The Effects of Exercise on Cognition Post-Stroke: Are There Sex Differences?

Abstract

Evidence in older adults suggest that the benefits of exercise on cognition may be moderated by sex. To our knowledge, no studies have examined this relationship in individuals with stroke. This thesis investigated whether there were sex differences in the effect of exercise on cognition post-stroke. The first study was a systematic review of the literature on exercise and cognition in individuals with stroke. The second study was a secondary analysis of data from a randomized controlled trial comparing the effect of aerobic vs. balance and flexibility exercise on cognition. Findings from the systematic review revealed no differences between studies of higher and lower female proportions with respect to memory (Verbal Digit Span Forward, Memory Domain of Stroke Impact Scale and Wechsler Memory Scale III - Verbal Pairing Domain: Chi2 =1.52, p=0.22), executive function (Stroop Test: Chi2 = 0.56, p=0.45; Trail Making Test B: Chi2 = 0.00, p=0.98), language (Communication Domain of Stroke Impact Scale: Chi2 = 3.17, p=0.08) or global cognition (Montreal Cognitive Assessment, Cognitive Domain of Functional Independence Measure and Addenbrooke’s Cognitive Examination-Revised: Chi2 = 0.88, p=0.35). Findings from the secondary analysis indicated that there was a group x time interaction in females (effect size 0.28, p=0.03) that was not observed in males (effect size 0.01, p=0.62). Females demonstrated a Stroop Colour-Word Interference test change of -2.3 seconds, whereas males demonstrated a change of +5.5 seconds following AE. There were no differences between exercise groups in either sex for any of the other outcomes (working memory and set-shifting/ cognitive flexibility). Together, these studies suggest that there is a clear need for future clinical trials that incorporate sex-based analysis to adequately investigate sex-dependent effects of interventions.