HIGH- AND LOW-INTENSITY EXERCISE DO NOT IMPROVE COGNITIVE FUNCTION AFTER STROKE: A RANDOMIZED CONTROLLED TRIAL

Objective: To determine the effects of high versus low-intensity exercise on cognitive function following stroke. Design: Secondary analysis from a randomized controlled trial with blinded assessors. Subjects: 50-80 years old, living in the community, >1 year post-stroke. Methods: Participants were randomized into a high-intensity Aerobic Exercise or low-intensity non-aerobic Balance/Flexibility program. Both programs were 6 months long, with 3 60-min sessions/week. Verbal item and working memory, selective attention and conflict resolution, set shifting were assessed before and after the program. Results: Forty-seven participants completed the study (22/25 in Aerobic Exercise group, 25/25 in Balance/Flexibility group). There was an improvement in verbal item memory in both groups (time effect p = 0.04), and no between-group differences in improvement in the other outcomes (p>0.27). There was no association between pre-exercise cognitive function and post-exercise improvement. Conclusions: In contrast to a small body of previous research suggesting positive benefits of exercise on cognition post-stroke, the current study found that 6 months of high or low intensity exercise was not effective in improving cognitive function, specifically executive functions. Further research in this area is warranted to establish the effectiveness of post-stroke exercise programs on cognition, and examine the mechanisms that underlie these changes.