More Evidence That Physical Activity
Protects the Aging Brain
Megan
Brooks
May
16, 2012 — New data from the Rush Memory and Aging Project provide more
evidence that staying physically active may protect the aging brain from
Alzheimer's disease (AD).
In
a group of more than 700 elderly individuals free of dementia at baseline, a
higher level of total daily physical activity, determined objectively via
24-hour actigraphy, was associated with a lower risk for the subsequent
development of AD, as well as a slower rate of cognitive decline.
The
association remained "robust" after accounting for a wide variety of
potentially confounding factors, and supports efforts to encourage physical
activity even in the very old, conclude Aron S. Buchman, MD, from the Rush
Alzheimer's Disease Center, Rush University Medical Center in Chicago,
Illinois, and colleagues.
Their
findings were published in the April 24 issue of Neurology.
Objective
Activity Data
The
authors of a linked editorial point out that this is the first study to
report prospective associations of physical activity with AD and cognitive
decline using an objective measurement of physical activity, which
"importantly eliminates recall bias, and includes an all-encompassing
measure of daily physical activity."
Most
prior studies have consistently associated physical activity with decreased
risk for cognitive decline and dementia but have relied on self-report measures
of physical activity without objective validation.
During
the study, 716 dementia-free individuals (mean age, 82 years) wore an actigraph
on the nondominant wrist 24 hours a day for up to 10 days. The device records
total daily exercise and nonexercise physical activity. As part of the ongoing
prospective observational Rush Memory and Aging Project, participants underwent
structured annual clinical exams, including a battery of 19 cognitive tests.
Over
an average of 3.5 years, 71 participants (9.9%) developed AD. According to a
Cox proportional hazards model adjusted for age, sex, and education, level of
total daily physical activity was associated with incident AD (hazard ratio,
0.477; 95% confidence interval, 0.273 - 0.832).
The
association remained after further adjustment for self-report physical, social,
and cognitive activities, as well as current level of motor function,
depressive symptoms, chronic health conditions, and APOE allele status.
According
to the investigators, an individual with low total daily physical activity
(10th percentile) had a more than 2-fold higher risk of developing AD as
compared with a participant with high total daily physical activity (90th
percentile).
In
a linear mixed-effect model, the level of total daily physical activity was
also associated with a slower rate of global cognitive decline (estimate, 0.033
[standard error, 0.012]; P = .007), particularly for episodic memory, working
memory, perceptual speed, and visuospatial abilities.
Pragmatic
Implications
Dr.
Buchman and colleagues say the finding that not only exercise but also higher
levels of nonexercise activity are associated with cognition in old age has
"important implications not only for observational studies but also for
the design of physical activity intervention studies and cognition in old age.
Older individuals, for whom participation in formal exercise may be constrained
because of underlying health problems, may nonetheless benefit from a more
active lifestyle through increases in the full spectrum of routine
activities," they explain.
Michal
Schnaider Beeri, PhD, from the Department of Psychiatry, Mount Sinai School of
Medicine in New York City, and Laura Middleton, PhD, from the Joseph Sagol
Neuroscience Center, Sheba Medical Center, Tel Hashomer, Israel, agree.
"These
results may have substantial pragmatic implications for public health,"
they write in their editorial. "Motivating the elderly to be physically
active, even if mobility is limited, may decrease their risk of developing AD.
Since in the Buchman et al. study the actigraph was attached to the wrist,
cooking, washing dishes, playing cards, and even activity in the setting of
reduced mobility, such as moving a wheelchair with one's arms, constitute
nonexercise physical activity from which elderly may benefit," they note.
As
for the research implications, Dr. Buchman and colleagues say, going forward,
it may be particularly important to measure exercise and nonexercise activities
in older adults.
"It
is likely that with falling cost and technologic advances," the study
authors conclude, the use of actigraphs and other devices that provide
objective data "will become more commonplace, increasing the precision and
specificity of physical activity measures and facilitating efforts to explicate
the link between physical activity and cognition in old age."
The
study was supported by the National Institutes of Health and the National
Institute on Aging, the Illinois Department of Public Health, and the Robert C.
Borwell Endowment Fund. The study and editorial authors have disclosed no
relevant financial relationships.
Neurology.
2012;78:1290-1291,1323-1329. AbstractEditorial
Medscape Medical News © 2012 WebMD,
LLC
Coffee Consumption Linked to Lower Risk
for Death
Steven Fox
May
16, 2012 — The controversy about whether coffee is harmful or healthful just
got a jolt of java.
Results
from the largest study carried out to date indicate that coffee consumption was
inversely associated with total and cause-specific mortality.
Men
who drank 2 to 3 cups of coffee daily had a 10% decrease in their risk for
death during the 13 years of the study compared with men who drank no coffee.
Women who drank 2 to 3 cups of coffee daily had a 13% decrease in their risk
for death.
The
study, conducted by Neal Freedman, PhD, from the Division of Cancer
Epidemiology and Genetics, National Cancer Institute, National Institutes of
Health, Rockville, Maryland, and colleagues, appears
in the May issue of the New England Journal of Medicine.
"Considerable
attention has been focused on the possibility that coffee may increase the risk
of heart disease, particularly since drinking coffee has been associated with
increased low-density lipoprotein cholesterol levels and short-term increases
in blood pressure," the authors note.
However,
the results of prior studies looking into that association have been
inconsistent. The authors say that may be because of differences in the way the
studies were conducted (case-controlled vs prospective study designs) or
because previous researchers have not adequately controlled for potentially
confounding variables such as tobacco smoking.
In
addition to those potential limitations, the authors note, the total number of
deaths examined in previous studies has been relatively small.
In
an effort to address those issues, this group of researchers checked into the
association of coffee consumption with subsequent total and cause-specific
mortality in 229,119 men and 173,141 women who completed questionnaires as part
of the wide-ranging National Institutes of Health–AARP Diet and Health Study.
When
joining the study, participants were given questionnaires that, among other
things, asked them about their coffee consumption. Ages at that baseline
assessment ranged from 50 to 71 years. People with cancer or heart disease and
those who had a history of stroke were excluded from the study.
During
the 13-year study (1995 - 2008), 33,731 men and 18,784 women died. When the
investigators used age-adjusted models to assess those results, they found that
risks for death were elevated for coffee drinkers compared with those people
who did not drink coffee.
However,
those who drank coffee were also more likely to be smokers, and when the
researchers adjusted for smoking status as well as other potentially
confounding variables, a very different picture emerged.
"In
this large, prospective U.S. cohort study, we observed a dose-dependent inverse
association between coffee drinking and total mortality, after adjusting for
potential confounders (smoking status in particular)," they write.
More
specifically, they found that men who consumed 6 or more cups of coffee each
day were 10% less likely to die during the study period than were men who did
not drink coffee. For women, the reduction in risk was even greater, at 15%.
Hazard
ratios for mortality in men who drank coffee compared with men who did not (P
< .001 for trend across categories) were:
- less than 1 cup of coffee per day: 0.99 (95% confidence
interval [CI], 0.95 - 1.04), - 1 cup: 0.94 (95% CI, 0.90 - 0.99),
- 2 to 3 cups: 0.90 (95% CI, 0.86 - 0.93),
- 4 to 5 cups: 0.88 (95% CI, 0.84 - 0.93), and
- 6 or more cups: 0.90 (95% CI, 0.85 - 0.96).
Corresponding
hazard ratios for women (P < .001 for trend across categories) were:
- less than 1 cup of coffee per day: 1.01 (95% CI, 0.96 -
1.07), - 1 cup: 0.95 (95% CI, 0.90 - 1.01),
- 2 to 3 cups: 0.87 (95% CI, 0.83 - 0.92),
- 4 to 5 cups: 0.84 (95% CI, 0.79 - 0.90), and
- 6 or more cups: 0.85 (95% CI, 0.78 - 0.93).
As
for cause-specific mortality, the researchers say they noted inverse
associations for deaths resulting from heart disease, stroke, diabetes,
respiratory disease, infections, injuries, and accidents, but the same was not
true of deaths from cancer.
"In
contrast, there was no significant association between coffee consumption and
deaths from cancer in women," the researchers say. They also found a
borderline positive association in men. Of the 13,402 deaths from cancer, 880
deaths were in men who consumed at least 6 cups of coffee each day (hazard
ratio, 1.08; 95% CI, 0.98 - 1.19; P = 0.02 for trend).
Mortality
rates were similar across all subgroups, the researchers note. That included
people who had never smoked as well as those who at baseline described
themselves as being in very good or excellent health.
The
authors emphasize several limitations of the study. For one, coffee consumption
was assessed at only a single point in time (upon entry into the study), so it
is possible that consumption patterns might have changed over time.
In
addition, the researchers note that they lacked specifics on how study
participants prepared their coffee, and it could be that healthful and/or
harmful attributes of the coffee might change depending on how it is prepared.
Still,
they note, this study was larger than any previous study, and the number of
deaths (>52,000) was more than double that in any earlier study.
"Our
results provide reassurance with respect to the concern that coffee drinking
might adversely affect health," they conclude.
The
research was supported by the Intramural Research Program of the National
Institutes of Health, National Cancer Institute, Division of Cancer
Epidemiology and Genetics. The authors have disclosed no relevant financial
relationships.
N
Engl J Med. 2012;366:1891-1904. Abstract
Medscape Medical News © 2012 WebMD,
LLC
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