Depression and anxiety symptoms among Kenyan adolescents: psychometric validation, prevalence, network analysis, and psychosocial determinants

BACKGROUND: Adolescent mental health in Sub-Saharan Africa remains critically understudied despite high burden estimates. We assessed the psychometric properties of Western-derived instruments, prevalence of depression and anxiety symptoms, associations with psychosocial and sociodemographic factors, and symptom network structures in a large multi-year sample of Kenyan adolescents. METHODS: We administered depression (PHQ-8), anxiety (GAD-7), social support, perceived control, and wellbeing measures to 7865 Kenyan secondary school students aged 12-20 across three studies (2021-2023). RESULTS: Both PHQ-8 (α = 0.70) and GAD-7 (α = 0.78) demonstrated adequate reliability, and confirmatory factor analyses supported unidimensional structures with acceptable fit (PHQ-8: RMSEA = 0.052, CFI = 0.945; GAD-7: RMSEA = 0.056, CFI = 0.970). Overall, 30.3% (95% CI 29.3-31.3%) and 25.1% (95% CI 24.2-26.1%) of participants met the ≥ 10 cut-off for clinically elevated depression and anxiety symptoms, respectively, with descriptive variation across study years (2021: 42.1% [39.6, 44.6%], 37.5% [35.1, 40.0%]; 2022: 25.3% [23.8, 26.8%], 21.7% [20.3, 23.2%]; 2023: 29.7% [28.1, 31.3%], 22.5% [21.1-24.0%]); direct year-on-year comparison is limited by differences in wave composition. Mixed-effects modelling identified social support (B = - 0.08) and perceived control (B = - 0.29 for depression, B = - 0.24 for anxiety) as robust protective factors. Final-year students showed elevated symptoms (B = 0.93, B = 0.77), as did students in girls' schools relative to mixed schools (B = 1.35, B = 1.27). Perceived academic ability showed a strong inverse gradient with both outcomes (excellent ability: B = - 2.51 for depression, B = - 1.76 for anxiety). Network analysis identified worry-related symptoms as most central, with hopelessness and nervousness serving as the primary bridges between depression and anxiety domains. DISCUSSION: Western-derived measures demonstrated adequate psychometric properties with Kenyan adolescents. Depression and anxiety were highly prevalent and varied by sex, school form, and school type. Social support and perceived control were the strongest protective factors; academic pressure and girls' school attendance were associated with elevated symptoms. Network analyses identify worry, hopelessness, and negative self-evaluation as possible candidate intervention targets warranting empirical evaluation. These findings underscore the urgent need for contextually grounded, school-based mental health provision in Kenya and comparable Sub-Saharan African settings.