Neuropsychologic functioning and structural MRI of the brain in patients with schizophrenia.

The first episode of schizophrenia represents a transition from a premorbid to a morbid state. Studying the first episode of schizophrenia is useful since it is devoid of the confounds of chronicity and long-term medication. It is also likely to direct us to the core deficits of the illness. Studies on first-episode schizophrenia suggest a generalized neuropsychologic impairment, but that memory, attention and executive function are more severely impaired. Support for a neurodevelopmental model of neuropsychologic impairment in schizophrenia is derived from the findings that much of the neuropsychologic impairment is present by illness onset, that neuropsychologic impairment remains stable over time and that there is a weak relation between duration of untreated psychosis and neuropsychologic impairment. However, neuropsychologic impairment is moderated by neuroleptic treatment, with some evidence that atypical antipsychotics may have some beneficial effects over conventional antipsychotics. The causal mechanisms of brain abnormality in the temporal and frontal lobes appear to be different to that of neuropsychologic impairment in schizophrenia. The observation that there is a brain volume decrement over time and that the rate of change is higher during the first 5 years would be consistent with a neurodegenerative model of schizophrenia. At the same time, the basal ganglia are vulnerable to volumetric increase secondary to neuroleptic medication. Understanding the roles of the neurodevelopmental and neurodegenerative models of schizophrenia is important in deciding intervention strategies.