Verbal memory in schizophrenia: additional evidence of subtypes having different cognitive deficits

Abstract

A prior study found a selective deficit in verbal working memory in a subgroup of patients with schizophrenia who performed as well as healthy controls on a screening test of attention and auditory perception [Arch. Gen. Psychiatry 55 (1998) 1093]. Given the importance of defining pathophysiologically distinct subtypes of schizophrenia, the present study aimed to replicate and extend this finding. Patients with schizophrenia who passed the screening test (discriminators or Dsz patients) were compared to those who did not (nondiscriminators, NDsz patients), and healthy controls on a word serial position test (WSPT) and on other tests of verbal and nonverbal cognitive function. Dsz patients performed more poorly than controls on the WSPT and showed serial position effects consistent with a verbal memory deficit. They also showed a deficit in verbal memory but not visual memory on the Wechsler Memory Scale-Revised. In contrast, the NDsz patients showed overall poor performance on both verbal and nonverbal tests, consistent with a generalized deficit. Verbal working memory deficits were not related to education, gender, severity of symptoms, medication status, or hemispheric dominance for perceiving dichotic words. The findings add to growing evidence for the existence of a subgroup of schizophrenia having a specific verbal memory deficit that is not limited to working memory, but extends to learning and recall of verbal material.