The interactive effects of genetics and cardiorespiratory fitness level on cognitive performance in healthy older adults

This study was conducted as an exploratory analysis of the potential interaction between genetics and cardiorespiratory fitness level on cognition in healthy older adults. The main questions were 1) can genetic status moderate the effect of cardiorespiratory fitness level on cognition and 2) can cardiorespiratory fitness level influence the effect of genetic status on cognition. A cross-sectional sample of healthy older adults were recruited for a longitudinal randomized controlled exercise intervention. Participants were admitted into the study based on their sedentary lifestyle and this analysis was conducted on data collected at the outset of the intervention. Dopamine-related genes were chosen based on dopamine's influence on cognition and its sensititvy to aging. The Catechol-O-Methyltransferase (COMT) and Dopmaine Beta Hydroxylase (DBH) genes were chosen because their protein products influence levels of dopamine within the brain. Further, each gene has two common functional single nucleotide polymorphisms which effect the functionality of the protein product. Two growth factor genes, Insulin-like Growth Factor I and Brain Derived Neurotrophic Factor, were chosen based on the role they play in brain development and overall health as well as their moderation by exercise. The primary measure of cardiorespiratory fitness was maximal oxygen uptake (VO2) and neuropsychological assessments were collected either through computer-based or paper-and-pencil methods. Overall, results suggest that genetic status did interact with cardiorespiratory fitness level to influence both working and spatial memory as well as various aspects of executive functioning including response inhibition, maintenance and coordination of multiple sets, and cognitive flexibility. Results of the study point to the need for approaches beyond single gene assocations such as genome wide association studies (GWAS), epigenetic analyses, gene-gene interactions and interactions with environmental factors to take into consideration all the factors that contribute to the variability in the cognitive aging process