Psychiatry research. Neuroimaging
August 1, 2026
Kengo Yonezawa, Shinichiro Nakajima, Shuhei Shibukawa et al.
Ketamine may alleviate treatment-resistant depression (TRD) primarily through glutamatergic modulation, with downstream dopaminergic activation. Iron plays an important role in monoaminergic metabolism, that is also implicated in the pathophysiology of TRD. Both Quantitative Susceptibility Mapping (QSM) and Effective Transverse Relaxation Rate (R2*) mapping can determine the extent of iron...
Pharmacopsychiatry
July 7, 2026
Kie Nomoto, Yohei Ohtani, Taisuke Yatomi et al.
Introduction: While the rapid and robust effects of ketamine on depressive symptoms in treatment-resistant depression (TRD) have been demonstrated, the influence of ketamine treatment on cognitive function has not yet been fully elucidated. We aimed to evaluate the effects of ketamine treatment on cognitive function as part of a study that investigated the efficacy of repeated ketamine...
Molecular Psychiatry
July 1, 2026
Waki Nakajima, Tetsu Arisawa, Susumu Jitsuki et al.
1 citation
Subanesthetic doses of ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, produce rapid and robust antidepressant effects in patients with treatment-resistant depression (TRD). However, after a single administration, the therapeutic benefit is short-lived, and strategies to maintain its efficacy remain unclear. This study focused on the glutamate...
Molecular Psychiatry
March 5, 2026
Waki Nakajima, Mai Hatano, Yohei Ohtani et al.
1 citation
Approximately 30% of patients with depression suffer from treatment-resistant depression (TRD). Ketamine has shown antidepressant efficacy for TRD. While glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) has been demonstrated to play crucial roles in the process of pharmacological action of ketamine in experimental animals, it remains elusive how ketamine exhibits...
Journal of Affective Disorders
August 15, 2025
Yohei Ohtani, Hideaki Tani, Shiori Honda et al.
3 citations
Approximately 30 % of patients with treatment-resistant depression (TRD) respond to ketamine; however, no replicable predictors of response have been reported. The imbalance between excitatory and inhibitory neurotransmissions may be implicated in the mechanism of action of ketamine. This study aimed to evaluate whether the ratio of glutamate and glutamine (Glx) to GABA levels at baseline in...
The International Journal of Neuropsychopharmacology
August 1, 2025
Yuko Ohtani, Hiroe Tani, Shiori Honda et al.
Abstract Background Only 18-45% of individuals with treatment-resistant depression (TRD) respond to intravenous ketamine therapy. Although some neurobiological predictors of response to ketamine have been reported, none have been consistently replicated across multiple studies. The imbalance between glutamatergic excitatory and GABAergic inhibitory neurotransmissions is implicated in the...
Psychiatry and Clinical Neurosciences
December 1, 2024
Yohei Ohtani, Hideaki Tani, Kie Nomoto-Takahashi et al.
13 citations
Although the antidepressant effect of ketamine on treatment-resistant depression (TRD) has been frequently reported in North American and European countries, evidence is scarce among the Asian population. We aimed to evaluate the efficacy and safety of intravenous ketamine in Japanese patients with TRD. In this double-blind randomized placebo-controlled trial, 34 Japanese patients with TRD were...
Pharmacopsychiatry
July 30, 2023
Kengo Yonezawa, Hiroyuki Uchida, Taisuke Yatomi et al.
8 citations
Abstract Introduction Predictors of treatment response to intravenous ketamine remain unclear in patients with treatment-resistant depression (TRD); therefore, this study aimed to clarify these predictors using the US National Institutes of Health database of clinical trials. Methods Data from a placebo-controlled, double-blind, randomized controlled trial were used to assess the efficacy of...