If cognitive deficits reflect the underlying genetic risk for schizophrenia, it would be beneficial to study first-degree relatives, since they likely share some of the genetic diathesis for schizophrenia without the aforementioned complications. Reports of cognitive deficits in schizophrenia are open to some criticism because multiple factors associated with chronic mental illness (e.g., lower education levels or medication effects) could potentially color performance and thus limit the conclusions that can be drawn. It is unclear whether working memory deficits in schizophrenia are limited to the spatial modality or whether the working memory dysfunction is more generalized and includes other domains. In contrast, findings indicative of verbal working memory deficits have been less consistent (3). Findings that suggest spatial working memory deficits in schizophrenia have been well-replicated (2). Working memory deficits in schizophrenia may have important implications both for the localization of underlying neurologic impairment and for explanations of disparate cognitive deficits associated with this disorder (1). Working memory deficits associated with schizophrenia appear to be generalized and not limited to the spatial modality. CONCLUSIONS: These results indicate that the forward and backward digit span tasks tap different cognitive abilities that are differentially associated with the diathesis for schizophrenia. Schizophrenia patients showed impairment on both the forward and backward digit span tasks. RESULTS: The nonpsychotic relatives showed no impairment on the forward digit span task, a measure of general attention, but did show impairment on the backward digit span task, a measure of verbal working memory. 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. 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 associated with chronic mental illness.
OBJECTIVE: The evidence for verbal working memory deficits in schizophrenia has been inconsistent.
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