Midlife Physical Activity Correlates With Late-Life Brain Structure

Higher levels of leisure time physical activity in midlife was associated with less late-life brain damage on MRI, a prospective study suggested.

Compared with no moderate-to-vigorous intensity physical activity in midlife, high levels were associated lower odds of lacunar infarct in late life (OR 0.68, 95% CI 0.46-0.99) and more intact white matter integrity, reported Priya Palta, PhD, of Columbia University Irving Medical Center in New York City, and colleagues in Neurology.

“Our study suggests that getting at least an hour and 15 minutes of moderate-to-vigorous intensity physical activity a week or more during midlife may be important throughout your lifetime for promoting brain health and preserving the actual structure of your brain,” Palta said in a statement. “In particular, engaging in more than 2 and a half hours of physical activity per week in middle age was associated with fewer signs of brain disease.”

Research about the effects of physical activity on brain measures or cognitive improvement has been mixed, with some studies showing benefit and some not. The “most consistent evidence for the protective effect of physical activity against dementia risk has been reported to be leisure time physical activity, and it is unclear whether there is benefit to other types of physical activity that may be less ‘enriching,'” observed Nicole Spartano, PhD, of Boston University School of Medicine, and Leonardo Pantoni, MD, PhD, of University of Milan in Italy, in an accompanying editorial.

“It is possible that future work will uncover the requirement that physical activity interventions to reduce dementia risk actually have an enriching element, such as in leisure-time activities, rather than be strictly rote, mechanical movement,” Spartano and Pantoni noted.

The study included 1,604 participants from the Atherosclerosis Risk in Communities (ARIC) cohort with a mean baseline age of 54. Participants had five examinations over 25 years and MRI at a mean age of 72. At baseline (1987-1989) and 25 years later, participants answered questions about their moderate-to-vigorous physical activity in the past year, which was classified as none, low, middle, or high at each time point. Activity was assessed with the modified Baecke questionnaire.

More than half (55%) of the group was female and 27% was Black. At midlife, 34% of participants reported no moderate-to-vigorous intensity physical activity; 11% had low levels (1 to 74 minutes a week), 16% middle levels (75 to 149 minutes a week), and 39% high levels (150 minutes a week or more).

High moderate-to-vigorous midlife activity was associated with better white matter integrity (mean fractional anisotropy difference 0.13 per SD, 95% CI 0.004-0.26; average mean diffusion difference -0.11 per SD, 95% CI -0.21 to -0.004) in late life, compared with no moderate-to-vigorous midlife activity. High moderate-to-vigorous activity was not associated with grey matter volume.

While odds of lacunar infarcts were lower with more intense midlife activity, odds of cortical infarcts or subcortical microhemorrhage were not. “The associations of greater levels of mid-life physical activity with fewer lacunar (but not cortical) infarcts and greater white matter microstructural integrity suggest cerebrovascular mechanisms are primarily at play,” Palta and colleagues wrote.

When findings were adjusted for vascular risk factors — hypertension, diabetes, BMI, and stroke — the relationship of midlife physical activity to lacunar infarcts was attenuated, but not the relationship to white matter microstructure. This implies that “evidence from this study supports a hypothesis that the mechanisms linking physical activity and the brain are likely multi-dimensional, including mechanisms other than simply improving cerebrovascular health,” the editorialists said.

Late-life moderate-to-vigorous physical activity also was associated with most brain measures compared with no moderate-to-vigorous activity, but because this was a prospective study that spanned decades, the “association between midlife physical activity levels and later-life brain imaging features makes a much stronger case for causality than does the same relationship when measured only in late life,” the researchers noted.

The study had several limitations. It relied on self-reported data and did not include physical activity besides leisure time activity, such as work-related activity. Attrition over the study period may have resulted in healthier participants attending the last examination.