[Memory disturbances in schizophrenia]

Abstract

The recent literature on memory disorders in schizophrenic persons is reanalysed. The present interest in memory disorders as a core symptom of cognitive changes in schizophrenia derives from the fact that brain imaging methods have revealed a reduction of substance in the regions surrounding the lateral ventricles. Given this localisation, schizophrenics should suffer from pronounced memory deficits. The paper addresses (1) the role of memory disorders in an overall view of cognitive losses, (2) the pattern of memory losses (verbal vs non-verbal, short-term memory vs long-term memory, implicit vs explicit memory etc.) and (3) recent investigations based on simultaneous use of imaging procedures (fNMR, PET) and cortical activation during memory tasks. A survey of the literature renders it likely that frontal functions play an essential role in the type of memory deficits found among schizophrenics. Thus, a purely temporal localisation is unlikely. The reduced learning efficiency which accounts for most of the schizophrenics' cognitive problems points to a working memory disturbance. On the basis of these results, a model for the memory disorders of schizophrenics is developed. The model covers recent literature on working memory as well as neural network models of schizophrenic disorders. However, a differential psychopathological symptom and syndrome analysis remains a prerequisite for reducing the great variance of the schizophrenics' performance in memory tasks. The importance of cognitive rehabilitation for sociopsychiatric efforts aimed at re-integrating mentally ill persons should not be underestimated.