Increased rate of P300 latency prolongation with age in drug-naive and first episode schizophrenia.

Objective: Previous studies have found an increased rate of P300 latency prolongation with age in medicated chronic patients with schizophrenia, suggesting a pathological neurodegenerative process. In this study, we investigated whether this abnormality was identified in drug-naive and first episode patients with schizophrenia.

Methods: P300 from auditory stimuli was recorded from 20 drug naive and first episode male patients with schizophrenia and compared with 23 age and handedness matched healthy male controls. The relationship of P300 latency and P300 amplitude to age in each group was evaluated using polynomial regression analyses.

Results: Reduction of P300 amplitude was significant in drug-naive and first episode schizophrenia patients. P300 amplitude negatively correlated with age in schizophrenia patients but not in controls. Although the prolongation of P300 latency with age was observed in both groups, the regression slope for P300 latency with age was significantly steeper in patients with schizophrenia than in normal controls. Significant overall curvilinear correlations with age were also found for P300 latency and amplitude in patients with schizophrenia, and for P300 latency in normal controls.

Conclusions: The greater increase in P300 latency and reduction in P300 amplitude with age may be a primary neuropathological effect of schizophrenia.

Significance: This study suggests that neurodegenerative processes are involved in the etiology of schizophrenia.