ABSTRACT
Semantic memory, the long term storage of knowledge without personal time and place connotations, may be relevant to schizophrenia for a number of reasons. First, there is a growing feeling that a dysfunction of “real world knowledge” (Cutting & Murphy, 1988), “stored regularities” (Gray et al., 1991; Hemsley, 1987) or “second order representations” (Frith & Frith, 1992) is central to the phenomenology of schizophrenia. Secondly, the neuropsychology of semantic memory, with its emphasis on executive/frontal and mnestic/temporal mechanisms, shows obvious overlap with putative areas of disorder in schizophrenia. Finally, the existence of episodic memory impairment in schizophrenia is well established and this has been argued to be selective and disproportionate to the overall level of intellectual impairment. The theoretical construct of semantic memory lacks a coherent conceptual framework, hampering developing of experimental tests. In the present studies, the commonly used existing tests of semantic memory were administered to groups of schizophrenic patients with and without memory impairment. In addition, a detailed, wide ranging, and theoretically sophisticated semantic memory battery, recently developed by Hodges, was applied to 46 schizophrenic patients classified into three groups: acutely ill, non-elderly chronic/severe, and elderly chronically hospitalised. The performance of the schizophrenic patients on the standard tests pointed to a marked semantic memory impairment. On the Hodges battery, all three groups showed evidence of substantial impairment in many of the aspects of semantic memory probed. There was evidence that the impairment was present in patients without evidence of overall intellectual impairment. Preliminary analysis suggested a pattern of impairment more consistent with “impaired access” rather than “degraded store”.
