Is clinical global impression associated with intelligence in schizophrenia

Introduction The findings of studies examining the association of cognition with symptoms or functioning in schizophrenia are contradictory. Aim To investigate the clinical and functional correlates of general intelligence in schizophrenia. Method Forty-nine stabilized individuals with schizophrenia were recruited in a cross-sectional study. Intelligence was assessed using the Wechsler Adult Intelligence Scale III (WAIS). Clinical symptoms were measured with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale (CGI). Functioning was assessed with the Global Assessment of Functioning Scale (GAF) and the Strauss-Carpenter Scale (SCS). Separate linear regression analyses were conducted using WAIS full scale as the dependent variable and the following predictors: PANSS total or PANSS positive or PANSS negative scores or CGI or GAF or SCS scores. Significant predictors were entered in one final overall model. Age and gender were entered as covariates in all analyses. Results ANOVA models for PANSS total, positive and negative psychopathology scores and SCS scores were not significant. However, negative symptoms were inversely associated with intelligence (B=−0.61, 95% CI=−1.012, −0.209, t =−3.06, df=45, P =0.004). CGI scores inversely correlated with WAIS total scores (B=−6.078, 95% CI=−9.029, −3.128, t =−4.151, df=44, P t =2.679, df=45, P =0.01). In the final (overall) model, only CGI remained significant. One unit increase in CGI (e.g. mildly versus moderately ill) was associated with 5.2 units decrease in full IQ scores (B=−5.168, 95% CI=−9.257, −1.078, t =−2.550, df=0.002, P =0.015). Conclusions Clinical global impression of stabilized individuals with schizophrenia predicts their level of general intelligence.