A meta-analysis of chronic exercise effects and moderating variables on depression severity and core symptoms in older adults

Previous meta-analyses have demonstrated the effectiveness of chronic exercise in treating depression in older adults; however, the moderating effects of intervention, population, and protocol characteristics remain unclear. This study aims to investigate the effectiveness of chronic exercise on depression severity and core symptoms of depression in older adults, as well as how intervention, population, and protocol characteristics moderate these effects. We searched Web of Science, Academic Search Complete, MEDLINE, CINAHL, APA PsycInfo, SPORTDiscus, and Cochrane from inception until July 2023 for randomized controlled trials of chronic exercise interventions. The primary outcome was overall depression severity; secondary outcomes were indicators of core symptoms of depression. We used multilevel meta-analysis, subgroup comparisons, and meta-regression for analysis. We identified 143 peer-reviewed articles comprising 182 effect sizes and representing 14,789 participants (exercise group: n = 7,664; control group: n = 7,125). Chronic exercise significantly reduced overall depression severity with a moderate effect size and alleviated indicators of core symptoms of depression, including moderate effects on anxiety and small effects on BMI, executive functions, processing speed, and sleep. Effects were particularly strong for interventions that included exergames, had high training volumes, and high cognitive demand. Additionally, effects decreased with advancing age and lower baseline depression severity. The benefits of high-cognitive-demand exercises increased with declining global cognition levels. Individuals with mild to moderate depression benefited most from high-intensity and high-cognitive-demand exercises. The certainty of evidence for reducing the severity of depression was rated as low according to the GRADE approach. There is evidence of low certainty that chronic exercise is effective in treating depression in older adults, especially when tailored to the specific needs of the target population.