Depression is a common and debilitating disorder that affects people from adolescence to old age. Its sub-groups are described and defined. The prevalence of depression is universally high: the cumulative prevalence in those aged 18-32 may be over 40%, although the retrospective figures, which depend on reliability of memory, are much lower, around 17% in one major study. The impact of depression extends beyond the individual with depressive symptoms. Depression adversely affects not only mental and phys-ical health but also the social and financial welfare of individuals and society. Major depressive disorder has a widespread prevalence. Symptom onset can be relatively early. There are genetic vulnerabilities and precipitation or accentuation can occur because of relatively unavoidable stressors. There is a longitudinal pattern of frequent recurrences with increasing frequency, severity, and consequences unless it is treat¬ed with effective maintenance strategies. However, the management of depression is characterised by severe underdiagnosis and under-treatment as well as inadequate prioritization of recurrence prevention by clinicians. Factors including sex, age, ethnicity, societal changes and common co-morbid conditions can all affect the prevalence of depression. These factors contribute to the morbidity and severity of the disease burden of depression. Early treatment for adequate duration can help to improve health, reduce morbidity and reduce the burden of depression. Treatment includes antidepressant medication for ade¬quate dose and duration, with due regard to the mode of action of the medication, in combination with appropriate psychotherapy. There are potential benefits in treating depression in ongoing illnesses such as stroke and coronary heart disease.
Keywords: depression, epidemiology, sex, age, ethnicity, treatment, cost