Research That Matters (January 17 - 20, 2008)

Purpose: Physical activity can be endorsed by many models in social work, such as empowerment, self-efficacy, resilience, strengths perspective, good health, hardiness, and self-determination, yet it has received little attention in social work literature as an effective outcome intervention. Among older adults, exercise has been shown to reduce costs for health care, limit injury, decrease heart disease and obesity, improve diabetes, and result in a more active life style. Moreover it has been shown to elevate mood. Some studies indicate that exercise can prevent or remit symptoms of major depression--a prevalent global disorder, a major contributor to a massive burden of disease, and a disorder seen by almost every venue of social work. Recent neuroimaging studies indicate that exercise stimulates the same neural networks as anti-depressant medication without the side effects. Previous meta-analyses have not found meaningful effect size due to study issues of internal validity, inappropriate sample constituency, lack of follow-up and lack of use of randomized studies.

Methods: This meta-analysis included randomized experimental studies of clinically depressed samples of older adults conducted 2000-2006. Clinical depression was defined according to the DSM-IV-TR and ICD-10 for conditions of unipolar depressive episodes. Thirteen publications met criteria. The null hypothesis proposed exercise would have no effect upon major depression, as defined by statistically significant differences and meaningful effect sizes. An exhaustive literature search was conducted and features of each study were coded independently by two coders. Comparisons looked at overall effect, type of exercise, dose effect, duration, assessment measures, and standards and protocols used to determine clinical effectiveness. All effect sizes were computed as standardized mean-change measures. Adjustments were corrected for small sample bias. Weighted analyses adjusted for variable sample size and violation of the assumption of independence. In fixed effects model analysis, each effect size was weighted by its inverse variance. In the random effects model, the estimate of between-studies variation was a method-of-moments estimator.

Results: Thirteen articles were included in the analysis. Inter-rater reliability was .96. Overall effect size was -.98 for treatment versus control group effects. This means that participants who exercised were -.96 of a standard deviation less depressed than individuals who did not exercise. The size of the effect is consistent with analyses that find larger effect sizes among depressed populations than with those with low mood or from the general population.

Implications: Results suggest that exercise is an evidence-based intervention for clinical depression. Such findings indicate efforts of social workers are worthwhile that develop effective individual and group activities and protocols using exercise. Use of such an intervention would add a low cost effective method for lessening the effects of major depression among older adults. Incorporating physical components in social work outcome interventions would not only enhance the quality of life for our clients, but serve as a catalyst for better health and longer life.