Can Physical Exercise Be Considered as a Promising Enhancer of Global Cognition in People with Parkinson's Disease? Results of a Systematic Review and Meta-Analysis.

BACKGROUND

Physical exercise interventions are known to improve quality of life, motor and non-motor symptoms in people with Parkinson's disease (PD). However, systematic reviews and meta-analyses on cognitive outcomes are rare.

OBJECTIVE

To perform a systematic review and meta-analysis of physical exercise intervention effects compared with passive and active control groups (CGs) on global cognition in people with PD.

METHODS

A literature search was performed for randomized controlled trials (RCTs) on physical exercise interventions in PD using nine databases. We included RCTs reporting global cognition outcomes. A meta-analysis was performed using random-effects models and standardized mean differences (SMDs) with 95% confidence intervals (CIs). Bias was assessed with the revised Cochrane Risk of Bias tool and the certainty of evidence was rated using the GRADE approach.

RESULTS

Seventeen studies (ten with passive, seven with active CGs) were included in the systematic review. Exercise interventions varied considerably between studies. The meta-analysis included nine studies with 236 people with PD (seven with passive, two with active CGs). The SMD was 0.33 (95% CI 0.00; 0.65) demonstrating a small effect (p = 0.05) in favor of physical exercise. Compared with passive CGs, physical exercise had a small non-significant effect (SMD = 0.22, 95% CI -0.14;0.58, p = 0.24). Compared with active CGs, physical exercise had a medium significant effect (SMD = 0.72, 95% CI 0.12;1.33, p = 0.02).

CONCLUSIONS

Physical exercise may increase global cognition in people with PD, but the evidence is very uncertain. Further large-scale RCTs are needed to confirm this finding and to identify the most effective type of physical exercise for improving cognition.