COGNITIVE FUNCTION IN SCHIZOPHRENIA

Impaired cognitive function in schizophrenia, once thought to be a sec ondary effect of the psychosis, is now seen as an enduring and core fe ature. It has many manifestations, but the most disruptive element is arguably a fundamental defect in the patient's ability to manipulate a vailable information. The magnitude of the cognitive deficit in schizo phrenia is considerable and remains relatively stable despite fluctuat ions in other symptoms. The degree of dysfunction also has a high pred ictive value for long-term disability. In recent years, more attention has been directed towards cognitive dysfunction in schizophrenia as a result of which assessment scales and diagnostic systems increasingly incorporate cognitive dysfunction as an independent domain. Good cogn itive function depends upon the brain's ability to prioritize tasks an d to switch from parallel processing to sequential processing when the processing load is excessive. This requires working executive memory. Neuroimaging and functional analyses suggest that such cognitive func tion relies upon unimpaired prefrontal activity. In addition, there is increasing evidence that antipsychotic drugs with 5-hydroxytryptamine (5-HT)(2A)-blocking activity produce better cognitive function in pat ients with schizophrenia than drugs with predominantly dopamine (D)(2) -blocking activity (conventional neuroleptics). The development of sop histicated, computer-delivered maze tasks has shown that newer antipsy chotics, such as clozapine and risperidone, differ from conventional n euroleptics in their effects on cognitive function. The prospects, the refore, are that patients treated with drugs having 5-HT2A-blocking ac tivity will have better cognitive function and will be better able to function in life's roles than will patients treated with conventional neuroleptics.