Long-term Effects of School-Based Mental Health Programmes on Adolescents in Lagos, Nigeria: A Seven-Year Study

School-based mental health programmes are integral in addressing the psychological needs of adolescents in Nigeria's educational settings. Lagos, with its diverse population and high adolescent prevalence rates, serves as a critical case study for examining these interventions' long-term impact. A mixed-methods approach was employed, including pre- and post-intervention surveys for quantitative data collection, alongside qualitative interviews to gather deeper insights into programme efficacy and adolescent experiences. Over the seven-year study, a statistically significant improvement in participants' self-reported mental health scores (p < 0.05) was observed, indicating sustained positive effects from the mental health programmes. The findings suggest that school-based mental health interventions can have lasting impacts on adolescents' psychological health, supporting their holistic development and academic performance. School administrators should continue implementing such programmes to ensure ongoing support for students' mental health needs. Policymakers could consider scaling these initiatives across broader educational systems in Nigeria.