Abnormal EEG activities induced by psychotropic drugs

In a retrospective study involving 680 EEG investigations in 593 patients the effects of various psychopharmaceutical agents were examined by visual interpretation of the EEG. The drugs were given singly in the majority of cases and were combined in others, and special attention was paid to the occurrence of paroxysmal EEG activity. The proportions of abnormal EEGs in the various groups were (in descending order): clozapine 59%, lithium salts 50%, butyrophenone 44%, maprotiline 37%, dibenzepine 32%, laevomepromazine and amitriptyline 31%, imipramine 9% and diazepam 4%. The proportions of paroxysmal discharges (13%) and generalized transient disturbances with groups of slow waves (16%) were also greatest in the clozapine group. During 3.5 years (1973-1974, May 1979-November 1980) we observed drug-induced generalized seizures in 16 inpatients = 0.28% of all inpatients (N = 5785) in that time. The psychotropic drugs given to these patients were either laevomepromazine (Neurocil 4x), perazine (Taxilan 3x), maprotiline (Ludiomil 3x), clozapine (Leponex 2x), lithium carbonate (Quilonum retard 2x) and amitriptyline (Saroten 2x) alone or partly in combination with butyrophenone (3x), fluphenazine (2x) and biperiden (3x). The appearance of paroxysmal EEG activity seems dose dependent and occurs more often during treatment with a combination of psychoactive compounds, than in patients receiving a single drug.