Only a minority of trauma-exposed individuals go on to develop post traumatic stress disorder (PTSD). Previous studies in high-income countries suggest that maladaptive family functioning adversities (MFFA) in childhood may partially ex-plain individual variation in vulnerability to PTSD following trauma. We test in a lower middle income setting (Sri Lanka) whether: (1) MFFA moderates the association between exposure to trauma and later (a) PTSD (b) other psychiatric diagnoses; (2) any moderation by MFFA is explained by experiences of interpersonal violence, cumulative trauma exposure or other psychopathology.

We conducted a population study of 3995 twins and 2019 singletons residing in Colombo, Sri Lanka. Participants completed the composite international diagnostic interview, including nine traumatic exposures and a questionnaire on MFFA.

In total, 23.4% of participants reported exposure to MFFA. We found that (1) MFFA moderates the association between trauma exposure and both (a) PTSD and (b) non-PTSD diagnosis. (2) This was not explained by interpersonal violence, cumulative trauma exposure or other psychopathology.

In our sample MFFA moderates the association between trauma and PTSD, and the association between trauma and non-PTSD psychopathology.