Memory impairment in schizophrenia--a comparison with that observed in the Alcoholic Korsakoff syndrome

Until very recently, memory impairment was not considered to be a central feature of schizophrenia, except in chronic, deteriorated patients. In this study of a heterogeneous sample of 40 patients with DSM-III-R schizophrenia, episodic memory impairment was found to be prevalent, and in some cases, severe. The degree of memory impairment was not attributable to neuroleptic or anticholinergic medication, or to poor motivation or cooperation. These results, therefore, replicate those reported by McKenna et al. (1990) and Tamlyn et al. (1992), who suggested that the pattern of memory impairment in schizophrenia may conform in important respects to that of the classic amnesic syndrome. However, in a direct comparison of the schizophrenic sample with 18 patients suffering from the Alcoholic Korsakoff Syndrome (AKS), both quantitative and qualitative differences were found to exist between the two groups of patients. In particular, the level of long-term episodic memory impairment was found in the AKS sample to be far greater than that in the schizophrenic group. An interesting possible double-dissociation emerged between the two groups; although demonstrating superior episodic memory functioning, the schizophrenic sample were found to perform significantly more poorly than the AKS sample on a test of semantic memory.