A long-term study that tracked activity levels of adults over a 30-year period suggests that physical activity may not help maintain one’s cognitive function or help avoid or delay the onset of Alzheimer’s disease.
Activity levels among the study participants in the later years were associated with high cognitive function 2 years later, however, according to the study, conducted by researchers at Johns Hopkins Bloomberg School of Public Health and published recently in the Journal of Alzheimer’s Disease.
“This study reminds us that physical activity has all sorts of benefits for people, including promoting cardiovascular health, managing optimal weight levels and maintaining bone and muscle mass,” says Alden L. Gross, assistant professor in the Bloomberg School’s Department of Epidemiology.
“Unfortunately it is too early for us to say the same about exercise and Alzheimer’s, especially as a possible long-term preventive measure,” he says in a media release from Johns Hopkins Bloomberg School of Public Health.
The researchers used data from the Johns Hopkins Precursors study, which registered students studying at Johns Hopkins School of Medicine between 1948 and 1964 and tracked them with annual questionnaires about their overall health.
The median age for study participants was 46 years in 1978 and 77 years in 2008. Every several years, the questionnaire asked about exercise, physical activity, and physical limitations. The researchers used responses from 1978 through 2008 from 646 participants (598 men, 48 women) to calculate so-called metabolic equivalents, which quantify physical activity levels. Participants were also asked whether they regularly exercise to a sweat.
The team administered cognitive tests in 2008, and, using participants’ medical records, scored for dementia through 2011. The researchers identified 28, or 4.5% of the cohort, to have Alzheimer’s.
No physical activity measure in mid-life was associated with late-life cognitive fitness or onset of dementia, the release explains.
The idea that exercise might play a role in preventing or limiting Alzheimer’s makes sense, the researchers say, because physical activity, at least in mouse models, has shown less accumulation of B-amyloid plaques, which are thought to play a role in dementia, including Alzheimer’s. In addition, physical activity improves blood flow to the brain, which is linked to better cognitive performance. This may explain why studies find that exercise may contribute to cognitive fitness in the short term, the release continues.
“These findings have implications for intervention work moving forward,” Gross states. “We still need to focus on causes and mechanisms of Alzheimer’s and dementia, since we don’t yet know which preventive measures may or may not work.”
“For now, when I speak in the community about Alzheimer’s, I find that people take some relief in understanding that there wasn’t anything that anyone might have done to avoid a loved one developing Alzheimer’s. Of course, the goal for researchers is to identify factors that may help older people maintain their cognitive function into their later years,” he adds.
[Source(s): Johns Hopkins Bloomberg School of Public Health, Newswise]