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
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...
Psychiatry and Clinical Neurosciences
February 26, 2026
Kengo Yonezawa, M. Hirata, Hiroaki Takano et al.
1 citation
Psilocybin, a classic psychedelic compound, has garnered renewed interest as a potential treatment for various psychiatric disorders. This review provides a comprehensive overview of psilocybin's history, recent clinical evidence, ongoing clinical trials, neuroimaging findings, and regulations. Historically used in spiritual and healing rituals, psilocybin was in the early 1970s subjected to...
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...
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...
Neuropsychopharmacology Reports
November 8, 2024
Hideaki Tani, Kengo Yonezawa, Keisuke Kusudo et al.
1 citation
Abstract Introduction The therapeutic potential of psychedelics for various mental disorders has gained significant interest. Previous studies have highlighted that psychedelics induce psychoactive effects, including challenging aspects of experiences. These experiences are assessed using the Challenging Experience Questionnaire (CEQ), yet its Japanese version has been unavailable. This study...
Neuropsychopharmacology Reports
March 13, 2024
Keisuke Kusudo, Hideaki Tani, Kengo Yonezawa et al.
2 citations
Abstract Aim Psychedelics have recently gained attention as potential therapeutic agents for various psychiatric disorders. Previous research has highlighted that a diminished sense of self, commonly termed “ego‐dissolution” is a pivotal feature of the psychedelic‐induced state. While the Ego‐Dissolution Inventory (EDI) is a widely acknowledged instrument for measuring this phenomenon, no...