The influence of a 16-week exercise program, APOE status, and age on executive function task performance: A randomized trial

Previous research has shown beneficial cognitive changes following exercise training in older adults. However, the work on the potential moderating effects of Apoliprotein E (APOE) e4 carrier status has been mixed, and the role of exercise intensity remains largely unexplored. The present study sought to examine the influence of APOE e4 status and exercise intensity on measures of cognitive performance in a group of older adults. Cross-sectional comparisons between a group of younger inactive adults (n = 44, age = 28.86 +/- 0.473 SD, 60.5% female) and a group of older inactive adults (n = 142, age = 67.8 +/- 5.4, 62.7% female) were made on baseline measurements of APOE e4 status, VO2peak, and cognitive performance in the domain of executive functioning. The older adults also participated in a randomized controlled exercise trial, exercising three times per week for 16-weeks in either a low-intensity continuous training (LICT) group or a moderate-intensity continuous training plus interval training (MICT+IT) group at the Center for Health and Neuroscience, Genes, and Environment (CUChange) Exercise Laboratory. Follow-up measurements of VO2peak and cognitive performance were collected on the older adults after the exercise intervention. Cross-sectional comparisons between the older and younger adults demonstrated significant impairments among older adults in Stroop effect on error and time, Category Switch mixing effects, and Keep Track task. This impairment was not moderated by APOE e4 carrier status. Improvements from pre- to post-exercise intervention were observed in both exercise groups in Stroop effect on error ([F (1, 256) = 9.381, p < 0.01, n2 = 0.031]) and Category Switch switching effect reaction time ([F(1, 274) = 4.442, p < 0.05, n2 = 0.020]), with no difference between exercise groups. The moderating effects of APOE e4 carrier status were mixed. Exercise did not improve the Stroop effect on error among e4 carriers assigned to MICT+IT when improvements were seen in all other groups. Further research is needed to examine the mechanisms of action by which exercise impacts cognitive task performance, and possible moderators such as genetic variability and exercise intensity.