Effect of multicomponent exercise in cognitive impairment: a systematic review and meta-analysis

Background: Multicomponent physical exercise is the most recommended type of physical intervention in older adults. Experimental data suggest the relevance of the muscle-brain axis and the relationship between muscle contraction and release of brain-derived neurotrophic factor, however, the impact of this relationship on cognition remains unclear, especially in people with diagnosis of cognitive impairment. This study assesses the effect of multicomponent physical exercise on global cognition in people with mild cognitive impairment or dementia. Methods: Randomized controlled trials published until January 2021 were searched across three electronic databases (PubMed, Scopus, and Cochrane Database). Data about exercises included in the multicomponent intervention (endurance, strength, balance, or flexibility), the inclusion of aerobic exercise, and the change in global cognition were extracted. The effect size was represented as a standardized mean difference. Risk of bias was assessed by the RoB2 tool. Results: A total of 8 studies were included. The overall effect size suggested an effect of multicomponent exercise on global cognition. However, the subgroup analysis showed an effect only when aerobic exercise was included in the intervention. No effect when mild cognitive impairment and dementia were assessed separately was found. Conclusion: This study suggests that multicomponent physical exercise could have an effect on global cognition in people with mild cognitive impairment or dementia only when aerobic exercise is included in the intervention. Our results support the inclusion of structured physical exercise programs in the management of people with cognitive impairment.