A study published in Neurology demonstrates that indices of brain pathology, including macroinfarcts, nigral neuronal loss, and white matter pathologies, are associated with total daily activity and its intensity proximate to mortality in older adults. Findings demonstrate that accumulation of these brain pathologies may independently contribute to reduced physical activity levels in older community-dwelling adults.
Brain autopsies of participants of the Rush Memory Aging project (n=428) were studied to identify the association between brain pathologies and total daily physical activity and mortality. Physical activity was measured by means of a wearable activity monitor for 24 hours/day for up to 10 days, providing activity counts every 15 seconds.
On average, the age at death was 90.6 years, and the mean total daily activity was 1.53 × 105 counts/day (standard deviation 1.14 × 105 counts/day). After controlling for age and sex in the multiple regression analysis, the investigators found independent associations between total daily physical activity proximate to death and nigral neuronal loss (estimate -0.232, standard error 0.070, P =.001) and macroinfarcts (estimate -0.266, standard error 0.112, P =.017). These associations represented an additional 2.4% of the variance of total daily physical activity.
Apathy, extraversion, and sleep fragmentation were additional factors associated with total daily physical activity. Alzheimer’s disease, Lewy bodies, TAR DNA-binding protein 43, hippocampal sclerosis, microinfarcts, atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy were postmortem indexes that were not associated with total daily activity in this cohort.
A limitation of the study includes the overrepresentation of female patients (72%), thereby limiting the generalizability of the findings.
Based on these findings, the investigators conclude that “accumulating health deficits in older adults impair diverse physiologic systems, which can degrade an individual’s ability or capacity to maintain prior levels of physical activity.”
Buchman AS, Dawe RJ, Yu L, et al. Brain pathology is related to total daily physical activity in older adults. Neurology. 2018;90(21):e1911-e1910.