Depression is one of the most common mental health problems, with around 1 in 5 people in the UK suffering from depression during their lifetime (Royal College of Psychiatrists, 2012) including an estimated 4% of children (NHS Choices, 2012).  Treatments for depression are different in children and young people, for example some antidepressant medications used in adults are not licensed for use in children.

The Mental Elf has previously blogged about preventing relapse in childhood depression and the effectiveness of exercise as a treatment for depression in other groups such as people with heart failure and older adults.

This meta-analysis was published by an internationally-based group of researchers, it compared the findings of studies about promoting or increasing physical activity in children and young people (up to 19 years) with depression.  It showed that physical activity had a small, but statistically significant, effect on depressive symptoms.

Methods

This systematic review and meta-analysis included a wide-ranging search across several of databases, including sources of unpublished trials. No date limits were used, although studies were limited to English language only. Of the 388 studies identified by their searches, 9 were included in the meta-analysis.

• The majority of studies were randomised controlled trials, one study used a quasi-experimental design
• Most of the studies were US-based, with others based in the UK and Chile
• The studies were conducted in schools, youth offending institutions and larger populations
• The interventions studied ranged from education and aerobic exercise 3 times a week, to yoga and mindfulness training

Authors independently extracted data from studies and assessed their quality to reduce bias or human error. A random effects model was used to combine the results from the studies because authors assumed there would be variation between studies and potential errors within studies. Hedges’ g was used to calculate the effect size because it has been shown to be suitable for small sample sizes and for studies of paediatric psychology (Durlak, 2009).

Results

• The review found that physical activity had a small, but statistically significant, treatment effect on depressive symptoms (9 trials, p = 0.004, 95% confidence interval [CI] -0.43 to -0.08)
• Only three of the trials individually showed a statistically significant treatment effect (Annesi, 2006; MacMahon and Cross, 1988; Daley et al., 2006)
• Because the effect size was small, the authors did not feel able to state why physical activity reduced depressive symptoms. They also did not feel confident that depressive symptoms didn’t reduce over time, regardless of the physical activity intervention

Conclusions

The authors concluded:

There was a small significant overall effect for physical activity on depression. More outcome-focused, high-quality trials are required to effectively inform the implementation of programmes to reduce depressive symptoms in children and adolescents.

This systematic review was generally well-conducted, but it was limited by a small, generally low quality evidence base. The authors found that study characteristics, including study quality, had the greatest impact on the effectiveness of the intervention. This suggests a need for high quality studies so that the overall effectiveness of physical activity interventions and the effectiveness of individual interventions can be accurately measured.

Links

Brown HE, Pearson N, Braithwaite RE, Brown WJ, Biddle SJ. Physical Activity Interventions and Depression in Children and Adolescents : A Systematic Review and Meta-Analysis. Sports Med. 2013 Jan 4. [Epub ahead of print] [PubMed abstract]

Depression: key facts. Royal College of Psychiatrists, 2012.

Understanding depression. Mind, 2012.

Clinical Depression. NHS Choices, 2012.

Durlak, J.A. How to Select, Calculate, and Interpret Effect Sizes (2009) J. Pediatr. Psychol. 34 (9): 917-928. doi: 10.1093/jpepsy/jsp004