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 Exercise, including activities like walking and running, is linked
to preserved brain structure, even among individuals with mild and
severe symptoms of mental decline, said coauthor James T. Becker,
professor of psychiatry at the University of Pittsburgh School of
Medicine.
“The volumes of these critical brain regions themselves predict the
transition from normal cognition to some degree of impairment (mild
or severe),” Becker told Reuters Health by email.
The researchers analyzed data from a long-term cardiovascular health
study of 876 people, aged 65 years and older when they enrolled, who
underwent cognitive assessments, volumetric brain imaging and
answered questionnaires about their activities.
Researchers estimated weekly energy expenditure based on the
questionnaires, and used total calories burned as a proxy for how
much physical activity participants got. About half the participants
were over age 78 when the brain scans measured their gray matter
volume.
After accounting for other factors that could affect brain volume,
including head size, age, sex, white matter lesions in the brain,
mild cognitive impairment and Alzheimer’s status, the researchers
found that higher energy output in leisure time activities was
associated with larger gray matter volumes in many regions of the
brain, according to the results the Journal of Alzheimer’s Disease.
Energy expenditure may be related to the release of a substance
known as brain-derived neurotrophic factor (BDNF), which promotes
the growth and differentiation of new neurons in the brain, Becker
said.
The volume of gray matter in the brain typically shrinks with age.
But past research has suggested that increased BDNF as a result of
exercise may help to preserve a more youthful amount of gray matter.
“Activity, and the resulting sparing of brain structure, likely acts
by supporting the brain and cognitive reserve,” Becker said. “Thus,
in the presence of a degenerative disorder such as Alzheimer’s
disease, the higher brain reserve extends the ‘dementia free’ time.”
The more activity, the better, both for heart and brain health,
Becker said.
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“Our data suggest that it may not matter so much what we do, so long
as we burn a lot of calories doing it,” since the biggest impact was
seen in the upper 25 percent of calorie expenditure, he said.
Being active in a social setting may be more effective than just
walking on a treadmill alone, he said.
The study team acknowledges that for some participants reduced
physical activity could be a result of an overall health decline
associated with dementia. They also did not look at whether the
greater gray matter volume associated with exercise had any
protective effect on cognitive function.
“Physical activity is multidimensional, not only energy expenditure
but also social, mental and emotional activities are involved,” said
Leandro Fornias Machado de Rezende of the department of preventive
medicine at the University of Sao Paulo School of Medicine in
Brazil, who was not part of the new research.
“In this sense, prevention of Alzheimer’s disease through physical
activity should be understood in a broad view,” Rezende told Reuters
Health by email.
SOURCE: bit.ly/1XmOHxy Journal of Alzheimer’s Disease, online March
11, 2016.
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