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October 1955

The Sedation Threshold, Manifest Anxiety, and Some Aspects of Ego Function

Author Affiliations

Montreal, Canada

From the Allan Memorial Institute of Psychiatry and McGill University.

AMA Arch NeurPsych. 1955;74(4):397-406. doi:10.1001/archneurpsyc.1955.02330160047007

The sedation threshold is an objective pharmacological determination, which depends upon EEG and speech changes produced by intravenously given amobarbital (Amytal) sodium.1 This procedure was developed to measure manifest anxiety,* and its validity for this purpose was demonstrated in two studies of psychoneurotic patients.† The main purpose of the present investigation was to determine whether the sedation threshold also measures manifest anxiety in nonpatient controls and in certain psychotic disorders.

There have been no previous attempts to correlate clinical findings in a control group with the sedation threshold. In another study,2 thresholds of the present control group were compared with those of psychoneurotics. Hysterical patients were the only neurotic group with thresholds similar to those of controls; in all other neurotic groups the threshold was significantly higher. Previous investigation of the sedation threshold in psychosis has been confined to the study of a group of 11 schizophrenics.1