IMPAIRED GENERATION AND USE OF STRATEGY IN SCHIZOPHRENIA - EVIDENCE FROM VISUOSPATIAL AND VERBAL TASKS

Background. The aim of this study was to investigate mnemonic strategi c deficits in schizophrenic patients. Methods. Analogous tasks were us ed that required the self-generation of an efficient strategy and its implementation in two domains: visuospatial and verbal. The tasks were given to 20 IQ preserved schizophrenics and 20 matched normal control s. A number of different scores was derived from each task including s trategy, short-term memory capacity and perseveration. Results. Overal l, the schizophrenic patients were significantly impaired in their abi lity to generate effective mnemonic strategies on both tasks. In addit ion, on the visuospatial task there was no difference between the grou ps on the memory scores, but the schizophrenic patients made significa ntly more perseverative errors than controls. They were disproportiona tely worse on the verbal strategy task, showing impairment on memory a s well as on strategy scores and were also impaired at semantically cl assifying the words. Performance was similar to the deficit seen in pa tients with frontal lobe excisions and Parkinson's disease, in terms o f the inability to generate an effective strategy. The deficit on the verbal task was similar to patients with temporal lobe excisions who s how impaired verbal memory. However, the pattern differed in the sense that the temporal lobe patients were able to generate effective strat egies, unlike the patients with schizophrenia. Conclusions. High funct ioning schizophrenic patients are impaired in utilizing visuospatial a nd verbal mnemonic strategies. By comparing the results with those of neurosurgical excision patients, further evidence is provided for both frontal and temporal lobe involvement in schizophrenia.