Psychopathology and Wisconsin Card Sorting Test performance in male schizophrenic patients: influence of dual diagnosis

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.

Performance in the Wisconsin Card Sorting Test and the C957T polymorphism of the DRD2 gene in healthy volunteers

INTRODUCTION

Previous studies have associated a decreased striatal D2 dopamine receptor (DRD2) binding with impaired performance in cognitive tasks. In vivo studies have found a lower DRD2 binding associated with the CC genotype of the C957T single nucleotide polymorphism (SNP) of the DRD2 gene.

OBJECTIVE

The aim of this study was to investigate the relationship between executive functions and the C957T DRD2 SNP. We hypothesized that the CC genotype would be associated with a poorer executive functioning.

METHODS

Our sample consisted of 83 healthy volunteers (28 males and 55 females; mean age 25.2, SD 1.7 years). To assess executive functions, the Wisconsin Card Sorting Test was used, considering the variables perseverative errors, perseverative responses, and number of categories achieved. The genotype distribution was 13 CC, 41 CT, and 29 TT, satisfying Hardy-Weinberg equilibrium.

RESULTS

Carriers of the CC genotype, compared with carriers of the CT/TT genotypes, achieved significantly fewer categories (5.00 vs. 5.81; p = 0.004), made a greater number of perseverative errors (13.46 vs. 8.39; p = 0.018), and had a greater number of perseverative responses (14.92 vs. 8.94; p = 0.014).

CONCLUSIONS

Our results support the hypothesis that the C957T DRD2 SNP may influence cognitive performance through its repercussions on central dopaminergic function.

Impulsivity and Sustained Attention in Pathological Gamblers: Influence of Childhood ADHD History

Pathological gambling (PG) has been associated to both impulsiveness and attention deficit/hyperactivity disorder (ADHD) in different studies. Our objective was to compare different impulsivity and sustained attention variables, using both behavioural tasks and self-administered questionnaires, in a group of pathological gamblers with a history of childhood ADHD (PG-ADHD; n = 16), a group of pathological gamblers without this history (PG-non-ADHD; n = 39), and a control group (n = 40). As instruments of measure, we used the stop signal task (to evaluate inhibitory control/impulsivity), the differential reinforcement of Low Rate Responding Task (delay of gratification/impulsivity) and the Continuous Performance Test (sustained attention). The Barratt Impulsivity Scale (BIS-11) was used as a self-administered questionnaire to measure impulsiveness. Our results show that patients in the PG-ADHD group exhibit a significantly lower capacity to delay gratification than those in the PG-non-ADHD and control groups, and less inhibitory control than patients in the PG-non-ADHD group. On self-administered questionnaires such as the BIS-11 the PG-ADHD group obtained higher scores than the PG-non-ADHD and control groups. However, no differences were found with respect to sustained attention using the CPT. Our results suggest a possible selective implication of the prefrontal cortex in PG, which would be especially evident in those with a childhood history of ADHD.