A systematic review on comorbid post-traumatic stress disorder in schizophrenia

Post-traumatic stress disorder (PTSD) appears to commonly co-occur with schizophrenia, which is widely considered the most disabling mental illness. Both conditions share neurological risk factors, and present with symptoms that are superficially similar, complicating diagnostic accuracy. The presence of comorbid PTSD is also of concern as additional diagnoses tend to worsen functioning and quality of life. In the current review, EMBASE, Medline, and PsycINFO were searched for articles pertaining to PTSD comorbidity in schizophrenia spectrum disorders. Articles went through two stages of review prior to inclusion - one at the abstract level and another at the full-text level. Thirty-four articles were ultimately included in the present review. Prevalence of PTSD in schizophrenia ranged from 0 to 57%, likely due to study heterogeneity. Findings generally indicated that comorbid PTSD was associated with higher levels of positive symptoms, general psychopathology, and neurocognitive impairment, as well as worse functioning and quality of life. As such, it is important for clinicians to differentiate between psychotic and PTSD symptoms, and to pay attention to the associated features of comorbid PTSD in order to provide the most appropriate intervention. Unfortunately, epidemiological and longitudinal studies in this area are lacking.