Background: Different neuropsychological studies have shown schizophrenic patients to have executive function deficits, as illustrated by their performance in neuropsychological tasks such as the Wisconsin Card Sorting Test (WCST); certain studies have described a relationship between these deficits and negative symptoms. Schizophrenic patients also exhibit a high lifetime prevalence (40-50%) of comorbid substance use disorders (SUDs). However, little attention has been paid to this comorbidity (dual diagnosis) in studies associating executive functions and negative symptoms.
Sampling and methods: Our objective is to investigate the relationship between performance in the WCST and psychopathology as measured by the Positive and Negative Syndrome Scale (PANSS) in a sample of 65 male schizophrenic patients with a history of SUDs (Sch SUD+) and in a sample of 48 male schizophrenic patients without such history (Sch SUD-).
Results: In the Sch SUD- group, patients who completed 4 or more categories in the WCST ('good performers') obtained a mean score of 21.2 +/- 8.8 on the negative subscale of the PANSS, compared with a mean score of 27.8 +/- 8.6 in those who completed 3 or less ('poor performers'); these differences were statistically significant (p = 0.015). In the Sch SUD+ group, however, no association was found between WCST performance and the PANSS negative subscale score.
Conclusions: The presence of a history of comorbid SUDs should be taken into consideration in studies investigating executive functions and negative symptoms in schizophrenia.
(c) 2007 S. Karger AG, Basel.