Impairments of executive/attentional functions in schizophrenia with primary and secondary negative symptoms.
Frontal cognitive inabilities have been amply described in schizophrenic patients with negative symptoms, but findings are controversial. These discrepancies could be due to the fact that negative symptoms are heterogeneous, composed of primary and secondary negative symptoms. The hypothesis tested was that executive/attentional dysfunctions would be significantly more impaired in patients with primary than in patients with secondary negative symptoms independently of IQ, the severity of negative or positive symptoms, treatments and side effects. Fifty-six DSM-IV schizophrenic patients characterized either by primary or secondary negative symptoms and 56 controls matched on age, sex and level of education were assessed with executive/attentional cognitive tests. The categories score of the Modified Card Sorting Test (MCST) and the Verbal Fluency Test, which reflect solving and organizing skills, were significantly more impaired in the primary negative subtype than in the secondary negative subtype. In contrast, scores on the MCST (perseveration), the Trail Making Test and the Stroop Color Word Test, which test the ability to inhibit an automatic response, did not differ between the two subtypes. In conclusion, this study supports the view that primary and secondary negative symptoms could be associated with different levels of executive/attentional dysfunctions.