EEG Abnormalities Under Treatment with Atypical Antipsychotics: Effects of Olanzapine and Amisulpride as Compared to Haloperidol

Abnormal EEG patterns are well known electrophysiological effects of treatment with antipsychotic drugs. To estimate the risk of EEG alterations including epileptiform activity under recently developed antipsychotics, we have analysed EEG recordings of all inpatients with schizophrenia medicated with atypical antipsychotics olanzapine or amisulpride in monotherapy, in comparison to a control group under haloperidol within a two-year period.

EEG effects of olanzapine (n = 45) and amisulpride (n = 25) were retrospectively investigated and compared with the effects of haloperidol (n = 20) using digital EEG recordings, visually assessed by two independent investigators.

Patients under olanzapine and amisulpride showed significantly higher rates of EEG abnormalities (46.7 and 44 %) as compared to haloperidol (10 %) (p < 0.01, and p < 0.05, respectively) and abnormal EEGs were associated with higher doses of medication. Epileptiform discharges were seen under olanzapine (15 %), and amisulpride (4 %), but not under haloperidol (statistical trend, p = 0.07).

EEG abnormalities are frequent, and dose-dependent findings under treatment with olanzapine and amisulpride, and the occurrence of epileptiform activity has to be taken into account.

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