Effects of home-based exercise alone or combined with cognitive training on cognition in community-dwelling older adults: A randomized clinical trial

Background: Structured and supervised physical exercise and cognitive training are two efficient ways to enhance cognition in older adults. Performing both within a combined intervention could maximize their effect on cognition due to their potential synergy on brain functions. During the COVID-19 pandemic, these interventions were particularly relevant due to the collateral impact of social restrictions regarding physical activity and the level of cognitive stimulation. However, the benefits of remotely monitored intervention combining physical exercise and cognitive training for older adult cognition remain to be demonstrated. Methods: 127 older adults (age: 65.20 +/- 7.95) were randomized in two arms, encouraging self-engagement in six months of home-based physical exercise alone or combined with cognitive training, monitored by phone once a week. Neuropsychological assessment was performed under videoconference supervision at baseline and after three and six months. Composite Z-scores were calculated for processing speed, executive functioning, working, and episodic memory to assess changes after three and six months of training. The weekly metabolic expenditure of self-reported activities was estimated using the compendium of physical activity to distinguish participants performing higher and lower doses of exercise (median split). Results: 106 participants (83.46 %) completed the 6-month training. Results showed a greater Z-score change in executive functioning for participants in the combined arm than those who only exercised (F = 4.127, p = 0.046, eta p 2 = 0.050). Group x Exercise dose interaction was observed for episodic memory Z-score change (F = 6.736, p = 0.011, eta p2 = 0.070), with a greater improvement for participants performing higher doses of exercise compared to those who performed a lower dose, only in exercise alone arm. Performing a higher dose of exercise increased the working memory Z-score change in both intervention arms compared to a lower dose (F = 7.391, p = 0.008, eta p2 = 0.076). Conclusion: Remote combined training may lead to larger improvement in executive functioning than exercise alone. Physical exercise showed a dose-related improvement in working and episodic memory performances. The combination of cognitive interventions mitigated the effects of exercise on episodic memory. These results suggest that home-based exercise and cognitive training may help improve older adults' cognition. Trial registration: COVEPIC was retrospectively registered on December 03, 2020. Clinical trials Identifier: NCT04635462- https://clinicaltrials.gov/ct2/show/record/NCT04635462?term=NCT04635462&draw=2&ra nk=1