Characterization of patients with major psychiatric disorders with AMPA receptor positron emission tomography.

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.

The Association Between Distinct Delusional Ideations and Depressive Symptoms in Alzheimer's Disease: A Re-Analysis of CATIE-AD.

Background: Delusional ideations, one of neuropsychiatric symptoms (NPSs), are frequently shown in the long-term progression of Alzheimer's disease (AD), and comorbid with other NPSs including depression or agitation. Despite various types of delusional ideations, the comorbidity between each delusional ideation and depressive symptoms has not been discussed. Objective: The present cross-sectional study is aimed at testing the hypothetical mechanism of comorbid pattern in AD. Methods: Among 421 patients with AD, we analyzed the dataset of the Clinical Antipsychotic Trials of Intervention Effectiveness-Alzheimer's Disease to compare age, sex, racial type, Mini-Mental State Examination (MMSE) scores, and Neuropsychiatric Inventory (NPI) depression score of between the presence and absence of each delusional ideation (delusion of persecution, theft, jealousy, abandonment, phantom boarder, Capgras syndrome, misidentification of place, or television sign). Next, with the stratification based on MMSE score of < or > = 15 points, we further explored association between delusional ideation and depressive symptom that was found significances in the primary analysis. Results: Among eight subtypes of delusional ideations, depression score was higher in those with persecution delusion or Capgras syndrome. Moreover, the Capgras syndrome was associated with presence of depression in severer global cognitive impairment status. Conclusions: As comorbid NPSs of delusional ideation in AD, depressive severity is associated with specific delusional subtype: persecution delusion and Capgras syndrome. Capgras syndrome may be attributable to severe cognitive impairment in addition to depressive symptom. The consideration of pathogenetic differences in the distinct delusional ideations may be helpful for clinicians to select the treatment strategy.

Efficacy and safety of intravenous ketamine treatment in Japanese patients with treatment-resistant depression: A double-blind, randomized, placebo-controlled trial.

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.

Impact of clozapine once-daily versus multiple-daily dosing regimen on relapse in patients with treatment-resistant schizophrenia: A 1-year retrospective cohort study.

RATIONALE: Clozapine, the standard treatment for treatment-resistant schizophrenia (TRS), is generally recommended in a multiple-daily dosing regimen. However, it is commonly administered once daily in clinical practice. Few studies have compared the longitudinal clinical outcomes of these two dosing regimens. OBJECTIVE: To investigate the effect of once-daily versus multiple-daily dosing regimens of clozapine on relapse in patients with TRS. METHODS: This retrospective cohort study included patients with TRS who commenced treatment with clozapine during hospitalization and were discharged between April 2012 and January 2022 from a tertiary psychiatric hospital in Japan. Relapse, defined as a psychiatric exacerbation requiring re-hospitalization within the first-year post-discharge, was analyzed. Multivariable Cox proportional hazards regression analysis compared the relapse risk between once-daily and multiple-daily dosing regimens. A subgroup analysis was conducted to examine the potential interactions between dosing regimen and dose category (low versus high dose). RESULTS: Among 179 patients, 107 (59.8%) received clozapine once daily. No significant difference in the relapse risk was observed between once-daily and multiple-daily dosing regimens (adjusted hazard ratio [aHR]: 1.16; 95% confidence interval [CI]: 0.68-1.99; p = 0.58). However, in patients receiving high doses of clozapine (> 300 mg/day), multiple-daily dosing increased the relapse risk compared to once-daily dosing (aHR: 2.23; 95% CI: 1.00-4.97; p = 0.049). CONCLUSIONS: Once-daily clozapine dosing may not be associated with an increased relapse risk. The increased relapse risk in high-dose multiple-daily dosing may be confounded by unmeasured non-adherence. Further randomized controlled trials are required to validate these findings.

Validation of the number of pulses required for TMS-EEG in the prefrontal cortex considering test feasibility.

BACKGROUND: Transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG), TMS-EEG, is a useful neuroscientific tool for the assessment of neurophysiology in the human cerebral cortex. Theoretically, TMS-EEG data is expected to have a better data quality as the number of stimulation pulses increases. However, since TMS-EEG testing is a modality that is examined on human subjects, the burden on the subject and tolerability of the test must also be carefully considered. METHOD: In this study, we aimed to determine the number of stimulation pulses that satisfy the reliability and validity of data quality in single-pulse TMS (spTMS) for the dorsolateral prefrontal cortex (DLPFC). TMS-EEG data for (1) 40-pulse, (2) 80-pulse, (3) 160-pulse, and (4) 240-pulse conditions were extracted from spTMS experimental data for the left DLPFC of 20 healthy subjects, and the similarities between TMS-evoked potentials (TEP) and oscillations across the conditions were evaluated. RESULTS: As a result, (2) 80-pulse and (3) 160-pulse conditions showed highly equivalent to the benchmark condition of (4) 240-pulse condition. However, (1) 40-pulse condition showed only weak to moderate equivalence to the (4) 240-pulse condition. Thus, in the DLPFC TMS-EEG experiment, 80 pulses of stimulations was found to be a reasonable enough number of pulses to extract reliable TEPs, compared to 160 or 240 pulses. CONCLUSIONS: This is the first substantial study to examine the appropriate number of stimulus pulses that are reasonable and feasible for TMS-EEG testing of the DLPFC.

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: Focus on antipsychotics.

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.

Neurophysiological profiles of patients with bipolar disorders as probed with transcranial magnetic stimulation: A systematic review.

AIM: Bipolar disorder (BD) has a significant impact on global health, yet its neurophysiological basis remains poorly understood. Conventional treatments have limitations, highlighting the need for a better understanding of the neurophysiology of BD for early diagnosis and novel therapeutic strategies. DESIGN: Employing a systematic review approach of the PRISMA guidelines, this study assessed the usefulness and validity of transcranial magnetic stimulation (TMS) neurophysiology in patients with BD. METHODS: Databases searched included PubMed, MEDLINE, Embase, and PsycINFO, covering studies from January 1985 to January 2024. RESULTS: Out of 6597 articles screened, nine studies met the inclusion criteria, providing neurophysiological insights into the pathophysiological basis of BD using TMS-electromyography and TMS-electroencephalography methods. Findings revealed significant neurophysiological impairments in patients with BD compared to healthy controls, specifically in cortical inhibition and excitability. In particular, short-interval cortical inhibition (SICI) was consistently diminished in BD across the studies, which suggests a fundamental impairment of cortical inhibitory function in BD. This systematic review corroborates the potential utility of TMS neurophysiology in elucidating the pathophysiological basis of BD. Specifically, the reduced cortical inhibition in the SICI paradigm observed in patients with BD suggests gamma-aminobutyric acid (GABA)-A receptor-mediated dysfunction, but results from other TMS paradigms have been inconsistent. Thus, complex neurophysiological processes may be involved in the pathological basis underlying BD. This study demonstrated that BD has a neural basis involving impaired GABAergic function, and it is highly expected that further research on TMS neurophysiology will further elucidate the pathophysiological basis of BD.

Development of the Japanese version of the Challenging Experience Questionnaire.

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 aimed to create a Japanese version of the CEQ. METHODS: We followed the "Principles of Good Practice for the Translation and Cultural Adaptation Process for Patient-Reported Outcomes (PRO) Measures: Report of the ISPOR Task Force for Translation and Cultural Adaptation." Initially, two Japanese psychiatrists independently conducted the forward translations. These were then reconciled into a single version, which was back-translated into English. The original authors reviewed this back-translation for accuracy, leading to revisions through continuous dialogue until the original authors approved the final version. RESULTS: The final, approved back-translated version of the CEQ is presented in the figure. CONCLUSIONS: This study developed a Japanese version of the CEQ, enabling the assessment of challenging experiences during psychedelic-assisted therapy for Japanese speakers. Further studies are needed to assess the reliability and validity of this newly translated version.

Clozapine treatment and astrocyte activity in treatment resistant schizophrenia: A proton magnetic resonance spectroscopy study.

Clozapine is the only antipsychotic approved for treating treatment-resistant schizophrenia (TRS), characterized by persistent positive symptoms despite adequate antipsychotic treatment. Unfortunately, clozapine demonstrates clinical efficacy in only ~30-60 % of patients with TRS (clozapine-responders; ClzR+), while the remaining ~40-70 % are left with no pharmacological recourse for improvement (clozapine-resistant; ClzR-). Mechanism(s) underlying clozapine's superior efficacy remain unclear. However, in vitro evidence suggests clozapine may mitigate glutamatergic dysregulations observed in TRS, by modulating astrocyte activity in ClzR+, but not ClzR-. A factor that if proven correct, may help the assessment of treatment response and development of more effective antipsychotics. To explore the presence of clozapine-astrocyte interaction and clinical improvement, we used 3 T proton-magnetic resonance spectroscopy to quantify levels of myo-Inositol, surrogate biomarker of astrocyte activity, in regions related to schizophrenia neurobiology: Dorsal-anterior-cingulate-cortex (dACC), left-dorsolateral-prefrontal-cortex (left-DLPFC), and left-striatum (left-striatum) of 157 participants (ClzR- = 30; ClzR+ = 37; responders = 38; controls = 52). Clozapine treatment was assessed using clozapine to norclozapine plasma levels, 11-12 h after last clozapine dose. Measures for symptom severity (i.e., Positive and Negative Symptoms Scale) and cognition (i.e., Mini-Mental State Examination) were also recorded. Higher levels of myo-Inositol were observed in TRS groups versus responders and controls (dACC (p < 0.001); left-striatum (p = 0.036); left-DLPFC (p = 0.023)). In ClzR+, but not ClzR-, clozapine to norclozapine ratios were positively associated with myo-Inositol levels (dACC (p = 0.004); left-DLPFC (p < 0.001)), and lower positive symptom severity (p < 0.001). Our results support growing in vitro evidence of clozapine-astrocyte interaction in clozapine-responders. Further research may determine the viability of clozapine-astrocyte interactions as an early marker of clozapine response.

The effect of second-generation antipsychotics on anxiety/depression in patients with schizophrenia: A systematic review and meta-analysis.

OBJECTIVE: Despite the high prevalence of anxiety in schizophrenia, no established guideline exists for the management of these symptoms. We aimed to synthesize evidence on the effect of second-generation antipsychotics (SGAs) on anxiety in patients with schizophrenia. METHODS: We systematically searched Medline, Embase, PsycInfo, Web of Science, PubMed, and Cochrane library to identify randomized controlled trials of SGAs that reporting anxiety measures in schizophrenia. The search was limited to English-language articles published before February 2024. Data were pooled using a random-effects model. RESULTS: Among 48 eligible studies, 29 (n = 7712) were included in the meta-analyses comparing SGAs to placebo, haloperidol, or another SGAs for their effect on anxiety/depression. SGAs had a small effect on anxiety/depression versus placebo (SMD = -0.28 (95 % CI [-0.34, -0.21], p < .00001, I2 = 47 %, n = 5576)) associated with efficacy for positive (z = 5.679, p < .001) and negative symptoms (z = 4.490, p < .001). Furthermore, SGAs were superior to haloperidol (SMD = -0.44, 95 % CI [-0.75, -0.13], p = .005, n = 1068) with substantial study-level heterogeneity (I2 = 85 %). Excluding one study of quetiapine in first-episode patients (SMD = -3.05, n = 73), SGAs showed a small effect on anxiety/depression versus haloperidol without heterogeneity (SMD = -0.23, 95 % CI [-0.35, -0.12], p = 01; I2 = %0). Risperidone's effect on anxiety/depression was comparable to olanzapine (SMD = -0.02, 95 % CI [-0.24,0.20], p = .87, I2 = 45 %, n = 753) and amisulpride (SMD = 0.27, 95 % CI [-1.08,0.61], p = .13, I2 = 50 %, n = 315). CONCLUSION: While SGAs showed a small effect on anxiety/depression, the findings are inconclusive due to scarcity of research on comorbid anxiety in schizophrenia, heterogeneity of anxiety symptoms, and the scales used to measure anxiety. Further studies employing specific anxiety scales are required to explore antipsychotics, considering their receptor affinity and augmentation with serotonin/norepinephrine reuptake inhibitors or benzodiazepines for managing anxiety in schizophrenia.

Real-world case series of maintenance theta burst stimulation therapy following response to acute theta burst stimulation therapy for difficult-to-treat depression.

OBJECTIVE: Treatment and management for difficult-to-treat depression are challenging, especially in a subset of patients who are at high risk for relapse and recurrence. The conditions that represent this subset are recurrent depressive disorder (RDD) and bipolar disorder (BD). In this context, we aimed to examine the effectiveness of maintenance transcranial magnetic stimulation (TMS) on a real-world clinical basis by retrospectively extracting data from the TMS registry data in Tokyo, Japan. METHODS: Data on patients diagnosed with treatment-resistant RDD and BD who received maintenance intermittent theta burst stimulation (iTBS) weekly after successful treatment with acute iTBS between March 2020 and October 2023 were extracted from the registry. RESULTS: All patients (21 cases: 10 cases with RDD and 11 cases with BD) could sustain response, and 19 of them further maintained remission. In this study, maintenance iTBS did not exacerbate depressive symptoms in any of the cases, but may rather have the effect of stabilizing the mental condition and preventing recurrence. CONCLUSIONS: This case series is of great clinical significance because it is the first study to report on the effectiveness of maintenance iTBS for RDD and BD, with a follow-up of more than 2 years. Further validation with a randomized controlled trial design with a larger sample size is warranted.

Evaluation of the Glymphatic System in Schizophrenia Spectrum Disorder Using Proton Magnetic Resonance Spectroscopy Measurement of Brain Macromolecule and Diffusion Tensor Image Analysis Along the Perivascular Space Index.

BACKGROUND AND HYPOTHESIS: The glymphatic system (GS), a brain waste clearance pathway, is disrupted in various neurodegenerative and vascular diseases. As schizophrenia shares clinical characteristics with these conditions, we hypothesized GS disruptions in patients with schizophrenia spectrum disorder (SCZ-SD), reflected in increased brain macromolecule (MM) and decreased diffusion-tensor-image-analysis along the perivascular space (DTI-ALPS) index. STUDY DESIGN: Forty-seven healthy controls (HCs) and 103 patients with SCZ-SD were studied. Data included 135 proton magnetic resonance spectroscopy (1H-MRS) sets, 96 DTI sets, with 79 participants contributing both. MM levels were quantified in the dorsal-anterior cingulate cortex (dACC), dorsolateral prefrontal cortex, and dorsal caudate (point resolved spectroscopy, echo-time = 35ms). Diffusivities in the projection and association fibers near the lateral ventricle were measured to calculate DTI-ALPS indices. General linear models were performed, adjusting for age, sex, and smoking. Correlation analyses examined relationships with age, illness duration, and symptoms severity. STUDY RESULTS: MM levels were not different between patients and HCs. However, left, right, and bilateral DTI-ALPS indices were lower in patients compared with HCs (P < .001). In HCs, age was positively correlated with dACC MM and negatively correlated with left, right, and bilateral DTI-ALPS indices (P < .001). In patients, illness duration was positively correlated with dACC MM and negatively correlated with the right DTI-ALPS index (P < .05). In the entire population, dACC MM and DTI-ALPS indices showed an inverse correlation (P < .01). CONCLUSIONS: Our results suggest potential disruptions in the GS of patients with SCZ-SD. Improving brain's waste clearance may offer a potential therapeutic approach for patients with SCZ-SD.

Elevated intrinsic cortical curvature in treatment-resistant schizophrenia: Evidence of structural deformation in functional connectivity areas and comparison with alternate indices of structure.

BACKGROUND: Research suggests structural and connectivity abnormalities in patients with treatment-resistant schizophrenia (TRS) compared to first-line responders and healthy-controls. However, measures of these abnormalities are often influenced by external factors like nicotine and antipsychotics, limiting their clinical utility. Intrinsic-cortical-curvature (ICC) presents a millimetre-scale measure of brain gyrification, highly sensitive to schizophrenia differences, and associated with TRS-like traits in early stages of the disorder. Despite this evidence, ICC in TRS remains unexplored. This study investigates ICC as a marker for treatment resistance in TRS, alongside structural indices for comparison. METHODS: We assessed ICC in anterior cingulate, dorsolateral prefrontal, temporal, and parietal cortices of 38 first-line responders, 30 clozapine-resistant TRS, 37 clozapine-responsive TRS, and 52 healthy-controls. For comparative purposes, Fold and Curvature indices were also analyzed. RESULTS: Adjusting for age, sex, nicotine-use, and chlorpromazine equivalence, principal findings indicate ICC elevations in the left hemisphere dorsolateral prefrontal (p < 0.001, η2partial = 0.142) and temporal cortices (LH p = 0.007, η2partial = 0.060; RH p = 0.011, η2partial = 0.076) of both TRS groups, and left anterior cingulate cortex of clozapine-resistant TRS (p = 0.026, η2partial = 0.065), compared to healthy-controls. Elevations that correlated with reduced cognition (p = 0.001) and negative symptomology (p < 0.034) in clozapine-resistant TRS. Fold and Curvature indices only detected group differences in the right parietal cortex, showing interactions with age, sex, and nicotine use. ICC showed interactions with age. CONCLUSION: ICC elevations were found among patients with TRS, and correlated with symptom severity. ICCs relative independence from sex, nicotine-use, and antipsychotics, may support ICC's potential as a viable marker for TRS, though age interactions should be considered.

A comparative study of the dorsolateral prefrontal cortex targeting approaches for transcranial magnetic stimulation treatment: Insights from the healthy control data.

Repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex (DLPFC) is an established treatment for medication-resistant depression. Several targeting methods for the left DLPFC have been proposed including identification with resting-state functional magnetic resonance imaging (rs-fMRI) neuronavigation, stimulus coordinates based on structural MRI, or electroencephalography (EEG) F3 site by Beam F3 method. To date, neuroanatomical and neurofunctional differences among those approaches have not been investigated on healthy subjects, which are structurally and functionally unaffected by psychiatric disorders. This study aimed to compare the mean location, its dispersion, and its functional connectivity with the subgenual cingulate cortex (SGC), which is known to be associated with the therapeutic outcome in depression, of various approaches to target the DLPFC in healthy subjects. Fifty-seven healthy subjects underwent MRI scans to identify the stimulation site based on their resting-state functional connectivity and were measured their head size for targeting with Beam F3 method. In addition, we included two fixed stimulus coordinates over the DLPFC in the analysis, as recommended in previous studies. From the results, the rs-fMRI method had, as expected, more dispersed target sites across subjects and the greatest anticorrelation with the SGC, reflecting the known fact that personalized neuronavigation yields the greatest antidepressant effect. In contrast, the targets located by the other methods were relatively close together with less dispersion, and did not differ in anticorrelation with the SGC, implying their limitation of the therapeutic efficacy and possible interchangeability of them.

Alterations in subcortical magnetic susceptibility and disease-specific relationship with brain volume in major depressive disorder and schizophrenia.

Quantitative susceptibility mapping is a magnetic resonance imaging technique that measures brain tissues' magnetic susceptibility, including iron deposition and myelination. This study examines the relationship between subcortical volume and magnetic susceptibility and determines specific differences in these measures among patients with major depressive disorder (MDD), patients with schizophrenia, and healthy controls (HCs). This was a cross-sectional study. Sex- and age- matched patients with MDD (n = 49), patients with schizophrenia (n = 24), and HCs (n = 50) were included. Magnetic resonance imaging was conducted using quantitative susceptibility mapping and T1-weighted imaging to measure subcortical susceptibility and volume. The acquired brain measurements were compared among groups using analyses of variance and post hoc comparisons. Finally, a general linear model examined the susceptibility-volume relationship. Significant group-level differences were found in the magnetic susceptibility of the nucleus accumbens and amygdala (p = 0.045). Post-hoc analyses indicated that the magnetic susceptibility of the nucleus accumbens and amygdala for the MDD group was significantly higher than that for the HC group (p = 0.0054, p = 0.0065, respectively). However, no significant differences in subcortical volume were found between the groups. The general linear model indicated a significant interaction between group and volume for the nucleus accumbens in MDD group but not schizophrenia or HC groups. This study showed susceptibility alterations in the nucleus accumbens and amygdala in MDD patients. A significant relationship was observed between subcortical susceptibility and volume in the MDD group's nucleus accumbens, which indicated abnormalities in myelination and the dopaminergic system related to iron deposition.

Short-Term Effect of Auditory Stimulation on Neural Activities: A Scoping Review of Longitudinal Electroencephalography and Magnetoencephalography Studies.

Explored through EEG/MEG, auditory stimuli function as a suitable research probe to reveal various neural activities, including event-related potentials, brain oscillations and functional connectivity. Accumulating evidence in this field stems from studies investigating neuroplasticity induced by long-term auditory training, specifically cross-sectional studies comparing musicians and non-musicians as well as longitudinal studies with musicians. In contrast, studies that address the neural effects of short-term interventions whose duration lasts from minutes to hours are only beginning to be featured. Over the past decade, an increasing body of evidence has shown that short-term auditory interventions evoke rapid changes in neural activities, and oscillatory fluctuations can be observed even in the prestimulus period. In this scoping review, we divided the extracted neurophysiological studies into three groups to discuss neural activities with short-term auditory interventions: the pre-stimulus period, during stimulation, and a comparison of before and after stimulation. We show that oscillatory activities vary depending on the context of the stimuli and are greatly affected by the interplay of bottom-up and top-down modulational mechanisms, including attention. We conclude that the observed rapid changes in neural activitiesin the auditory cortex and the higher-order cognitive part of the brain are causally attributed to short-term auditory interventions.

Development of the Japanese version of the Ego-Dissolution Inventory (EDI).

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 Japanese version has been available. This study aimed to develop a Japanese version of the EDI. METHODS: We adhered to the "Guidelines for Best Practices in the Translation and Cultural Modification Process for Patient-Reported Outcomes Instruments: Document from the ISPOR Committee on Translation and Cultural Modification" during our translation approach. Two Japanese psychiatrists independently conducted initial translations, and a consolidated version was achieved via mutual agreement. This version was then back-translated to English and assessed by the original authors for consistency. The repetitive modification process was conducted in continuous dialogues with the original authors until they accepted the concluding back-translated version. RESULTS: The finalized, approved back-translated version of the EDI is presented in the accompanying figure. In addition, the authorized Japanese version of the EDI is included in the Appendix. CONCLUSIONS: In this study, we successfully developed the Japanese version of the EDI. This instrument will assist in assessing ego-dissolution experiences associated with psychedelic-assisted therapy among Japanese speakers. Additional studies are necessary to evaluate the reliability and validity of this newly translated instrument.

Decreased short-latency afferent inhibition in individuals with mild cognitive impairment: A TMS-EEG study.

TMS combined with EEG (TMS-EEG) is a tool to characterize the neurophysiological dynamics of the cortex. Among the TMS paradigms, short-latency afferent inhibition (SAI) allows the investigation of inhibitory effects mediated by the cholinergic system. The aim of this study was to compare cholinergic function in the DLPFC between individuals with mild cognitive impairment (MCI) and healthy controls (HC) using TMS-EEG with the SAI paradigm. In this study, 30 MCI and 30 HC subjects were included. The SAI paradigm consisted of 80 single pulse TMS and 80 SAI stimulations applied to the left DLPFC. N100 components, global mean field power (GMFP) and total power were calculated. As a result, individuals with MCI showed reduced inhibitory effects on N100 components and GMFP at approximately 100 ms post-stimulation and on ß-band activity at 200 ms post-stimulation compared to HC. Individuals with MCI showed reduced SAI, suggesting impaired cholinergic function in the DLPFC compared to the HC group. We conclude that these findings underscore the clinical applicability of the TMS-EEG method as a powerful tool for assessing cholinergic function in individuals with MCI.