Autism spectrum conditions in hikikomori: A pilot case-control study.

AIM: Hikikomori, a form of pathological social withdrawal, has been suggested to have comorbidity with autism spectrum disorder (ASD). This study aimed to clarify how characteristics of hikikomori are associated with ASD, including undiagnosed autism spectrum conditions (ASC), in clinical settings. METHODS: A total of 416 clinical patients were recruited through the Mood Disorder/Hikikomori Clinic at Kyushu University Hospital. A total of 103 hikikomori cases and 221 clinical controls without hikikomori conditions were extracted using a semi-structured interview, and completed a series of self-rated scales, including the Japanese version of the Autism-Spectrum Quotient (AQ-J). RESULTS: Compared to non-hikikomori controls, hikikomori cases were more likely to have higher autistic tendency based on the AQ-J. The cases showed more severe subjective depressive symptoms based on the self-rated Beck Depression Inventory II, whereas no significant difference was found on interview-based severity evaluation using the Hamilton Depression Rating Scale. Comparison within hikikomori cases based on the AQ-J cut-off score revealed that hikikomori cases with high ASC were significantly more likely to have higher traits of modern-type depression, smaller social networks, and less social support. CONCLUSION: The present data suggest that hikikomori sufferers are more likely to have autistic tendency, and that hikikomori sufferers with high ASC may have much more difficulty in social communication and social interaction. In addition, those with high ASC may also have lower self-esteem and higher complaint tendencies as aspects of modern-type depression traits, which may relate to the occurrence of hikikomori. Thus, evaluating autistic tendencies is important for appropriate interventions in hikikomori. Further investigations should be conducted to validate our pilot findings using structured diagnostic systems of ASD.

Development and validation of the 22-item Tarumi's Modern-Type Depression Trait Scale: Avoidance of Social Roles, Complaint, and Low Self-Esteem (TACS-22).

AIM: Understanding premorbid personality is important, especially when considering treatment selection. Historically, the premorbid personality of patients with major depression in Japan was described as Shuchaku-kishitsu [similar to Typus melancholicus], as proposed by Shimoda in the 1930s. Since around 2000, there have been increased reports in Japan of young adults with depression who have had premorbid personality differing from the traditional type. In 2005, Tarumi termed this novel condition 'dysthymic-type depression,' and more recently the condition has been called Shin-gata/Gendai-gata Utsu-byo [modern-type depression (MTD)]. We recently developed a semi-structured diagnostic interview to evaluate MTD. Development of a tool that enables understanding of premorbid personality in a short time, especially at the early stage of treatment, is desirable. The object of this study was to develop a self-report scale to evaluate the traits of MTD, and to assess the scale's psychometric properties, diagnostic accuracy, and biological validity. METHODS: A sample of 340 participants from clinical and community settings completed measures. Psychometric properties were assessed with factor analysis. Diagnostic accuracy of the MTD traits was compared against a semi-structured interview. RESULTS: The questionnaire contained 22 items across three subscales, thus we termed it the 22-item Tarumi's Modern-Type Depression Trait Scale: Avoidance of Social Roles, Complaint, and Low Self-Esteem (TACS-22). Internal consistency, test-retest reliability, and convergent validity were all satisfactory. Among patients with major depression, the area under the curve was 0.757 (sensitivity of 63.1% and specificity of 82.9%) and the score was positively correlated with plasma tryptophan. CONCLUSION: The TACS-22 possessed adequate psychometric properties and diagnostic accuracy in an initial sample of Japanese adults. Additional research on its ability to support clinical assessment of MTD is warranted.

Plasma acetylcholine and nicotinic acid are correlated with focused preference for photographed females in depressed males: an economic game study.

Interpersonal difficulties are often observed in major depressive disorder (MDD), while the underlying psychological and biological mechanisms have not yet been elucidated. In the present case-control study, a PC-based trust game was conducted for 38 drug-free MDD patients and 38 healthy controls (HC). In the trust game, participants invested money in a partner (trusting behaviors), and also rated each partner's attractiveness (preference for others). In addition, blood biomarkers including metabolites were measured. Both MDD and HC males exhibited more trusting behaviors compared to females. MDD males' preference for ordinary-attractive partners (lay-person photographs) was lower than HC males, whereas their preference for high-attractive females (fashion-model photographs) was similar levels to HC males. This tendency in MDD males could reflect a "focused (narrowed) preference for females". As for blood biomarker analysis, the levels of 37 metabolites including acetylcholine, AMP, GMP, nicotinic acid and tryptophan were significantly different between two groups. Interestingly, among male participants, acetylcholine and nicotinic acid were negatively correlated with the level of focused preference for photographed females. In sum, we have revealed some behavioral, psychological and biological traits of trusting behaviors and preference for others especially in MDD males. Larger studies should be conducted to validate our preliminary findings.

Personality classification enhances blood metabolome analysis and biotyping for major depressive disorders: two-species investigation.

BACKGROUND: The relationship between depression and personality has long been suggested, however, biomarker investigations for depression have mostly overlooked this connection. METHODS: We collected personality traits from 100 drug-free patients with major depressive disorders (MDD) and 100 healthy controls based on the Five-Factor Model (FFM) such as Neuroticism (N) and Extraversion (E), and also obtained 63 plasma metabolites profiles by LCMS-based metabolome analysis. RESULTS: Partitional clustering analysis using the NEO-FFI data classified all subjects into three major clusters. Eighty-six subjects belonging to Cluster 1 (C1: less personality-biased group) constituted half of MDD patients and half of healthy controls. C2 constituted 50 subjects mainly MDD patients (N high + E low), and C3 constituted 64 subjects mainly healthy subjects (N low + E high). Using metabolome information, the machine learning model was optimized to discriminate MDD patients from healthy controls among all subjects and C1, respectively. The performance of the model for all subjects was moderate (AUC = 0. 715), while the performance was extremely improved when limited to C1 (AUC = 0. 907). Tryptophan-pathway plasma metabolites including tryptophan, serotonin and kynurenine were significantly lower in MDD patients especially among C1. We also validated metabolomic findings using a social-defeat mice model of stress-induced depression. LIMITATIONS: A case-control study design and sample size is not large. CONCLUSIONS: Our results suggest that personality classification enhances blood biomarker analysis for MDD patients and further translational investigations should be conducted to clarify the biological relationship between personality traits, stress and depression.

Clarifying Deeper Psychological Characteristics of Hikikomori Using the Rorschach Comprehensive System: A Pilot Case-Control Study.

Hikikomori, a form of severe social withdrawal more than 6 months, has increasingly become a crucial issue especially among adolescents. Loneliness, avoidant personality, Japanese culture-related attachment style ("amae"), and difficulty in expressing emotions are suggested to be related to hikikomori. However, deeper psychological aspects have not been well clarified. The Rorschach test is one of the most popular psychological assessment tools to evaluate deeper personality traits. The Rorschach Comprehensive System (CS) has been established as the most reliable scoring method. Until now, no CS research has been conducted focusing on hikikomori. Therefore, we herein conducted a pilot case-control study using CS in clinical cases with and without hikikomori condition. Participants were recruited from the Mood Disorder/Hikikomori Clinic at Kyushu University Hospital. Twenty-two patients with hikikomori (HK patients) and 18 patients without hikikomori (non-HK patients) participated in the present study. All the 40 participants conducted the self-report Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) personality questionnaire and CS. Regarding the SCID-II personality questionnaire, various personality traits including passive aggressive trait were significantly higher in HK patients. Among CS variables, HK patients showed higher scores on FC (Form Color) and SumT (total number of texture-related responses). In addition, frequency of SumT was higher in HK patients. The present results suggest that persons with hikikomori are more likely to express emotions indirectly and expect others to presume their feelings and thoughts. Persons with hikikomori may also have difficulty in becoming independent emotionally from primitive dependence and attachment on significant others. Further investigations with larger samples are warranted for validation.

Suicide and Microglia: Recent Findings and Future Perspectives Based on Human Studies.

Suicide is one of the most disastrous outcomes for psychiatric disorders. Recent advances in biological psychiatry have suggested a positive relationship between some specific brain abnormalities and specific symptoms in psychiatric disorders whose organic bases were previously completely unknown. Microglia, immune cells in the brain, are regarded to play crucial roles in brain inflammation by releasing inflammatory mediators and are suggested to contribute to various psychiatric disorders such as depression and schizophrenia. Recently, activated microglia have been suggested to be one of the possible contributing cells to suicide and suicidal behaviors via various mechanisms especially including the tryptophan-kynurenine pathway. Animal model research focusing on psychiatric disorders has a long history, however, there are only limited animal models that can properly express psychiatric symptoms. In particular, to our knowledge, animal models of human suicidal behaviors have not been established. Suicide is believed to be limited to humans, therefore human subjects should be the targets of research despite various ethical and technical limitations. From this perspective, we introduce human biological studies focusing on suicide and microglia. We first present neuropathological studies using the human postmortem brain of suicide victims. Second, we show recent findings based on positron emission tomography (PET) imaging and peripheral blood biomarker analysis on living subjects with suicidal ideation and/or suicide-related behaviors especially focusing on the tryptophan-kynurenine pathway. Finally, we propose future perspectives and tasks to clarify the role of microglia in suicide using multi-dimensional analytical methods focusing on human subjects with suicidal ideation, suicide-related behaviors and suicide victims.

Tryptophan-kynurenine and lipid related metabolites as blood biomarkers for first-episode drug-naïve patients with major depressive disorder: An exploratory pilot case-control study.

BACKGROUND: Early intervention in depression has been critical to prevent its negative impact including suicide. Recent blood biomarker studies for major depressive disorder (MDD) have suggested that tryptophan-kynurenine and lipid related metabolites are involved in the pathophysiology of MDD. However, there have been limited studies investigating these blood biomarkers in first-episode drug-naïve MDD, which are particularly important for early intervention in depression. METHODS: As an exploratory pilot case-control study, we examined the above blood biomarkers, and analyzed how these biomarkers are associated with clinical variables in first-episode drug-naïve MDD patients, based on metabolome/lipidome analysis. RESULTS: Plasma tryptophan and kynurenine levels were significantly lower in MDD group (N = 15) compared to healthy controls (HC) group (N = 19), and plasma tryptophan was the significant biomarker to identify MDD group (area under the curve = 0.740). Lower serum high density lipoprotein-cholesterol (HDL-C) was the predictive biomarker for severity of depression in MDD group (R2 = 0.444). Interestingly, depressive symptoms were variously correlated with plasma tryptophan-kynurenine and lipid related metabolites. Moreover, plasma tryptophan-kynurenine metabolites and cholesteryl esters (CEs) were significantly correlated in MDD group, but not in HC group. LIMITATIONS: This study had small sample size, and we did not use the multiple test correction. CONCLUSIONS: This is the first study to suggest that not only tryptophan-kynurenine metabolites but also HDL-C and CEs are important blood biomarkers for first-episode drug-naïve MDD patients. The present study sheds new light on early intervention in clinical practice in depression, and further clinical studies especially large-scale prospective studies are warranted.

Neuron-related blood inflammatory markers as an objective evaluation tool for major depressive disorder: An exploratory pilot case-control study.

BACKGROUND: Neuroinflammation is suggested to be a crucial factor in the pathophysiology of major depressive disorder (MDD). Analysis of neuron-derived exosomes (NDE) in peripheral blood has recently been highlighted to reveal the pathophysiology of brain diseases without using brain biopsy. Currently, human NDE studies require a considerable amount of peripheral blood to measure multiple substances inside exosomes. Previously, NDE-based clinical studies focusing on MDD have not been reported. METHODS: As an exploratory pilot case-control study between healthy controls (HC) and drug-free MDD patients (each; N = 34), we searched for NDE-related blood biomarkers with a small amount of peripheral blood using a novel sandwich immunoassay between anti-neuron antibody and antibodies against CD81 (an exosome marker) and against other proteins related to neuroinflammation and synaptic functions. RESULTS: Most neuron-related blood biomarkers had moderately to strongly positive correlation with CD81 (NDE), thus we normalized the above biomarkers by CD81 (quantity of each biomarker/CD81) to predict NDE-related blood substances. Interleukin 34 (IL34)/CD81 levels were significantly higher in MDD group compared to HC group. Synaptophysin (SYP), SYP/CD81, and tumor necrosis factor receptor 1 (TNFR1)/CD81 were positively correlated with severities of depression and/or various sub-symptoms. LIMITATIONS: We did not actually extract NDE from peripheral blood. CONCLUSIONS: Using a small amount of peripheral blood, we have successfully detected possible NDE-related blood biomarkers. This is the first study to suggest that not only SYP and TNFR1 but also IL34 are important blood biomarkers for patients with MDD. Further studies are warranted to evaluate the present study.

Blood biomarkers of Hikikomori, a severe social withdrawal syndrome.

Hikikomori, a severe form of social withdrawal syndrome, is a growing social issue in Japan and internationally. The pathophysiology of hikikomori has not yet been elucidated and an effective treatment remains to be established. Recently, we revealed that avoidant personality disorder is the most common comorbidity of hikikomori. Thus, we have postulated that avoidant personality is the personality underpinning hikikomori. First, we herein show relationships between avoidant personality traits, blood biomarkers, hikikomori-related psychological features, and behavioural characteristics assessed by a trust game in non-hikikomori volunteers. Avoidant personality traits were negatively associated with high-density lipoprotein cholesterol (HDL-C) and uric acid (UA) in men, and positively associated with fibrin degeneration products (FDP) and high sensitivity C-reactive protein (hsCRP) in women. Next, we recruited actual individuals with hikikomori, and compared avoidant personality traits, blood biomarkers, and psychological features between individuals with hikikomori and age-matched healthy controls. Individuals with hikikomori had higher avoidant personality scores in both sexes, and showed lower serum UA levels in men and lower HDL-C levels in women compared with healthy controls. This is the first report showing possible blood biomarkers for hikikomori, and opens the door to clarify the underlying biological pathophysiology of hikikomori.

Dysregulated gene expressions of MEX3D, FOS and BCL2 in human induced-neuronal (iN) cells from NF1 patients: a pilot study.

Direct conversion technique to produce induced-neuronal (iN) cells from human fibroblasts within 2 weeks is expected to discover unknown neuronal phenotypes of neuropsychiatric disorders. Here, we present unique gene expression profiles in iN cells from patients with neurofibromatosis type 1 (NF1), a single-gene multifaceted disorder with comparatively high co-occurrence of autism spectrum disorder (ASD). Microarray-based transcriptomic analysis on iN cells from male healthy controls and male NF1 patients (NF1-iN cells) revealed that 149 genes expressions were significantly different (110 upregulated and 39 downregulated). We validated that mRNA of MEX3D (mex-3 RNA binding family member D) was lower in NF1-iN cells by real-time PCR with 12 sex-mixed samples. In NF1-iN cells on day 14, higher expression of FOS mRNA was observed with lower expression of MEX3D mRNA. Interestingly, BCL2 mRNA was higher in NF1-iN cells on day 5 (early-period) but not on day 14. Our data suggest that aberrant molecular signals due to NF1 mutations may disturb gene expressions, a subset of which defines continuum of the neuronal phenotypes of NF1 with ASD. Further translational studies using induced pluripotent stem (iPS) cell-derived neuronal cells are needed to validate our preliminary findings especially confirming meanings of analysis using early-period iN cells.