Depression Mental disorder classified as a mood disturbance or episodes of unhappiness persistent low mood and inability to find enjoyment Prevalence 2nd in disease burden to CVD 20 25 of US adults suffer from some type of diagnosable mental health problem o CVD and depression possibly linked expensive Costs of absenteeism and reduced work productivity Mood disorders rank within the top 10 causes of disability worldwide costs High mortality Causes Not well understood Treatment People reluctant to seek treatment because of social stigma Pharmacology Biological psychosocial and experience factors in response to stressor o 30 actually see results Psychology Physical activity William P Morgan did stuff Measurement Self report o Questionnaires Exercise as Treatment Physicians do prescribe exercise as a treatment Some GPs refer patients with depressive symptoms to physical activity programs Evidence o Farmer et al sedentary women 2x more likely to develop depression o Camacho et al relative risk of developing depression greater if initially inactive o Mobily et al older individuals reporting greater depression at baseline had reduced depression after beginning a walking program o Motl et al PA and depression in adolescents over 2 years higher PA lower depression o Goodwin dose response relationship o Galper et al dose response led to higher fitness levels meant lowest symptoms Exercise and non clinical depression o Exercise resulted in decreased depression o Exercise is as effective as traditional therapies o Sometimes exercise is even better o Moderating factors Mode No difference Aerobic anaerobic Length of program Not as important as just starting one Longer programs showed increased reduction in depression Dose response Exercise intensity o Not examined consistently o Not as much of a reduction in symptoms in high intensity workout groups Duration and frequency o No systematic influence Acute and chronic Reduction occurred for both Age Decreased for all ages Effects larger for middle aged adults o Not significantly Gender Equal for both Race ethnicity Poorly reported Difficult to draw conclusions Exercise and clinical depression o Exercise is similar to medication in terms of effectiveness o Both were greater than the placebo o Exercise is a cheaper alternative o Can decrease Medication level Whether medication is actually needed Length needed Mechanisms of change Anthropological hypothesis o Physical activity is a genetic predisposition so if we aren t physically active cant that mess with our bodies make us depressed Endorphin hypothesis Monoamine hypothesis o During stress body produces endorphins natural painkillers o Exercise effects due to altered neurotransmitters Serotonin Norepinephrine Dopamine o All have been implicated in emotion regulation o Exercise influences neurotransmitters Mastery Hypothesis o Sense of accomplishment after task completion Social Interaction Hypothesis o Exercise provides opportunity for interaction with others o Cannot be sole explanation Distraction time out hypothesis o Exercise provides escape from normal routine