Transportation Physical Activity Earlier in Life and Areas of the Brain related to Dementia Later in Life

Efforts to preserve brain function may be most effective when administered before there are changes in the brain, which may occur decades before the onset of Alzheimer's disease symptoms. White matter hyperintensities (WMH), a cardiovascular disease biomarker, are areas of hyperintense signals scattered in the white matter of the brain evident on magnetic resonance images. WMH increase with age and are associated with a higher risk of dementia. The purpose of this study was to determine if there was an association between different domains and intensities of physical activity earlier in life and lower risk of dementia later in life as indicated by less WMH.

In this cross-sectional study, face-to-face interviews were conducted with the Lifetime Total Physical Activity Questionnaire. The metabolic equivalent of task (MET) hours/week/year of moderate (3.0-5.9 METs) and vigorous-intensity (≥6 METs) occupation, transportation, household and leisure-time physical activity was obtained across school-age (6-11), adolescence (12-18), young (19-39) and middle adulthood (40-64). WMH were calculated as the percent of intracranial volume in cognitively unimpaired middle (age 40-64) and older adults (age 65+). Simultaneous multiple linear regression determined associations between moderate and vigorous-intensity occupation, transportation, household and leisure-time physical activity across school-age, adolescence, young and middle adulthood with WMH.

Greater moderate-intensity transportation physical activity during young (b= -.09, p=.008) and middle adulthood (b= -.14, p=.013) was associated with lower WMH in middle and older adulthood, explaining 28% (p=.003) to 29% (p=.002) of the variance in WMH (n=54).

Changes to the physical environment that encourage walking, running or biking, such as sidewalks and bike paths, may be strategies to mitigate the age-related increases in WMH, areas of the brain associated with higher risk of dementia.