The Economic Cost of Untreated Common Mental Disorders to Nigerian Households: A Human Capital and Disability-Adjusted Life Year Analysis

The economic burden of untreated common mental disorders on Nigerian households represents a critical but poorly quantified barrier to investment in mental health services. This study estimates the economic cost of untreated depression, anxiety, and substance use disorders to Nigerian households using human capital and disability-adjusted life year (DALY) methodologies. A nationally representative sample design will recruit 2,400 household heads across six geopolitical zones through multistage probability sampling. Common mental disorders will be identified using the WHO Composite International Diagnostic Interview (CIDI-SF). Economic productivity loss will be estimated using the human capital approach, capturing lost workdays, reduced work productivity, educational attainment loss, and informal caregiving costs. DALYs will be calculated using standard WHO methodology, combining years of life lost and years lived with disability specific to Nigerian epidemiological data. Multivariate regression will identify household and community-level factors associated with greatest economic burden. This study generates the first nationally representative household-level economic burden estimate for common mental disorders in Nigeria, directly supporting the economic case for mental health investment to the Federal Ministry of Finance and health sector advocates. Keywords: economic burden, common mental disorders, DALYs, Nigeria, human capital