Physical exercise and clinically depressed patients: a systematic review and meta-analysis.

OBJECTIVE The aim of this meta-analysis is to evaluate the effect of aerobic training and strength training as a treatment for depression in patients diagnosed with major depressive disorder. METHODS PubMed (Medline), ISI knowledge (Institute for Scientific Information), SciELO (Scientific Electronic Library) and Scopus databases were consulted from January 1970 to September 2011. Data were collected on variables as follows: total number of patients (pre- and postintervention), age, randomized (yes or no), diagnostic criteria, assessment instruments, and the percentage of remission and treatment response. Subsequently, we collected information on time intervention, intensity, duration, frequency, method of training (aerobic training and strength training) and type of supervision. Standardized mean differences were used for pooling continuous variables as endpoint scores. Binary outcomes, such as proportion of remission (no symptoms) and at least 50% reduction of initial scores (response), were pooled using relative risks. Random effects models were used that take into account the variance within and between studies. RESULTS Ten articles were selected and subdivided by their interventions, controlled training modality and levels of intensity. As there was no statistically significant difference between the two types of intervention (strength or aerobic training), we combined data which finally showed a 0.61 (95% CI: -0.88 to -0.33) standard deviation reduction in the intervention group compared to the control group. When the analysis was restricted only to those studies that used the Hamilton scale (n = 15), we observed a reduction of 3.49 points compared with the control group. CONCLUSION Despite the heterogeneity of the studies, the present meta-analysis concluded that physical exercise improves the response to treatment, especially aerobic training. However, the efficacy of exercise in the treatment of depression was influenced by age and severity of symptoms.