NEUROPSYCHOLOGY OF SCHIZOPHRENIA - WHAT ARE THE IMPLICATIONS OF INTELLECTUAL AND EXPERIENTIAL ABNORMALITIES FOR THE NEUROBIOLOGY OF SCHIZOPHRENIA

The diagnosis of schizophrenia is largely based on reports of bizarre experiences such as having alien thoughts inserted into one's mind. Ma ny patients with this diagnosis show a marked intellectual decline and particular problems with tasks involving certain kinds of memory or r equiring mental flexibility Similar patterns of performance can be see n in patients with damage in the prefrontal cortex. However, patients with schizophrenia show a very varied pattern of impairments relating to their current mental state. Chronic patients with negative Features , such as poverty of speech, are most likely to show poor test perform ance, while the presence of severe hallucinations and delusions need n ot be associated with any impairment. A cognitive approach suggests th at hallucinations and delusions result from the patient attributing hi s own actions to an external agency. This error is due to an inability to distinguish between external events and perceptual changes caused by his own actions. The basis of this failure could be a functional di sconnection between frontal brain areas concerned with action and post erior areas concerned with perception.