Published papers

治療抵抗性うつ病患者にケタミンを投与し、その治療前後でAMPA-PETを用いてAMPA受容体の密度と分布の変化を検証し、ケタミンの作用発現過程およびうつ病の回復過程をAMPA受容体の観点から検討した。本研究はプラセボ対照二重盲検無作為化比較試験であり、現在のうつエピソードに対して抗うつ薬を2種類以上使用しても反応しなかった34名を対象とした。主要評価尺度であるモンゴメリ・アスベルグうつ病評価尺度(MADRS)を用いて評価した気分症状の重症度の変化は、intention-to-treat解析においてケタミン群とプラセボ群の間でのMADRS総点の低下に有意差は認めず、per-protocol解析ではケタミン群のMADRS総点の有意な低下が認められた。ケタミン部分反応者において、ケタミン治療介入により有意にstandardized uptake value ratioが有意に上昇している領域として、下前頭回、中眼窩回などの前頭葉、中心後回、下頭頂葉、縁上回が抽出された。腹側被蓋野～内側視床にかけての領域、海馬、被殼におけるケタミン治療介入前のstandardized uptake value ratioが低いことと治療介入前後のMADRS総点の減少が有意に相関していた。

Local and global functional connectivity densities (lFCD and gFCD, respectively), derived from functional magnetic resonance imaging (fMRI) data, represent the degree of functional centrality within local and global brain networks. While these methods are well-established for mapping brain connectivity, the molecular and synaptic foundations of these connectivity patterns remain unclear. Glutamate, the principal excitatory neurotransmitter in the brain, plays a key role in these processes. Among its receptors, the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) is crucial for neurotransmission, particularly in cognitive functions such as learning and memory. This study aimed to examine the association of the AMPAR density and FCD metrics of intraregional and interregional functional centrality. Using [11C]K-2, a positron emission tomography (PET) tracer specific for AMPARs, we measured AMPAR density in the brains of 35 healthy participants. Our findings revealed a strong positive correlation between AMPAR density and both lFCD and gFCD-lFCD across the entire brain. This correlation was especially notable in key regions such as the anterior cingulate cortex, posterior cingulate cortex, pre-subgenual frontal cortex, Default Mode Network, and Visual Network. These results highlight that postsynaptic AMPARs significantly contribute to both local and global functional connectivity in the brain, particularly in network hub regions. This study provides valuable insights into the molecular and synaptic underpinnings of brain functional connectomes.

Background: Mild behavioral impairment (MBI) and loneliness are associated with cognitive decline and an increased risk of dementia. Objective: Our aim was to examine the validity of the Japanese version of the MBI checklist (MBI-C) and investigate the relationship between loneliness and MBI. Methods: The participants in this cross-sectional study included 5 cognitively normal persons and 75 persons with mild cognitive impairment. MBI-C and the revised University of California at Los Angeles loneliness scale (LS) were used to assess MBI and loneliness, respectively. Diagnostic performance of MBI-C was examined using receiver operating characteristic analysis. The relationship between MBI-C and LS was examined using multiple linear regression in 67 subjects who were assessed with both scales, with MBI-C total or domain score as the dependent variable and LS as the independent variable, adjusted for age, gender, living situation, presence of visual and hearing impairment, and Mini-Mental State Examination score. Results: Per the Youden index, in this mostly MCI sample, the optimal MBI-C cut-off score was 5.5 with sensitivity 0.917 and specificity 0.949. In multiple linear regression analysis, LS score was detected as a significant predictor of MBI-C total scores, and MBI-C decreased motivation, affective dysregulation, and abnormal thought and perception scores. Conclusions: The caregiver-rated Japanese MBI-C has excellent diagnostic performance. Loneliness is associated with a greater MBI burden, especially in the decreased motivation, affective dysregulation, and abnormal thought and perception domains. Interventions for loneliness in older people may have the potential to improve MBI.

Objective: Non-GABAergic hypnotics introduced into clinical practice within the last two decades are pharmacologically presumed to have a lower risk of falls, but clinical investigations are scarce. We aimed to evaluate the risk of falls associated with different classes of hypnotics, namely benzodiazepines, ramelteon, suvorexant, and trazodone, in hospitalized individuals at a general hospital. Method: In this retrospective cohort study, data on the incidence of falls, hypnotic use, age, sex, body mass index (BMI), activities of daily living (ADL) score, presence of surgery, emergency admission, and ambulance use were collected for hospitalized patients aged 20 years or older who had been discharged from a tertiary general hospital in Japan between April 1, 2014, and March 31, 2019. The Cox proportional hazards model was used to examine factors associated with falls, adjusting for other demographics as covariates. Results: Among 28,029 patients, 383 falls occurred in 322 patients. Ramelteon or suvorexant was not associated with an elevated incidence of falls (adjusted hazard ratio [aHR], 0.78; 95 % CI, 0.34 to 1.81 and 0.44; 95 % CI, 0.13–1.46, respectively), in contrast to benzodiazepines (aHR, 2.17; 95 % CI 1.67–2.83) or trazodone (aHR, 1.96; 95 % CI 1.25–3.07). Advanced age, lower BMI, wheelchair dependency, non-surgical status, absence of emergency admissions, and ambulance use were also associated with the elevated incidence of falls. Conclusions: In hospitalized patients at general hospitals, ramelteon and suvorexant may not increase the risk of falls, while the use of benzodiazepines and trazodone requires careful attention to minimize this risk.

Background and Hypothesis: Schizophrenia is associated with widespread cortical thinning and abnormality in the structural covariance network, which may reflect connectome alterations due to treatment effect or disease progression. Notably, patients with treatment-resistant schizophrenia (TRS) have stronger and more widespread cortical thinning, but it remains unclear whether structural covariance is associated with treatment response in schizophrenia. Study Design: We organized a multicenter magnetic resonance imaging study to assess structural covariance in a large population of TRS and non-TRS, who had been resistant and responsive to non-clozapine antipsychotics, respectively. Whole-brain structural covariance for cortical thickness was assessed in 102 patients with TRS, 77 patients with non-TRS, and 79 healthy controls (HC). Network-based statistics were used to examine the difference in structural covariance networks among the 3 groups. Moreover, the relationship between altered individual differentiated structural covariance and clinicodemographics was also explored. Study Results: Patients with non-TRS exhibited greater structural covariance compared with HC, mainly in the fronto-temporal and frontooccipital regions, while there were no significant differences in structural covariance between TRS and non-TRS or HC. Higher individual differentiated structural covariance was associated with lower general scores of the Positive and Negative Syndrome Scale in the non-TRS group, but not in the TRS group. Conclusions: These findings suggest that reconfiguration of brain networks via coordinated cortical thinning is related to treatment response in schizophrenia. Further longitudinal studies are warranted to confirm if greater structural covariance could serve as a marker for treatment response in this disease.

Synaptic phenotypes in living patients with psychiatric disorders are poorly characterized. Excitatory glutamate α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) is a fundamental component for neurotransmission. We recently developed a positron emission tomography (PET) tracer for AMPAR, [11C]K-2, the first technology to visualize and quantify AMPARs density in living human brain. In this study, we characterized patients with major psychiatric disorders with [11C]K-2. One hundred forty-nine patients with psychiatric disorders (schizophrenia, n = 42; bipolar disorder, n = 37; depression, n = 35; and autism spectrum disorder, n = 35) and 70 healthy participants underwent a PET scan with [11C]K-2 for measurement of AMPAR density. We detected brain regions that showed correlation between AMPAR density and symptomatology scores in each of four disorders. We also found brain areas with significant differences in AMPAR density between patients with each psychiatric disorder and healthy participants. Some of these areas were observed across diseases, indicating that these are commonly affected areas throughout psychiatric disorders. Schizophrenia, bipolar disorder, depression, and autism spectrum disorder are uniquely characterized by AMPAR distribution patterns. Our approach to psychiatric disorders using [11C]K-2 can elucidate the biological mechanisms across diseases and pave the way to develop novel diagnostics and therapeutics based on the synapse physiology.

Objective: Although antipsychotics are used commonly for delirium, they increase the risk of mortality in elderly patients and those with dementia. As hydroxyzine has sedative and anxiolytic effects, it can be used in the treatment of delirium. We performed a retrospective study to compare the effects of intravenous hydroxyzine and haloperidol monotherapy on delirium. Methods: Patients who admitted to a university hospital from April 1, 2017, to September 30, 2022, and received either hydroxyzine or haloperidol intravenously as monotherapy for the treatment of delirium were included. The time to and rate of delirium improvement were compared. Improvement of delirium was defined as negative on the Confusion Assessment Method (CAM) or Confusion Assessment Method for the ICU (CAM-ICU) for 3 consecutive days. Results: Among 5,555 patients who developed delirium, 71 (1.3%) and 82 (1.5%) received intravenous hydroxyzine and haloperidol monotherapy, respectively. The time to delirium improvement was 7.0 days (95% CI, 5.7–8.3 days) for hydroxyzine and 8.2 days (95% CI, 7.6–8.8 days) for haloperidol, with no significant difference between the two groups (P= .059). On the other hand, the rate of delirium improvement was 23.9% for hydroxyzine and 8.5% for haloperidol, with a significant difference in favor of the hydroxyzine group (P = .009). Conclusions: We first showed that intravenous hydroxyzine monotherapy was not inferior for the time to delirium improvement and superior for the rate of delirium improvement to intravenous haloperidol monotherapy. Considering that hydroxyzine is relatively safe with few side effects, it can be a viable option for delirium as an alternative to antipsychotics.

Aim: Although numerous studies have reported that chronic alcohol consumption causes brain volume reduction and cerebrospinal fluid volume increase, few studies have examined the acute effects of alcohol on brain structure. This study aims to investigate the short-term brain volume changes following alcohol administration. Methods: Moderate doses of alcohol were administered intravenously to 18 healthy volunteers for a total of 90 min to achieve a blood alcohol concentration of 0.5 mg/mL. An alcohol clamp method combined with physiologically based pharmacokinetic modeling was used to achieve fine control over blood alcohol concentration. T1 images with 3T MRI were scanned at three time points: baseline, 0 min, and 90 min after the end of alcohol administration. Cortical, subcortical, and ventricular volumes were computed after segmentation with FreeSurfer. Repeated measures analysis of variance was used to evaluate longitudinal changes in brain volume at 96 regions. Results: Acute alcohol administration increased bilateral lateral ventricular volumes, which lasted until 90 min after the end of alcohol injection. On the other hand, the volumes of total gray matter, left precentral cortex, left caudal middle frontal cortex, and left superior frontal cortex decreased after alcohol administration, but these changes disappeared 90 min after the end of alcohol administration. Conclusion: Acute injection of moderate doses of alcohol may enlarge ventricle volumes and reduce gray matter volumes. The transient volume changes caused by acute administration of alcohol may be related to changes in CSF flow and water content of brain tissue, which warrants further study.

Objectives The primary objective of this study was to evaluate the efficacy and safety of increasing the dose of lurasidone from 40 mg/d to 80 mg/d in patients with schizophrenia. Methods This post hoc analysis focused on patients who completed a 6-week double-blind, placebo-controlled trial of lurasidone and transitioned to a subsequent 12-week open-label extension trial. Patients initially assigned to lurasidone (40 mg/d) or placebo during the double-blind trial (DBT-LUR group or DBT-PLA group, respectively) received lurasidone (40 mg/d) during the extension. Clinicians could increase the dose to 80 mg/d based on clinical judgment. The efficacy outcomes included the change in the Positive and Negative Syndrome Scale (PANSS) total score from the start to the end of the lurasidone (80 mg/d) treatment period. Safety outcome was the rate of newly emergent adverse events. Results Of 287 patients in the intention-to-treat population, 153 received an increased dose of lurasidone from 40 mg/d to 80 mg/d. Significant reductions in the PANSS total scores were observed in both groups (all P values, ≤0.001). Additionally, 35.9% of the DBT-LUR group and 40.0% of the DBT-PLA group achieved a ≥20% reduction in the PANSS total score. New adverse events emerged in 47.4% of the DBT-LUR group and 48.0% of the DBT-PLA group during the lurasidone (80 mg/d) treatment period. Conclusions Increasing the dose of lurasidone from 40 mg/d to 80 mg/d may be effective and well tolerated in patients with schizophrenia. Because of the lack of a control group and blinding, the results should be interpreted with caution.

Aim: 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. Methods: In this double-blind randomized placebo-controlled trial, 34 Japanese patients with TRD were randomized to receive either intravenous ketamine (0.5 mg/kg) or placebo, administered over 40 min, twice a week, for 2 weeks. The primary outcome was the change in the Montgomery Åsberg Depression Rating Scale (MADRS) total score from baseline to post-treatment. Secondary outcomes included changes in other depressive symptomatology scores and remission, response, and partial response rates. We also examined the association between baseline clinical demographic characteristics and changes in the MADRS total score. Results: Intention-to-treat analysis indicated no significant difference in the decrease in MADRS total score between the groups (−8.1 ± 10.0 vs −2.5 ± 5.2, t[32] = 2.02, P = 0.052), whereas per-protocol analysis showed a significant reduction in the ketamine group compared to the placebo group (−9.1 ± 10.2 vs −2.7 ± 5.3, t[29] = 2.22, P = 0.034). No significant group differences were observed in other outcomes. Adverse events were more frequent in the ketamine group than in the placebo group, and no serious adverse events were reported. A higher baseline MADRS total score and body mass index were associated with a greater reduction in the MADRS total score. Conclusion: Intravenous ketamine outperformed placebo in Japanese patients with TRD who completed the study, suggesting that ketamine could alleviate depressive symptoms of TRD across diverse ethnic populations.

Given that approximately one-third of patients with schizophrenia do not respond to antipsychotics, different neurobiological bases may underlie treatment resistance in schizophrenia. Previous studies showed that treatment response is associated with both frontostriatal connectivity and glutamatergic neurometabolite levels in the caudate in patients with schizophrenia, which leads to the hypothesis that the relationship between them may be altered, specifically in patients with treatment-resistant schizophrenia (TRS). Employing analyses of covariance and subsequent partial correlation analyses, we compared the relationship between glutamate+glutamine (Glx) levels in the caudate and fractional anisotropy (FA) values in the tract between the dorsolateral prefrontal cortex and caudate in 19 patients with TRS, 20 patients responsive to first-line antipsychotics (FL-Resp), and 19 healthy controls (HCs). TRS was defined by severe positive symptomatology despite first-line antipsychotic treatment. Patients with TRS had lower FA values in the bilateral frontostriatal tracts than patients with FL-Resp and HCs (P < .001), while no group differences were found in caudate Glx levels. There was a significant frontostriatal FA value-by-group interaction on caudate Glx levels (F = 7.37, P = .009). Frontostriatal FA values positively correlated with caudate Glx levels in HCs (r = −.55, P = .028), while they were negatively associated with caudate Glx levels in the TRS group (r = .53, P = .043). Furthermore, in the FL-Resp group, frontostriatal FA values did not significantly correlated with caudate Glx levels. The altered relationship between white matter integrity and the glutamate system in the frontostriatal circuit in the TRS group may reflect the pathophysiology underlying treatment response/resistance in schizophrenia.

Schizophrenia is a mental illness involving multiple symptom domains and is often associated with substantial physical health comorbidities. Guidelines exist, but these tend to be country-specific and are often missing a concise yet comprehensive algorithmic approach. From May 1, 2023, to Jan 1, 2025, International Guidelines for Algorithmic Treatment (INTEGRATE) authors from all UN regions collaborated to develop a consensus guideline focused on the pharmacological treatment of schizophrenia. Following an umbrella review of the literature, input from expert workshops, a consensus survey, and lived experience focus groups, a consensus algorithmic guideline and associated digital tool were developed. Key recommendations include a focus on metabolic health from treatment initiation, timely assessment and management of non-response, symptom domain-specific interventions, mitigation of side-effects, and the prompt use of clozapine in cases of treatment resistance.

Background: For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialised tools are used. Three tools have been proven useful to personalise drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging. Methods: In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 45 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)). Results: Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings. Conclusion: All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimise treatment effects, minimise side effects and ultimately reduce the global burden of diseases, personalised drug treatment has not yet become the standard of care in psychiatry.

Introduction Currently available systematic reviews on the pharmacological treatment of autism spectrum disorder (ASD) do not encompass all the evidence, as they exclude guidelines issued by national or local authorities that are not indexed in search engines such as PubMed. Methods A systematic literature search was conducted to identify clinical guidelines on this topic using EMBASE, Medline, and PsycINFO. A manual search was also performed to identify guidelines by national or local authorities not included in the aforementioned databases. Results Thirty-eight guidelines were identified through manual search, including 27 items through search engines, 2 general guidelines, and 9 government agency guidelines. Many guidelines recommended risperidone (N=16) for the characteristic behaviors of ASD core features. For attention-deficit/hyperactivity disorder (ADHD) features, methylphenidate was most frequently recommended (N=23) for both inattention (N=6) and hyperactivity/impulsivity (N=16). Risperidone was also frequently recommended for maladaptive behaviors (N=33). Discussion A comprehensive literature search identified treatment guidelines for ASD issued by local or national administrative bodies that were not captured through search engines alone. There was some consensus among the guidelines on the use of psychotropics in alleviating specific features of ASD. However, physicians need to be aware of the lack of high-quality evidence supporting these recommendations.

No established blood markers can preoperatively predict postoperative delirium. Blood concentrations of amino acid catabolites and dipeptides, including those secreted extracellularly during T-lymphocyte activation, were investigated as predictors of postoperative delirium using metabolomic analyses to ascertain whether preoperative blood metabolites could predict postoperative delirium. Eighteen and 24 participants were included in the delirium and non-delirium groups, respectively. Higher preoperative levels of amino acid (tryptophan) catabolites, via the indoleamine 2,3-dioxygenase pathway, were observed in the delirium group and identified as potential predictors of postoperative delirium in this study. The delirium group had preoperatively elevated levels of tryptophan catabolites and only a limited increase postoperatively, suggesting that the tryptophan catabolic pathway may be activated preoperatively in patients at high risk of delirium. Non-targeted metabolomic analysis found a set of preoperatively elevated γ-glutamyl dipeptides as potential predictors of postoperative delirium. In vitro experiments showed that T-cell-receptor stimulation increases tryptophan metabolism and specific γ-glutamyl dipeptide secretion, offering a possible explanation for the increased levels of metabolites in postoperative delirium. This study showed that levels of amino acid metabolites associated with blood immune activity may have the potential to predict postoperative delirium.

Introduction Conventional antipsychotic drugs that attenuate dopaminergic neural transmission are ineffective in approximately one-third of patients with schizophrenia. This necessitates the development of non-dopaminergic agents. Methods A systematic search was conducted for completed phase II and III trials of compounds for schizophrenia treatment using the US Clinical Trials Registry and the EU Clinical Trials Register. Compounds demonstrating significant superiority over placebo in the primary outcome measure in the latest phase II and III trials were identified. Collateral information on the included compounds was gathered through manual searches in PubMed and press releases. Results Sixteen compounds were identified; four compounds (ulotaront, xanomeline/trospium chloride, vabicaserin, and roluperidone) were investigated as monotherapy and the remaining 12 (pimavanserin, bitopertin, BI 425809, encenicline, tropisetron, pregnenolone, D-serine, estradiol, tolcapone, valacyclovir, cannabidiol, and rimonabant) were examined as add-on therapy. Compared to the placebo, ulotaront, xanomeline/trospium chloride, vabicaserin, bitopertin, estradiol, cannabidiol, rimonabant, and D-serine showed efficacy for positive symptoms; roluperidone and pimavanserin were effective for negative symptoms; and encenicline, tropisetron, pregnenolone, tolcapone, BI 425809, and valacyclovir improved cognitive function. Discussion Compounds that function differently from existing antipsychotics may offer novel symptom-specific therapeutic strategies for patients with schizophrenia.

Background: Microstructural deficits of brain tissue are implicated in the pathophysiology of major depressive disorder (MDD). Recent studies have highlighted the neurotrophic mechanisms underlying effective treatments such as ketamine for treatment-resistant depression (TRD). However, little is known about microstructural changes in TRD. Neurite orientation dispersion and density imaging (NODDI) has enabled in vivo investigation of gray matter (GM) and white matter (WM) microstructure. This study sought to examine microstructural abnormalities in gray and white matter in patients with TRD using NODDI. Methods: This study compared the neurite density index (NDI) and orientation dispersion index (ODI) of neurites in 70 patients with TRD and 35 healthy controls. We fitted separate optimal NODDI models for gray and white matter. The locations of microstructural deficit were identified using region-based and voxel-based analysis. The affected white matter fibers were tracked with correlational tractography analysis. Results: An increase of ODI at the middle to the ventral part of the right anterior limb of the internal capsule (ALIC) was observed in patients with TRD compared with healthy controls. The quantitative anisotropy of frontothalamic fibers passing through the ALIC negatively correlated with the ODI increase in the TRD group. Conclusion: The microstructural disorganization of the frontothalamic pathway could be linked to the pathophysiology and individual heterogeneity of TRD.

Phosphodiesterase 10 A (PDE10A), a pivotal element of the second messenger signaling downstream of the dopamine receptor stimulation, is conceived to be crucially involved in the mood instability of bipolar I disorder (BD-I) as a primary causal factor or in response to dysregulated dopaminergic tone. We aimed to determine whether striatal PDE10A availability is altered in patients with BD-I and assessed its relationship with the clinical characteristics of BD-I. This case-control study used positron emission tomography (PET) with 2-(2-(3-(4-(2-[18F]fluoroethoxy)phenyl)-7-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione ([18F]MNI-659), a radioligand that binds to PDE10A, to examine the alterations of the striatal PDE10A availability in the living brains of individuals with BD-I and their association with the clinical characteristics of BD-I. [18F]MNI-659 PET data were acquired from 25 patients with BD-I and 27 age- and sex-matched healthy controls. Patients with BD-I had significantly lower PDE10A availability than controls in the executive (F = 8.86; P = 0.005) and sensorimotor (F = 6.13; P = 0.017) subregions of the striatum. Lower PDE10A availability in the executive subregion was significantly associated with a higher frequency of mood episodes in patients with BD-I (r = –0.546; P = 0.007). This study provides the first evidence of altered PDE10A availability in patients with BD-I. Lower PDE10A availability in the executive subregion of the striatum is associated with an increased recurrence risk, suggesting that PDE10A may prevent BD-I relapse. Further studies are required to elucidate the role of PDE10A in BD-I pathophysiology and explore its potential as a treatment target.