Verbal working memory impairment in schizophrenia patients and their first-degree relatives: Evidence from the digit span task

Objective: The evidence for verbal working memory deficits in schizophrenia has been inconsistent. Few studies have evaluated verbal working memory in the first-degree relatives of schizophrenia patients, who likely share the genetic diathesis for schizophrenia but not the potential confounds associ ated with chronic mental illness. Method: The Wechsler Digit Span Task was used to investigate verbal working memory in 52 schizophrenia patients, 56 of their first-degree relatives, and 73 nonpsychiatric comparison subjects. Results: The nonpsychotic relatives showed no impairment on the forward di git span task, a measure of general attention, but did show impairment on t he backward digit span task, a measure of verbal working memory. Schizophre nia patients showed impairment on both the forward and backward digit span tasks. Conclusions: These results indicate that the forward and backward di git span tasks tap different cognitive abilities that are differentially as sociated with the diathesis for schizophrenia. Working memory deficits asso ciated with schizophrenia appear to be generalized and not limited to the s patial modality.