Physical Activity Helps to Counter Genetic Risk of Alzheimer’s Disease

The presence of an APOE epsilon-4 allele is the most established genetic risk factor for Alzheimer’s Disease. A higher percentage of individuals with Alzheimer’s having an epsilon-4 allele (as compared to the general population); as well, in these carriers the age at dementia onset is earlier, and the rate of cognitive decline may be higher.  Denise Head, from Washington University (Missouri, USA), and colleagues studied 201 men and women, ages 45 to 88 years, who tested cognitively normal at a single Alzheimer's research center.  Among the 163 individuals imaged with a PET scan to measure amyloid deposits, 52 were APOE epsilon-4 carriers. Carriers had significantly higher mean binding potential on that imaging as expected, and sedentary individuals -- regardless of carrier status -- also showed higher binding potential and lower cerebrospinal beta-amyloid 42, as compared to those who were more active.  Carrier status and exercise level interacted significantly for amyloid imaging, though not on cerebrospinal fluid measures.  Being less active was associated with more cortical amyloid binding potential in APOE epsilon-4 carriers but not in noncarriers.  The study authors conclude that: “Collectively, these results suggest that cognitively normal sedentary APOE epsilon-4 -positive individuals may be at augmented risk for cerebral amyloid deposition.”