Effects of a GABA-mimetic drug (sodium valproate) on visually evoked potentials in chronic schizophrenics.

Data were obtained from 14 chronically schizophrenic women (age 40-59) living in the same ward of a psychiatric hospital (Marburg, FRG), and having been treated with clozapine (450-600 mg/day) during the last 2 years. The uncontrolled study was initiated by the addition of sodium valproate (900 mg/day) for 3 months. The observation commenced after the discontinuation of the valproate medication with the evaluation of the symptoms (Brief Psychiatric Rating Scale, BPRS) and the visually evoked potentials (VEP). The VEP were recorded after 3, 12 and 30 days and the rating was repeated after 4 weeks. No significant changes in symptomatology were obtained with the BPRS in patients under combination therapy in comparison with the scores 30 days after discontinuation of the valproate medication. On the other hand, after single flash stimulation, the amplitudes of the components N110, P260, and N300 of the VEP were significantly (p less than 0.05) increased during the same time interval. These findings are interpreted as an expression of an inhibiting action of the GABA system on the reactivity of the visual system in chronic schizophrenics induced by the comedication of sodium valproate.