Relationships between physical activities performed under free-living conditions and non-motor symptoms in people with Parkinson's: A systematic review and meta-analysis.

The review pooled observational studies, so it cannot show that physical activity caused better symptoms or that symptoms caused lower activity. Many studies used retrospective questionnaires for physical activity or symptoms, which can be affected by recall bias. Physical activity and non-motor symptoms were measured in different ways across studies, so only some results could be pooled. The pooled anxiety, depression, or apathy result had substantial heterogeneity, with I squared 81.03 percent. No eligible articles included people with atypical parkinsonism, so the findings may not apply to them. Only one reviewer screened titles and abstracts, so relevant articles could have been missed. Non-English publications and qualitative designs were not included. The original articles did not report standard errors for their correlation or regression estimates, so the review had to obtain or impute them.

The authors declared no potential conflicts of interest and received no financial support for the research, authorship, or publication.

Do not conclude that increasing free-living physical activity causes better cognition or fewer anxiety, depression, or apathy symptoms. The review pooled observational studies, so it cannot separate cause and effect, and the authors note that non-motor symptoms may also influence activity levels.