Background: Informal settlements have high rates of poor mental health, yet little research has looked at PTSD-depression co-occurrence in these settings. We investigated the prevalence of depression, PTSD, and comorbid PTSD-depression amongst a non-clinical sample of 18–30 year old women, in informal settlements in South Africa. Methods: Cross-sectional analysis of self-selecting young women, enrolled at baseline of an intervention trial. We assessed the occurrence of depression, PTSD and co-occurring PTSD and depression, and used multinomial and logistic regressions to assess risk factors for these. Results: Depression, PTSD and comorbid PTSD-depression were reported by 45.2%, 21.0% and 18.6% of the women respectively. Depression was associated with social group membership (ß -0.74, p = 0.022), food insecurity (ß. 0.97, p = 0.001), stress related to lack of work (ß 0.61, p = 0.022), childhood traumas (ß 0.07, p = 0.004), IPV (ß 0.58, p = 0.007), other lifetime traumas (ß 0.51, p = 0.021) and alcohol misuse (ß 0.04, p = 0.002). Comorbid PTSD-depression was associated with social group membership (ß -0.73, p = 0.008), lack of work stress (ß 1.13, p = 0.009), disability (ß 0.99, p = 0.002), childhood traumas (ß 0.19, p <0.001), alcohol misuse (ß 0.05, p = 0.036) and other lifetime traumas (ß 1.32, p <0.001). Differentiating depression and comorbid PTSD-depression were disability (adj.OR 2.20, p = 0.013), childhood traumas (adj.OR 1.13, p <0.001) and other lifetime traumas (adj.OR 2.44, p = 0.012). Limitations: This was a cross-sectional study, limiting delineation of the direction of associations. Findings cannot be generalised as the study was non-representative. Conclusions: Findings motivate for trauma informed mental health interventions. Potential for group-based interventions is indicated.
