Cognitive training in Parkinson disease: A systematic review and meta-analysis

OBJECTIVE: To quantify the effects of cognitive training (CT) on cognitive and behavioral outcome measures in patients with Parkinson disease (PD). METHODS: We systematically searched 5 databases for randomized controlled trials (RCTs) of CT in patients with PD reporting cognitive or behavioral outcomes. Efficacy was measured as standardized mean difference (Hedges g) of post-training change. RESULTS: Seven studies encompassing 272 patients with Hoehn & Yahr Stages 1–3 were included. The overall effect of CT over and above control conditions was small but statistically significant (7 studies: g = 0.23, 95% confidence interval [CI] 0.014–0.44, p = 0.037). True heterogeneity across studies was low (I(2) = 0%) and there was no evidence of publication bias. Larger effect sizes were noted on working memory (4 studies: g = 0.74, CI 0.32–1.17, p = 0.001), processing speed (4 studies: g = 0.31, CI 0.01–0.61, p = 0.04), and executive function (5 studies: g = 0.30, CI 0.01–0.58, p = 0.042), while effects on measures of global cognition (4 studies), memory (5 studies), visuospatial skills (4 studies), and depression (5 studies), as well as attention, quality of life, and instrumental activities of daily living (3 studies each), were not statistically significant. No adverse events were reported. CONCLUSIONS: Though still small, the current body of RCT evidence indicates that CT is safe and modestly effective on cognition in patients with mild to moderate PD. Larger RCTs are necessary to examine the utility of CT for secondary prevention of cognitive decline in this population.