Interactive effects of physical activity and APOE-ε4 on white matter tract diffusivity in healthy elders

摘要: Older adult apolipoprotein-E epsilon 4 (APOE-e4) allele carriers vary considerably in the expression of clinical symptoms Alzheimer's disease (AD), suggesting that lifestyle or other factors may offer protection from AD-related neurodegeneration. We recently reported physically active APOE-e4 exhibit a stable cognitive trajectory and hippocampal atrophy over 18months compared to sedentary e4 carriers. The aim this study was examine interactions between genetic risk for AD physical activity (PA) on white matter (WM) tract integrity, using diffusion tensor imaging (DTI) MRI, cohort healthy older adults (ages 65 89). Four groups were based presence absence an (High Risk; Low Risk) self-reported frequency intensity leisure time PA; PA). As predicted, greater levels PA associated with fractional anisotropy (FA) lower radial diffusivity who did not possess allele. However, effects reversed at increased AD, resulting significant several WM tracts. In High Risk-Low participants, had exhibited episodic memory decline previous 18-months, higher, Risk-High participants. tracts subserve learning processes, (DR) negatively correlated performance inactive carriers, whereas DR positively two Risk groups. common model demyelination-induced increase cannot directly explain these results. Rather, we hypothesize protect selective neurodegeneration individual fiber populations locations crossing fibers within projection association