18 epilepsy patients at UCLA Health. The electrodes had been implanted in the patients' brains to help identify the source of their seizures during hospital stays typically lasting around 10 days.
The study was conducted across two nights and mornings. Just before bedtime, study participants were shown photo pairings of animals and 25 celebrities, including easily identifiable stars like Marilyn Monroe and Jack Nicholson. They were immediately tested on their ability to recall which celebrity was paired with which animal, and they were tested again in the morning after a night of undisturbed sleep.
On another night, they were shown 25 new animal and celebrity pairings before bedtime. This time, they received targeted electrical stimulation overnight, and their ability recall the pairings was tested in the morning. To deliver this electrical stimulation, the researchers had created a real-time closed-loop system that Fried likened to a musical conductor: The system "listened" to brain's electrical signals, and when patients fell into the period of deep sleep associated with memory consolidation, it delivered gentle electrical pulses instructing the rapidly firing neurons to "play" in sync.
Each individual tested performed better on memory tests following a night of sleep with the electrical stimulation compared to a night of undisturbed sleep. Key electrophysiological markers also indicated that information was flowing between the hippocampus and throughout the cortex, providing physical evidence supporting of memory consolidation.
"We found we basically enhanced this highway by which information flows to more permanent storage places in the brain," Fried said.
Fried in 2012 authored a New England Journal of Medicine study that for the first time showed that electrical stimulation can strengthen memory, and his work has continued to explore how deep brain stimulation could improve memory, now moving into the critical stage of sleep. He recently received a $7 million NIH grant to study whether artificial intelligence can help pinpoint and strengthen specific memories in the brain.
"In our new study, we showed we can enhance memory in general," Fried said. "Our next challenge is whether we have the ability to modulate specific memories."
https://www.sciencedaily.com/releases/2023/06/230601155923.htm
Landmark study finds that the shape of the brain influences the way it works
Shape of brain, not interactions between different regions, crucial in how we think, feel and behave
May 31, 2023
Science Daily/Monash University
For over a century, researchers have thought that the patterns of brain activity that define our experiences, hopes and dreams are determined by how different brain regions communicate with each other through a complex web of trillions of cellular connections.
Now, a study led by from researchers at Monash University's Turner Institute for Brain and Mental Health has examined more than 10,000 different maps of human brain activity and found that the overall shape of a person's brain exerts a far greater influence on how we think, feel and behave than its intricate neuronal connectivity.
The study, published today in the journal, Nature draws together approaches from physics, neuroscience and psychology to overturn the century-old paradigm emphasising the importance of complex brain connectivity, instead identifying a previously unappreciated relationship between brain shape and activity.
Lead author and Research Fellow Dr James Pang, from the Turner Institute and Monash University's School of Psychological Sciences, said the findings were significant because they greatly simplified the way that we can study how the brain functions, develops and ages.
"The work opens opportunities to understand the effects of diseases like dementia and stroke by considering models of brain shape, which are far easier to deal with than models of the brain's full array of connections," Dr Pang said.
"We have long thought that specific thoughts or sensations elicit activity in specific parts of the brain, but this study reveals that structured patterns of activity are excited across nearly the entire brain, just like the way in which a musical note arises from vibrations occurring along the entire length of a violin string, and not just an isolated segment," he said.
The research team used magnetic resonance imaging (MRI) to study eigenmodes, which are the natural patterns of vibration or excitation in a system, where different parts of the system are all excited at the same frequency. Eigenmodes are normally used to study physical systems in areas such as physics and engineering and have only recently been adapted to study the brain.
This work focused on developing the best way to efficiently construct the eigenmodes of the brain.
"Just as the resonant frequencies of a violin string are determined by its length, density and tension, the eigenmodes of the brain are determined by its structural -- physical, geometric and anatomical -- properties, but which specific properties are most important has remained a mystery," said co-lead author, Dr Kevin Aquino, of BrainKey and The University of Sydney.
The team, led by the Turner Institute and School of Psychological Sciences ARC Laureate Fellow, Professor Alex Fornito, compared how well eigenmodes obtained from models of the shape of the brain could account for different patterns of activity when compared to eigenmodes obtained from models of brain connectivity.
"We found that eigenmodes defined by brain geometry -- its contours and curvature -- represented the strongest anatomical constraint on brain function, much like the shape of a drum influences the sounds that it can make," said Professor Fornito.
"Using mathematical models, we confirmed theoretical predictions that the close link between geometry and function is driven by wave-like activity propagating throughout the brain, just as the shape of a pond influences the wave ripples that are formed by a falling pebble," he said.
"These findings raise the possibility of predicting the function of the brain directly from its shape, opening new avenues for exploring how the brain contributes to individual differences in behaviour and risk for psychiatric and neurological diseases."
The research team found that, across over 10,000 MRI activity maps, obtained as people performed different tasks developed by neuroscientists to probe the human brain, activity was dominated by eigenmodes with spatial patterns that have very long wavelengths, extending over distances exceeding 40 mm.
"This result counters conventional wisdom, in which activity during different tasks is often assumed to occur in focal, isolated areas of elevated activity, and tells us that traditional approaches to brain mapping may only show the tip of the iceberg when it comes to understanding how the brain works," Dr Pang said.
https://www.sciencedaily.com/releases/2023/05/230531150131.htm
Can we learn to think further ahead?
Cognitive scientists' computational model shows how expertise improves planning depth
May 31, 2023
Science Daily/New York University
Chess grandmasters are often held up as the epitome of thinking far ahead. But can others, with a modest amount of practice, learn to think further ahead?
In addressing this question, a team of cognitive scientists has created a computational model that reveals our ability to plan for future events. The work enhances our understanding of the factors that affect decision-making and shows how we can boost our planning skills through practice.
The research, conducted by scientists in New York University's Center for Neural Science and reported in the journal Nature, centers on the role of "planning depth" -- the number of steps that an individual thinks ahead -- in decision-making.
"While artificial intelligence has made impressive progress in solving complex planning problems, much less is understood about the nature and depth of planning in people," explains Wei Ji Ma, a professor of neuroscience and psychology at NYU and the paper's senior author. "Our work adds to this body of knowledge by showing that even a relatively modest amount of practice can improve depth of planning."
It's been long established that a hallmark of human intelligence is the ability to plan multiple steps into the future. However, it's less clear whether or not skilled decision makers plan more steps ahead than do novices. This is because methods for measuring this aptitude (e.g., experiments involving board games) have notable shortcomings -- in part, because they don't reliably estimate planning depth.
The Nature paper's authors had people play a relatively simple game -- a more sophisticated version of tic-tac-toe -- that still required players to plan deeply (i.e., multiple steps ahead). Then, to understand precisely what goes on in people's minds as they are thinking of their next move in this game, the authors designed a computer model based on AI principles. The model allows them to describe and subsequently predict the moves that people make when faced with new situations in the game.
"In this computational model, players build a 'decision tree' in their heads the same way that you might plan for multiple possible scenarios for a complex travel itinerary," Ma explains.
ere, their calculations showed that human behavior can be captured using a computational cognitive model based on a heuristic search algorithm -- one that maps out a sequence of promising moves for both players.
To validate the model, the researchers conducted a series of behavioral experiments with human participants. Specifically, they tracked how players planned their moves under different scenarios while also testing their memory and their ability to learn from and reconstruct their game-playing experiences. In addition, the team conducted a Turing test experiment in which observers, who had played the game before, were asked to determine whether sequences of moves they witnessed were generated by the model or by human players. These observers were able to make the correct distinction only about half the time, suggesting that the model makes similar decisions that a human would make. Several of these experiments may be played online by going to Ma's laboratory website.
Overall, their results showed that better planning is driven by the ability to recognize patterns more accurately and in less time -- outcomes that point to the benefits of practice and experience.
"It is known that cognitive abilities can improve in adulthood through practice," observes Ma. "These findings show that even a relatively modest amount of practice can improve one's depth of planning. This opens up new avenues of research. For example, we can use these methods to study the development of planning abilities in children, or test whether planning abilities can be retained in old age. Of course, it is also crucial that we connect planning in the laboratory to planning in real life."
The paper's other authors are: Bas van Opheusden, an NYU doctoral student at the time of the study and now a research scientist at Generally Intelligent; Ionatan Kuperwajs, an NYU doctoral student; Gianni Galbiati, an NYU researcher at the time of the study and now director of research and development at Vidrovr; Zahy Bnaya, a postdoctoral researcher at NYU's Center for Neural Science; and Yunqi Li, an NYU researcher at the time of the study and now a doctoral student at Stanford University.
The research was supported by grants from the National Science Foundation (IIS-1344256, DGE1839302).
https://www.sciencedaily.com/releases/2023/05/230531150112.htm
Low sexual satisfaction linked to memory decline later in life
May 30, 2023
Science Daily/Penn State
Low sexual satisfaction in middle age may serve as an early warning sign for future cognitive decline, according to a new study led by Penn State researchers. The study, which tracked associations between erectile function, sexual satisfaction and cognition in hundreds of men aged 56 through 68, found that declines in sexual satisfaction and erectile function were correlated with future memory loss.
The study, published in the latest issue of the journal Gerontologist, is the first to longitudinally track sexual satisfaction in tandem with sexual health and cognition, the researchers state, and its findings point to a potential novel risk factor for cognitive decline.
"What was unique about our approach is that we measured memory function and sexual function at each point in the longitudinal study, so we could look at how they changed together over time," said Martin Sliwinski, professor of human development and family studies at Penn State and co-author on the study. "What we found connects to what scientists are beginning to understand about the link between life satisfaction and cognitive performance."
The study explored the relationship between physical changes like the microvascular changes relevant for erectile function, and psychological changes, such as lower sexual satisfaction, to determine how the changes relate to cognition. They examined the shifts starting in middle age because it represents a transition period where declines in erectile function, cognition and sexual satisfaction begin to emerge.
Sliwinski added that while the team discovered a strong correlation between the three health factors, they can only speculate as to the cause.
"Scientists have found that if you have low satisfaction generally, you are at a higher risk for health problems like dementia, Alzheimer's disease, cardiovascular disease and other stress-related issues that can lead to cognitive decline," he said. "Improvements in sexual satisfaction may actually spark improvement in memory function. We tell people they should get more exercise and eat better foods. We're showing that sexual satisfaction also has importance for our health and general quality of life."
For the study, the researchers used survey data from 818 men who participated in the Vietnam Era Twin Study of Aging. Through neuropsychological tests, such as tests of memory and processing speed, they examined cognitive changes of participants over the 12-year span from age 56 to 68, adjusting for participants' cognitive ability in young adulthood. Their erectile function and sexual satisfaction were measured alongside cognition, using the International Index of Erectile Function, a self-reported assessment for male sexual health. The researchers then built a statistical model to understand how the three variables changed as individuals aged.
"Research on sexual health has historically focused on quantifiable facets of sexuality like number of sexual partners or frequency of sexual activity," said Riki Slayday, a doctoral candidate at Penn State and lead author on the study. "What we were interested in is the perception of that activity, how someone feels about their sex life, and how that influences cognitive function, because multiple people could be in the same situation physically but experience completely different levels of satisfaction."
The study found that decreases in erectile function and sexual satisfaction were both associated with memory decline, which the researchers say points to a connection between psychological and physical health.
"When we mapped the relationship over time, we found increases or decreases in erectile function and sexual satisfaction were associated with concurrent increases or decreases in cognitive function," Slayday said. "These associations survived adjustment for demographic and health factors, which tells us there is a clear connection between our sex lives and our cognition."
Prior studies have found a link between microvascular changes and changes in erectile function over time. In fact, the active ingredient in Viagra (Sildenafil) was originally developed to treat cardiovascular problems, Sliwinski explained, so the connection between vascular health and erectile function is well understood. How erectile function connects to other aspects of health should be an area of focus for future research, he added.
Increasing the assessment and monitoring of erectile function as a vital sign of health may help identify those at risk of cognitive decline before their 70s, he said. The researchers note that the older adult population in the U.S. is expected to double over the next 30 years, which means twice as many people will likely enter their 60s and experience declines in erectile function and sexual satisfaction.
"We already have a pill for treating erectile dysfunction. What we don't have is an effective treatment for memory loss," Sliwinski said. "Instead of the conversation being about treating ED, we should see that as a leading indicator for other health problems and also focus on improving sexual satisfaction and overall well-being, not just treating the symptom."
https://www.sciencedaily.com/releases/2023/05/230530125414.htm
Low-flavanol diet drives age-related memory loss
May 29, 2023
Science Daily/Columbia University Irving Medical Center
Age-related memory loss is likely caused, in part, by lack of flavanols -- nutrients found in certain fruits and vegetables -- according to a large study in older adults.
A large-scale study led by researchers at Columbia and Brigham and Women's Hospital/Harvard is the first to establish that a diet low in flavanols -- nutrients found in certain fruits and vegetables -- drives age-related memory loss.
The study found that flavanol intake among older adults tracks with scores on tests designed to detect memory loss due to normal aging and that replenishing these bioactive dietary components in mildly flavanol-deficient adults over age 60 improves performance on these tests.
"The improvement among study participants with low-flavanol diets was substantial and raises the possibility of using flavanol-rich diets or supplements to improve cognitive function in older adults," says Adam Brickman, PhD, professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons and co-leader of the study.
The finding also supports the emerging idea that the aging brain requires specific nutrients for optimal health, just as the developing brain requires specific nutrients for proper development.
"The identification of nutrients critical for the proper development of an infant's nervous system was a crowning achievement of 20th century nutrition science," says the study's senior author, Scott Small, MD, the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons.
"In this century, as we are living longer research is starting to reveal that different nutrients are needed to fortify our aging minds. Our study, which relies on biomarkers of flavanol consumption, can be used as a template by other researchers to identify additional, necessary nutrients."
Age-related memory loss linked to changes in hippocampus
The current study builds on over 15 years of research in Small's lab linking age-related memory loss to changes in the dentate gyrus, a specific area within the brain's hippocampus -- a region that is vital for learning new memories -- and showing that flavanols improved function in this brain region.
Additional research, in mice, found that flavanols -- particularly a bioactive substance in flavanols called epicatechin -- improved memory by enhancing the growth of neurons and blood vessels and in the hippocampus.
Next, Small's team tested flavanol supplements in people. One small study confirmed that the dentate gyrus is linked to cognitive aging. A second, larger trial showed that flavanols improved memory by acting selectively on this brain region and had the most impact on those starting out with a poor-quality diet.
In the new study, the Columbia team collaborated with researchers at Brigham and Women's Hospital studying the effects of flavanols and multivitamins in COSMOS (COcoa Supplements and Multivitamin Outcomes Study). The current study, COSMOS-Web, was designed to test the impact of flavanols in a much larger group and explore whether flavanol deficiency drives cognitive aging in this area of the brain.
Study methods
More than 3,500 healthy older adults were randomly assigned to receive a daily flavanol supplement (in pill form) or placebo pill for three years. The active supplement contained 500 mg of flavanols, including 80 mg epicatechins, an amount that adults are advised to get from food.
At the beginning of the study, all participants completed a survey that assessed the quality of their diet, including foods known to be high in flavanols. Participants then performed a series of web-based activities in their own homes, designed and validated by Brickman, to assess the types of short-term memory governed by the hippocampus. The tests were repeated after years one, two, and three. Most of the participants identified themselves as non-Hispanic and white.
More than a third of the participants also supplied urine samples that allowed researchers to measure a biomarker for dietary flavanol levels, developed by co-study authors at Reading University in the UK, before and during the study. The biomarker gave the researchers a more precise way to determine if flavanol levels corresponded to performance on the cognitive tests and ensure that participants were sticking to their assigned regimen (compliance was high throughout the study). Flavanol levels varied moderately, though no participants were severely flavanol-deficient.
People with mild flavanol deficiency benefited from flavanol supplement
Memory scores improved only slightly for the entire group taking the daily flavanol supplement, most of whom were already eating a healthy diet with plenty of flavanols.
But at the end of the first year of taking the flavanol supplement, participants who reported consuming a poorer diet and had lower baseline levels of flavanols saw their memory scores increase by an average of 10.5% compared to placebo and 16% compared to their memory at baseline. Annual cognitive testing showed the improvement observed at one year was sustained for at least two more years.
The results strongly suggest that flavanol deficiency is a driver of age-related memory loss, the researchers say, because flavanol consumption correlated with memory scores and flavanol supplements improved memory in flavanol-deficient adults.
The findings of the new study are consistent with those of a recent study, which found that flavanol supplements did not improve memory in a group of people with a range of baseline flavanol levels. The previous study did not look at the effects of flavanol supplements on people with low and high flavanol levels separately.
"What both studies show is that flavanols have no effect on people who don't have a flavanol deficiency," Small says.
It's also possible that the memory tests used in the previous study did not assess memory processes in the area of the hippocampus affected by flavanols. In the new study, flavanols only improved memory processes governed by the hippocampus and did not improve memory mediated by other areas of the brain.
Next steps
"We cannot yet definitively conclude that low dietary intake of flavanols alone causes poor memory performance, because we did not conduct the opposite experiment: depleting flavanol in people who are not deficient," Small says, adding that such an experiment might be considered unethical.
The next step needed to confirm flavanols' effect on the brain, Small says, is a clinical trial to restore flavanol levels in adults with severe flavanol deficiency.
"Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability," says Small. "If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they're in their 40s and 50s."
https://www.sciencedaily.com/releases/2023/05/230529171757.htm
Running throughout middle age keeps 'old' adult-born neurons 'wired'
'Mice on the run:' study reveals how exercise helps maintain memory function during aging
May 25, 2023
Science Daily/Florida Atlantic University
A new study provides novel insight into the benefits of exercise, which should motivate adults to keep moving throughout their lifetime, especially during middle age. Long-term exercise profoundly benefits the aging brain and may prevent aging-related memory function decline by increasing the survival and modifying the network of the adult-born neurons born during early adulthood, and thereby facilitating their participation in cognitive processes.
Aging often is accompanied by cognitive decline. Among the first structures of the brain affected are the hippocampus and adjacent cortices, areas essential for learning and memory. Deficits in cognitive ability are associated with reduced hippocampal volume and degradation of synaptic connectivity between the hippocampus and the (peri)-entorhinal cortex.
Increasing evidence indicates that physical activity can delay or prevent these structural and functional reductions in older adults. A new study by Florida Atlantic University and CINVESTAV, Mexico City, Mexico, provides novel insight into the benefits of exercise, which should motivate adults to keep moving throughout their lifetime, especially during middle age.
For the study, researchers focused on the effects of long-term running on a network of new hippocampal neurons that were generated in young adult mice, at middle age. These "mice on the run" demonstrate that running throughout middle age keeps old adult-born neurons wired, which may prevent or delay aging-related memory loss and neurodegeneration.
Adult-born neurons are thought to contribute to hippocampus-dependent memory function and are believed to be temporarily important, during the so-called 'critical period' at about three to six weeks of cell age, when they can fleetingly display increased synaptic plasticity. However, these new neurons do remain present for many months, but it was unclear whether those born in early adulthood remain integrated into neural networks and whether their circuitry is modifiable by physical activity in middle age.
To address these questions, researchers used a unique rabies virus-based circuit tracing approach with a long-time interval between the initial labeling of new neurons and subsequent analysis of their neural circuitry in rodents. More than six months after tagging of the adult-born neurons with a fluorescent reporter vector, they identified and quantified the direct afferent inputs to these adult-born neurons within the hippocampus and (sub)cortical areas, when the mice were middle-aged.
Results of the study, published in the journal eNeuro, show long-term running wires 'old' new neurons, born during early adulthood, into a network that is relevant to the maintenance of episodic memory encoding during aging.
"Long-term exercise profoundly benefits the aging brain and may prevent aging-related memory function decline by increasing the survival and modifying the network of the adult-born neurons born during early adulthood, and thereby facilitating their participation in cognitive processes," said Henriette van Praag, Ph.D., corresponding author, an associate professor of biomedical science in FAU's Schmidt College of Medicine and a member of the FAU Stiles-Nicholson Brain Institute.
Findings from the study showed long-term running significantly increased the number of adult-born neurons and enhanced the recruitment of presynaptic (sub)-cortical cells to their network.
"Long-term running may enhance pattern separation ability, our ability to distinguish between highly similar events and stimuli, a behavior closely linked to adult neurogenesis, which is among the first to display deficits indicative of age-related memory decline," said Carmen Vivar, Ph.D., corresponding author, Department of Physiology, Biophysics and Neuroscience, Centro de Investigacion y de Estudios Avanzados del IPN in Mexico.
Aging-related memory function decline is associated with the degradation of synaptic inputs from the perirhinal and entorhinal cortex onto the hippocampus, brain areas that are essential for pattern separation, and contextual and spatial memory.
"We show that running also substantially increases the back-projection from the dorsal subiculum onto old adult-born granule cells," said van Praag. "This connectivity may provide navigation-associated information and mediate the long-term running-induced improvement in spatial memory function."
Results from the study show that running not only rescued perirhinal connectivity but also increased and altered the contribution of the entorhinal cortices to the network of old adult-born neurons.
"Our study provides insight as to how chronic exercise, beginning in young adulthood and continuing throughout middle age, helps maintain memory function during aging, emphasizing the relevance of including exercise in our daily lives," said Vivar.
https://www.sciencedaily.com/releases/2023/05/230525140336.htm
Brain connectivity, memory improves in older adults after walking
May 25, 2023
Science Daily/University of Maryland
Regular walks strengthen connections in and between brain networks, according to new research, adding to growing evidence linking exercise with slowing the onset of Alzheimer's disease. The study examined the brains and story recollection abilities of older adults with normal brain function and those diagnosed with mild cognitive impairment, which is a slight decline in mental abilities like memory, reasoning and judgment and a risk factor for Alzheimer's.
A new University of Maryland School of Public Health study reveals how walking strengthens connections within and between three of the brain's networks, including one associated with Alzheimer's disease, adding to the growing evidence that exercise improves brain health.
Published this month in the Journal for Alzheimer's Disease Reports, the study examined the brains and story recollection abilities of older adults with normal brain function and those diagnosed with mild cognitive impairment, which is a slight decline in mental abilities like memory, reasoning and judgment and a risk factor for Alzheimer's.
"Historically, the brain networks we studied in this research show deterioration over time in people with mild cognitive impairment and Alzheimer's disease," said J. Carson Smith, a kinesiology professor with the School of Public Health and principal investigator of the study. "They become disconnected, and as a result, people lose their ability to think clearly and remember things. We're demonstrating that exercise training strengthens these connections."
The study builds upon Smith's previous research, which showed how walking may decrease cerebral blood flow and improve brain function in older adults with mild cognitive impairment.
Thirty-three participants, who ranged between 71 and 85 years old, walked while supervised on a treadmill four days a week for 12 weeks. Before and after this exercise regimen, researchers asked participants to read a short story and then repeat it out loud with as many details as possible.
Participants also underwent functional magnetic resonance imaging (fMRI) so researchers could measure changes in communication within and between the three brain networks that control cognitive function:
Default mode network - Activates when a person isn't doing a specific task (think daydreaming about the grocery list) and is connected to the hippocampus -- one of the first brain regions affected by Alzheimer's disease. It's also where Alzheimer's and amyloid plaques, a prime suspect for Alzheimer's disease found around nerve cells, show up in tests.
Frontoparietal network -- Regulates decisions made when a person is completing a task. It also involves memory.
Salience network -- Monitors the external world and stimuli and then decides what deserves attention. It also facilitates switching between networks to optimize performance.
After 12 weeks of exercise, researchers repeated the tests and saw significant improvements in participants' story recall abilities.
"The brain activity was stronger and more synchronized, demonstrating exercise actually can induce the brain's ability to change and adapt," Smith said. "These results provide even more hope that exercise may be useful as a way to prevent or help stabilize people with mild cognitive impairment and maybe, over the long term, delay their conversion to Alzheimer's dementia."
Researchers also observed stronger activity within the default mode network, within the salience network and in the connections between the three networks.
https://www.sciencedaily.com/releases/2023/05/230525135932.htm
People who live to be 90+ with superior thinking skills are resilient to Alzheimer's pathology in their brains
These oldest-old are also less susceptible to other types of neurodegenerative changes
May 24, 2023
Science Daily/University of California - Irvine
Researchers have discovered that the oldest-old, those who live to be 90+ and have superior cognitive skills, have similar levels of brain pathology as Alzheimer's patients, however, they also have less brain pathology of other neurodegenerative diseases that cause memory and thinking problems.
A University of California, Irvine-led team of researchers have discovered that the oldest-old, those who live to be 90+ and have superior cognitive skills, have similar levels of brain pathology as Alzheimer's patients, however, they also have less brain pathology of other neurodegenerative diseases that cause memory and thinking problems.
The study, "Superior Global Cognition in Oldest-Old is Associated with Resistance to Neurodegenerative Pathologies: Results from the 90+ Study," was published in the Journal of Alzheimer's Disease.
"People who are 90+ and still have good memory and thinking abilities tend to have similar levels of Alzheimer's pathology in their brains," Roshni Biswas, post-doctoral scholar with The 90+ Study. "Our findings indicate that while Alzheimer's Disease neuropathological changes and vascular changes are common in their brains, these individuals are less susceptible to other types of neurodegenerative changes such as Lewy body disease."
Age is the primary risk factor for cognitive issues, such as Alzheimer's, Lewy body disease and other related dementias. Over the past 30 years, the number of people aged 90 and older in the U.S. has nearly tripled, and this number is projected to quadruple in the next four decades.
With this rise in age, many people see increased problems with memory and brain function. However, little data is available on the changes in the brains of 90+ people who maintain superior cognitive abilities, despite their age.
The objective of the study was to examine the brain features of people without cognitive impairment and their relation to superior cognitive skills and reasoning in those that are 90+.
"There are some individuals who can maintain high levels of cognitive function well into advanced ages," said María M. Corrada, ScD, co-principal investigator of the study and professor in the Department of Neurology at UCI School of Medicine. "Further research into the factors that enable these individuals to maintain their cognitive function could provide insights into how to preserve cognitive health despite advanced age."
The study results were derived by analyzing autopsy data from 102 cognitively normal individuals who died at a mean age of 97.6 years. They also used cognitive test scores from people taken between two to twelve months before death. The average age of study participants at the time of their last visit was 97.1 years of age.
"In our future research, we will examine how lifestyle habits and health conditions are associated with superior cognition in individuals who are 90+ and the factors that contribute to maintaining stable cognitive function over time," said Biswas.
The 90+ Study is a longitudinal study on aging and dementia that was initiated in 2003 to study the oldest-old population, which is the fastest growing age group in the United States.
With more than 2000 participants enrolled, it is now one of the largest studies of its kind in the world. The project has produced several significant findings regarding cognitive function, health and lifestyle habits in the oldest-old population information obtained during life.
This work was supported by the National Institutes of Health.
https://www.sciencedaily.com/releases/2023/05/230524182040.htm
Multivitamin improves memory in older adults
May 24, 2023
Science Daily/Columbia University Irving Medical Center
Taking a daily multivitamin supplement can slow age-related memory decline, finds a large study led by researchers at Columbia University and Brigham and Women's Hospital/Harvard.
"Cognitive aging is a top health concern for older adults, and this study suggests that there may be a simple, inexpensive way to help older adults slow down memory decline," says study leader Adam M. Brickman, PhD, professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons.
Many older people take vitamins or dietary supplements under the assumption that they will help maintain general health. But studies that have tested whether they improve memory and brain function have been mixed, and very few large-scale, randomized trials have been done.
Study methods
In the current study, more than 3,500 adults (mostly non-Hispanic white) over age 60 were randomly assigned to take a daily multivitamin supplement or placebo for three years. At the end of each year, participants performed a series of online cognitive assessments at home designed to test memory function of the hippocampus, an area of the brain that is affected by normal aging. The COSMOS-Web study is part of a large clinical trial led by Brigham & Women's Hospital and Harvard called the COcoa Supplement and Multivitamin Outcomes Study (COSMOS).
By the end of the first year, memory improved for people taking a daily multivitamin, compared with those taking a placebo. The researchers estimate the improvement, which was sustained over the three-year study period, was equivalent to about three years of age-related memory decline. The effect was more pronounced in participants with underlying cardiovascular disease.
The results of the new study are consistent with another recent COSMOS study of more than 2,200 older adults that found that taking a daily multivitamin improved overall cognition, memory recall, and attention, effects that were also more pronounced in those with underlying cardiovascular disease.
"There is evidence that people with cardiovascular disease may have lower micronutrient levels that multivitamins may correct, but we don't really know right now why the effect is stronger in this group," says Brickman.
Good nutrition important for aging brain
Though the researchers did not look at whether any specific component of the multivitamin supplement was linked to the improvement in memory, the findings support growing evidence that nutrition is important for optimizing brain health as we age.
"Our study shows that the aging brain may be more sensitive to nutrition than we realized, though it may not be so important to find out which specific nutrient helps slow age-related cognitive decline," says Lok-Kin Yeung, PhD, a postdoctoral researcher in Columbia's Taub Institute for Research on Alzheimer's Disease and the Aging Brain and first author of the study.
"The finding that a daily multivitamin improved memory in two separate cognition studies in the COSMOS randomized trial is remarkable, suggesting that multivitamin supplementation holds promise as a safe, accessible, and affordable approach to protecting cognitive health in older adults," says co-author JoAnn Manson, MD, chief of the Division of Preventive Medicine at Brigham and Women's Hospital.
"Supplementation of any kind shouldn't take the place of more holistic ways of getting the same micronutrients," adds Brickman. "Though multivitamins are generally safe, people should always consult a physician before taking them."
https://www.sciencedaily.com/releases/2023/05/230524181916.htm
Vitamin D alters developing neurons in the brain's dopamine circuit
May 24, 2023
Science Daily/University of Queensland
Neuroscientists at The University of Queensland have uncovered how vitamin D deficiency affects developing neurons in schizophrenia, using new technology.
Professor Darryl Eyles has built on past research out of his laboratory at the Queensland Brain Institute linking maternal vitamin D deficiency and brain development disorders, such as schizophrenia, to understand the functional changes taking place in the brain.
Schizophrenia is associated with many developmental risk factors, both genetic and environmental. While the precise neurological causes of the disorder are unknown, what is known is that schizophrenia is associated with a pronounced change in the way the brain uses dopamine, the neurotransmitter often referred to as the brain's 'reward molecule'.
Professor Eyles has followed the mechanisms that might relate to abnormal dopamine release and discovered that maternal vitamin D deficiency affects the early development and later differentiation of dopaminergic neurons.
The team at the Queensland Brain Institute developed dopamine-like cells to replicate the process of differentiation into early dopaminergic neurons that usually takes place during embryonic development.
They cultured the neurons both in the presence and absence of the active vitamin D hormone. In three different model systems they showed dopamine neurite outgrowth was markedly increased. They then showed alterations in the distribution of presynaptic proteins responsible for dopamine release within these neurites.
"What we found was the altered differentiation process in the presence of vitamin D not only makes the cells grow differently, but recruits machinery to release dopamine differently," Professor Eyles said.
Using a new visualisation tool known as false fluorescent neurotransmitters, the team could then analyse the functional changes in presynaptic dopamine uptake and release in the presence and absence of vitamin D.
They showed that dopamine release was enhanced in cells grown in the presence of the hormone compared to a control.
"This is conclusive evidence that vitamin D affects the structural differentiation of dopaminergic neurons."
Leveraging advances in targeting and visualising single molecules within presynaptic nerve terminals has enabled Professor Eyles and his team to further explore their long-standing belief that maternal vitamin D deficiency changes how early dopaminergic circuits are formed.
The team is now exploring whether other environmental risk factors for schizophrenia such as maternal hypoxia or infection similarly alter the trajectory of dopamine neuron differentiation.
Eyles and his team believe such early alterations to dopamine neuron differentiation and function may be the neurodevelopmental origin of dopamine dysfunction later in adults who develop schizophrenia.
https://www.sciencedaily.com/releases/2023/05/230524182026.htm
Forgetfulness, even fatal cases, can happen to anyone
May 18, 2023
Science Daily/University of Notre Dame
Since 1998, approximately 496 children have died of pediatric vehicular heatstroke in the United States because their caregiver forgot they were in the car, according to recent data from NoHeatStroke.org.
Advocacy groups have been lobbying Congress to enact laws to help protect against this particular forgetfulness by requiring certain safety mechanisms be installed into automobiles. Researchers at the University of Notre Dame set out to understand how and why this kind of forgetfulness is even possible.
Nathan Rose, the William P. and Hazel B. White Assistant Professor of Brain, Behavior and Cognition in the Department of Psychology, set up an experiment to better understand this lapse in what researchers call prospective memory, or the ability to remember critical but routine behaviors such as turning off the oven when you leave the house for the day.
In a study recently published in the Journal of Applied Research in Memory and Cognition, Rose and doctoral candidates Abigail Doolen and Andrea O'Rear designed a naturalistic procedure to measure if and how college students could forget their cellphones -- something most are dearly attached to and that could have serious consequences for them if forgotten. Their "babies," so to speak.
The researchers took the cellphones of 192 Notre Dame students while they participated in an unrelated experiment and then examined how often the students forgot to retrieve their phone when they left the lab at the end of the experiment, and whether it mattered if they were given explicit reminders to grab the phone once the experiment was complete.
For the study, students were also given activity trackers to attach to the back of their waistbands. One group was reminded to ask for their cellphone and to return the tracker when finished; the other group was not. After the students finished the unrelated experiment, they were debriefed and guided to an exit, while the experimenters pretended to go on with business as usual -- watching to see if and when the participants remembered to retrieve their phone or return the tracker.
About 7 percent of students forgot their cellphones without the reminder, compared to almost 5 percent of those who were reminded. Nearly 18 percent of either category forgot to return the tracker.
The researchers discovered that forgetting occurs when environmental cues fail to trigger one's memory of that intention at the right moment, and the intention gets lost in the shuffle, Rose said. They also found that prospective memory errors can happen to anyone.
"You process those more automatically, so you can get lost in your thoughts because your behaviors are being driven by the environment," Rose said. "It's not that you forget what it is you're supposed to be doing; you're just forgetting to do it at the appropriate moment."
The same way the students missed the environmental cues to remind them to pick up their phone or return the tracker, so it is for parents who are driving to work or running errands with a baby in the backseat, the researchers theorized. Before laws were established in the 1990s requiring car seats to be placed rear-facing in the back seat, forgetting babies in cars was uncommon. "The absence of salient visual and auditory cues from a child who is sleeping in the backseat creates a scenario conducive to forgetting the child is in the car," the researchers wrote.
Or, Rose explained, if a parent is taking a child in the car but is not typically the caregiver who does that activity, and he or she gets into the routine and set pattern of driving to work, he or she may forget the child is even there.
Rose explained that memory errors occur at the same frequency between men and women. "When you talk about the forgotten baby scenarios, people often make assumptions about who forgets their babies, who the caregivers are," Rose said. "And there's no evidence to support the idea that men are more likely to commit this kind of error than women, or vice versa."
Rose and his co-authors believe this research can have serious implications when it comes to exonerating parents who mistakenly forget to retrieve their children out of their car seats, resulting in their deaths. "This study should help inform the public and judicial system about what does and does not cause such memory errors to happen," the researchers wrote, "even those with tragic consequences."
https://www.sciencedaily.com/releases/2023/05/230518171959.htm