Physical activity and exercise in the treatment of depression

Mental health problems continue topresent a global challenge and contributesigniﬁcantly to the global burden ofhuman disease (DALYs). Depression isthe most common psychiatric disorderand is thought to affect 121 million adultsworldwide, and as such was rated as thefourth leading cause of disease burden in2000 (Moussavi et al., 2007), projected tobecome the highest cause of disease bur-den by 2020. Antidepressant drugs are aneffective and commonly used treatmentfor depression in primary care (Arrollet al., 2009), although almost half of thosetreated do not achieve full remission oftheir symptoms, and there remains a riskof residual symptoms, relapse/recurrence(Fava and Ruini, 2002). In those patientswho do demonstrate improvements indepressive symptoms with antidepres-sant therapies, a time-lag in the onset oftherapeutic effects is frequently reported.Antidepressant drugs are associated withadverse side effects (Agency for HealthResearch and Quality (AHRQ), 2012)and an increased risk of cardiovascu-lar disease, particularly in those withpre-existing cardiovascular conditions ormajor cardiovascular risk factors (Waring,2012). Furthermore, adherence to antide-pressant medications is often poor andpatients often prematurely discontinuetheir antidepressant therapy; it has beensuggested that approximately 50% of psy-chiatric patients and 50% of primary carepatients are non-adherent when assessed6-months after the initiation of treatment(Sansone andSansone, 2012). Psychological treatments for depres-sion have been recommended in theUK National Institute for Health andClinical Excellence (NICE) guidelines(NICE, 2009) and are becoming morecommonplace for helping to reducesymptoms in depressed adults (Ambresinet al., 2012; Brakemeier and Frase, 2012),with even brief psychosocial interven-tions showing promise for improvingadherence to depression medication treat-ment in primary care settings (Sirey et al.,2010). However,attendance atpsychologi-cal intervention sessions can be poor sincemany depressed adults who may beneﬁtfromsuch treatments choosenotto attendmental health clinics due to the perceivedstigma ofpsychological therapies.As such there has been an increasinginterest in the role of alternative inter-ventions for depression. Physical exercisehas been proposed as a complementarytreatment which may help to improveresidual symptoms of depression and pre-vent relapse (Trivedi et al., 2006). Exercisehas been proposed by many as a poten-tial treatment for depression and meta-analysis has demonstrated that effect sizesin intervention studies range from -0.80to -1.1 (Rethorst et al., 2009). However,the evidence is not always consistent;recent research has shown that that pro-vision of tailored advice and encourage-ment for physical activity did not improvedepression outcome or antidepressant usein depressed adults when compared withusual care (Chalder et al., 2012). Otherresearchers have failed to ﬁnd an antide-pressant effect of exercise in patientswith major depression but have foundshort term positive effects on physicaloutcomes, body composition and mem-ory (Krogh et al., 2012). Others haveargued that the nature of exercise deliv-ery is an important factor, with exer-cise of preferred (rather than prescribed)intensity shown to improve psychological,physiological and social outcomes, andexercise participation rates in depressedindividuals(Callaghanet al., 2011). Research ﬁndings have beensummarized by a recent Cochrane reviewwhichreportedtheﬁndingsof32random-ized controlled trials in which exercisewas compared to standard treatment,no treatment or a placebo treatment inadults (aged 18 and over) with depression(Rimeretal.,2012). Thisreviewconcludedthat exercise seems to improve depressivesymptoms in people with a diagnosis ofdepression when compared with no treat-ment or control intervention, althoughhighlighted that this should be interpretedwith caution since the positive effects ofexercise were smaller in methodologi-cally robust trials. Similarly, a systematicreview found that physical exercise pro-grams obtain clinically relevant outcomesin the treatment of depressive symptomsin depressed older people (