Apathy and Physical Activity: A Systematic Review and Meta-Analysis.

Purpose: Patient motivation is essential for successful rehabilitation, so apathy may hinder physiotherapists' interventions aimed at increasing physical activity. We examined the relationship between apathy and physical activity to identify the factors that influence it. Methods: Pearson product-moment correlations were pooled from eligible studies to examine the relationship between apathy and physical activity. Subgroup meta-analyses and meta-regressions were also conducted. Results: From the systematic review (28 articles) and main meta-analysis (22 studies; N = 12,541), the results showed a negative correlation between apathy and physical activity (r = -0.13; 95% CI: -0.18, -0.09; p < 0.0001 based on Pearson's r-values; r = -0.40; 95% CI: -0.68, -0.02; p = 0.043 based on Spearman's ρ-values). The correlation was statistically significant in patients with Parkinson's disease and in older adults who were healthy, depressed, fallers, or had mild cognitive impairment. A meta-regression showed an effect of age, with a stronger correlation between apathy and physical activity in older adults compared to younger adults (p = 0.003). Conclusion: Higher levels of apathy are associated with lower levels of physical activity, and this negative association is stronger with age. Therefore, apathy may limit exercise therapy efficacy and carry prognostic implications for patients whose condition requires physical activity.