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.
Psychiatry research. Neuroimaging
August 1, 2026
Kengo Yonezawa, Shinichiro Nakajima, Shuhei Shibukawa et al.
In patients with treatment-resistant depression, higher baseline levels of magnetic substances in the right nucleus accumbens and the left amygdala, measured by brain imaging, predicted a greater reduction in specific depressive symptoms after repeated ketamine infusions. The study included 17 Japanese patients and used a double-blind, randomized placebo-controlled design followed by an open-label phase. Baseline magnetic susceptibility in the right nucleus accumbens correlated with improvement in retardation symptoms, while baseline R2* in the left amygdala correlated with improvement in vegetative symptoms. These brain markers may help predict which patients will benefit from ketamine treatment.
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.