Cognitive deficits in nonaffective functional psychoses: a study in the Democratic Republic of Congo.

Cognition has been studied extensively in schizophrenia in Western countries. Far less research is devoted, however, to cognitive functioning in brief psychotic disorder and schizophreniform disorder. Moreover, few studies have been performed in third world countries. In this study, we want to fill this gap by comparing the cognitive functioning of three groups of ambulant, first-episode patients with a non-affective psychosis in the Democratic Republic of Congo. To test if cognitive dysfunction is a core symptom of psychosis in an African population, 153 healthy control subjects are compared with a sample of 68 patients with brief psychotic disorder, 50 patients with schizophreniform disorder, and 70 patients with schizophrenia in a cross-sectional study on several distinctive cognitive domains including verbal, visual, and working memory, attention, visuomotor control, motor speed, verbal fluency, and executive functions. In addition, these three groups of patients are compared among themselves on these cognitive domains. Results indicate that patients perform significantly worse than healthy controls on all cognitive domains with cognitive deficits being most pronounced in verbal and working memory, attention, motor speed, and executive functions. No major differences were found, however, between the three patient groups.