Abstract
BACKGROUND: Internalising disorder, which is characterised by anxiety and depression, is a mental health disorder observed among in-school adolescents in Nigeria, with consequent school dropout, substance use and suicide. AIM: This study examined the effects of adverse childhood experiences (ACEs) and personality traits on internalising disorder among in-school adolescents in Lagos State, Nigeria. SETTING: The study was conducted among in-school adolescents attending secondary schools in Lagos State, Nigeria. METHODS: A cross-sectional design and multistage sampling techniques were used to select 357 participants (138 males = 38.7%; 219 females = 61.3%) from five high schools in Lagos State, who responded to the ACEs Questionnaire, Personality Inventory and Revised Children's Anxiety and Depression Scale. RESULTS: The prevalence of ACEs is 23.8% mild, 33.1% moderate, 13.4% severe experiences being higher on internalising disorder, and 29.7% with no experience. Sixteen per cent of children were clinically significant on internalising behaviour, with 19.3% significant on anxiety and 9% on depression. Adverse childhood experiences significantly predicted internalising disorder; likewise, conscientiousness, neuroticism, and openness to experience consistently and significantly predicted internalising disorder. Adverse childhood experiences and personality traits contributed a significant variance of 16% in anxiety, 26% in depression and a combined 20% to the total variance in internalising disorder. CONCLUSION: The study encourages practical, tailored interventions that address ACEs and foster positive personality traits to mitigate against internalising disorder. CONTRIBUTION: The study underscores the importance of personality traits in the outcomes of children and adolescents exposed to ACEs in Nigeria.