Cognitive activity relates to cognitive performance but not to Alzheimer disease biomarkers

Objective: We aimed to determine whether there was a relationship between lifestyle factors and Alzheimer disease biomarkers. Methods: In a cross-sectional study, we evaluated self-reported histories of recent and past cognitive activity, self-reported history of recent physical activity, and objective recent walking activity in 186 clinically normal individuals with mean age of 74 +/- 6 years. Using backward elimination general linear models, we tested the hypotheses that greater cognitive or physical activity would be associated with lower Pittsburgh compound B-PET retention, greater F-18-fluorodeoxyglucose-PET metabolism, and larger hippocampal volume, as well as better cognitive performance on neuropsychological testing. Results: Linear regression demonstrated that history of greater cognitive activity was correlated with greater estimated IQ and education, as well as better neuropsychological testing performance. Self-reported recent physical activity was related to objective exercise monitoring. However, contrary to hypotheses, we did not find evidence of an association of Pittsburgh compound B retention, F-18-fluorodeoxyglucose uptake, or hippocampal volume with past or current levels of cognitive activity, or with current physical activity. Conclusions: We conclude that a history of lifelong cognitive activity may support better cognitive performance by a mechanism that is independent of brain beta-amyloid burden, brain glucose metabolism, or hippocampal volume.