Effects of Six-Month Aerobic Exercise Intervention on Sleep in Healthy Older Adults in the Brain in Motion Study: A Pilot Study

Abstract

Background: Sleep disturbances have been shown to be associated with the presence of the apolipoprotein (APOE) 4 allele, the well-known genetic risk factor for late-onset sporadic Alzheimer's disease (AD). Objective: This study quantifies the effects of a six-month aerobic exercise intervention on objective and subjective sleep quality in middle-aged to older individuals including those at increased genetic risk for late-onset sporadic Alzheimer's disease (AD), who carry the apolipoprotein (APOE) 4 risk allele. Methods: 199 sedentary men and women without significant cognitive impairments were enrolled in the Brain in Motion study, a quasi-experimental single group pre-test/post-test study with no control group. Participants completed a six-month aerobic exercise intervention and consented to genetic testing. Genotyping of APOE confirmed that 54 individuals were carriers of the 4 allele. Participants' subjective quality of sleep was assessed with the Pittsburgh Sleep Quality Index (PSQI) pre-and post-intervention. A convenience sample of participants (n = 29, APOE 4+ = 7) consented to undergo two nights of in-home polysomnography (PSG) pre-and post intervention. Sleep architecture and respiratory variables were assessed. Results: The six-month aerobic exercise intervention significantly improved participants' total PSQI score, sleep efficiency, and sleep latency in the full sample (n = 199). PSG results showed that total sleep time and sleep onset latency significantly improved over the course of the exercise intervention only in individuals who carried the APOE 4 allele. These results are, however, exploratory and need to be carefully interpreted due to the rather small number of APOE 4+ in the PSG subgroup. Conclusions: The six-month aerobic exercise intervention significantly improved participants' sleep quality with beneficial effects on PSG shown in individuals at increased genetic risk for late-onset sporadic AD.