P4-127: The effect of midlife physical activity on subsequent structural brain changes

Abstract

Background: Physical activity has been associated with decreased risk of dementia in recent studies. Simultaneously, several dementia risk factors have been associated with WML and/or brain atrophy in magnetic resonance images (MRI), but the role of physical activity is unclear. In this study, we aimed at clarifying the associations between midlife physical activity and subsequent structural brain changes using MRI. Methods: The CAIDE subjects were randomly selected from population based samples first studied in 1972-1987, and re-examined in 1998 (average follow-up time 21 years). For this study, a subpopulation of 91 persons was scanned at the re-examination with Siemens Magnetom 1.5T MR scanner, and T1-weighted images were used to investigate grey matter (GM) density using voxel-based morphometry. WML were assessed on FLAIR-images using a semi-quantitative visual rating scale. Additionally, all participants were investigated for their health status/habits at midlife and re-examination. Results: Persons who participated in leisure time physical activity at midlife tended to have larger total brain volume ( 0.12; 95% CI -0.171.16, p 0.10) later in life than the more sedentary persons even after adjustments for socio-demographic and vascular factors, apoE 4 genotype, smoking, diagnosis of dementia or mild cognitive impairment and cerebrospinal fluid/white matter/grey matter volumes. Interestingly, GM volume was significantly larger among the active ( 0.19; 95% CI 0.071.48, p 0.03), whereas the association between midlife physical activity and larger WM volume became non-significant after full adjustments. Further, the differences in the GM density between the active and sedentary groups localized mainly in frontal lobes. Finally, there was no significant association between midlife physical activity and severe WML later in life after full adjustments. Conclusions: Midlife physical activity might have an effect on total brain and GM volumes later in life, while there might not be an association between midlife physical activity and either WM volume or WML later in life. However, more studies with different methods are warranted for further understanding about the association between physical activity and structural brain changes.