Common psychiatric disorders over a lifetime: age of onset, risk and treatment contact in the Nigerian survey of mental health and wellbeing.

The study is to estimate prevalence, risk, and contact with services of mental health problems in the Nigerian community. Face-to-face interviews with a representative sample of persons aged 18 years and over (n = 6752) using the World Health Organization's Composite International Diagnostic Interview, Version 3. Lifetime DSM-IV prevalence estimates were 6.5% for anxiety disorders, 3.3% for mood disorders, 3.7% for substance use disorders, and 12.0% for any disorder. The median age of onset (represented by the 50th percentile age of onset) is 25 years for any disorder but ranged from 11 years for anxiety disorder to 42 years for mood disorder. The projected lifetime risks at age 75 years were considerably higher than prevalence estimates. For mood disorders, lifetime risk was 170% higher than the prevalence estimate. Ascertainment bottlenecks seem to account for some low prevalence estimates. In general, only a minority of persons with mental disorders made any treatment contact. The median delay in duration before seeking care ranged between 6 years for mood disorders and 16 years for anxiety disorders. Projected lifetime risks of mood disorders and possible false negatives for some disorders suggest that the societal burden of mental disorders is considerably higher than the prevalence estimates indicate. Nevertheless, even for identified cases, current treatment coverage falls far short of need.