Rachel M. Brand, Carla McEnery, Susan Rossell, Sarah Bendall, Neil Thomas

There is growing recognition of the relationship between trauma, posttraumatic stress disorder (PTSD) and psychosis. There may be overlaps in casual mechanisms involved in the development of PTSD and psychosis following traumatic or adverse events. Trauma-focussed treatments found to be effective in treating PTSD may therefore represent a new direction in the psychological treatment of psychosis. This systematic review examined the literature on trauma-focussed treatments conducted with people with schizophrenia spectrum or psychotic disorders to determine effects on psychotic symptoms. Secondary outcomes were symptoms of PTSD, depression and anxiety. Twenty-five studies were included in the review, with 12 being included in the meta-analysis. Trauma-focussed treatments had a small, significant effect (g=0.31, CI [0.55, 0.06]) on positive symptoms immediately post-treatment, but the significance and magnitude of this effect was not maintained at follow-up (g=0.18, CI [0.42, -0.06]). Trauma-focussed treatments also had a small effect on delusions at both post-treatment (g=0.37, CI [0.87, -0.12]) and follow-up (g=0.38, CI [0.67, 0.10]), but this only reached significance at follow-up. Effects on hallucinations and negative symptoms were small and non-significant. Effects on PTSD symptoms were also small (post-treatment g=0.21, CI [0.70, -0.27], follow up g=0.31, CI [0.62, 0.00]) and only met significance at follow-up. No significant effects were found on symptoms of depression and anxiety. Results show promising effects of trauma-focussed treatments for the positive symptoms of psychosis, however further studies developing and evaluating trauma-focussed treatments for trauma-related psychotic symptoms are needed.