Catatonia, a condition recognized since the 1800s, remains difficult to diagnose and treat. A systematic review of 20 studies involving 25 patients who received ketamine or esketamine for catatonia found that 80% of patients responded to treatment and 44% achieved remission, with no worsening of catatonic or psychotic symptoms. Only one patient stopped treatment due to intolerable dissociative effects. Most patients were female (61.9%), with an average age of 44.4 years, and had underlying mood disorders. The evidence suggests ketamine may be effective for catatonia, even in patients with psychotic disorders, where it has traditionally been considered contraindicated. The authors advocate reevaluating this contraindication, noting potentially greater benefits for those with mood disorders.
In a small pilot trial, the antidepressant arketamine was compared with placebo for treatment-resistant depression. Ten participants received both arketamine (0.5 mg/kg) and saline one week apart in a randomized, double-blind, crossover design. Depression improved over time, but there was no significant difference between arketamine and placebo. Dissociation and other adverse events were minimal. The study was underpowered, and the authors conclude that arketamine was not superior to placebo but was extremely safe, recommending larger trials with different dosing strategies.