An electroencephalographic study on the tolerance of psychiatric and neurologic patients to the hypnotic effect of diphenhydramine.

Abstract

Summary1) The tolerance to the hypnotic effect of the diphenhydramine (Dph), one of anti‐histaminics, of normal subjects and psychiatric and neurologic patients was investigated on EEG data obtained in the routine EEG examination including Dph activation on 392 patients and 69 adult normal controls. EEG was recorded for 30 min following intravenous injection of 1 mg/kg body weight of Dph, and the time occupied by the stage of wakefulness and by each sleep stage were measured. The percent time waking EEG (% W‐EEG) was used as an index of the tolerance to the hypnotic effect of Dph.2) The mean with standard deviation (SD) of % W‐EEG of the 69 controls was 35.6±29.0%, with no differences in age and sex. The cyclothymic and immodithy‐mic normals showed higher % W‐EEG than those with the other types of personality.3) The means with SD of % W‐EEG following intravenous injection of Dph in various psychiatric and neurologic patient groups were as follows: 62.4±33.1% in 93 schizophrenics, 55.4±34.7% in 44 manic‐depressives, 71.1±31.4% in 143 psycho‐neurotics, 50.0±35.6% in 92 epileptics and 81.3±22.6% in 20 patients with organic brain diseases. They were all significantly higher than the % W‐EEG of normal controls. In the following pairs of groups, the former % W‐EEG was higher than the latter (P<0.05): between the patients with organic brain diseases and each of schizophrenics, manic‐depressives and epileptics; between schizophrenics and epileptics. No significant difference was found among the other groups.4) No significant difference was found between the % W‐EEG's of the following two different stages and cases in both schizophrenics and manic‐depressives: the aggravated stage with active mental symptoms and improved stage; cases showing favorable response to pharmacotherapy and those without satisfactory effect. In psychoneurotics, the % W‐EEG's were higher in hysteria, hypochondriasis, anxiety neurosis, obsessive‐compulsive neurosis in this order. Significant differences in % W‐EEG were found between either of hysteria or hypochondriasis and obsessive‐compulsive neurosis (P<0.05), but not between cases received EEG examinations in aggravated and improved stages. Among epileptics, the % W‐EEG of cases with psychomotor seizure was lower than that of cases with generalized convulsion, and the value was close to that of normal controls.5) From the finding mentioned above, it was demonstrated that some of the neuropsychiatric patients have higher tolerance to the hypnotic effect of Dph than normals. The higher tolerance was considered to be due not only to the clinical state of the patients but also to the predisposing factors or biological changes underlying the illness. The problems on the tolerance to Dph were discussed from various viewpoints.