Psychiatry and clinical neurosciences
December 1, 2024
Yohei Ohtani, Hideaki Tani, Kie Nomoto-Takahashi et al.
13 citations
In a double-blind randomized placebo-controlled trial with 34 Japanese patients suffering from treatment-resistant depression, intravenous ketamine (0.5 mg/kg) given twice a week for two weeks did not show a statistically significant advantage over placebo in reducing depression scores when all participants were analyzed together. However, among those who completed the full treatment protocol, ketamine led to a significantly greater reduction in depressive symptoms than placebo. Higher baseline depression severity and body mass index were linked to greater symptom improvement with ketamine. Adverse events were more common with ketamine but no serious events occurred. These results suggest ketamine may be effective for treatment-resistant depression across diverse ethnic groups.
Molecular psychiatry
July 1, 2026
Waki Nakajima, Tetsu Arisawa, Susumu Jitsuki et al.
1 citation
A novel compound, K-4, which positively modulates AMPA receptors, produced longer-lasting antidepressant-like effects in a rat model of treatment-resistant depression than ketamine alone. K-4 reduced expression of the enzyme NOX-1 in the medial prefrontal cortex. Blocking NOX-1, either with an inhibitor or by genetic knockdown, prolonged ketamine's antidepressant-like effects and reduced abnormal bursting in the lateral habenula, a brain region linked to depression. Suppressing NOX-1 may be a promising strategy for extending the benefits of ketamine in treatment-resistant depression.
Pharmacopsychiatry
July 7, 2026
Kie Nomoto, Yohei Ohtani, Taisuke Yatomi et al.
In a double-blind, randomized, placebo-controlled trial, 34 Japanese patients with treatment-resistant depression received four intravenous doses of either ketamine (0.5 mg/kg) or saline. No significant differences emerged between the groups on objective or subjective cognitive function measures. Among ketamine-treated patients, those who responded to treatment (at least 50% reduction on the Montgomery-Åsberg Depression Rating Scale) showed greater improvement in subjective cognitive function than non-responders. Participants with weaker inhibitory control at baseline experienced larger reductions in depressive symptoms after ketamine. Repeated ketamine administration did not worsen cognitive function compared to placebo, suggesting cognitive safety, and baseline cognitive control deficits may predict better treatment response.