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 Researchers assessed data from 19 studies conducted between 2002 and
2015 that examined the effects of exercise on cognitive ability in
1,145 people at risk of or diagnosed with Alzheimer’s disease.
Nearly 90 percent were randomized controlled trials, which are the
most reliable type of study.
Most participants were female (71%); the average age was 77. Just
over half of the study subjects participated either in an aerobic
exercise program, or an aerobic program plus a resistance training
intervention. The rest of the study participants received only usual
care.
Aerobic exercises include brisk walking, jogging, swimming, cycling
and other activities that boost the heart rate and strengthen the
heart and lungs.
On average, participants exercised 3.5 days per week at moderate
intensity, with each session lasting 30 to 60 minutes. While the
programs tested in some of the studies were as short as 8 weeks,
others lasted more than 6 months.
Results indicated that exercise - specifically, cardiovascular
exercise - had a strong favorable impact, researchers reported in
the Journal of the American Geriatrics Society.
“We found a statistically significant increase in cognitive function
that favored the groups receiving the exercise interventions
compared to the non-exercise control groups,” lead study author
Gregory Panza, from the University of Connecticut in Storrs, told
Reuters Health by email.
For example, he said, among people with similar cognitive test
scores at the start, “an individual in the exercise group would
score higher on the cognitive function tests than 69% of patients in
the non-exercise control group” by the end of the study.
Cognitive function was most commonly assessed using the Mini-Mental
State Exam (MMSE), but other validated tools also were used. The
tools evaluate things like problem solving and processing speed,
motor ability, multi-tasking and recollection of events as well as
object recognition and ability to plan, all of which serve as
proxies for mental sharpness.
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The positive effect of exercise wasn’t the only thing researchers
discovered.
“True, we found that brain function improved,” coauthor Linda
Pescatello, also from the University of Connecticut, said in a phone
interview. “But in the group that did not receive exercise, there
was actually a deterioration. This deterioration was unanticipated
and really accentuates the importance of our findings.”
Adding resistance training to aerobic exercise did not appear to
make a difference, however.
This study is the first to suggest that aerobic exercise may be more
effective than other types of exercise when the goal is to preserve
the cognitive health of older adults at risk of or with Alzheimer’s
disease, Panza said.
“Exercise can change the brain chemistry. It can change
neurotransmitters associated with depression, anxiety and stress as
well as brain chemicals associated with learning,” said Carol Ewing
Garber, Director of the Applied Physiology Lab at Columbia
University, Teachers College, in New York City, who wasn’t involved
in the study. “These changes can result in improved mood, resilience
to stress and improve functions of the brain such as processing
speed, attention, short term memory and cognitive flexibility among
other things.”
“To date, evidence supports aerobic exercise as the preferred
modality for (Alzheimer’s disease), but more studies are needed to
confirm this,” Pescatello said. “This is a relatively new area of
research, and there really just isn’t enough data available to make
a clear determination.”
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