Clinical symptom dimensions and deficits on the Continuous Performance Test in schizophrenia

We examined the relationships between symptom dimensions derived from factor analytic studies of schizophrenic symptoms and sustained attention deficits. Four factors, negative, delusion/hallucination, disorganization, and excitement, were yielded from factor analysis on 14 items of the Positive and Negative Syndrome Scale (PANSS) among 60 Chinese inpatients with acute schizophrenia. The negative dimension was associated with lower sensitivity index (d') while the excitement dimension was associated with higher d' on the Continuous Performance Test (CPT) after sex, age and education were adjusted for in multiple linear regressions. The positive dimension affected only response criterion (ln beta) and was not associated with the d' on the CPT. In contrast, the summed scores of PANSS Positive and Negative scales did not have significant correlations with d' on the CPT. Thus, the discriminant validity of these symptom dimensions of schizophrenia is supported by their correlations with CPT performance indices.