Depression is a common relapsing di

Depression is a common relapsing disorder that causes significant distress and impairment in social and occupational functioning. It is associated with an increased risk of death, not only through suicide but also from physical illnesses such as cardiovascular disease. It is under-recognized and undertreated and it should be screened for in those at high-risk for depression such as those suffering from chronic physical health problems. Its aetiology is multifactorial and comorbidity with other psychiatric disorders is common. Assessment of depression requires the clinician to determine the duration, symptom severity, suicide risk and functional impairment in the current episode, co-morbid diagnoses, past mood and treatment history, as well as a developmental, social and family history. Treatment is guided by illness severity, presentation and prior history and includes psychosocial interventions, medication and their combination, with antidepressant medication reserved for persistent and moderate-to-severe depression. Prevention of relapse is a priority and risk factors for this should be assessed and used to guide prophylactic drug and psychological treatment.