International Journal of Neuropsychopharmacology
September 9, 2026
L Harada, K Yonezawa, K Kusudo et al.
Abstract Background Despite sequential treatments with conventional antidepressants, many patients with depression experience insufficient clinical improvement, referred to as treatment-resistant depression (TRD). Psilocybin, a serotonergic psychedelic acting as a 5-HT2A receptor agonist, has attracted increasing attention as a novel treatment, with clinical trials demonstrating rapid and...
International Journal of Neuropsychopharmacology
September 9, 2026
S Tomiyama, K Yonezawa, K Kusudo et al.
Abstract Background Cognitive dysfunction is associated with impaired psychosocial functioning in patients with major depressive disorder (MDD). Patients with treatment-resistant depression (TRD) exhibit more pronounced cognitive dysfunction than those with non-resistant MDD, underscoring the need for effective therapeutic strategies. Psilocybin has emerged as a promising treatment for...
The International Journal of Neuropsychopharmacology
September 1, 2026
K Kusudo, K Yonezawa, S Tomiyama et al.
Abstract Background Psilocybin, a prodrug metabolized to psilocin, a serotonin 2A receptor agonist, has reemerged as a promising therapeutic option for treatment-resistant depression (TRD). Clinical trials conducted mainly in North America and Europe have demonstrated that psilocybin administered with psychological support can produce rapid and sustained antidepressant effects with favorable...
The International Journal of Neuropsychopharmacology
September 1, 2026
K Yonezawa, K Kusudo, S Tomiyama et al.
Abstract Background Despite recent advances in the treatment of major depression, approximately 30% of patients show insufficient improvement with conventional antidepressants, a condition commonly referred to as treatment-resistant depression (TRD). Psilocybin is a classic psychedelic compound that has received renewed attention as a promising therapeutic candidate for TRD. Clinical trials...
Schizophrenia
August 31, 2026
Nataliia Maronchuk, Jean Paul, Fabienne Post et al.
Abstract Background Delays in seeking help are common in schizophrenia and are associated with negative outcomes. In addition to structural barriers, there is growing evidence that subjective interpretations of psychotic experiences, including delusions, voices, and religious or spiritual attributions, play a crucial role in recognizing symptoms and seeking care. Objective This study explores...
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...
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...