Effect of water-based exercise combined with cognitive training on cognitive and physical performance in elderly with mild cognitive impairment: a randomized controlled trial

Background: Mild cognitive impairment (MCI) is a transitional stage between normal cognition and dementia. Physical activity and exercise represent non-pharmacological interventions that have positive effects on cognitive function. Moderate-intensity exercise has been shown to enhance cognitive performance in both healthy older adults and those with cognitive impairment. The combined cognitive and physical interventions offer greater efficacy in promoting functional activities among elderly with MCI, compare to cognitive training or physical training alone. The water-based exercise presents as a low-impact activity on the joints and increased resistance compared to exercises performed in air. It is well-suited for elderly and is often perceived as enjoyable. Fewer evidences were found regarding the effect of water-based exercise on promoting cognitive and physical performance in the elderly with MCI. The objectives of this study were to investigate and compare the post-training effects of water-based exercise and water-based exercise combined with cognitive training on cognitive function and physical performance in elderly with MCI. Methods: Thirty-seven elderly with MCI, aged 65 years or older were recruited to the study . They were divided into 2 groups; a water-based group (W group; n=18) and a water-based exercise combined with a cognitive training group (W-COG group; n=19). Both groups received an aerobic exercise program in water 60 min./d, 3 d/wk., for 12 wk. The W-COG group received simultaneous aerobic exercise and cognitive training in water. The cognitive and physical performances were collected at baseline and following the 12 weeks intervention. The cognitive performance composed of global cognition (The Montreal Cognitive Assessment; MoCA), executive function (Stroop Color and Word Test; SCWT, Trail Making Test A,B; TMT-A,B) and working memory (Digit Span Forward and Backward Test; DSFT & DSBT). The physical performance composed of cardiovascular fitness (the 6-minutes-walk Test; 6MWT) and mobility, balance, and walking ability (The Timed up and go test ;TUG and The Timed up and go test with calculation; TUGdt-cal). The two-ways mixed analysis of variance was used for analysis the variables both in within and between-groups. The post-hoc analysis was performed with Bonferroni test. The statistically significant level was set as 0.05.Results: The improvement of global cognitions and executive function (visuospatial ability) were found in W (p < 0.001, p < 0.01; respectively) and W-COG groups (p < 0.001, p < 0.05; respectively) after 12 weeks of intervention. The executive function (inhibitory control) was improved only in W-COG group (p < 0.05). The improvement of cardiovascular fitness was found only in W-COG group (p < 0.05). No significant difference was observed in the changes in cognitive and physical performances between the two groups.Conclusion: Both water-based exercise interventions have the potential to enhance cognitive function and restore cognition in the elderly with MCI. Additionally, the water-based exercise combined with cognitive training group may offer additional benefits for cardiovascular fitness.