First month of neuroleptic treatment in schizophrenia: only partial normalization of the late positive components of visual ERP.

In a previous study we recorded visual event-related potentials (ERP) in drug-naive schizophrenics during passive-attention and active-attention tasks. Patients, compared to normal controls, had much lower late positive components (LPC) in both sessions, but nearly normal LPC increase from passive to active task. The present sample consisted of drug-naive and drug-free patients who were tested before and during the first month of neuroleptic treatment. Neuroleptics initiated gradual amelioration of psychiatric symptoms expressed by reduced Brief Psychiatric Rating Scale (BPRS) scores. Schizophrenics compared to controls showed a session-related increase in LPC amplitude, but this process of LPC recovery was too minor to fully normalize the low LPC amplitudes in patients. Furthermore, the treatment either did not improve or even reduce the LPC reaction to the active-attention task. These findings indicate that normalization of low LPC in schizophrenia might require a long period of treatment, and that patients' reduced LPC reactivity to the task might be contributed, rather than treated, by neuroleptics.