Externalizing Disorders and Substance Use Among Nigerian Adolescents: Prevalence, Comorbidity, and Dose-Response Association

Objective To estimate prevalence of externalizing disorders (attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and conduct disorder (CD) among Nigerian adolescents and examine associations with substance use disorder (SUD), alcohol use disorder (AUD), and associated factors. Method Cross-sectional analysis of 9,437 adolescents aged 11–17 years from 47 Lagos State public secondary schools using the MINI-Kid adapted for self-administration within its validated age range. Weighted multivariable logistic regression examined associations adjusting for demographic, family, and school factors. Results Overall, 15.1% met criteria for at least one externalizing disorder, with male predominance (17.7% vs. 12.4%; odds ratio (OR) = 1.52, 95% CI 1.35–1.71). Comorbidity was common, with 43.7% meeting criteria for two or more diagnoses. A graded dose-response association was observed: each additional co-occurring diagnosis was associated with a 2.84-fold increase in SUD odds (95% CI 2.48–3.25). Adolescents meeting all three disorder criteria showed SUD prevalence of 18.8% (adjusted odds ratio (AOR) = 9.87, 95% CI 5.84–16.68) and AUD prevalence of 23.2% (AOR = 6.73, 95% CI 3.91–11.59) compared to those with no externalizing disorder. Class repetition (AOR = 2.26, 95% CI 2.00–2.55), maternal drinking (AOR = 1.69, 95% CI 1.15–2.48), and witnessing domestic violence (AOR = 1.64, 95% CI 1.35–1.99) were most strongly associated with externalizing disorders. Conclusion Externalizing disorders are common among Nigerian adolescents and strongly associated with substance use and functional impairment. The observed dose-response pattern is consistent with developmental cascade models; longitudinal research is needed to establish sequential disorder progression. School-based screening and integrated behavioral and academic interventions may reduce associated substance use burden.