How exercise may protect against Alzheimer's
February 8, 2019
Science Daily/Columbia University Irving Medical Center
A hormone called irisin -- produced during exercise -- may protect neurons against Alzheimer's disease.
Athletes know a vigorous workout can release a flood of endorphins: "feel-good" hormones that boost mood. Now there's evidence that exercise produces another hormone that may improve memory and protect against Alzheimer's disease, according to a study co-led by Ottavio Arancio, MD, PhD, a researcher at Columbia University's Vagelos College of Physicians and Surgeons and Taub Institute for Research on Alzheimer's Disease and the Aging Brain.
The study was published in Nature Medicine.
Physical activity is known to improve memory, and studies suggest it may also reduce the risk of Alzheimer's disease. But researchers don't understand why.
A few years ago, exercise researchers discovered a hormone called irisin that is released into the circulation during physical activity. Initial studies suggested that irisin mainly played a role in energy metabolism. But newer research found that the hormone may also promote neuronal growth in the brain's hippocampus, a region critical for learning and memory.
"This raised the possibility that irisin may help explain why physical activity improves memory and seems to play a protective role in brain disorders such as Alzheimer's disease" says Arancio, who is a professor of pathology and cell biology and of medicine at Columbia University Vagelos College of Physicians and Surgeons.
Irisin is reduced in brains of people with Alzheimer's
In the new study, Arancio and his colleagues at the Federal University of Rio de Janeiro in Brazil and Queens University in Canada first looked for a link between irisin and Alzheimer's in people. Using tissue samples from brain banks, they found that irisin is present in the human hippocampus and that hippocampal levels of the hormone are reduced in individuals with Alzheimer's.
To explore what irisin does in the brain, the team turned to mice. These experiments show that irisin, in mice, protects the brain's synapses and the animals' memory: When irisin was disabled in the hippocampus of healthy mice, synapses and memory weakened. Similarly, boosting brain levels of irisin improved both measures of brain health.
Swimming boosts irisin, protects memory in mice
The researchers then looked at the effect of exercise on irisin and the brain. In the study's most compelling experiments, the researchers found that mice who swam nearly every day for five weeks did not develop memory impairment despite getting infusions of beta amyloid -- the neuron-clogging, memory-robbing protein implicated in Alzheimer's.
Blocking irisin with a drug completely eliminated the benefits of swimming, the researchers also found. Mice who swam and were treated with irisin-blocking substances performed no better on memory tests than sedentary animals after infusions with beta amyloid.
Together the findings suggest that irisin could be exploited to find a novel therapy for preventing or treating dementia in humans, Arancio says. His team is now searching for pharmaceutical compounds that can increase brain levels of the hormone or can mimic its action.
"In the meantime, I would certainly encourage everyone to exercise, to promote brain function and overall health," he said. "But that's not possible for many people, especially those with age-related conditions like heart disease, arthritis, or dementia. For those individuals, there's a particular need for drugs that can mimic the effects of irisin and protect synapses and prevent cognitive decline."
https://www.sciencedaily.com/releases/2019/02/190208173511.htm
Dutch study estimates 1 in 2 women and 1 in 3 men set to develop dementia/parkinsonism/stroke
Preventive strategies could, in theory, more than halve lifetime risk for those aged 85-plus, say researchers
Science Daily/October 1, 2018
BMJ
One in two women and one in three men will likely be diagnosed with dementia, Parkinson's disease, or stroke in their lifetime, estimate Dutch researchers in an observational study.
But preventive strategies, which delay the onset of these common diseases by even a few years, could, in theory, cut this lifetime risk by between 20 and more than 50 per cent, they say.
The global costs of dementia, stroke, and parkinsonism are thought to amount to more than 2 per cent of the world's annual economic productivity (GDP), a figure that is set to rise steeply as life expectancy continues to increase.
But while the lifetime risks of other serious illnesses, such as breast cancer and heart disease are well known and used to raise public awareness, the same can't be said of dementia, stroke, parkinsonism, say the researchers.
To try and redress this, they tracked the neurological health of more than 12,000 people taking part in the Rotterdam Study between 1990 and 2016. This study has been looking at the incidence of, and influential factors behind, diseases of ageing in the general population.
All the participants were aged at least 45 years old when they were recruited, and more than half (just under 58 per cent) were women.
When they joined, participants were given a thorough health check, which was repeated every four years. Family doctor health records were also scrutinised for signs of disease or diagnoses arising between the four yearly check-ups.
Monitoring for dementia, parkinsonism, and stroke continued until death, or January 1 2016, whichever came first.
Between 1990 and 2016, 5291 people died, 3260 of whom had not been diagnosed with any neurological disease. But 1489 people were diagnosed with dementia, mostly Alzheimer's disease (just under 80%); 1285 had a stroke, nearly two thirds of which (65%) was caused by a blood clot (ischaemic); and 263 were diagnosed with parkinsonism.
A higher prevalence of high blood pressure, abnormal heart rhythm (atrial fibrillation), high cholesterol and type 2 diabetes was evident at the start of the monitoring period among those subsequently diagnosed with any of the three conditions.
Unsurprisingly, the risk of developing any of them rose steeply with age, but based on the data, the overall lifetime risk of a 45 year-old developing dementia, parkinsonism, or having a stroke was one in two for a woman (48%) and one in three for a man (36%).
This gender difference was largely driven by women being at heightened risk of developing dementia before men. But there were other gender differences in risk.
While 45 year-olds of both sexes had a similar lifetime risk of stroke, men were at substantially higher risk of having a stroke at younger ages than women.
And women were twice as likely as men to be diagnosed with both dementia and stroke during their lifetime.
The researchers calculated that if the onset of dementia, stroke, and parkinsonism were delayed by 1 to 3 years, the remaining lifetime risk could, in theory, be reduced by 20 per cent in 45 year-olds, and by more than 50 per cent in those aged 85+.
A delay of only a few years for one disease could also have a significant impact on combined lifetime risk, suggest the researchers.
"For instance, delaying dementia onset by 3 years has the potential to reduce lifetime risk of any disease by 15 per cent for men and women aged 45, and by up to 30 per cent for those aged 85 and older," they write.
The researchers point out that their study included only people of European ancestry with a relatively long life expectancy, so might not be applicable to other ethnicities/populations, and that they weren't able to measure the severity of any of the diagnosed conditions.
This research is observational, so no definitive conclusions can be drawn. But the researchers nevertheless conclude: "These findings strengthen the call for prioritising the focus on preventive interventions at population level which could substantially reduce the burden of common neurological diseases in the ageing population."
https://www.sciencedaily.com/releases/2018/10/181001190712.htm
With Fat: What's Good or Bad for the Heart, May Be the Same for the Brain
May 18, 2012
Science Daily/Brigham and Women's Hospital
It has been known for years that eating too many foods containing "bad" fats, such as saturated fats or trans fats, isn't healthy for your heart. However, according to new research from Brigham and Women's Hospital (BWH), one "bad" fat -- saturated fat -- was found to be associated with worse overall cognitive function and memory in women over time. By contrast, a "good" fat -- mono-unsaturated fat was associated with better overall cognitive function and memory.
The research team analyzed data from the Women's Health Study -- originally a cohort of nearly 40,000 women, 45 years and older. The researchers focused on data from a subset of 6,000 women, all over the age of 65. The women participated in three cognitive function tests, which were spaced out every two years for an average testing span of four years. These women filled out very detailed food frequency surveys at the start of the Women's Health Study, prior to the cognitive testing.
"When looking at changes in cognitive function, what we found is that the total amount of fat intake did not really matter, but the type of fat did," explained Olivia Okereke, MD, MS, BWH Department of Psychiatry.
Women who consumed the highest amounts of saturated fat, which can come from animal fats such as red meat and butter, compared to those who consumed the lowest amounts, had worse overall cognition and memory over the four years of testing. Women who ate the most of the monounsaturated fats, which can be found in olive oil, had better patterns of cognitive scores over time.
"Our findings have significant public health implications," said Okereke. "Substituting in the good fat in place of the bad fat is a fairly simple dietary modification that could help prevent decline in memory."
Okereke notes that strategies to prevent cognitive decline in older people are particularly important. Even subtle declines in cognitive functioning can lead to higher risk of developing more serious problems, like dementia and Alzheimer disease.
http://www.sciencedaily.com/releases/2012/05/120518081358.htm
Physical activity keeps hippocampus healthy those at risk for Alzheimer's disease
April 23, 2014
Science Daily/University of Maryland
A study of older adults at increased risk for Alzheimer's disease shows that moderate physical activity may protect brain health and stave off shrinkage of the hippocampus- the brain region responsible for memory and spatial orientation that is attacked first in Alzheimer's disease. Dr. J. Carson Smith, a kinesiology researcher in the University of Maryland School of Public Health who conducted the study, says that while all of us will lose some brain volume as we age, those with an increased genetic risk for Alzheimer's disease typically show greater hippocampal atrophy over time. The findings are published in the open-access journal Frontiers in Aging Neuroscience.
"The good news is that being physically active may offer protection from the neurodegeneration associated with genetic risk for Alzheimer's disease," Dr. Smith suggests. "We found that physical activity has the potential to preserve the volume of the hippocampus in those with increased risk for Alzheimer's disease, which means we can possibly delay cognitive decline and the onset of dementia symptoms in these individuals. Physical activity interventions may be especially potent and important for this group."
Dr. Smith and colleagues, including Dr. Stephen Rao from the Cleveland Clinic, tracked four groups of healthy older adults ages 65-89, who had normal cognitive abilities, over an 18-month period and measured the volume of their hippocampus (using structural magnetic resonance imaging, or MRI) at the beginning and end of that time period. The groups were classified both for low or high Alzheimer's risk (based on the absence or presence of the apolipoprotein E epsilon 4 allele) and for low or high physical activity levels.
Of all four groups studied, only those at high genetic risk for Alzheimer's who did not exercise experienced a decrease in hippocampal volume (3%) over the 18-month period. All other groups, including those at high risk for Alzheimer's but who were physically active, maintained the volume of their hippocampus.
"This is the first study to look at how physical activity may impact the loss of hippocampal volume in people at genetic risk for Alzheimer's disease," says Dr. Kirk Erickson, an associate professor of psychology at the University of Pittsburgh. "There are no other treatments shown to preserve hippocampal volume in those that may develop Alzheimer's disease. This study has tremendous implications for how we may intervene, prior to the development of any dementia symptoms, in older adults who are at increased genetic risk for Alzheimer's disease."
Individuals were classified as high risk for Alzheimer's if a DNA test identified the presence of a genetic marker -- having one or both of the apolipoprotein E-epsilon 4 allele (APOE-e4 allele) on chromosome 19 -- which increases the risk of developing the disease. Physical activity levels were measured using a standardized survey, with low activity being two or fewer days/week of low intensity activity, and high activity being three or more days/week of moderate to vigorous activity.
"We know that the majority of people who carry the APOE-e4 allele will show substantial cognitive decline with age and may develop Alzheimer's disease, but many will not. So, there is reason to believe that there are other genetic and lifestyle factors at work," Dr. Smith says. "Our study provides additional evidence that exercise plays a protective role against cognitive decline and suggests the need for future research to investigate how physical activity may interact with genetics and decrease Alzheimer's risk."
Dr. Smith has previously shown that a walking exercise intervention for patients with mild cognitive decline improved cognitive function by improving the efficiency of brain activity associated with memory. He is planning to conduct a prescribed exercise intervention in a population of healthy older adults with genetic and other risk factors for Alzheimer's disease and to measure the impact on hippocampal volume and brain function.
http://www.sciencedaily.com/releases/2014/04/140423102746.htm
Self-rated physical fitness in midlife an indicator of dementia risk
February 26, 2014
Science Daily/Suomen Akatemia (Academy of Finland)
How would you rate your own physical fitness? Is it good, satisfactory or maybe even poor? Surprisingly, your answer may reveal your future risk of getting dementia. A recent collaborative study from Finland, involving the follow-up of 3,559 adults for 30 years, has found that a simple question about self-rated physical fitness in midlife may reveal individuals who are at an increased risk of developing dementia. Those who reported poor self-rated physical fitness in midlife, at the mean age of 50 years, were four times more likely to get dementia during the next three decades compared to those with good self-rated physical fitness.
"Chronic conditions independently increase the dementia risk. Furthermore, if a person additionally feels that his or her physical fitness is poor, the risk is even higher. In terms of dementia prevention, maintaining good physical fitness seems to be especially important for people with chronic diseases," Kulmala says.
Poor self-rated fitness is known to be affected by lifestyle factors such as physical inactivity, poor mental wellbeing, lack of social connections, lower education, high body mass index and smoking. Perceived poor physical fitness therefore integrates several unfavourable aspects of lifestyle that have all been previously linked to increased dementia risk.
"The perception of poor physical fitness is most likely affected by different factors for different people. Therefore, I would encourage those who rate their fitness as poor to think about the factors behind this perception. Increasing physical and social activity, making better dietary choices or quitting smoking, for example, could change the rating into more positive. Individual choices that make you feel physically better may substantially decrease your future risk of developing dementia," Kulmala says.
http://www.sciencedaily.com/releases/2014/02/140226074825.htm
Keeping up your overall health may keep dementia away
July 13, 2011
Science Daily/American Academy of Neurology
Improving and maintaining health factors not traditionally associated with dementia, such as denture fit, vision and hearing, may lower a person's risk for developing dementia, according to a new study.
"Our study suggests that rather than just paying attention to already known risk factors for dementia, such as diabetes or heart disease, keeping up with your general health may help reduce the risk for dementia," said study author Kenneth Rockwood, MD, of Dalhousie University in Halifax, Nova Scotia, Canada.
The study found that each health problem increased a person's odds of developing dementia by 3.2 percent compared to people without such health problems. Older adults without health problems at baseline had an 18 percent chance to become demented in 10 years, while such risk increased to 30 percent and 40 percent in those who had 8 and 12 health problems, respectively.
http://www.sciencedaily.com/releases/2011/07/110713161824.htm
Common irregular heartbeat raises risk of dementia
August 30, 2011
Science Daily/Group Health Research Institute
The most common kind of chronically irregular heartbeat, known as atrial fibrillation, is associated with a greater risk of dementia, including Alzheimer's disease, according to a new study.
"Both atrial fibrillation and dementia increase with age," said Sascha Dublin, MD, PhD, a Group Health Research Institute assistant investigator who led the research. "Before our prospective cohort study, we knew that atrial fibrillation can cause stroke, which can lead to dementia. Now we've learned that atrial fibrillation may increase dementia risk in other, more subtle ways as well."
The results of Dr. Dublin's study suggest a relationship between atrial fibrillation and dementia beyond the connection through stroke. The people in the study had a mean age of 74 years when the study began. None had dementia or a history of stroke. At the beginning of the study, 4.3 percent had atrial fibrillation, and an additional 12.2 percent developed it during the study.
In the course of the study, 18.8 percent developed some type of dementia. People with atrial fibrillation were more likely to have other cardiovascular risk factors and disease than were those without the condition. So the researchers looked to see if atrial fibrillation increased dementia risk more than just through its association with other kinds of heart disease.
http://www.sciencedaily.com/releases/2011/08/110808104621.htm
A changing society: 100 is the new 80
Centenarians healthier than previously thought during last years of life
July 20, 2017
Science Daily/Charité - Universitätsmedizin Berlin
When it comes to aging successfully and remaining in good health, are centenarians the perfect role models? Researchers have been studying illness trajectories in centenarians during the final years of their lives. According to their findings, people who died aged 100 or older suffered fewer diseases than those who died aged 90 to 99, or 80 to 89.
Forty years ago, life expectancy was such that, in the industrialized world, only (approximately) one in 10,000 people were expected to reach the age of 100 or more. Today's estimates suggest that half of all children born in the developed world during this century will live to at least 100. Therefore, the question that poses itself is whether extreme old age is necessarily associated with increased morbidity. There is evidence to suggest that centenarians develop fewer diseases than younger cohorts of extreme old people. In discussions surrounding the issues associated with aging populations, this is referred to as the 'compression of morbidity' hypothesis -- a term which describes the phenomenon of the onset of disability and age-related diseases being increasingly being well into old age, resulting in a shortening (or compression) of this phase. "Our aim was to gain a better understanding of multimorbidity, i.e. the number and severity of chronic diseases affecting centenarians towards the end of their lives," explains Dr. Paul Gellert of Charité's Institute of Medical Sociology and Rehabilitation Science.
Using diagnoses and health care utilization data routinely collected by the German statutory health insurance company Knappschaft, the researchers studied relevant events during the final six years of life of approximately 1,400 of the oldest old. For the purposes of analysis, this cohort was then divided into three groups. Data on persons who had died aged 100 or older were compared with random samples of persons who had died in their eighties or nineties. The analysis, which included data on very old persons living in their own homes as well as data on those living in residential care, focused on comorbid conditions classified by the Elixhauser Comorbidity Index as being usually associated with in-hospital mortality. "According to the data, centenarians suffered from an average of 3.3 such conditions during the three months prior to their deaths, compared with an average of 4.6 conditions for those who had died in their eighties," says Dr. Gellert, summarizing the findings. "Our results also show that the increase in conditions seen during the last few years of life was lower in centenarians than in those who had died between the ages of 90 and 99, or 80 and 89."
If one includes disorders commonly associated with extreme old age, such as different types of dementia and musculoskeletal disorders, approximately half of all centenarians recorded a total of five or more comorbid conditions. The same number of comorbid conditions was found in 60 percent of persons who had died in their nineties and 66 percent of persons who had died in their eighties. While different types of dementia and heart failure were found to be more common among centenarians than among the younger cohorts, high blood pressure, cardiac arrhythmia, renal failure, and chronic diseases were less common in those who had died after reaching 100 years of age. The incidence of musculoskeletal disorders was found to be similar in all three age groups. While there appears to be a clear link between extreme old age and the number of diseases recorded, the extent to which this is the case requires careful analysis.
https://www.sciencedaily.com/releases/2017/07/170720103148.htm
Moderate drinking may protect against Alzheimer's and cognitive impairment
August 19, 2011
Science Daily/Loyola University Health System
Moderate social drinking may significantly reduce the risk of dementia and cognitive impairment, suggests a new analysis of 143 studies.
Wine was more beneficial than beer or spirits. But this finding was based on a relatively small number of studies, because most papers did not distinguish among different types of alcohol.
Heavy drinking (more than 3 to 5 drinks per day) was associated with a higher risk of cognitive impairment and dementia, but this finding was not statistically significant. "We don't recommend that nondrinkers start drinking," Neafsey said. "But moderate drinking -- if it is truly moderate -- can be beneficial." Moderate drinking is defined as a maximum of two drinks per day for men and 1 drink per day for women.
The researchers note that there are other things besides moderate drinking that can reduce the risk of dementia, including exercise, education and a Mediterranean diet high in fruits, vegetables, cereals, beans, nuts and seeds. Even gardening has been shown to reduce the risk of dementia.
http://www.sciencedaily.com/releases/2011/08/110816112134.htm
Over half of Alzheimer's cases may be preventable
July 19, 2011
Science Daily/University of California - San Francisco
Over half of all Alzheimer's disease cases could potentially be prevented through lifestyle changes and treatment or prevention of chronic medical conditions, according to a new study.
Analyzing data from studies around the world involving hundreds of thousands of participants, Barnes concluded that worldwide, the biggest modifiable risk factors for Alzheimer's disease are, in descending order of magnitude, low education, smoking, physical inactivity, depression, mid-life hypertension, diabetes and mid-life obesity.
In the United States, Barnes found that the biggest modifiable risk factors are physical inactivity, depression, smoking, mid-life hypertension, mid-life obesity, low education and diabetes.
Together, these risk factors are associated with up to 51 percent of Alzheimer's cases worldwide (17.2 million cases) and up to 54 percent of Alzheimer's cases in the United States (2.9 million cases), according to Barnes.
"What's exciting is that this suggests that some very simple lifestyle changes, such as increasing physical activity and quitting smoking, could have a tremendous impact on preventing Alzheimer's and other dementias in the United States and worldwide," said Barnes, who is also an associate professor of psychiatry at the University of California, San Francisco.
http://www.sciencedaily.com/releases/2011/07/110719072809.htm