Depression in adult Nigerians: results from the Nigerian Survey of Mental Health and Well-being.

Background: Community-based studies of the rates and profile of depression among Africans are still sparse.

Methods: As part of the World Mental Health Surveys initiative, a clustered multi-stage sampling of households in 21 of Nigeria's 36 states (representing 57% of the national population) was implemented to select adults aged 18 years and over (N=6752) for face-to-face interviews using the Composite International Diagnostic Interview (CIDI 3.0). Diagnosis of major depressive episode (MDE) was based on the criteria of the Diagnostic and Statistical Manual, 4th edition.

Results: Lifetime and 12-month estimates of MDE were 3.1% (standard error 0.3) and 1.1% (s.e. 0.1), receptively. Increasing age was associated with higher estimates of positive responses to stem (screen) questions for depression and of lifetime disorders among stem-positive respondents. The mean age of onset was about 29.2 years. The median (inter quartile range, IQR) duration of an episode among lifetime cases was 1.0 (2.0-2.4) year and the median (IQR) number of lifetime episodes was 1.5 (2.0-2.8). MDE was highly comorbid with anxiety disorders, musculoskeletal conditions, chronic pain and ulcer. The odds ratio of lifetime suicide attempt among persons with lifetime MDE was 11.6 (95% confidence interval, 3.9-34.9). Over 25% of 12-month cases were rated as severely disabled in the performance of usual roles. Only 16.9% (s.e. 5.0) of 12-month cases had received any treatment.

Limitations: All data were based on self-reports.

Conclusion: MDE, defined according to DSM-IV, is a risk factor for mental and physical comorbidity as well as disability in Nigerians. Age-related telescoping or denial may partly explain the low rates in this young population.