I. Cuthbert

Decision making deficits in patients with first-episode and chronic schizophrenia

A considerable body of evidence suggests that the dorsolateral prefrontal cortex is dysfunctional in schizophrenia. However, relatively few studies have explored the involvement of other areas of the frontal cortex. Research suggests that the orbitofrontal cortex (OFC) plays an important role in decision making processes. We assessed the decision making cognition of first-episode and chronic schizophrenic patients with a novel task sensitive to orbitofrontal dysfunction. Both first-episode and chronic patients with schizophrenia took longer than matched controls to make decisions, and both groups were also impaired on a measure of risk adjustment. The impairment in these measures was more severe in the chronic patients than in the first-episode patients, and only the chronic patients made significantly fewer optimal decisions than controls. These results contribute to increasing evidence of orbitofrontal dysfunction in schizophrenia, and suggest that disease progression or the effects of long term antipsychotic medication may influence performance on this task.

Saccadic hypometria in drug-naive and drug-treated schizophrenic patients: A working memory deficit?

In certain conditions patients with schizophrenia make markedly smaller (hypometric) saccades than controls. This hypometria has been thought to reflect dopaminergic blockade as a result of antipsychotic medication. We tested this hypothesis by comparing the performance of an antipsychotic-naïve group and an antipsychotic-treated group of first-episode schizophrenic patients on a predictive saccade paradigm. We explored the possibility that hypometria reflects a spatial working memory deficit by correlating performance on neuropsychological tests of mnemonic function with saccadic accuracy. Both the drug-naïve and treated schizophrenic patients made hypometric saccades when compared with a group of matched controls. Primary saccade amplitude also correlated significantly with performance on some of the neuropsychological tests. These results are discussed in terms of the roles of cortical dopamine and working memory deficits in schizophrenic patients.