Parkinson’s Disease is a neurodegenerative disorder, which results in both motor and non-motor impairments. Depression is one of the most common non-motor symptoms for people with Parkinson’s Disease, ranging from 20-50%, with a 2022 systematic review and meta-analysis finding an overall prevalence of 38%. Depression in Parkinson’s Disease has been associated with worse motor symptoms, disability and quality of life. Exercise has been shown to result in smaller increases in Leva-dopa medications, improvements in gait speed and endurance, less disability and improved quality of life, but it’s effect on depressive symptoms is unclear. This systematic review aimed to estimate the effects of physical exercise interventions compared to control on depressive symptoms in people with Parkinson’s Disease, and also to investigate whether the effects differ by exercise type or intensity.
A search of two databases (PubMed and Web of Science) from inception to February 2022 was performed to identify randomised controlled trials evaluating physical exercise interventions. The participants were people with Parkinson’s Disease (no age range specified). The intervention was any type of physical exercise training of more than one session. The comparator could be either mild and regular physical activity programs (e.g. stretching only) or no physical exercise training. The primary outcome was the change in depressive symptoms. Three reviewers independently selected the trials, extracted data and evaluated trial quality. Disagreements were resolved through arbitration by a fourth reviewer. Trial quality was assessed using the Cochrane risk of bias tool, however no tool was used to evaluate the certainty of the evidence. Individual effect sizes were quantified for each study by calculating standardised mean differences (SMD) and 95% confidence intervals (CI). Then overall effect sizes were estimated by statistically incorporating individual effect sizes, using a random-effects meta-analysis model. Pre-defined moderator variable analyses were performed to determine whether the effects differ by exercise type (e.g. aerobic, strength, balance, flexibility or combined training) or intensity (e.g. light-moderate or moderate-vigorous).
Nineteen trials (1,302 participants) published between 2015 and 2021 were included in this review. Some trials had more than one exercise intervention and there were 23 total comparisons from the 19 trials. The trials were conducted in 10 countries from Asia, Europe, North and South America. All trials included men and women, with a range of mean age at enrolment of 59.3 to 75.5 years and range of mean disease duration of 1.8 to 8.0 years. Frequency of training was 1 to 5 sessions per week and the duration of the exercise programs ranged from 3 to 288 weeks, with most from 13 to 26 weeks. Combined exercise programs (e.g. balance and strength) were the most common type (14 programs), followed by aerobic training only (five programs), then flexibility training only (two programs) and one program each for strength training only and balance training only. Of the 14 combined training programs, 12 included aerobic training. Moderate-vigorous intensity exercise programs were the most common (17 programs) and six exercise programs involved light-moderate intensity exercise.
Overall, physical exercise interventions had significant positive effects on the reduction in depressive symptoms in patients with Parkinson’s Disease with a SMD of 0.83 (95%CI 0.52 to 1.14). The pre-defined moderator variable analysis revealed that combined exercise training programs had significant positive effects on the reduction in depressive symptoms in patients with Parkinson’s Disease with a SMD of 1.11 (95%CI 0.64 to 1.59), however neither aerobic training alone nor flexibility training alone had a significant effect. The other pre-defined moderator variable analysis revealed that both exercise intensities had significant positive effects on the reduction in depressive symptoms in patients with Parkinson’s Disease (light-moderate exercise intensity SMD of 0.97 (95%CI 0.52 to 1.42) and moderate-vigorous exercise intensity SMD of 0.78 (95%CI 0.41 to 1.15)).
Physical exercise interventions have significant and large positive effects on the reduction in depressive symptoms in patients with Parkinson’s Disease. These effects are more closely associated with exercise type than exercise intensity.