Abstract
BACKGROUND Cognitive impairment and dementia have emerged as one of the greatest global challenges for health and social care. Multidomain interventions that target several risk factors simultaneously may achieve optimal preventive effects for dementia. OBJECTIVE This systematic review aimed to evaluate the effectiveness of multidomain lifestyle interventions for improving cognition and reducing the risk of dementia. DESIGN Systematic review and meta-analysis. METHODS Five electronic databases, PubMed, Embase, Cochrane Library, CINAHL, and PsycINFO, were systematically searched from inception to April 17, 2021. Randomised controlled trials (RCTs) that assessed multidomain lifestyle interventions on the outcomes of cognition or dementia risk were included. The standardized mean difference (Hedges' g) was calculated using random-effects models. Risk of bias was assessed using the Revised Cochrane risk-of-bias assessment tool for randomised trials (RoB2), and the certainty of evidence was assessed using the five Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. RESULTS Seventeen RCTs involving 12,312 participants were included. The meta-analysis indicated that multidomain lifestyle interventions showed small but significant effects on both the risk of dementia (SMD = -0.11; 95%CI, -0.18 to -0.05; P <0.001; I2 = 0%; 6RCTs, 1981 participants) and the cognitive composite score (SMD = 0.10; 95%CI, 0.02 to 0.17; P = 0.012; I2 = 27.5%; 7 RCTs, 2643 participants). No significant improvements were found in global cognition (SMD = -0.04; 95% CI, -0.12 to 0.04; P = 0.330; I2 = 38.3%; 9 RCTs, 3740 participants). CONCLUSIONS Multidomain lifestyle interventions have the potential to reduce the risk of dementia (high-certainty evidence) and improve the cognitive composite score (moderate-certainty evidence). There is no moderate- or high-certainty evidence that multidomain interventions improve global cognition. Future large-scale, high-quality studies are required to determine the effects of multidomain interventions on global cognition or other cognitive domains. REGISTRATION The systematic review and meta-analysis have been registered in PROSPERO (CRD42021260122).
