Physical activity and exercise in the treatment of depression

Abstract

Mental health problems continue to present a global challenge and contribute significantly to the global burden of human disease (DALYs). Depression is the most common psychiatric disorder and is thought to affect 121 million adults worldwide, and as such was rated as the fourth leading cause of disease burden in 2000 (Moussavi et al., 2007), projected to become the highest cause of disease burden by 2020. Antidepressant drugs are an effective and commonly used treatment for depression in primary care (Arroll et al., 2009), although almost half of those treated do not achieve full remission of their symptoms, and there remains a risk of residual symptoms, relapse/recurrence (Fava and Ruini, 2002). In those patients who do demonstrate improvements in depressive symptoms with antidepressant therapies, a time-lag in the onset of therapeutic effects is frequently reported. Antidepressant drugs are associated with adverse side effects (Agency for Health Research and Quality (AHRQ), 2012) and an increased risk of cardiovascular disease, particularly in those with pre-existing cardiovascular conditions or major cardiovascular risk factors (Waring, 2012). Furthermore, adherence to antidepressant medications is often poor and patients often prematurely discontinue their antidepressant therapy; it has been suggested that approximately 50% of psychiatric patients and 50% of primary care patients are non-adherent when assessed 6-months after the initiation of treatment (Sansone and Sansone, 2012). Psychological treatments for depression have been recommended in the UK National Institute for Health and Clinical Excellence (NICE) guidelines (NICE, 2009) and are becoming more commonplace for helping to reduce symptoms in depressed adults (Ambresin et al., 2012; Brakemeier and Frase, 2012), with even brief psychosocial interventions showing promise for improving adherence to depression medication treatment in primary care settings (Sirey et al., 2010). However, attendance at psychological intervention sessions can be poor since many depressed adults who may benefit from such treatments choose not to attend mental health clinics due to the perceived stigma of psychological therapies. As such there has been an increasing interest in the role of alternative interventions for depression. Physical exercise has been proposed as a complementary treatment which may help to improve residual symptoms of depression and prevent relapse (Trivedi et al., 2006). Exercise has been proposed by many as a potential treatment for depression and meta-analysis has demonstrated that effect sizes in intervention studies range from -0.80 to -1.1 (Rethorst et al., 2009). However, the evidence is not always consistent; recent research has shown that that provision of tailored advice and encouragement for physical activity did not improve depression outcome or antidepressant use in depressed adults when compared with usual care (Chalder et al., 2012). Other researchers have failed to find an antidepressant effect of exercise in patients with major depression but have found short term positive effects on physical outcomes, body composition and memory (Krogh et al., 2012). Others have argued that the nature of exercise delivery is an important factor, with exercise of preferred (rather than prescribed) intensity shown to improve psychological, physiological and social outcomes, and exercise participation rates in depressed individuals (Callaghan et al., 2011). Research findings have been summarized by a recent Cochrane review which reported the findings of 32 randomized controlled trials in which exercise was compared to standard treatment, no treatment or a placebo treatment in adults (aged 18 and over) with depression (Rimer et al., 2012). This review concluded that exercise seems to improve depressive symptoms in people with a diagnosis of depression when compared with no treatment or control intervention, although highlighted that this should be interpreted with caution since the positive effects of exercise were smaller in methodologically robust trials. Similarly, a systematic review found that physical exercise programs obtain clinically relevant outcomes in the treatment of depressive symptoms in depressed older people (>60 years; Blake et al., 2009). Although the positive effects of exercise intervention on depressive symptoms are gaining more clarity, reviews suggest that there are currently insufficient high quality data to determine cost-benefit of exercise intervention in depression (Blake et al., 2009; Rimer et al., 2012). Many intervention studies with depressed populations are hampered by methodological weaknesses and small samples sizes. Further, comparisons between studies are often difficult due to variations in assessment or diagnosis of depression, level of severity of the condition, setting for delivery and size of the sample, outcomes of interest and the nature of the intervention delivered (type, frequency and duration of the intervention). Despite some inconsistencies in research findings, in the UK, the value of exercise continues to be substantiated by current reports and guidelines which include exercise as a management strategy for depression; NICE guidelines have recommended structured, supervised exercise programs, three times a week (45 min to 1 h) over 10–14 weeks, as a low-intensity Step 2 intervention for mild to moderate depression (NICE, 2009); Scottish Intercollegiate Guidelines Network (SIGN) for non-pharmaceutical management of depression in adults has recommended that structured exercise may be considered as a treatment option for patients with depression (SIGN, 2010); and exercise is specified as a treatment option for people with depression in a report for the National Service Framework for Mental Health (Donaghy and Durward, 2000). This is further substantiated by research which demonstrates that patients also find value in physical activity as an effective treatment for...