Ketamine, an N-methyl-D-aspartate receptor antagonist, produced a rapid improvement in depressive and anxiety symptoms in 25 drug-free men with severe depression. Improvement was observed within one hour of the first subanesthetic dose (0.5 mg/kg intravenous bolus) and was sustained one month after the last of six doses given over two weeks. Illness severity did not improve. Transient adverse effects occurred in some patients but resolved within an hour. The findings suggest ketamine has a robust and rapid antidepressant effect, though the study lacks a control group and is limited to men.
Male patients with new-onset Cannabis Induced Psychotic Disorder (CIPD) present with less severe psychotic symptoms and show greater improvement in both psychosis and cognitive deficits over four weeks of hospitalization compared to patients with psychosis unrelated to cannabis. Among 16 CIPD patients followed after discharge, 10 relapsed into psychosis within six months after resuming cannabis use. The findings suggest CIPD has a distinct short-term course with better acute resolution, but relapse of cannabis use may lead to poorer long-term outcomes. The study did not include female patients.