Category: Dementia

A large, prospective study led by a researcher at Rush University Medical Center indicates that chronic exposure to particulate air pollution may accelerate cognitive decline in older adults. The results of the study will be published in the Feb. 13 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

In the study, women who were exposed to higher levels of ambient particulate matter (PM) over the long term experienced more decline in their cognitive functioning over a four-year period. Higher levels of long-term exposure to both coarse PM (PM2.5-10) and fine PM (PM2.5) were associated with significantly faster cognitive decline.

PM air pollution consists of small particles suspended in the air. Particles that are less than 2.5 microns in diameter, which is 1/30th the width of human hair, are called fine PM and particles larger than 2.5-10 microns is called coarse PM.

These associations were present at levels of PM exposure typical in many areas of the United States.

There are few recent studies that analyze air pollution and cognitive function in older adults, but this is the first study to examine change in cognitive function over a period of time and whether exposure to the size of particulate matter is important.

Jennifer Weuve, MPH., ScD, assistant professor of the Rush Institute of Healthy Aging and the principal investigator of the study, along with her colleagues, evaluated air pollution, both coarse and fine, in relation to cognitive decline in older women using a study population from the Nurses' Health Study Cognitive Cohort, which included 19,409 U.S. women ages 70 to 81 for a 14-year period going back as far as 1988.

"Our study explored chronic exposure to particulate air pollution in relation to decline in cognitive functioning among older women," said Weuve. "Very is little known about the role of particulate matter exposure and its association with cognitive decline."

Exposure to particulate air pollution is associated with cardiovascular risk, which itself may play a role in causing or accelerating cognitive decline.

"Unlike other factors that may be involved in dementia such as diet and physical activity, air pollution is something we can intervene on as a society at large through policy, regulation and technology," said Weuve.

"Therefore, if our findings are confirmed in other research, air pollution reduction is a potential means for reducing the future population burden of age-related cognitive decline, and eventually, dementia," said Weuve.

The studies were supported by grants from the National Institute of Environmental Health Sciences, National Cancer Institute and the U.S. Environmental Protection Agency.

Jennifer Weuve, MPH, ScD, is an assistant professor of internal medicine at the Rush Medical College and the Rush Institute for Healthy Aging, Rush University Medical Center.

Co-authors of the study include Robin Puett, MPH, PhD of University of Maryland School of Public Health, Joel Schwartz, PhD, and Francine Laden, MS, ScD, and Francine Grodstein, ScD, of the Harvard School of Public Health, and Jeff Yanosky, MS, ScD of Penn State University College of Medicine.

Simple tests such as walking speed and hand grip strength may help doctors determine how likely it is a middle-aged person will develop dementia or stroke. That's according to new research that was just released and will be presented at the American Academy of Neurology's 64th Annual Meeting in New Orleans April 21 to April 28, 2012.

"These are basic office tests which can provide insight into risk of dementia and stroke and can be easily performed by a neurologist or general practitioner," said Erica C. Camargo, MD, MSc, PhD, with Boston Medical Center.

More than 2,400 men and women with an average age of 62 underwent tests for walking speed, hand grip strength and cognitive function. Brain scans were also performed. During the follow-up period of up to 11 years, 34 people developed dementia and 70 people had a stroke.

The study found people with a slower walking speed in middle age were one-and-a-half times more likely to develop dementia compared to people with faster walking speed. Stronger hand grip strength was associated with a 42 percent lower risk of stroke or transient ischemic attack (TIA) in people over age 65 compared to those with weaker hand grip strength. This was not the case, however, for people in the study under age 65.

"While frailty and lower physical performance in elderly people have been associated with an increased risk of dementia, we weren't sure until now how it impacted people of middle age," said Camargo.

Researchers also found that slower walking speed was associated with lower total cerebral brain volume and poorer performance on memory, language and decision-making tests. Stronger hand grip strength was associated with larger total cerebral brain volume as well as better performance on cognitive tests asking people to identify similarities among objects. "Further research is needed to understand why this is happening and whether preclinical disease could cause slow walking and decreased strength," said Camargo.

The study was supported by the National Heart, Lung and Blood Institute's Framingham Heart Study and by the National Institute of Neurological Disorders and Stroke and the National Institute on Aging.

People with symptoms suggesting rapid eye movement sleep behavior disorder, or RBD, have twice the risk of developing mild cognitive impairment (MCI) or Parkinson's disease within four years of diagnosis with the sleep problem, compared with people without the disorder, a Mayo Clinic study has found.

The researchers published their findings recently in the Annals of Neurology.

One of the hallmarks of rapid eye movement (REM) sleep is a state of paralysis. In contrast, people with rapid eye movement sleep behavior disorder, appear to act out their dreams when they are in REM sleep. Researchers used the Mayo Sleep Questionnaire to diagnose probable RBD in people who were otherwise neurologically normal. Approximately 34 percent of people diagnosed with probable RBD developed MCI or Parkinson's disease within four years of entering the study, a rate 2.2 times greater than those with normal rapid eye movement sleep.

"Understanding that certain patients are at greater risk for MCI or Parkinson's disease will allow for early intervention, which is vital in the case of such disorders that destroy brain cells. Although we are still searching for effective treatments, our best chance of success is to identify and treat these disorders early, before cell death," says co-author Brad Boeve, M.D., a Mayo Clinic neurologist.

Previous studies of Mayo Clinic patients have shown that an estimated 45 percent of people who suffer from RBD will develop a neurodegenerative syndrome such as mild cognitive impairment or Parkinson's disease within five years of diagnosis.

RBD, MCI and Parkinson's Disease

"This study is the first to quantify the risk associated with probable RBD in average people, not clinical patients, and it shows that we can predict the onset of some neurodegenerative disorders simply by asking a few critical questions," says lead author Brendon P. Boot, M.D., a behavioral neurologist. Dr. Boot was at Mayo Clinic when the study was conducted. He is now at Harvard University.

• MCI is an intermediate stage between the expected cognitive decline of normal aging and the more pronounced decline of dementia. It involves problems with memory, language, thinking and judgment that are greater than typical age-related changes.
• An estimated 500,000 Americans suffer from Parkinson's disease, which is characterized by tremor or shakiness, stiffness of the limbs and trunk, slowness of movement, and impaired balance and coordination.

Cognitive training including puzzles, handicrafts and life skills are known to reduce the risk, and help slow down the progress, of dementia amongst the elderly. A new study published in BioMed Central's open access journal BMC Medicine showed that cognitive training was able to improve reasoning, memory, language and hand eye co-ordination of healthy, older adults.

It is estimated that by 2050 the number of people over 65 years old will have increased to 1.1 billion worldwide, and that 37 million of these will suffer from dementia. Research has already shown that mental activity can reduce a person's risk of dementia but the effect of mental training on healthy people is less well understood. To address this researchers from China have investigated the use of cognitive training as a defence against mental decline for healthy older adults who live independently.

To be recruited onto the trial participants had to be between 65 and 75 years old, and have good enough eyesight, hearing, and communication skills, to be able to complete all parts of the training. The hour long training sessions occurred twice a week, for 12 weeks, and the subjects were provided with homework. Training included a multi-approach system tackling memory, reasoning, problem solving, map reading, handicrafts, health education and exercise, or focussing on reasoning only. The effect of booster training, provided six months later, was also tested.

The results of the study were positive. Profs Chunbo Li and Wenyuan Wu who led the research explained, "Compared to the control group, who received no training, both levels of cognitive training improved mental ability, although the multifaceted training had more of a long term effect. The more detailed training also improved memory, even when measured a year later and booster training had an additional improvement on mental ability scores."

This study shows that cognitive training therapy may prevent mental decline amongst healthy older people and help them to continue independent living longer in their advancing years.

New research explains how speaking more than one language may translate to better mental health. A paper published by Cell Press in the March 29th issue of the journal Trends in Cognitive Sciences examines how being bilingual can offer protection from the symptoms of dementia, and also suggests that the increasing diversity in our world populations may have an unexpected positive impact on the resiliency of the adult brain.

"Previous studies have established that bilingualism has a beneficial effect on cognitive development in children," explains lead study author, Dr. Ellen Bialystok from York University. "In our paper, we reviewed recent studies using both behavioral and neuroimaging methods to examine the effects of bilingualism on cognition in adults."

Dr. Bialystok and colleagues discuss the intriguing finding that the need to monitor two languages in order to select the appropriate one recruits brain regions that are critical for general attention and cognitive control. Using these cognitive control networks for bilingual language processing may reconfigure and strengthen them, perhaps enhancing "mental flexibility," the ability to adapt to ongoing changes and process information efficiently.

Studies also suggest that bilingualism improves "cognitive reserve," the protective effect that stimulating mental or physical activity has on cognitive functioning in healthy aging. Cognitive reserve can also postpone the onset of symptoms in those suffering from dementia. This is supported by studies showing that bilinguals experience onset symptoms of dementia years later than monolinguals.

"Our conclusion is that lifelong experience in managing attention to two languages reorganizes specific brain networks, creating a more effective basis for executive control and sustaining better cognitive performance throughout the lifespan," says Dr. Bialystok. "It should not be surprising that intense and sustained experience leaves its mark on our minds and brains, and it is now clear that the bilingual brain has been uniquely shaped by experience."

Can the course of dementias and mild cognitive impairment be influenced by diseases and risk factors?

This is the subject of a study reported by Thorleif Etgen and co-authors in the current issue of Deutsches Ärzteblatt International.

Larger numbers of people are affected by mild cognitive impairments and dementia, which means that early detection of possible precursors as well as diagnosis and therapy of risk factors that can actually be influenced are gaining in importance. The term "mild cognitive impairment" describes impairments in memory, attention, and intellectual capacity that are common at an advanced age. It is notably below the usual standard for the age group and educational level under investigation, without presenting substantial limitations to people's everyday lives. Mild cognitive impairment may occur as a precursor stage to actual dementia.

The current data situation is based on less conclusive cross sectional studies and longitudinal studies. In spite of the fact that interventional studies have been negative so far, the authors are of the opinion that a biologically plausible association exists between cognitive degeneration and hypertension, diabetes, and hyperlipidemia. Chronic renal failure has been identified as a new somatic risk factor in recent years. Epidemiological data indicate a protective effect for a Mediterranean diet, physical activity, and moderate alcohol consumption. Smoking, on the other hand, raises the risk for developing cognitive impairments.

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Journal Reference:

1. Etgen T, Sander D, Bickel H, Förstl H. Mild cognitive impairment and dementia: the importance of modifiable risk factors. Dtsch Arztebl Int, 2011 DOI: 10.3238/arztebl.2011.0743

Any exercise that gets the heart pumping may reduce the risk of dementia and slow the condition's progression once it starts, reported a Mayo Clinic study published this month in Mayo Clinic Proceedings. Researchers examined the role of aerobic exercise in preserving cognitive abilities and concluded that it should not be overlooked as an important therapy against dementia.

The researchers broadly defined exercise as enough aerobic physical activity to raise the heart rate and increase the body's need for oxygen. Examples include walking, gym workouts and activities at home such as shoveling snow or raking leaves.

"We culled through all the scientific literature we could find on the subject of exercise and cognition, including animal studies and observational studies, reviewing over 1,600 papers, with 130 bearing directly on this issue. We attempted to put together a balanced view of the subject," says J. Eric Ahlskog, M.D., Ph.D., a neurologist at Mayo Clinic. "We concluded that you can make a very compelling argument for exercise as a disease-modifying strategy to prevent dementia and mild cognitive impairment, and for favorably modifying these processes once they have developed." The researchers note that brain imaging studies have consistently revealed objective evidence of favorable effects of exercise on human brain integrity. Also, they note, animal research has shown that exercise generates trophic factors that improve brain functioning, plus exercise facilitates brain connections (neuroplasticity).

More research is needed on the relationship between exercise and cognitive function, the study's authors say, but they encourage exercise, in general, especially for those with or worried about cognitive issues.

"Whether addressing our patients in primary care or neurology clinics, we should continue to encourage exercise for not only general health, but also cognitive health," Dr. Ahlskog says.

Co-authors include Yonas Geda, M.D.; Neill Graff-Radford, M.D.; and Ronald Petersen, Ph.D., M.D.

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Journal Reference:

1. J. E. Ahlskog, Y. E. Geda, N. R. Graff-Radford, R. C. Petersen. Physical Exercise as a Preventive or Disease-Modifying Treatment of Dementia and Brain Aging. Mayo Clinic Proceedings, 2011; 86 (9): 876 DOI: 10.4065/mcp.2011.0252

A new University of Colorado Boulder study shows that a small amount of physical exercise could profoundly protect the elderly from long-term memory loss that can happen suddenly following infection, illnesses or injury in old age.

In the study, CU-Boulder Research Associate Ruth Barrientos and her colleagues showed that aging rats that ran just over half a kilometer each week were protected against infection-induced memory loss.

"Our research shows that a small amount of physical exercise by late middle-aged rats profoundly protects against exaggerated inflammation in the brain and long-lasting memory impairments that follow a serious bacterial infection," said Barrientos of the psychology and neuroscience department.

The results of the study will appear in the Aug. 10 edition of The Journal of Neuroscience.

"Strikingly, this small amount of running was sufficient to confer robust benefits for those that ran over those that did not run," Barrientos said. "This is an important finding because those of advanced age are more vulnerable to memory impairments following immune challenges such as bacterial infections or surgery. With baby boomers currently at retirement age, the risk of diminished memory function in this population is of great concern. Thus, effective noninvasive therapies are of substantial clinical value."

Past research has shown that exercise in humans protects against declines in cognitive function associated with aging and protects against dementia. Researchers also have shown that dementia is often preceded by bacterial infections, such as pneumonia, or other immune challenges.

"To the best of our knowledge, this is the first study to show that voluntary exercise in rats reduces aging-induced susceptibility to the cognitive impairments that follow a bacterial infection, and the processes thought to underlie these impairments," Barrientos said.

In the study, the researchers found that rats infected with E. coli bacteria experienced detrimental effects on the hippocampus, an area of the brain that mediates learning and memory.

Previous research has shown that immune cells of the brain, called microglia, become more reactive with age. When the older rats in the study encountered a bacterial infection, these immune cells released inflammatory molecules called cytokines in an exaggerated and prolonged manner.

"In the current study we found that small amounts of voluntary exercise prevented the priming of microglia, the exaggerated inflammation in the brain, and the decrease of growth factors," Barrientos said.

The next step of this research is to examine the role that stress hormones may play in sensitizing microglia, and whether physical exercise slows these hormones in older rats, she said.

Barrientos co-authored the paper with CU-Boulder professors of psychology and neuroscience Steven Maier, Linda Watkins, Serge Campeau, Heidi Day and Susan Patterson; and CU-Boulder psychology research assistants Timothy Chapman, Matthew Frank, Nicole Crysdale and Jared Ahrendsen.

The research was funded by the National Institute on Aging, which is part of the National Institutes of Health.

Older women with sleep-disordered breathing, as indicated by measures of hypoxia (oxygen deficiency), were more likely to develop cognitive impairment or dementia than women without this disorder, according to a study in the August 10 issue of JAMA.

"Sleep-disordered breathing, a disorder characterized by recurrent arousals from sleep and intermittent hypoxemia, is common among older adults and affects up to 60 percent of elderly populations. A number of adverse health outcomes including hypertension, cardiovascular disease, and diabetes have been associated with sleep-disordered breathing," according to background information in the article. Cognitive impairment also has been linked to sleep-disordered breathing in some studies, but the design of most of these studies has limited the ability to draw conclusions regarding this association. "Given the high prevalence and significant morbidity associated with both sleep-disordered breathing and cognitive impairment in older populations, establishing whether a prospective association exists between sleep-disordered breathing and cognition is important. This is especially important because effective treatments for sleep-disordered breathing exist."

Kristine Yaffe, M.D., of the University of California, San Francisco, and colleagues examined the association between prevalent sleep-disordered breathing as measured with polysomnography (monitoring of physiological activity during sleep) and subsequent diagnoses of mild cognitive impairment and dementia. The study included 298 women without dementia at the beginning of the study (average age, 82.3 years) who had overnight polysomnography measured between January 2002 and April 2004 in a substudy of the Study of Osteoporotic Fractures. Sleep-disordered breathing was defined as an apnea-hypopnea index of 15 or more events per hour of sleep. The apnea-hypopnea index is the number of complete cessations (apnea) and partial obstructions (hypopnea) of breathing occurring per hour of sleep. Cognitive status (normal, dementia, or mild cognitive impairment) was based on data collected between November 2006 and September 2008. Measures of hypoxia, sleep fragmentation, and sleep duration were investigated as underlying mechanisms for any association between sleep-disordered breathing and cognitive impairment.

Among the 298 women, 35.2 percent met criteria for sleep-disordered breathing. After an average of 4.7 years of follow-up, 35.9 percent of the women developed mild cognitive impairment or dementia (mild cognitive impairment: 20.1 percent; dementia: 15.8 percent). Forty-seven women (44.8 percent) with prevalent sleep-disordered breathing developed mild cognitive impairment or dementia compared with 31.1 percent of those without sleep-disordered breathing. Analysis of the data indicated that the presence of sleep-disordered breathing was associated with an increased odds of subsequent mild cognitive impairment or dementia.

The researchers also found, after adjusting for various demographic risk factors, that two measures of hypoxia (an oxygen desaturation index of 15 or greater and a high percentage of total sleep time [greater than 7 percent] in apnea or hypopnea) were associated with higher incidence of mild cognitive impairment or dementia. "Measures of sleep fragmentation (arousal index and wake after sleep onset) or sleep duration (total sleep time) were not associated with risk of cognitive impairment." The authors add that their finding that sleep-disordered breathing was associated with an increased risk of cognitive impairment seems to be related primarily to measures of hypoxia.

"Given the high prevalence of both sleep-disordered breathing and cognitive impairment among older adults, the possibility of an association between the 2 conditions, even a modest one, has the potential for a large public health impact. Furthermore, the finding that hypoxia and not sleep fragmentation or duration seems to be associated with risk of mild cognitive impairment or dementia provides clues to the mechanisms through which sleep-disordered breathing might promote cognitive impairment. The increased risk for cognitive impairment associated with sleep-disordered breathing opens a new avenue for additional research on the risk for development of mild cognitive impairment or dementia and exploration of preventive strategies that target sleep quality including sleep-disordered breathing," the researchers write.

They add that to fully evaluate the impact of treatment for sleep-disordered breathing in elderly populations, additional trials with larger sample sizes, longer treatment periods, and more diverse populations are required. "Of interest, our findings suggest a potential role for supplemental oxygen therapy for sleep-disordered breathing in elderly individuals; however, its role requires critical evaluation in intervention studies."

Editorial: Sleep-Disordered Breathing and Cognitive Decline in Older Adults

In an accompanying editorial, Nicola Canessa, Ph.D., of the Center for Cognitive Neuroscience, and Luigi Ferini-Strambi, M.D., of the Universita Vita-Salute San Raffaele, Milan, Italy, write that "the study by Yaffe et al and related studies to date suggest that large trials with continuous positive air pressure (CPAP) treatment in elderly participants with sleep-disordered breathing should be performed."

"Moreover, in trials evaluating the effects of pharmacological and nonpharmacological (e.g., cognitive training and rehabilitation) interventions on cognitive function in patients with mild cognitive impairment or dementia, the possible coexistence of sleep-disordered breathing should be considered. Finally, physicians of patients with mild cognitive impairment and sleep-disordered breathing for whom treatment with CPAP may be indicated should consider these results, and future guidelines to formalize the clinical management of patients with mild cognitive impairment should consider the implications of this study and related research."

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Journal References:

1. Kristine Yaffe, Alison M. Laffan, Stephanie Litwack Harrison, Susan Redline, Adam P. Spira, Kristine E. Ensrud, Sonia Ancoli-Israel, Katie L. Stone. Sleep-Disordered Breathing, Hypoxia, and Risk of Mild Cognitive Impairment and Dementia in Older Women. JAMA, 2011; 306 (6): 613-619 DOI: 10.1001/jama.2011.1115
2. Nicola Canessa, Luigi Ferini-Strambi. Sleep-Disordered Breathing and Cognitive Decline in Older Adults. JAMA, 2011; 306 (6): 654-655 DOI: 10.1001/jama.2011.1124

Older women who live in a lower socioeconomic status neighborhood are more likely to exhibit lower cognitive functioning than women who live in more affluent neighborhoods, according to a new RAND Corporation study.

The study, published online by the American Journal of Public Health, is the largest of its type to examine whether living in a poor neighborhood is associated with lower cognitive function.

The study found that potential confounders such as vascular health, health behaviors and psychosocial factors such as depressive symptoms explained only a portion of the relationship between neighborhood socioeconomic status and cognitive function.

"This study provides the best evidence yet that living in a neighborhood with lower socioeconomic standing can have an impact on women's cognitive abilities in late life," said Regina A. Shih, the study's lead author and a behavioral scientist at RAND, a nonprofit research organization. "More work is needed to find out whether living in a lower socioeconomic status neighborhood influences cognitive decline that may affect a woman's risk of developing dementia, and to consider ways to intervene."

Researchers analyzed information collected from 6,137 women from across the United States who were surveyed as a part of the Women's Health Initiative Memory Study, an ancillary study to the Women's Health Initiative hormone therapy trials.

Women from 39 locations who were at least 65 years old and free of dementia were enrolled in the memory study from May 1996 to December 1999. All the women in the study were given a standard test that measures cognitive function by assessing items such as memory, reasoning and spatial functions.

Researchers found that women who lived in neighborhoods with lower socioeconomic status were substantially more likely to have low cognitive scores than similar women who lived in more affluent neighborhoods.

Unlike previous reports, the latest study did not find that older individuals are more vulnerable to the effects of neighborhood socioeconomic status because of a longer exposure to poor or declining neighborhoods.

The study also found that non-whites may be particularly vulnerable to the effects of living in a neighborhood with a lower socioeconomic status. But researchers did not find that an individual's income level or education strengthened or weakened the relationship between neighborhood socioeconomic status and their cognitive functioning.

Support for the study was provided by the National Heart, Lung, and Blood Institute.

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Journal Reference:

1. R. A. Shih, B. Ghosh-Dastidar, K. L. Margolis, M. E. Slaughter, A. Jewell, C. E. Bird, C. Eibner, N. L. Denburg, J. Ockene, C. R. Messina, M. A. Espeland. Neighborhood Socioeconomic Status and Cognitive Function in Women.. American Journal of Public Health, 2011; DOI: 10.2105/AJPH.2011.300169