1. Sound waves boost older adults’ memory, deep sleep

    March 23, 2017 by Ashley

    From the Northwestern University press release:

    IF

    Gentle sound stimulation — such as the rush of a waterfall — synchronized to the rhythm of brain waves significantly enhanced deep sleep in older adults and improved their ability to recall words, reports a new Northwestern Medicine study.

    Deep sleep is critical for memory consolidation. But beginning in middle age, deep sleep decreases substantially, which scientists believe contributes to memory loss in aging.

    The sound stimulation significantly enhanced deep sleep in participants and their scores on a memory test.

    “This is an innovative, simple and safe non-medication approach that may help improve brain health,” said senior author Dr. Phyllis Zee, professor of neurology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine sleep specialist. “This is a potential tool for enhancing memory in older populations and attenuating normal age-related memory decline.”

    The study will be published March 8 in Frontiers in Human Neuroscience.

    In the study, 13 participants 60 and older received one night of acoustic stimulation and one night of sham stimulation. The sham stimulation procedure was identical to the acoustic one, but participants did not hear any noise during sleep. For both the sham and acoustic stimulation sessions, the individuals took a memory test at night and again the next morning. Recall ability after the sham stimulation generally improved on the morning test by a few percent. However, the average improvement was three times larger after pink-noise stimulation.

    The older adults were recruited from the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern.

    The degree of slow wave sleep enhancement was related to the degree of memory improvement, suggesting slow wave sleep remains important for memory, even in old age.

    Although the Northwestern scientists have not yet studied the effect of repeated nights of stimulation, this method could be a viable intervention for longer-term use in the home, Zee said.

    Previous research showed acoustic simulation played during deep sleep could improve memory consolidation in young people. But it has not been tested in older adults.

    The new study targeted older individuals — who have much more to gain memory-wise from enhanced deep sleep — and used a novel sound system that increased the effectiveness of the sound stimulation in older populations.

    The study used a new approach, which reads an individual’s brain waves in real time and locks in the gentle sound stimulation during a precise moment of neuron communication during deep sleep, which varies for each person.

    During deep sleep, each brain wave or oscillation slows to about one per second compared to 10 oscillations per second during wakefulness.

    Giovanni Santostasi, a study coauthor, developed an algorithm that delivers the sound during the rising portion of slow wave oscillations. This stimulation enhances synchronization of the neurons’ activity.

    After the sound stimulation, the older participants’ slow waves increased during sleep.

    Larger studies are needed to confirm the efficacy of this method and then “the idea is to be able to offer this for people to use at home,” said first author Nelly Papalambros, a Ph.D. student in neuroscience working in Zee’s lab. “We want to move this to long-term, at-home studies.”

    Northwestern scientists, under the direction of Dr. Roneil Malkani, assistant professor of neurology at Feinberg and a Northwestern Medicine sleep specialist, are currently testing the acoustic stimulation in overnight sleep studies in patients with memory complaints. The goal is to determine whether acoustic stimulation can enhance memory in adults with mild cognitive impairment.

    Previous studies conducted in individuals with mild cognitive impairment in collaboration with Ken Paller, professor of psychology at the Weinberg College of Arts and Sciences at Northwestern, have demonstrated a possible link between their sleep and their memory impairments.


  2. Blueberry concentrate improves brain function in older people

    March 20, 2017 by Ashley

    From the University of Exeter press release:

    Blueberries

    Drinking concentrated blueberry juice improves brain function in older people, according to research by the University of Exeter.

    In the study, healthy people aged 65-77 who drank concentrated blueberry juice every day showed improvements in cognitive function, blood flow to the brain and activation of the brain while carrying out cognitive tests.

    There was also evidence suggesting improvement in working memory.

    Blueberries are rich in flavonoids, which possess antioxidant and anti-inflammatory properties.

    Dr Joanna Bowtell, head of Sport and Health Sciences at the University of Exeter, said: “Our cognitive function tends to decline as we get older, but previous research has shown that cognitive function is better preserved in healthy older adults with a diet rich in plant-based foods.

    “In this study we have shown that with just 12 weeks of consuming 30ml of concentrated blueberry juice every day, brain blood flow, brain activation and some aspects of working memory were improved in this group of healthy older adults.”

    Of the 26 healthy adults in the study, 12 were given concentrated blueberry juice — providing the equivalent of 230g of blueberries — once a day, while 14 received a placebo.

    Before and after the 12-week period, participants took a range of cognitive tests while an MRI scanner monitored their brain function and resting brain blood flow was measured.

    Compared to the placebo group, those who took the blueberry supplement showed significant increases in brain activity in brain areas related to the tests.

    The study excluded anyone who said they consumed more than five portions of fruit and vegetables per day, and all participants were told to stick to their normal diet throughout.

    Previous research has shown that risk of dementia is reduced by higher fruit and vegetable intake, and cognitive function is better preserved in healthy older adults with a diet rich in plant-based foods.

    Flavonoids, which are abundant in plants, are likely to be an important component in causing these effects.


  3. Might smartphones help to maintain memory in patients with mild Alzheimer’s disease?

    by Ashley

    From the IOS Press press release:

    The patient is a retired teacher who had reported memory difficulties 12 months prior to the study. These difficulties referred to trouble remembering names and groceries she wanted to purchase, as well as frequently losing her papers and keys. According to the patient and her husband, the main difficulties that she encountered were related to prospective memory (e.g., forgetting medical appointments or to take her medication).

    To help her with her symptoms, Mohamad El Haj, a psychologist and assistant professor at the University of Lille, proposed Google Calendar, a time-management and scheduling calendar service developed by Google. The patient accepted as she was already comfortable using her smartphone. She also declared that she preferred the application as it offers more discrete assistance than a paper-based calendar.

    With the patient and her husband, Dr. El Haj and his colleagues defined several prospective omissions in the patient, such as forgetting her weekly medical appointment, forgetting her weekly bridge game in the community club, and forgetting to go to weekly mass at the church. These omissions were targeted by sending automatic alerts, prompted by Google Calendar, at different times before each event (e.g., the medical appointment).

    The researchers compared omissions before after the use of Google Calendar, they observed less omission after implementing the application.

    The study is the first to suggest positive effects of smartphones applications on everyday life prospective memory in Alzheimer’s disease. The findings, published in Journal of Alzheimer’s disease, are encouraging, however, Dr. El Haj notes that this is a case study and therefore entails a few limitations, including generalizability of the results. The current, anecdotal findings require a larger study, not only to confirm or refute the findings reported here, but also to address challenges such as the long-term benefits of Google calendar.

    Regardless of its potential limitations, Dr. El Haj notes that this study addresses memory loss, the main cognitive hallmark of Alzheimer’s disease and the major concern of the patients and their families. By demonstrating positive effect of Google Calendar on prospective memory in this patient, Dr. El Haj hopes that his study paves the way for exploring the potential of smartphone-integrated memory aids in Alzheimer’s disease. The future generation of patients may be particularly sensitive to the use of smartphones as a tool to alleviate their memory compromise.


  4. Rapid blood pressure drops in middle age linked to dementia in old age

    March 14, 2017 by Ashley

    From the Johns Hopkins University Bloomberg School of Public Health media release:

    Middle-aged people who experience temporary blood pressure drops that often cause dizziness upon standing up may be at an increased risk of developing cognitive decline and dementia 20 years later, new Johns Hopkins Bloomberg School of Public Health research suggests.

    The findings, being presented March 10 at the American Heart Association’s EPI|LIFESTYLE 2017 Scientific Sessions in Portland, Ore., suggest that these temporary episodes — known as orthostatic hypotension — may cause lasting damage, possibly because they reduce needed blood flow to the brain. Previous research has suggested a connection between orthostatic hypotension and cognitive decline in older people, but this appears to be the first to look at long-term associations.

    “Even though these episodes are fleeting, they may have impacts that are long lasting,” says study leader Andreea Rawlings, PhD, MS, a post-doctoral researcher in the Department of Epidemiology at the Bloomberg School. “We found that those people who suffered from orthostatic hypotension in middle age were 40 percent more likely to develop dementia than those who did not. It’s a significant finding and we need to better understand just what is happening.”

    An estimated four million to five million Americans currently have dementia and, as the population ages, that number is only expected to grow. There currently is no treatment and no cure for the condition.

    For the study, the researchers analyzed data from the Atherosclerosis Risk in Communities (ARIC) cohort, a study of 15,792 residents in four communities in the United States, who were between the ages of 45 and 64 when the study began in 1987. For this study, they focused on the 11,503 participants at visit one who had no history of coronary heart disease or stroke. After 20 minutes lying down, researchers took the participants’ blood pressure upon standing. Orthostatic hypotension was defined as a drop of 20 mmHg or more in systolic blood pressure or 10 mmHg or more in diastolic blood pressure. Roughly six percent of participants, or 703 people, met the definition.

    These participants, who were on average 54 years old upon enrolling in the study, continued to be followed over the next 20 or more years. People with orthostatic hypotension at the first visit were 40 percent more likely to develop dementia than those who did not have it. They had 15 percent more cognitive decline.

    Rawlings says it is not possible to tease out for certain whether the orthostatic hypotension was an indicator of some other underlying disease or whether the drop in blood pressure itself is the cause, though it is likely that the reduction in blood flow to the brain, however temporary, could have lasting consequences.

    It also wasn’t clear, she says, whether these participants had repeated problems with orthostatic hypotension over many years or whether they had just a brief episode of orthostatic hypotension at the original enrollment visit, as patients were not retested over time.

    “Identifying risk factors for cognitive decline and dementia is important for understanding disease progression, and being able to identify those most at risk gives us possible strategies for prevention and intervention,” Rawlings says. “This is one of those factors worth more investigation.”


  5. Benzodiazepines, related drugs increase stroke risk among persons with Alzheimer’s disease

    January 25, 2017 by Ashley

    From the University of Eastern Finland media release:

    memory lossThe use of benzodiazepines and benzodiazepine-like drugs was associated with a 20 per cent increased risk of stroke among persons with Alzheimer’s disease, shows a recent study from the University of Eastern Finland. Benzodiazepines were associated with a similar risk of stroke as benzodiazepine-like drugs.

    The use of benzodiazepines and benzodiazepine-like drugs was associated with an increased risk of any stroke and ischemic stroke, whereas the association with hemorrhagic stroke was not significant. However, due to the small number of hemorrhagic stroke events in the study population, the possibility of such an association cannot be excluded. The findings are important, as benzodiazepines and benzodiazepine-like drugs were not previously known to predispose to strokes or other cerebrovascular events. Cardiovascular risk factors were taken into account in the analysis and they did not explain the association.

    The findings encourage a careful consideration of the use of benzodiazepines and benzodiazepine-like drugs among persons with Alzheimer’s disease, as stroke is one of the leading causes of death in this population group. Earlier, the researchers have also shown that these drugs are associated with an increased risk of hip fracture.

    The study was based on data from a nationwide register-based study (MEDALZ) conducted at the University of Eastern Finland in 2005-2011. The study population included 45,050 persons diagnosed with Alzheimer’s disease, and 22 per cent of them started using benzodiazepines or benzodiazepine-like drugs.

    The findings were published in International Clinical Psychopharmacology.


  6. The lasting effects of ministrokes may contribute to dementia

    January 24, 2017 by Ashley

    From the Medical University of South Carolina media release:

    hospital emergency signEvidence overwhelmingly supports a link between cognitive decline and cerebrovascular diseases such as atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy.

    Not only do individuals with cerebrovascular diseases have a much higher incidence of cortical microinfarcts (mini-strokes), but post-mortem histological and in vivo radiological studies also find that the burden of microinfarcts is significantly greater among people with vascular cognitive impairment and dementia (VCID) than in age-matched, non-demented individuals.

    Until now, the mechanisms by which these miniscule lesions (~0.05 to 3 millimeters in diameter) contribute to cognitive deficits including dementia have been poorly understood.

    Findings from a recent study by investigators at the Medical University of South Carolina (MUSC) provide crucial information for better understanding the impact of microinfarcts, showing that the functional deficits caused by a single microinfarct can affect a larger area of brain tissue and last longer than was previously thought to be the case.

    The functional effects of microinfarcts are extremely difficult to study. Not only are most microinfarcts difficult to detect with standard neuroimaging techniques, mismatches between in vivo functional data and post-mortem histological evidence make it nearly impossible to connect microinfarcts to the timeline of cognitive decline.

    These infarcts are so small and unpredictable, we just haven’t had good tools to detect them while the person was still alive,” said Andy Shih, Ph.D., Assistant Professor of Neurosciences and senior author on the article. “So, until now, we basically just had post-mortem snapshots of these infarcts at the end of the dementia battle as well as measures of the person’s cognitive decline, which might have been taken years before the brain became available for study.”

    Intrigued by the mounting evidence linking cognitive decline and microinfarct burden, Shih’s group hypothesized that microinfarcts might disrupt brain function beyond what was visible by histology or magnetic resonance imaging (MRI).

    Even though a person may experience hundreds of thousands of microinfarcts in their lifetime, each event is extremely small and thought to resolve in a matter of days,” said Shih. “It’s been estimated that, overall, microinfarcts affect less than 2% of the entire human brain. But those estimates of tissue loss are based only on the ‘core’ of the microinfarct, the area of dead or dying tissue that we can see in routine, post-mortem, histological stains.”

    To investigate their theory of broader impacts, the team developed a mouse model so that they could examine the effects of individual cortical microinfarcts on surrounding tissue function in vivo over several weeks post-event. “We needed a preclinical model to create very predictable lesions that we could follow over time,” said Shih. “Also, we needed to be able to obtain readouts of brain activity that were consistent over time.”

    The team used photothrombosis to occlude a single arteriole in the barrel cortex of mice fitted with cranial windows. They then compared functional readouts of sensory-evoked brain activity, indicated by activity-dependent c-Fos expression or in vivo two-photon imaging of single vessel hemodynamic responses, to the location of the microinfarct core.

    Post-mortem, c-Fos immunostaining revealed that an area estimated to be at least 12-times greater in volume than the microinfarct core had been affected by the event. Furthermore, in vivo, two-photon imaging of single vessel, sensory-evoked hemodynamics found that neuronal activity across the affected tissue area remained partially depressed for 14 to 17 days after the microinfarct.

    Together, these data indicate that functional deficits caused by a single microinfarct occur across a much larger area of viable peri-lesional tissue than was previously understood and that the resulting deficits are much longer-lasting.

    I knew larger strokes could have distant effects, but I was surprised that something of this scale could have such a large effect,” said Shih.

    The duration of effect from a single microinfarct was also a surprise for Shih’s team. “The MRI signal increased and then went away as we’d expected, but we were surprised on autopsy to see that there was still lots going on — tissue damage and neuroinflammation,” Shih explained. “Even after three weeks the neurally evoked blood flow responses had only partially recovered. So, that means a microinfarct can come and go and you can see it briefly with MRI but it leaves a lasting impression on brain function-possibly for months.”

    Importantly, a person with VCID is likely to experience other microinfarcts during this recovery time. Furthermore, these tiny infarcts occur not only in the brain’s grey matter, where this study was conducted, but also in the white matter, which sends messages from one part of the brain to another.

    “Over time, after you have a lot of microinfarcts, there may be enough accumulated damage in the brain’s circuitry to equal the impact of a larger event,” said Shih.

    According to Shih, one of the most important messages from this study is that conventional methods used in clinical trials do not reveal the entire impact that microinfarcts have on brain function. He hopes that his team’s contribution to illuminating microinfarct pathology will help inform MRI interpretation in humans and help researchers better explain some of the relationships that they see in clinical studies.

    These findings might also lead to new preventive protocols. “On a clinical level, maybe it’s a situation where therapeutics can play a bigger role. Maybe drugs that we already have can mitigate the cumulative damage of microinfarcts,” speculated Shih. “The neuro-protective idea hasn’t flown very far for acute stroke, in part, because the window of time for protecting the brain from stroke damage is very narrow. But, for microinfarcts, you don’t have to know exactly when they occur. If an MRI shows a person is at high risk for microinfarcts, maybe one day we can put them on a drug for a while to reduce the impacts of these lesions.”


  7. Living near major traffic linked to higher risk of dementia

    January 13, 2017 by Ashley

    From the Public Health Ontario media release:

    night trafficPeople who live close to high-traffic roadways face a higher risk of developing dementia than those who live further away, new research from Public Health Ontario (PHO) and the Institute for Clinical Evaluative Sciences (ICES) has found.

    Led by PHO and ICES scientists, the study found that people who lived within 50 metres of high-traffic roads had a seven per cent higher likelihood of developing dementia compared to those who lived more than 300 meters away from busy roads.

    Published in The Lancet, the researchers examined records of more than 6.5 million Ontario residents aged 20-85 to investigate the correlation between living close to major roads and dementia, Parkinson’s disease and multiple sclerosis.

    Scientists identified 243,611 cases of dementia, 31,577 cases of Parkinson’s disease, and 9,247 cases of multiple sclerosis in Ontario between 2001 and 2012. In addition, they mapped individuals’ proximity to major roadways using the postal code of their residence. The findings indicate that living close to major roads increased the risk of developing dementia, but not Parkinson’s disease or multiple sclerosis, two other major neurological disorders.

    “Little is known in current research about how to reduce the risk of dementia. Our findings show the closer you live to roads with heavy day-to-day traffic, the greater the risk of developing dementia. With our widespread exposure to traffic and the greater tendency for people to live in cities these days, this has serious public health implications,” says Dr. Hong Chen, environmental and occupational health scientist at PHO and an adjunct scientist at ICES. Dr. Chen is lead author on the paper titled Living Near Major Roads and the Incidence of Dementia, Parkinson’s Disease, and Multiple Sclerosis: A Population-based Cohort Study.

    Our study is the first in Canada to suggest that pollutants from heavy, day-to-day traffic are linked to dementia. We know from previous research that air pollutants can get into the blood stream and lead to inflammation, which is linked with cardiovascular disease and possibly other conditions such as diabetes. This study suggests air pollutants that can get into the brain via the blood stream can lead to neurological problems,” says Dr. Ray Copes, chief of environmental and occupational health at PHO and an author on the paper.

    As urban centres become more densely populated and more congested with vehicles on major roads, Dr. Copes suggests the findings of this paper could be used to help inform municipal land use decisions as well as building design to take into account air pollution factors and the impact on residents.

    This research was conducted in collaboration with scientists from the University of Toronto, Carleton University, Dalhousie University, Oregon State University, and Health Canada. The study was funded by Health Canada.

    Key findings:

    • Using data held at ICES, the researchers examined records of more than 6.5 million Ontario residents, aged 20-85, and mapped them according to residential postal codes five years before the study started.
    • Between 2001 and 2012, 243,611 cases of dementia, 31,577 cases of Parkinson’s disease, and 9,247 cases of multiple sclerosis were identified in Ontario.
    • People who lived within 50 metres of high-traffic roads had a seven per cent higher likelihood of dementia than those who lived more 300 meters away from busy roads.
    • The increase in the risk of developing dementia went down to four per cent if people lived 50-100 metres from major traffic, and to two per cent if they lived within 101-200 metres. At over 200 metres, there was no elevated risk of dementia.
    • There was no correlation between major traffic proximity and Parkinson’s disease or multiple sclerosis.

     


  8. Mediterranean diet may have lasting effects on brain health

    by Ashley

    From the American Academy of Neurology (AAN) media release:

    healthy, vital seniorA new study shows that older people who followed a Mediterranean diet retained more brain volume over a three-year period than those who did not follow the diet as closely.

    The study is published in the January 4, 2017, online issue of Neurlogy®, the medical journal of the American Academy of Neurology. But contrary to earlier studies, eating more fish and less meat was not related to changes in the brain.

    The Mediterranean diet includes large amounts of fruits, vegetables, olive oil, beans and cereal grains such as wheat and rice, moderate amounts of fish, dairy and wine, and limited red meat and poultry.

    As we age, the brain shrinks and we lose brain cells which can affect learning and memory,” said study author Michelle Luciano, PhD, of the University of Edinburgh in Scotland. “This study adds to the body of evidence that suggests the Mediterranean diet has a positive impact on brain health.”

    Researchers gathered information on the eating habits of 967 Scottish people around age 70 who did not have dementia. Of those people, 562 had an MRI brain scan around age 73 to measure overall brain volume, gray matter volume and thickness of the cortex, which is the outer layer of the brain. From that group, 401 people then returned for a second MRI at age 76. These measurements were compared to how closely participants followed the Mediterranean diet.

    The participants varied in how closely their dietary habits followed the Mediterranean diet principles. People who didn’t follow as closely to the Mediterranean diet were more likely to have a higher loss of total brain volume over the three years than people who followed the diet more closely. The difference in diet explained 0.5 percent of the variation in total brain volume, an effect that was half the size of that due to normal aging.

    The results were the same when researchers adjusted for other factors that could affect brain volume, such as age, education and having diabetes or high blood pressure [hypertension].

    There was no relationship between grey matter volume or cortical thickness and the Mediterranean diet.

    The researchers also found that fish and meat consumption were not related to brain changes, which is contrary to earlier studies.

    It’s possible that other components of the Mediterranean diet are responsible for this relationship, or that it’s due to all of the components in combination,” Luciano said.

    Luciano noted that earlier studies looked at brain measurements at one point in time, whereas the current study followed people over time.

    “In our study, eating habits were measured before brain volume was, which suggests that the diet may be able to provide long-term protection to the brain,” said Luciano. “Still, larger studies are needed to confirm these results.”

     


  9. Tablet devices show promise in managing agitation among patients with dementia

    January 9, 2017 by Ashley

    From the McLean Hospital media release:

    senior researcher with tabletA new pilot study led by McLean Hospital’s Ipsit Vahia, MD, medical director of Geriatric Psychiatry Outpatient Services at McLean Hospital, suggests that the use of tablet computers is both a safe and a potentially effective approach to managing agitation among patients with dementia.

    “Tablet use as a nonpharmacologic intervention for agitation in older adults, including those with severe dementia, appears to be feasible, safe, and of potential utility,” said Vahia. “Our preliminary results are a first step in developing much-needed empirical data for clinicians and caregivers on how to use technology such as tablets as tools to enhance care and also for app developers working to serve the technologic needs of this population.”

    “Use of Tablet Devices in the Management of Agitation Among Inpatients with Dementia: An Open Label Study” was recently published in the online version of The American Journal of Geriatric Psychiatry. This research builds upon previous studies demonstrating that art, music, and other similar therapies can effectively reduce symptoms of dementia without medication. By using tablet devices to employ these therapies, however, patients and providers also benefit from a computer’s inherent flexibility.

    “The biggest advantage is versatility,” said Vahia. “We know that art therapy can work, music therapy can work. The tablet, however, gives you the option of switching from one app to another easily, modifying the therapy seamlessly to suit the individual. You don’t need to invest in new equipment or infrastructure.”

    Researchers loaded a menu of 70 apps onto the tablets for the study. The apps were freely available on iTunes and varied greatly in their cognitive complexity — from an app that displayed puppy photos to one that featured Sudoku puzzles.

    The researchers found that tablet use was safe for every patient, regardless of the severity of their dementia, and that with proper supervision and training, the engagement rate with the devices was nearly 100 percent. The study also found that the tablets demonstrated significant effectiveness in reducing symptoms of agitation, particularly — but not exclusively — among patients with milder forms of dementia.

    Vahia cited several examples of the tablet’s potential to improve a patient’s condition. One particular patient, who only spoke Romanian, was very withdrawn and irritable, and medications were ineffective in controlling his symptoms.

    “We started showing him Romanian video clips on YouTube, and his behavior changed dramatically and instantaneously,” said Vahia. “His mood improved. He became more interactive. He and his medical support team also started using a translation app so that staff could ask him simple questions in Romanian, facilitating increased interaction. These significant improvements are a clear testament of the tablet’s potential as a clinical tool.”

    Based on such promising outcomes, the Geriatric Psychiatry Outpatient Services clinical team is expanding the use of tablet devices as a means to control agitation in dementia patients at McLean. This will allow researchers to develop more robust data and expand the scope of the study, including a focus on specific clinical factors that may impact how patients with dementia engage with and respond to apps.


  10. Missed connections: As people age, memory-related brain activity loses cohesion

    November 28, 2016 by Ashley

    From the PLOS media release:

    brain scansGroups of brain regions that synchronize their activity during memory tasks become smaller and more numerous as people age, according to a study published in PLOS Computational Biology.

    Typically, research on brain activity relies on average brain measurements across entire groups of people. In a new study, Elizabeth Davison of Princeton University, New Jersey, and colleagues describe a novel method to characterize and compare the brain dynamics of individual people.

    The researchers used functional magnetic resonance imaging (fMRI) to record healthy people’s brain activity during memory tasks, attention tasks, and at rest. For each person, fMRI data was recast as a network composed of brain regions and the connections between them. The scientists then use this network to measure how closely different groups of connections changed together over time.

    They found that, regardless of whether a person is using memory, directing attention, or resting, the number of synchronous groups of connections within one brain is consistent for that person. However, between people, these numbers vary dramatically.

    During memory specifically, variations between people are closely linked to age. Younger participants have only a few large synchronous groups that link nearly the entire brain in coordinated activity, while older participants show progressively more and smaller groups of connections, indicating loss of cohesive brain activity — even in the absence of memory impairment.

    “This method elegantly captures important differences between individual brains, which are often complex and difficult to describe,” Davison says. “The resulting tools show promise for understanding how different brain characteristics are related to behavior, health, and disease.

    Future work will investigate how to use individual brain signatures to differentiate between healthily aging brains and brains with age-related impairments.