The genome-wide DNA methylation profiles among neurosurgery patients with and without post-operative delirium.

AIMS: There is no previous study demonstrating the differences of genome-wide DNA methylation (DNAm) profiles between patients with and without postoperative delirium (POD). We aimed to discover epigenetic (DNAm) markers that are associated with POD in blood obtained from patients before and after neurosurgery. METHODS: Pre- and post-surgical blood DNA samples from 37 patients, including 10 POD cases, were analyzed using the Illumina EPIC array genome-wide platform. We examined DNAm differences in blood from patients with and without POD. Enrichment analysis with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms were also conducted. RESULTS: When POD cases were tested for DNAm change before and after surgery, enrichment analyses showed many relevant signals with statistical significance in immune response related-pathways and inflammatory cytokine related-pathways such as "cellular response to cytokine stimulus", "regulation of immune system process", "regulation of cell activation", and "regulation of cytokine production". Furthermore, after excluding the potential effect of common factors related to surgery and anesthesia between POD cases and non-POD controls, the enrichment analyses showed significant signals such as "immune response" and "T cell activation", which are same pathways previously identified from an independent non-surgical inpatient cohort. CONCLUSIONS: Our first genome-wide DNAm investigation of POD showed promising signals related to immune response, inflammatory response and other relevant signals considered to be associated with delirium pathophysiology. Our data supports the hypothesis that epigenetics play an important role in the pathophysiological mechanism of delirium and suggest the potential usefulness of an epigenetics-based biomarker of POD.

Discontinuation of antidepressants after remission with antidepressant medication in major depressive disorder: a systematic review and meta-analysis.

A significant clinical issue encountered after a successful acute major depressive disorder (MDD) treatment is the relapse of depressive symptoms. Although continuing maintenance therapy with antidepressants is generally recommended, there is no established protocol on whether or not it is necessary to prescribe the antidepressant used to achieve remission. In this meta-analysis, the risk of relapse and treatment failure when either continuing with the same drug used to achieved remission or switching to a placebo was assessed in several clinically significant subgroups. The pooled odds ratio (OR) (±95% confidence intervals (CI)) was calculated using a random effects model. Across 40 studies (n = 8890), the relapse rate was significantly lower in the antidepressant group than the placebo group by about 20% (OR = 0.38, CI: 0.33-0.43, p < 0.00001; 20.9% vs 39.7%). The difference in the relapse rate between the antidepressant and placebo groups was greater for tricyclics (25.3%; OR = 0.30, CI: 0.17-0.50, p < 0.00001), SSRIs (21.8%; OR = 0.33, CI: 0.28-0.38, p < 0.00001), and other newer agents (16.0%; OR = 0.44, CI: 0.36-0.54, p < 0.00001) in that order, while the effect size of acceptability was greater for SSRIs than for other antidepressants. A flexible dose schedule (OR = 0.30, CI: 0.23-0.48, p < 0.00001) had a greater effect size than a fixed dose (OR = 0.41, CI: 0.36-0.48, p < 0.00001) in comparison to placebo. Even in studies assigned after continuous treatment for more than 6 months after remission, the continued use of antidepressants had a lower relapse rate than the use of a placebo (OR = 0.40, CI: 0.29-0.55, p < 0.00001; 20.2% vs 37.2%). The difference in relapse rate was similar from a maintenance period of 6 months (OR = 0.41, CI: 0.35-0.48, p < 0.00001; 19.6% vs 37.6%) to over 1 year (OR = 0.35, CI: 0.29-0.41, p < 0.00001; 19.9% vs 39.8%). The all-cause dropout of antidepressant and placebo groups was 43% and 58%, respectively, (OR = 0.47, CI: 0.40-0.55, p < 0.00001). The tolerability rate was ~4% for both groups. The rate of relapse (OR = 0.32, CI: 0.18-0.64, p = 0.0010, 41.0% vs 66.7%) and all-cause dropout among adolescents was higher than in adults. To prevent relapse and treatment failure, maintenance therapy, and careful attention for at least 6 months after remission is recommended. SSRIs are well-balanced agents, and flexible dose adjustments are more effective for relapse prevention.

Integrating neuroimmune systems in the neurobiology of depression.

Data from clinical and preclinical studies indicate that immune dysregulation, specifically of inflammatory processes, is associated with symptoms of major depressive disorder (MDD). In particular, increased levels of circulating pro-inflammatory cytokines and concomitant activation of brain-resident microglia can lead to depressive behavioural symptoms. Repeated exposure to psychological stress has a profound impact on peripheral immune responses and perturbs the function of brain microglia, which may contribute to neurobiological changes underlying MDD. Here, we review these findings and discuss ongoing studies examining neuroimmune mechanisms that influence neuronal activity as well as synaptic plasticity. Interventions targeting immune-related cellular and molecular pathways may benefit subsets of MDD patients with immune dysregulation.

Evaluation of point-of-care thumb-size bispectral electroencephalography device to quantify delirium severity and predict mortality.

BACKGROUND: We have developed the bispectral electroencephalography (BSEEG) method for detection of delirium and prediction of poor outcomes. AIMS: To improve the BSEEG method by introducing a new EEG device. METHOD: In a prospective cohort study, EEG data were obtained and BSEEG scores were calculated. BSEEG scores were filtered on the basis of standard deviation (s.d.) values to exclude signals with high noise. Both non-filtered and s.d.-filtered BSEEG scores were analysed. BSEEG scores were compared with the results of three delirium screening scales: the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), the Delirium Rating Scale-Revised-98 (DRS) and the Delirium Observation Screening Scale (DOSS). Additionally, the 365-day mortalities and the length of stay (LOS) in the hospital were analysed. RESULTS: We enrolled 279 elderly participants and obtained 620 BSEEG recordings; 142 participants were categorised as BSEEG-positive, reflecting slower EEG activity. BSEEG scores were higher in the CAM-ICU-positive group than in the CAM-ICU-negative group. There were significant correlations between BSEEG scores and scores on the DRS and the DOSS. The mortality rate of the BSEEG-positive group was significantly higher than that of the BSEEG-negative group. The LOS of the BSEEG-positive group was longer compared with that of the BSEEG-negative group. BSEEG scores after s.d. filtering showed stronger correlations with delirium screening scores and more significant prediction of mortality. CONCLUSIONS: We confirmed the usefulness of the BSEEG method for detection of delirium and of delirium severity, and prediction of patient outcomes with a new EEG device.

Improvement of psychiatrists' clinical knowledge of the treatment guidelines for schizophrenia and major depressive disorders using the 'Effectiveness of Guidelines for Dissemination and Education in Psychiatric Treatment (EGUIDE)' project: A nationwide dissemination, education, and evaluation study.

AIM: Although treatment guidelines for pharmacological therapy for schizophrenia and major depressive disorder have been issued by the Japanese Societies of Neuropsychopharmacology and Mood Disorders, these guidelines have not been well applied by psychiatrists throughout the nation. To address this issue, we developed the 'Effectiveness of Guidelines for Dissemination and Education in Psychiatric Treatment (EGUIDE)' integrated education programs for psychiatrists to disseminate the clinical guidelines. Additionally, we conducted a systematic efficacy evaluation of the programs. METHODS: Four hundred thirteen out of 461 psychiatrists attended two 1-day educational programs based on the treatment guidelines for schizophrenia and major depressive disorder from October 2016 to March 2018. We measured the participants' clinical knowledge of the treatment guidelines using self-completed questionnaires administered before and after the program to assess the effectiveness of the programs for improving knowledge. We also examined the relation between the participants' demographics and their clinical knowledge scores. RESULTS: The clinical knowledge scores for both guidelines were significantly improved after the program. There was no correlation between clinical knowledge and participant demographics for the program on schizophrenia; however, a weak positive correlation was found between clinical knowledge and the years of professional experience for the program on major depressive disorder. CONCLUSION: Our results provide evidence that educational programs on the clinical practices recommended in guidelines for schizophrenia and major depressive disorder might effectively improve participants' clinical knowledge of the guidelines. These data are encouraging to facilitate the standardization of clinical practices for psychiatric disorders.

Association between social functioning and prefrontal cortex function during a verbal fluency task in schizophrenia: A near-infrared spectroscopic study.

AIM: Impaired social functioning is a common characteristic of patients with schizophrenia. Social functioning requires the complex operation of various executive functions. Deficits in the prefrontal cortex (PFC) have been implicated in executive dysfunction. Here we aimed to clarify the relation between subjectively and objectively assessed social functioning, and their associations with PFC function in patients with schizophrenia. METHODS: Twenty-three patients and 22 age- and sex-matched healthy controls (HC) were assessed. In the schizophrenia group, self- and caregiver-rated social functioning were measured using the Specific Level of Functioning Assessment (SLOF). The hemodynamic responses elicited by a verbal fluency task (VFT) in three regions of interest in the frontotemporal area were measured using multi-channel near-infrared spectroscopy (NIRS). We also investigated psychiatric symptoms, neurocognition, and cognitive insight to assess possible confounding factors. RESULTS: Significant positive correlations were found between self- and caregiver-rated SLOF composite scores and three subdomain scores. Self- and caregiver-rated SLOF composite scores were significantly associated with dorsolateral PFC and frontopolar cortex (DLPFC/FPC) activation during the VFT. Psychiatric symptoms, global functioning, neurocognition, and cognitive insight were not associated with NIRS signals. General psychopathology was associated with NIRS signals in the ventrolateral PFC and the anterior temporal cortex. DLPFC and FPC activity may be associated with social functioning in patients with schizophrenia. CONCLUSION: Our results suggest that the two distinct assessments of social functioning were significantly correlated. Moreover, DLPFC and FPC function was strongly associated with social functioning and the ability to carry out daily life in patients with schizophrenia.

Spontaneous recovery from post-COVID-19 brain fog.

Background: One-third of individuals who contract novel coronavirus disease 2019 (COVID-19) reportedly experience persistent symptoms, including respiratory issues, headache, dizziness, taste disorders, fatigue, and various psychiatric and neurological symptoms, known as post-acute sequelae of SARS-CoV-2. In this case report, we present a patient who became aware of brain fog, which is cognitive impairment, approximately 2 months after their COVID-19 symptoms had resolved, accompanied by anxiety and depression. Case Presentation: The patient, a 35-year-old Japanese man, was infected with COVID-19 and resumed work approximately 2 weeks later after symptoms improved. Approximately 1 month after returning to work, the patient's concentration became impaired and he started making noticeable errors at work. These symptoms did not improve, leading him to the outpatient clinic specializing in COVID-19 sequelae at our hospital. Here, he underwent blood tests, electroencephalography, and head magnetic resonance imaging, which did not reveal any abnormalities. Cognitive decline due to COVID-19 sequelae was therefore suspected, prompting his evaluation in our department approximately 5 months after his initial COVID-19 infection. Detailed cognitive function tests were performed. He was monitored without the use of medications, and his cognitive function gradually improved. Approximately 11 months after his initial COVID-19 infection, the same cognitive function tests were conducted again, because his subjective cognitive function symptoms had disappeared, and improvement was observed in many items. Conclusion: Since brain fog is a relatively common sequela, we emphasize the importance of keeping this in mind from the initial consultations and comparing results over time.

Obsessive-compulsive disorder after traumatic injury to the right frontal and left temporal lobes: A case report.

Background: Obsessive-compulsive disorder (OCD) is a common neuropsychiatric disorder affecting many behaviors in daily life. Hyperactivity of the fronto-striato-thalamic circuit via the orbitofrontal cortex (OFC) is assumed to play a major role in the pathophysiology of OCD; however, its pathogenesis is not fully understood. Several reports have described the development of OCD after traumatic brain injury (TBI); however, the pathogenesis of post-TBI OCD remains unknown. Moreover, patients with TBI often have a variety of sequelae, including cognitive dysfunction and mood disorders, which make the diagnosis and treatment of OCD more complex. Case presentation: We report the case of a 17-year-old Japanese male who developed OCD after traffic trauma. The patient developed a fear of contamination and checking compulsion after injuring his right OFC and left temporal lobe when he ran into a running truck during a suicide attempt. We believe that the patient's fear of contamination can be diagnosed as true post-TBI OCD. However, his memory impairment was significant, and we considered his checking compulsion to be strongly influenced by cognitive dysfunction due to TBI. We attempted behavioral therapy for OCD; however, sufficient results were not achieved because of the interference from the sequelae of TBI. Conclusion: It is not rare for OCD symptoms to appear after TBI. Differentiating the OCD symptoms induced by brain injury or cognitive dysfunction associated with TBI is important to determine a treatment strategy.

Idiopathic basal ganglia calcification presenting with obsessive-compulsive symptoms: A case report.

Background: Idiopathic basal ganglia calcification (IBGC), also known as Farh's disease, is a rare neurodegenerative disorder characterized by calcification of the basal ganglia and other brain regions. This disease usually occurs in middle-aged patients and presents with various neurological and psychiatric symptoms. The exact prevalence is unknown; however, population genomic data analysis suggests a prevalence of at least 4.5/10,000 to 3.3/1000, indicating that the disease is more common than previously thought and remains underdiagnosed. Case Presentation: We report the case of a middle-aged Japanese man who attempted suicide twice because of obsessive-compulsive ideation caused by trivial triggers. The patient's psychiatric symptoms resolved relatively quickly after hospitalization, and imaging and genetic testing led to a diagnosis of IBGC. Conclusion: This case report illustrates the importance of including IBGC in the differential diagnosis of psychiatric symptoms that initially develop in middle-aged patients.

The Genome-wide DNA methylation changes in gastrointestinal surgery patients with and without postoperative delirium: Evidence of immune process in its pathophysiology.

AIM: The pathophysiological mechanisms of postoperative delirium (POD) are still unclear, and there is no reliable biomarker to distinguish between those with and without POD. Our aim was to discover DNAm markers associated with POD in blood collected from patients before and after gastrointestinal surgery. METHOD: We collected blood samples from 16 patients including 7 POD patients at three timepoints; before surgery (pre), the first and third postoperative days (day1 and day3). We measured differences in DNA methylation between POD and control groups between pre and day1 as well as between pre and day3 using the Illumina EPIC array method. Besides, enrichment analysis with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms were also performed after excluding influence of common factors related to surgery and anesthesia. RESULT: The results showed that pre and day1 comparisons showed that immune and inflammatory signals such as 'T-cell activation' were significantly different, consistent with our previous studies with non-Hispanic White subjects. In contrast, we found that these signals were not significant any more when pre was compared with day3. CONCLUSION: These results provide strong evidence for the involvement of inflammatory and immune-related epigenetic signals in the pathogenesis of delirium, including POD, regardless of ethnic background. These findings also suggest that DNAm, which is involved in inflammation and immunity, is dynamically altered in patients with POD. In summary, the present results indicate that these signals may serve as a new diagnostic tool for POD.

Discovery of novel protective agents for infection-related delirium through bispectral electroencephalography.

Delirium is a multifactorial medical condition of waxing and waning impairment across various domains of mental functioning over time. Importantly, delirium is also one of the greatest risk factors for prolonged hospitalization, morbidity, and mortality. Studying this important condition is challenging due to the difficulty in both objective diagnosis in patients and validation of laboratory models. As a result, there is a lack of protective treatments for delirium. Our recent studies report the efficacy of bispectral electroencephalography (BSEEG) in diagnosing delirium in patients and predicting patient outcomes, advancing the concept that this simple measure could represent an additional vital sign for patients. Here, we applied BSEEG to characterize and validate a novel lipopolysaccharide (LPS) mouse model of infection-related delirium. We then applied this model to evaluate the protective efficacy of three putative therapeutic agents: the conventional antipsychotic medication haloperidol, the neuroprotective compound P7C3-A20, and the antibiotic minocycline. Aged mice were more susceptible than young mice to LPS-induced aberration in BSEEG, reminiscent of the greater vulnerability of older adults to delirium. In both young and old mice, P7C3-A20 and minocycline administration prevented LPS-induced BSEEG abnormality. By contrast, haloperidol did not. P7C3-A20 and minocycline have been shown to limit different aspects of LPS toxicity, and our data offers proof of principle that these agents might help protect patients from developing infection-related delirium. Thus, utilization of BSEEG in a mouse model for infection-related delirium can identify putative therapeutic agents for applications in patient clinical trials.

The Bispectral Electroencephalography Method Quantifies Postoperative Delirium-Like States in Young and Aged Male Mice After Head-Mount Implantation Surgery.

Delirium, a syndrome characterized by an acute change in attention, awareness, and cognition, is commonly observed in older adults, although there are few quantitative monitoring methods in the clinical setting. We developed a bispectral electroencephalography (BSEEG) method capable of detecting delirium and can quantify the severity of delirium using a novel algorithm. Preclinical application of this novel BSEEG method can capture a delirium-like state in mice following lipopolysaccharide administration. However, its application to postoperative delirium (POD) has not yet been validated in animal experiments. This study aimed to create a POD model in mice with the BSEEG method by monitoring BSEEG scores following EEG head-mount implantation surgery and throughout the recovery. We compared the BSEEG scores of C57BL/6J young (2-3 months old) with aged (18-19 months old) male mice for quantitative evaluation of POD-like states. Postoperatively, both groups displayed increased BSEEG scores and a loss of regular diurnal changes in BSEEG scores. In young mice, BSEEG scores and regular diurnal changes recovered relatively quickly to baseline by postoperative day (PO-Day) 3. Conversely, aged mice exhibited prolonged increases in postoperative BSEEG scores and it reached steady states only after PO-Day 8. This study suggests that the BSEEG method can be utilized as a quantitative measure of POD and assess the effect of aging on recovery from POD in the preclinical model.

LPS-induced delirium-like behavior and microglial activation in mice correlate with bispectral electroencephalography (BSEEG).

Delirium is a multifactorial medical condition characterized by impairment across various mental functions and is one of the greatest risk factors for prolonged hospitalization, morbidity, and mortality. Research focused on delirium has proven to be challenging due to a lack of objective measures for diagnosing patients, and few laboratory models have been validated. Our recent studies report the efficacy of bispectral electroencephalography (BSEEG) in diagnosing delirium in patients and predicting patient outcomes. We applied BSEEG to validate a lipopolysaccharide (LPS)-induced mouse model of delirium. Moreover, we investigated the relationship between BSEEG score, delirium-like behaviors, and microglia activation in hippocampal dentate gyrus and cortex regions in young and aged mice. There was a significant correlation between BSEEG score and impairment of attention in young mice. Additionally, there was a significant correlation between BSEEG score and microglial activation in hippocampal dentate gyrus and cortex regions in young and aged mice. We have successfully validated the BSEEG method by showing its associations with a level of behavioral change and microglial activation in an LPS-induced mouse model of delirium. In addition, the BSEEG method was able to sensitively capture an LPS-induced delirium-like condition that behavioral tests could not capture because of a hypoactive state.

Epigenetic signals associated with delirium replicated across four independent cohorts.

Delirium is risky and indicates poor outcomes for patients. Therefore, it is crucial to create an effective delirium detection method. However, the epigenetic pathophysiology of delirium remains largely unknown. We aimed to discover reliable and replicable epigenetic (DNA methylation: DNAm) markers that are associated with delirium including post-operative delirium (POD) in blood obtained from patients among four independent cohorts. Blood DNA from four independent cohorts (two inpatient cohorts and two surgery cohorts; 16 to 88 patients each) were analyzed using the Illumina EPIC array platform for genome-wide DNAm analysis. We examined DNAm differences in blood between patients with and without delirium including POD. When we compared top CpG sites previously identified from the initial inpatient cohort with three additional cohorts (one inpatient and two surgery cohorts), 11 of the top 13 CpG sites showed statistically significant differences in DNAm values between the delirium group and non-delirium group in the same directions as found in the initial cohort. This study demonstrated the potential value of epigenetic biomarkers as future diagnostic tools. Furthermore, our findings provide additional evidence of the potential role of epigenetics in the pathophysiology of delirium including POD.

The inflammasome: pathways linking psychological stress, depression, and systemic illnesses.

Stress is a common occurrence in everyday life and repeated or traumatic stress can be a precipitating factor for illnesses of the central nervous system, as well as peripheral organ systems. For example, severe or long-term psychological stress can not only induce depression, a leading illness worldwide, but can also cause psychosomatic diseases such as asthma and rheumatoid arthritis. Related key questions include how psychological stress influences both brain and peripheral systems, and what detection mechanisms underlie these effects? A clue is provided by the discovery of the pathways underlying the responses to host "danger" substances that cause systemic diseases, but can also contribute to depression. The inflammasome is a protein complex that can detect diverse danger signals and produce the accompanying immune-inflammatory reactions. Interestingly, the inflammasome can detect not only pathogen-associated molecules, but also cell damage-associated molecules such as ATP. Here, we propose a new inflammasome hypothesis of depression and related comorbid systemic illnesses. According to this hypothesis, the inflammasome is a central mediator by which psychological and physical stressors can contribute to the development of depression, and as well as a bridge to systemic diseases. This hypothesis includes an explanation for how psychological stress can influence systemic diseases, and conversely how systemic diseases can lead to psychiatric illnesses. The evidence suggests that the inflammasome may be a new target for the development of treatments for depression, as well as psychosomatic and somato-psycho diseases.

Comparative efficacy and safety of suvorexant and lemborexant for insomnia treatment.

Aim: Although suvorexant and lemborexant, which have orexin receptor antagonist activity, are used as sleep medications in Japan, no report has directly compared their efficacy and safety. This study compared the efficacy and safety of the drugs. Methods: This retrospective cohort study included patients who presented to the Outpatient Department of Psychiatry at Tottori University Hospital between December 1, 2020, and December 31, 2021. Information was obtained from 108 patients who were newly treated with suvorexant or lemborexant. Data were analyzed after excluding one case of discontinuation due to a post-administration allergic reaction. Improvement in sleep status after administration was assessed retrospectively from medical records by using the Clinical Global Impressions-Improvement (CGI-I) Scale, which is a subscale of the Clinical Global Impressions (CGI) Scale. The incidence of side-effects was obtained from the medical records of the patient's first visit after administration. Results: There was no significant difference between the CGI-I scores in the suvorexant (mean [SD], 3.05 [0.93]) and lemborexant groups (mean [SD], 3.38 [0.83]) (p = 0.10). The incidence of side-effects with continued treatment was not significantly different between the suvorexant group (12.5%) and the lemborexant group (2.9%) (p = 0.10). Patients who switched from suvorexant to lemborexant had CGI-I scores ≤4, and no side-effects were observed after switching to lemborexant. Conclusion: There was no difference in effectiveness between suvorexant and lemborexant. However, lemborexant might cause side-effects less frequently than suvorexant, at least in the early stages of treatment.

Adequate diagnosis of the cause of Parkinsonism and treatment in an elderly patient with schizophrenia: A case report.

Background: Parkinsonism is frequently observed in patients with schizophrenia, and most patients are diagnosed with drug-induced parkinsonism. However, comorbidity with idiopathic Parkinson's disease or Parkinson-plus syndrome is also possible. The pathophysiology and treatment for each of these are entirely different, thus an appropriate diagnosis is required. However, distinguishing them based on clinical symptoms alone is often difficult, and many cases are misdiagnosed. Additionally, Parkinsonism is frequently mistaken for negative symptoms. Case Description: We report a case of 68-year-old woman diagnosed with schizophrenia, who was admitted to a welfare center. At approximately age 60, the patient experienced motivation reduction, a loss of appetite, and pain in the extremities. In her mid-60s, tremor and muscle rigidity appeared; nuclear medicine testing was performed for a detailed examination, resulting in a diagnosis of levodopa-responsive Parkinson's syndrome. Notably, the patient's parkinsonism and emotional symptoms, which had been considered negative symptoms thus far, improved with levodopa treatment. Conclusion: This case report illustrates the importance of properly diagnosing the cause of parkinsonism in patients with schizophrenia.

Trends and Characteristics of Suicide-Related Behaviors Before and After the COVID-19 Epidemic in Tottori, Japan: A Retrospective Study.

Background: In Japan, the number of suicides has increased since the coronavirus disease (COVID-19) epidemic. However, only a few studies have examined the trends among individuals who attempted suicide. In this study, we examined the background characteristics and motives of individuals who attempted suicide and visited the emergency room because of suicide-related behavior before and after the spread of COVID-19. Methods: This single-center retrospective observational study collected information from electronic medical records. We included patients who presented to the emergency department of Tottori University Hospital with suicide-related behaviors between May 1, 2017, to August 31, 2022. The period from May 1, 2017, through December 31, 2019, was designated as 'the period before COVID-19" (before-period), and that from January 1, 2020, through August 31, 2022, was designated as "the period after COVID-19" (after-period). We compared the total number of cases, their background, and motives for suicide-related behaviors between the before- and after-periods. Results: The total number of suicide events was 304. Of these, 182 and 122 occurred during the before-period and after-period, respectively. The incidence of the F3 category of the International Classification of Diseases, 10th Revision, increased, while that of the F4 and F6 categories decreased during the after-period. The proportion of suicide attempts due to health problems decreased and that of work problems increased during the after-period. Conclusion: The total number of suicide-related behaviors decreased after the COVID-19 pandemic. This may be because patients with psychiatric disorders other than depression and schizophrenia often engage in suicidal behavior through non-fatal methods, such as drug overdose and wrist-cutting, which may have led them to refrain from seeing a doctor. The proportion of suicidal motivation due to work-related fatigue has increased, perhaps because the quality and quantity of work changed significantly due to COVID-19.

Infusions of beta-hydroxybutyrate, an endogenous NLRP3 inflammasome inhibitor, produce antidepressant-like effects on learned helplessness rats through BDNF-TrkB signaling and AMPA receptor activation, and strengthen learning ability.

Beta-hydroxybutyrate (BHB), an endogenous NLRP3 inflammasome inhibitor, has been shown to be associated with the pathophysiology of depression in rodents. However its active mechanism has not been revealed. Herein, we probed both the pathways and brain regions involved in BHB's antidepressant-like effects in a learned helplessness (LH) rat model of depression. A single bilateral infusion of BHB into the cerebral ventricles induced the antidepressant-like effects on the LH rats. The antidepressant-like effects of BHB were blocked by the TrkB inhibitor ANA-12 and the AMPA receptor antagonist NBQX, indicating that the antidepressant-like effects of BHB involve BDNF-TrkB signaling and AMPA receptor activation. Further, infusions of BHB into the prelimbic and infralimbic portions of medial prefrontal cortex, the dentate gyrus of hippocampus, and the basolateral region of amygdala produced the antidepressant-like effects on LH rats. However, infusions of BHB into the central region of amygdala, the CA3 region of hippocampus, and the shell and core regions of nucleus accumbens had no effect. Finally, a single bilateral infusion of BHB into the cerebral ventricles of naive rats strengthened learning ability on repeated active avoidance test where saline-infused animals failed to increase avoidance responses.