Depression And Higher Iq Associated With Premorbid Tbi In Schizophrenia

Exposure to traumatic brain injury (TBI) is associated with schizophrenia. It is not clear if TBI 1) produces phenocopies 2) increases penetrance or 3) has a spurious association with schizophrenia as a marker of some third factor. We examined clinical correlates of premorbid TBI in patients admitted to a schizophrenia research unit. History of TBI was assessed by chart review for 183 patients (113 males, 70 females). 93 patients (58 males, 39 females) also had structured clinical interviews with the Diagnostic Interview for Genetic Studies (DIGS) to assess TBI. Associations of TBI with sex, SES, race, diagnosis, symptoms (PANSS, Hamilton Depression Scale) and neuropsychological measures were examined. Chart review (CR) and DIGS interviews yielded similar TBI rates with no significant sex or SES differences (though whites had significantly greater TBI exposure than nonwhites). Patients with and without TBI did not differ in global assessment of functioning, age of onset, or current age. TBI rates were similar in schizophrenia and schizoaffective disorder, and TBI was unrelated to schizophrenia subtype. Patients with TBI scored significantly higher on the HDS (t = −2.48, df = 24.21 and p = .02) but did not differ in positive or negative symptoms. Among medicated patients, patients with TBI had significantly fewer perserverative errors on the WCST (t = 2.30, df = 43.85, p = .026) and higher IQ (t = −2.17, df = 50, p = .035). Schizophrenia patients with premorbid TBI represent a subgroup with more depression and relative sparing of cognition. These data support the hypothesis that the association of TBI with schizophrenia is causal and not spurious.