A total of 325, newly admitted, depressed patients from nine hospitals were randomly assigned to treatment with either diazepam, phenelzine, or a placebo. The study was conducted double-blind and ran for seven weeks. Median daily dosages were 30 mg of diazepam and 45 mg of phenelzine.
The major study finding was the differential effects of diazepam for patients categorized as anxious and hostile depressions. There was a significant number of anxious-depressive patients who were diazepam responders, ie, their symptoms subsided on this treatment and became worse when this drug was discontinued.
In contrast, diazepam was a poor treatment for the hostile depressions. These patients were restless, anxious, negativistic, suspicious, and irritable when they entered the study. These symptoms persisted on diazepam and improved on either phenelzine or a placebo.