Scientists continue to find evidence that the brain and gastrointestinal tract are closely linked—and that keeping one healthy will benefit the other.
The brain and gut are connected, but the exact nature of that connection is still a mystery. Research suggests, however, that the better we treat our guts, the healthier our brains will be, and vice versa.
Encompassing all the organs that process food, the gut consists of the mouth, esophagus, stomach, pancreas, liver, gallbladder, small intestine, and large intestine, which includes the colon and rectum. Scientists have been studying the gut components to better understand how they may put people at risk for Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, and other neurologic disorders.
“The notion of gastrointestinal health, and thus normal gut flora, may be as old as medicine itself,” says Michael G. Schlossmacher, MD, endowed chair in neurodegeneration at Canada’s Ottawa Hospital Research Institute and co-director of the Parkinson Research Consortium.
Living within the gut are trillions of microorganisms, including bacteria, fungi, protozoa, and viruses. These microbes aid multiple bodily functions, like breaking down food, producing vitamins, responding to pathogens, and helping the body absorb nutrients. The genes that produce these microorganisms—which also live in saliva, skin, and other body parts—and the microorganisms themselves are collectively known as the microbiome. Various factors, including genetics, lifestyle, diet, environmental exposures, and use of antibiotics, likely influence the microbiome’s composition.
Add an improved memory to the list of the many benefits that accompany having a sense of purpose in life.
A new study led by Florida State University researchers showed a link between an individual’s sense of purpose and his ability to recall vivid details. The researchers found that while both a sense of purpose and cognitive function made memories easier to recall, only a sense of purpose bestowed the benefits of vividness and coherence.
The study, which focused on memories related to the COVID-19 pandemic, was published in the journal Memory.
“Personal memories serve really important functions in everyday life,” said Angelina Sutin, a professor in the College of Medicine and the paper’s lead author. “They help us to set goals, control emotions and build intimacy with others. We also know people with a greater sense of purpose perform better on objective memory tests, like remembering a list of words. We were interested in whether purpose was also associated with the quality of memories of important personal experiences because such qualities may be one reason why purpose is associated with better mental and physical health.”
Exercise training could be a useful supplemental treatment for people with moderate to severe obstructive sleep apnea, the research showed. The condition is characterized by loud snoring and disrupted breathing and can raise the risk for heart disease, stroke and cognitive decline. It is typically treated with continuous positive airway pressure, or CPAP, a machine that pushes air through a mask into the airway to keep it open while a person sleeps.
Researchers at Washington University School of Medicine in St. Louis have developed an approach to estimating when a person who is likely to develop Alzheimer’s disease, but has no cognitive symptoms, will start showing signs of Alzheimer’s dementia.
The algorithm, available online in the journal Neurology, uses data from a kind of brain scan known as amyloid positron emission tomography (PET) to gauge brain levels of the key Alzheimer’s protein amyloid beta.
In those who eventually develop Alzheimer’s dementia, amyloid silently builds up in the brain for up to two decades before the first signs of confusion and forgetfulness appear. Amyloid PET scans already are used widely in Alzheimer’s research, and this algorithm represents a new way of analyzing such scans to approximate when symptoms will arise. Using a person’s age and data from a single amyloid PET scan, the algorithm yields an estimate of how far a person has progressed toward dementia — and how much time is left before cognitive impairment sets in.
“I perform amyloid PET scans for research studies, and when I tell cognitively normal individuals about positive results, the first question is always, ‘How long do I have until I get dementia?’,” said senior author Suzanne Schindler, MD, PhD, an assistant professor of neurology. “Until now, the answer I’d have to give was something like, ‘You have an increased risk of developing dementia in the next five years.’ But what does that mean? Individuals want to know when they are likely to develop symptoms, not just whether they are at higher risk.”
Schindler and colleagues analyzed amyloid PET scans from 236 people participating in Alzheimer’s research studies through Washington University’s Charles F. and Joanne Knight Alzheimer Disease Research Center. The participants were an average of 67 years old at the beginning of the study. All participants underwent at least two brain scans an average of 4½ years apart. The researchers applied a widely used metric known as the standard uptake value ratio (SUVR) to the scans to estimate the amount of amyloid in each participant’s brain at each time point.
How do we decide whether or not an activity which requires work is ‘worth the effort?’ Researchers at the University of Birmingham & University of Oxford have shown that the willingness to work is not static, and depends upon the fluctuating rhythms of fatigue.
Fatigue – the feeling of exhaustion from doing effortful tasks – is something we all experience daily. It makes us lose motivation and want to take a break. Although scientists understand the mechanisms the brain uses to decide whether a given task is worth the effort, the influence of fatigue on this process is not yet well understood.
The research team conducted a study to investigate the impact of fatigue on a person’s decision to exert effort. They found that people were less likely to work and exert effort – even for a reward – if they were fatigued. The results are published in Nature Communications.
Intriguingly, the researchers found that there were two different types of fatigue that were detected in distinct parts of the brain. In the first, fatigue is experienced as a short-term feeling, which can be overcome after a short rest. Over time, however, a second, longer term feeling builds up, stops people from wanting to work, and doesn’t go away with short rests.
Having high blood pressure, high cholesterol and/or obesity from childhood through middle age were linked to poorer brain function by middle age.
These cardiovascular risk factors were linked with low memory, learning, visual processing, attention span, and reaction and movement time.
Strategies to prevent heart disease and stroke should begin in childhood to promote better brain health by middle age.
Managing weight, blood pressure and cholesterol in children may help protect brain function in later life, according to new research published today in the American Heart Association’s flagship journal Circulation. This is the first study to highlight that cardiovascular risk factors accumulated from childhood through mid-life may influence poor cognitive performance at midlife.
Previous research has indicated that nearly 1 in 5 people older than 60 have at least mild loss of brain function. Cognitive deficits are known to be linked with cardiovascular risk factors, such as high blood pressure, obesity, type 2 diabetes, smoking, physical inactivity and poor diet, as well as depression and low education level.
Many diseases that cause neurological deficits, such as Alzheimer’s, have a long preclinical phase before noticeable symptoms begin, so finding links between childhood obesity and other cardiovascular risk factors is important for cognitive health. The researchers noted that there are currently no cures for major causes of dementia, so it is important to learn how early in life cardiovascular risk factors may affect the brain.
“We can use these results to turn the focus of brain health from old age and midlife to people in younger age groups,” said the study’s first author Juuso O. Hakala, M.D., a Ph.D. student at the Research Centre of Applied and Prevention Cardiovascular Medicine at the University of Turku, in Turku, Finland. ”Our results show active monitoring and prevention of heart disease and stroke risk factors, beginning from early childhood, can also matter greatly when it comes to brain health. Children who have adverse cardiovascular risk factors might benefit from early intervention and lifestyle modifications.”
The Cardiovascular Risk in Young Finns Study is a national, longitudinal study on cardiovascular risk from childhood to adulthood in Finland. Researchers followed the participants’ cardiovascular risk factor profiles for 31 years from childhood to adulthood. Baseline clinical examinations were conducted in 1980 on approximately 3,600 randomly selected boys and girls, ranging in ages from 3 to 18, all of whom were white. More than 2,000 of the participants, ranging in ages from 34 to 49, underwent a computerized cognitive function test in 2011. The test measured four different cognitive domains: episodic memory and associative learning; short-term working memory; reaction and movement time; and visual processing and sustained attention.
Researchers found:
Systolic blood pressure, total blood cholesterol and low-density lipoprotein (LDL) cholesterol, as well as body mass index, from childhood to midlife are associated with brain function in middle age.
Consistently high systolic blood pressure or high blood total cholesterol and LDL cholesterol were linked to worse memory and learning by midlife when compared with lower measures.
Obesity from childhood to adulthood was associated with lower visual information processing speed and maintaining attention.
Having all three cardiovascular risk factors was linked to poorer memory and associative learning, worse visual processing, decreased attention span, and slower reaction and movement time.
These results are from observational findings, so more studies are needed to learn whether there are specific ages in childhood and/or adolescence when cardiovascular risk factors are particularly important to brain health in adulthood. Study limitations include that a definite cause-and-effect link between cardiovascular risk factors and cognitive performance cannot be determined in this type of population-based study; cognition was measured at a single point in time; and because all study participants are white, the results may not be generalizable to people from other racial or ethnic groups.
Neurons lack the ability to replicate their DNA, so they’re constantly working to repair damage to their genome. Now, a new study by Salk scientists finds that these repairs are not random, but instead focus on protecting certain genetic “hot spots” that appear to play a critical role in neural identity and function, according to Science Daily.
The findings, published in the April 2, 2021, issue of Science, give novel insights into the genetic structures involved in aging and neuro-degeneration, and could point to the development of potential new therapies for diseases such Alzheimer’s, Parkinson’s and other age-related dementia disorders.
“This research shows for the first time that there are sections of genome that neurons prioritize when it comes to repair,” says Professor and Salk President Rusty Gage, the paper’s co-corresponding author. “We’re excited about the potential of these findings to change the way we view many age-related diseases of the nervous system and potentially explore DNA repair as a therapeutic approach.”
Scientists have more evidence that exercise improves brain health and could be a lifesaving ingredient that prevents Alzheimer’s disease.
In particular, a new study from the University of Texas (UT) Southwestern’s O’Donnell Brain Institute suggests that the lower the fitness level, the faster the deterioration of vital nerve fibers in the brain. This deterioration results in cognitive decline, including memory issues characteristic of dementia patients.
Brain imaging shows yellow and reddish pixels representing areas where the functionality of white matter is associated with higher fitness levels. The images are based on cumulative data from patients in a study showing potential links between physical fitness and deterioration of white matter.
“This research supports the hypothesis that improving people’s fitness may improve their brain health and slow down the aging process,” said Dr. Kan Ding, a neurologist from the Peter O’Donnell Jr. Brain Institute who authored the study.
White matter
The study published in the Journal of Alzheimer’s Disease focused on a type of brain tissue called white matter, which is comprised of millions of bundles of nerve fibers used by neurons to communicate across the brain.
Dr. Ding’s team enrolled older patients at high risk to develop Alzheimer’s disease who have early signs of memory loss, or mild cognitive impairment (MCI). The researchers determined that lower fitness levels were associated with weaker white matter, which in turn correlated with lower brain function.
Distinctive tactics
Unlike previous studies that relied on study participants to assess their own fitness, the new research objectively measured cardiorespiratory fitness with a scientific formula called maximal oxygen uptake. Scientists also used brain imaging to measure the functionality of each patient’s white matter.
Patients were then given memory and other cognitive tests to measure brain function, allowing scientists to establish strong correlations between exercise, brain health, and cognition.
Lingering Mysteries
The study adds to a growing body of evidence pointing to a simple yet crucial mandate for human health: Exercise regularly.
However, the study leaves plenty of unanswered questions about how fitness and Alzheimer’s disease are intertwined. For instance, what fitness level is needed to notably reduce the risk of dementia? Is it too late to intervene when patients begin showing symptoms?
Some of these topics are already being researched through a five-year national clinical trial led by the O’Donnell Brain Institute.
The trial, which includes six medical centers across the country, aims to determine whether regular aerobic exercise and taking specific medications to reduce high blood pressure and cholesterol levels can help preserve brain function. It involves more than 600 older adults at high risk to develop Alzheimer’s disease.
“Evidence suggests that what is bad for your heart is bad for your brain. We need studies like this to find out how the two are intertwined and hopefully find the right formula to help prevent Alzheimer’s disease,” said Dr. Rong Zhang of UT Southwestern, who oversees the clinical trial and is Director of the Cerebrovascular Laboratory in the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, where the Dallas arm of the study is being carried out.
Prior Findings
The research builds upon prior investigations linking healthy lifestyles to better brain function, including a 2013 study from Dr. Zhang’s team that found neuronal messages are more efficiently relayed in the brains of older adults who exercise.
In addition, other teams at the O’Donnell Brain Institute are designing tests for the early detection of patients who will develop dementia, and seeking methods to slow or stop the spread of toxic proteins associated with the disease such as beta-amyloid and tau, which are blamed for destroying certain groups of neurons in the brain.
“A lot of work remains to better understand and treat dementia,” said Dr. Ding, Assistant Professor of Neurology & Neurotherapeutics. “But, eventually, the hope is that our studies will convince people to exercise more.
Higher BMI is linked to decreased cerebral blood flow, which is associated with increased risk of Alzheimer’s disease and mental illness, according to a new study in the Journal of Alzheimer’s Diseast (JAD).
As a person’s weight goes up, all regions of the brain go down in activity and blood flow, according to a new brain imaging study in the Journal of Alzheimer’s Disease. One of the largest studies linking obesity with brain dysfunction, scientists analyzed over 35,000 functional neuro-imaging scans using single-photon emission computerized tomography from more than 17,000 individuals to measure blood flow and brain activity.
3D renderings of blood flow averaged across normal BMI (BMI = 23), overweight (BMI = 29), and obese (BMI = 37) men, each 40 years of age (credit: Amen Clinics)
Low cerebral blood flow is the #1 brain imaging predictor that a person will develop Alzheimer’s disease. It is also associated with depression, ADHD, bipolar disorder, schizophrenia, traumatic brain injury, addiction, suicide, and other conditions. “This study shows that being overweight or obese seriously impacts brain activity and increases the risk for Alzheimer’s disease as well as many other psychiatric and cognitive conditions,” explained Daniel G. Amen, MD, the study’s lead author and founder of Amen Clinics, one of the leading brain-centered mental health clinics in the United States.
People with dementia may experience increased levels of pain 16 years before their diagnosis, according to new research. The study, funded in part by NIA and published in Pain, is the first to examine the link between pain and dementia over an extended period.
Dementia and chronic pain both cause changes to the brain and can affect a person’s brain health. Although many people who have dementia also have chronic pain, it is unclear whether chronic pain causes or accelerates the onset of dementia, is a symptom of dementia, or is simply associated with dementia because both are caused by some other factor. The new study, led by researchers at Université de Paris, examined the timeline of the association between dementia and self-reported pain by analyzing data from a study that has been gathering data on participants for as many as 27 years.
The researchers used data from the Whitehall II study, a long-term study of health in British government employees. Participants were between the ages of 35 and 55 when they enrolled in the study. Using surveys conducted multiple times over the course of the study, the researchers measured two aspects of participant-reported pain: pain intensity, which is how much bodily pain a participant experiences, and pain interference, which is how much a participant’s pain affects his or her daily activities. They used electronic health records to determine whether (and when) participants were diagnosed with dementia.
Out of 9,046 participants, 567 developed dementia during the period of observation. People who were diagnosed with dementia reported slightly more pain as early as 16 years before their diagnosis, driven mostly by differences in pain interference. These participants reported steadily increasing pain levels relative to those who were never diagnosed with dementia. At the time of diagnosis, people with dementia reported significantly more pain than people without dementia.
The researchers note that, because the brain changes associated with dementia start decades before diagnosis, it is unlikely that pain causes or increases the risk of dementia. Instead, they suggest that chronic pain might be an early symptom of dementia or simply correlated with dementia. Future studies that include data on the cause, type, location, and characteristics of pain and the type and seriousness of a patient’s dementia could help define in more detail the link between dementia and pain.
Primary care doctors can play an important role in helping to preserve brain health by encouraging healthy behaviors and addressing risk factors associated with cognitive decline, according to a new scientific report.
The American Heart Association statement published in the journal Stroke outlines seven lifestyle targets and six risk factors for brain health that primary care doctors should address in adults of all ages. The statement also has been endorsed by the American Academy of Neurology as an educational tool for neurologists.
As the nation ages, preserving brain health has become a growing concern. Mild cognitive impairment affects an estimated 1 in 5 Americans age 65 and older; 1 in 7 has dementia – a number expected to triple by 2050.
“Primary care is the right home for practice-based efforts to prevent or postpone cognitive decline,” Ronald Lazar, chair of the scientific statement writing group, said in a news release. Lazar directs the Evelyn F. McKnight Brain Institute at the University of Alabama at Birmingham.
“Prevention doesn’t start in older age; it exists along the health care continuum from pediatrics to adulthood,” he said. “The evidence in this statement demonstrates that early attention to these factors improves later life outcomes.”
The statement asks primary care doctors to integrate brain health into their treatment of adults guided by the AHA’s Life’s Simple 7, a collection of lifestyle targets shown to help achieve ideal heart and brain health. These include managing blood pressure, cholesterol and blood sugar levels; increasing physical activity; eating a healthy diet; losing weight; and not smoking.
The statement also asks them to assess their patients’ risk factors for cognitive health, including depression, social isolation, excessive alcohol use, sleep disorders, lower education levels and hearing loss.
“Scientists are learning more about how to prevent cognitive decline before changes to the brain have begun,” Lazar, a professor of neurology and neurobiology, said. “We have compiled the latest research and found Life’s Simple 7 plus other factors like sleep, mental health and education are a more comprehensive lifestyle strategy that optimizes brain health in addition to cardiovascular health.”
Dr. Deborah Levine, one of the statement’s co-authors, said it is never too soon to target risk factors for ideal heart and brain health. It’s also never too late.
“For example, lower blood pressure levels reduce the risk of cognitive impairment and dementia in older adults,” she said. “In adults of all ages, the metrics in Life’s Simple 7 prevent stroke, and stroke increases the risk of dementia by more than twofold.”
Additional risk factors can help physicians identify which patients may need special attention, said Levine, an associate professor of medicine at the University of Michigan Medical School in Ann Arbor.
For example, “Primary care doctors can help their patients reduce dementia risk by identifying and aggressively treating vascular risk factors like high blood pressure. Black and Hispanic individuals, women and individuals with lower educational levels appear at higher risk for dementia, so these high-risk groups are a top priority,” Levine said.
According to the statement, recent research shows high blood pressure, diabetes and smoking in adulthood and midlife increase the odds of cognitive decline in middle age. And they accelerate cognitive decline in older age.
“Many people think of high blood pressure, Type 2 diabetes and other risk factors as affecting only heart health, yet these very same risk factors affect our brain health,” Lazar said. “Patients might be more likely to pay attention to the importance of addressing modifiable risk factors if they understood the links.”
The statement defines brain health using the term cognition, which includes memory, thinking, reasoning, communication and problem-solving.
Together, these functions enable people to navigate the everyday world, according to the report. The ability to think, solve problems, remember, perceive and communicate are crucial to successful living; their loss can lead to helplessness and dependency.
“Studies have shown that these domains are impacted by factors that are within our control to change,” Lazar said. “Prevention and mitigation are important, because once people have impaired cognition, the current treatment options are very limited.”
Music-based interventions have become a core ingredient of effective neurorehabilitation in the past 20 years thanks to the growing body of knowledge. In this theme issue of Neurorehabilitation, experts in the field highlight some of the current critical gaps in clinical applications that have been less thoroughly investigated, such as post-stroke cognition, traumatic brain injury, and autism and specific learning disabilities.
Neurologic Music Therapy is the clinical and evidence-based use of music interventions by a credentialed professional. Research in the 1990s showed for the first time how musical-rhythmic stimuli can improve mobility in stroke and Parkinson’s disease patients. We now know that music-based interventions can effectively address a wide range of impairments in sensorimotor, speech/language, and cognitive functions.
A new study led by the University of Portsmouth has identified that one of the major factors of age-related brain deterioration is the loss of a substance called myelin.
Myelin acts like the protective and insulating plastic casing around the electrical wires of the brain – called axons. Myelin is essential for superfast communication between nerve cells that lie behind the supercomputer power of the human brain.
The loss of myelin results in cognitive decline and is central to several neurodegenerative diseases, such as Multiple Sclerosis and Alzheimer’s disease. This new study found that the cells that drive myelin repair become less efficient as we age and identified a key gene that is most affected by ageing, which reduces the cells ability to replace lost myelin.
A computer network closely modelled on part of the human brain is enabling new insights into the way our brains process moving images – and explains some perplexing optical illusions.
By using decades’ worth of data from human motion perception studies, researchers have trained an artificial neural network to estimate the speed and direction of image sequences.
The new system, called MotionNet, is designed to closely match the motion-processing structures inside a human brain. This has allowed the researchers to explore features of human visual processing that cannot be directly measured in the brain.
Their study, published in the Journal of Vision, uses the artificial system to describe how space and time information is combined in our brain to produce our perceptions, or misperceptions, of moving images.
People with prediabetes, whose blood sugar levels are higher than normal, may have an increased risk of cognitive decline and vascular dementia, according to a new study led by University College London (UCL) researchers.
For the study, published in the journal Diabetes, Obesity and Metabolism, researchers analyzed data from the UK Biobank of 500,000 people aged 58 years on average, and found that people with higher than normal blood sugar levels were 42% more likely to experience cognitive decline over an average of four years, and were 54% more likely to develop vascular dementia over an average of eight years (although absolute rates of both cognitive decline and dementia were low).
The associations remained true after other influential factors had been taken into account – including age, deprivation, smoking, BMI and whether or not participants had cardiovascular disease.
Previous research has led to findings that support links between a positive mental outlook and physical health benefits such as lower blood pressure, less heart disease, and healthier blood sugar levels. In a recent study of mood changes in older adults, scientists also have discovered that healthy brain function may result in maintaining a positive outlook.
For this study, which was funded in part by NIA and published in the American Journal of Geriatric Psychiatry in September 2020, scientists proposed a potential neurobiological connection between an older adult’s mood with changes, over a period of time, in white brain matter and cognitive ability. White matter is where information is transmitted from one brain region to another. As we age, changes can occur in the white matter that may lead to thinking, walking, and balance problems.
