Does sleep moderate the effects of exercise training or complex mental and social activities on cognitive function in adults with chronic stroke? Secondary analysis of a randomized trial

Abstract

Background Exercise (EX) or cognitive and social enrichment (ENRICH) are two strategies for promoting cognition post-stroke. Whether sleep moderates the effects of EX or ENRICH on cognition in adults with chronic stroke is unknown. Methods A three-arm parallel randomized clinical trial among community-dwelling adults aged 55+ years with chronic stroke (i.e., ≥12 months since stroke). Participants were randomized to 2x/week EX, ENRICH, or balance and tone control (BAT). At baseline, device-measured sleep duration and efficiency were measured using wrist-worn actigraphy; self-reported quality was measured by Pittsburgh Sleep Quality Index (PSQI). Participants were categorized at baseline as having good or poor device-measured duration, device-measured efficiency, or self-reported quality based on PSQI. The primary cognitive outcome was Alzheimer’s Disease Assessment Scale Plus (ADAS-Cog-Plus) measured at baseline, 6 months (end of intervention), and 12 months (6-month follow-up). We examined if baseline sleep categorizations (i.e., good/poor) moderated effects of EX or ENRICH on ADAS-Cog-Plus. Results We enrolled 120 participants in the trial (EX=34; ENRICH=34; BAT=52). Sleep quality (i.e., device-measured sleep efficiency or self-reported sleep quality) categorization moderated effects of EX (but not ENRICH) on ADAS-Cog-Plus. Compared with BAT participants with poor sleep quality, EX participants with poor sleep quality had better ADAS-Cog-Plus performance at 6 months (estimated mean difference for those with poor device-measured sleep efficiency: -0.48; 95% CI:[-0.85, -0.10]; p=0.010); estimated mean difference for those with poor self-reported sleep quality: -0.38; 95% CI:[-0.70, -0.07]; p=0.014). There was no effect of EX on ADAS-Cog-Plus for participants with good sleep quality. Device-measured sleep duration did not moderate intervention effects. Conclusion Exercise is particularly beneficial in improving cognitive function in adults with chronic stroke and poor sleep quality.