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

Shifting the paradigm of social withdrawal: a new era of coexisting pathological and non-pathological hikikomori

PURPOSE OF REVIEW

Social withdrawal syndrome, known as "hikikomori," has been highlighted since the late 1990 s in Japan. Hikikomori is more common in urban areas, and often comorbid with mental disorders, and now spreading throughout the world. In the post-COVID-19 era, not outing is no longer considered pathological in itself as the "new normal," and a novel concept of hikikomori is needed. This review summarizes the concept of hikikomori, and presents the latest methods for identification of hikikomori.

RECENT FINDINGS

The novel definition can distinguish between pathological and non-pathological hikikomori using the scale of "Hikikomori Diagnostic Evaluation (HiDE)," which has been developed in the hikikomori research lab at Kyushu University. An online survey among non-working adults has revealed that persons who have become pathological hikikomori for less than three months showed a particularly strong tendency toward gaming disorder and depression.

SUMMARY

Now, physical isolation itself is not pathological, but when dysfunction and distress are present, rapid mental health support should be provided. In the novel urban society, the establishment of a checkup system to assess whether persons who stay home are happy or suffering is important for prevention against mental disorders triggered by social isolation.

Prevalence of and factors influencing Hikikomori in Osaka City, Japan: A population-based cross-sectional study

OBJECTIVES

Hikikomori is commonly defined as a social condition in which individuals avoid social participation and relationships beyond their family members by confining themselves to a room or their house for 6 months or longer. Hikikomori has been predominantly considered a problem among young people; however, as the population is ageing, hikikomori has also emerged as a social issue among adults. Nevertheless, no comparative studies have examined the differences in the factors associated with hikikomori among teenagers/young adults and middle-aged/older adults. Thus, this phenomenon has not been thoroughly examined, and it remains unclear whether the risk factors vary between teenagers/young adults and middle-aged/older adults. Based on the Japan Cabinet Office's definition of hikikomori, this cross-sectional study evaluated the prevalence and related factors of hikikomori among the working age population (15-64 years), utilising univariate and multivariate analyses. The study also compared differences in the prevalence of and factors related to hikikomori between teenagers/young adults and middle-aged/older adults.

METHODS

We distributed self-administered questionnaires to individual participants and their families between 24 December 2020 and 18 January 2021.

RESULTS

Data from an anonymised sample of 3,092 individuals (split into two groups of 15-39 and 40-64 years) were subjected to analysis. The results revealed a hikikomori prevalence of 2.3% in the target population; the prevalence rate was 2.12% among individuals aged 15 to 39 years and 2.42% among those aged 40 to 64 years. The analysis demonstrated strong correlations between hikikomori and several factors, including unemployment, truancy, a history of psychiatric consultation or hospitalisation, being male and the absence of ibasho, which is defined as a place where individuals can feel peace, security, acceptance and belonging. The factors associated with hikikomori differed between teenagers/young adults and middle-aged/older adults.

CONCLUSION

Our findings, thus, contribute to existing research by providing a comparative analysis of risk factors across different age groups.

Korean autistic persons facing systemic stigmatization from middle education schools: daily survival on the edge as a puppet

Introduction

Korean autistic persons who have endured an integrated secondary education system have been exposed to school bullying, causing trauma and stigma to them. It also blocks them from entering a tertiary education system and a decent work, resulting in a lower quality of life. However, research on how it affects autistic persons has not yet been conducted in Korea.

Methods

Fourteen adult autistic persons in the Republic of Korea participated in the semi-structured focused group interviews. Their conversations were analyzed through qualitative coding.

Results

The interview results show the rare voice of Korean autistic people. Although interviewees experienced physical, verbal, and sexual violence against them during the secondary education period, they could not get substantial assistance from schools and society. Interviewees agreed that bullying is inherent in the secondary education system of Korea, even in Korean culture. They experienced the cause of bullying being attributed to them as victims rather than perpetrators, and impunity is given to the bullying assailants. Early analyses of this article confirm that such experiences are combined with the sociocultural climate of elitism, meritocracy, and authoritarianism in the Republic of Korea.

Conclusion

The study confirmed that the autistic person's bullying experience does not come from the social inability of autistic people but the "profound" competition and discriminative atmosphere of the society. The result urges further studies on the bullying experience of East Asian autistic persons and the construction of Korean intervention strategies to prevent school violence against Koreans with disabilities, especially autistic pupils.

Granulocyte macrophage colony-stimulating factor-induced macrophages of individuals with autism spectrum disorder adversely affect neuronal dendrites through the secretion of pro-inflammatory cytokines

BACKGROUND

A growing body of evidence suggests that immune dysfunction and inflammation in the peripheral tissues as well as the central nervous system are associated with the neurodevelopmental deficits observed in autism spectrum disorder (ASD). Elevated expression of pro-inflammatory cytokines in the plasma, serum, and peripheral blood mononuclear cells of ASD has been reported. These cytokine expression levels are associated with the severity of behavioral impairments and symptoms in ASD. In a prior study, our group reported that tumor necrosis factor-α (TNF-α) expression in granulocyte-macrophage colony-stimulating factor-induced macrophages (GM-CSF MΦ) and the TNF-α expression ratio in GM-CSF MΦ/M-CSF MΦ (macrophage colony-stimulating factor-induced macrophages) was markedly higher in individuals with ASD than in typically developed (TD) individuals. However, the mechanisms of how the macrophages and the highly expressed cytokines affect neurons remain to be addressed.

METHODS

To elucidate the effect of macrophages on human neurons, we used a co-culture system of control human-induced pluripotent stem cell-derived neurons and differentiated macrophages obtained from the peripheral blood mononuclear cells of five TD individuals and five individuals with ASD. All participants were male and ethnically Japanese.

RESULTS

Our results of co-culture experiments showed that GM-CSF MΦ affect the dendritic outgrowth of neurons through the secretion of pro-inflammatory cytokines, interleukin-1α and TNF-α. Macrophages derived from individuals with ASD exerted more severe effects than those derived from TD individuals.

LIMITATIONS

The main limitations of our study were the small sample size with a gender bias toward males, the use of artificially polarized macrophages, and the inability to directly observe the interaction between neurons and macrophages from the same individuals.

CONCLUSIONS

Our co-culture system revealed the non-cell autonomous adverse effects of GM-CSF MΦ in individuals with ASD on neurons, mediated by interleukin-1α and TNF-α. These results may support the immune dysfunction hypothesis of ASD, providing new insights into its pathology.

Autism Spectrum, Hikikomori Syndrome and Internet Gaming Disorder: Is There a Link?

The aim of this study is to review the available literature investigating the relationship between hikikomori, a pathological condition characterized by severe social withdrawal or isolation, autism spectrum disorder (ASD) and Internet gaming disorder (IGD). Studies on the relationship between ASD and IGD have found significant positive correlations between these two conditions. Individuals with ASD would appear to be at risk of developing a problematic use of the Internet, which, to the right extent, would represent a useful tool for social interaction and cognitive development. Even subjects with hikikomori, in whom rarefied interpersonal relationships and social isolation could be balanced by the use of online connections, appear to be at high risk of developing IGD. On the other hand, the finding of significant autistic traits in populations with hikikomori could lead to considering this psychopathological condition as a particular presentation of autism spectrum, a hypothesis that requires further investigation.

Hikikomori: A Scientometric Review of 20 Years of Research

The Japanese term hikikomori was first used to describe prolonged social withdrawal in the 1990s. Since then, research across the world have reported similar prolonged social withdrawal in many countries outside Japan. This study systematically analyses the evolution of literature on hikikomori in the past 20 years to gain a better understanding of the development of the knowledge base on hikikomori since it garnered attention in Japan. Findings from the scientometric review indicate many perspectives on the etiology of hikikomori including cultural, attachment, family systems and sociological approaches. However, similarities with modern type depression, a novel psychiatric syndrome, have been proposed and there are signs of a recent paradigm shift of hikikomori as a society-bound syndrome rather than a cultural-bound syndrome unique to Japan. As research into hikikomori continues to grow, results from the review also highlight the need for a more universally shared definition of hikikomori in order to better consolidate cross-cultural research for meaningful and valid cross-cultural comparisons which can help to promote evidence-based therapeutic interventions for hikikomori.

Hikikomori Syndrome and Digital Technologies: A Systematic Review

ABSTRACT

Hikikomori syndrome (HS) is a voluntary prolonged social isolation associated with personal and community impact. Previous evidence pointed out a possible relationship between this syndrome with addiction to digital technologies. Here we aim to understand the relationship between HS and digital technology use, overuse, and addictive behaviors, as well as potential therapeutic approaches.We conducted a systematic review of observational and intervention studies available in PubMed/MEDLINE, LILACS, IBECS, Embase, PsycINFO, and SciELO databases, following the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA 2020) criteria. The risk of bias was assessed with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) and Consensus-based Clinical Case Reporting Guideline Development (CARE). Eligibility criteria were pre-, at-risk populations, or those with HS diagnosis, and any kind of technological overuse. Seventeen studies were included in the review, of which eight were cross-sectional, eight were case reports, and one was quasi-experimental. Hikikomori syndrome was associated with addition to digital technologies; no cultural differences were found. Environmental factors, such as a history of bullying, low self-esteem, and grief were identified as precursors of addictive behaviors. The included articles addressed addiction to digital technologies, electronic games, and social networks, among others, in HS. HS is cross-culturally associated with such addiction. The management of these patients remains challenging, and no target evidence-based treatments have been developed. The studies included in this review had several limitations, and more studies with a higher level of evidence are needed to support the results.

Contemporary Hermits: A Developmental Psychopathology Account of Extreme Social Withdrawal (Hikikomori) in Young People

Although it is widely accepted that human beings have an ingrained 'need to belong,' there seem to be a substantial subset of young people who seclude themselves for most of the time at home and no longer engage in education or work, ultimately withdrawing from participation in society. In Japan, this phenomenon has been labeled as 'hikikomori,' but given its global presence it may be preferable to use the term 'extreme social withdrawal' (ESW). In this qualitative review, we provide a description and definition of ESW, provide figures on its prevalence, and discuss a number of associated concepts, including loneliness and "aloneliness," school absenteeism and dropout, the 'new' developmental stage of adultolescence, and the labor force categories of freeter ('freelance arbeiter') and NEET (a young person not in employment, education, or training). The core of the paper is focused on the origins of ESW in young people and provides a narrative overview of relevant etiological factors, such as aberrant brain processes, unfavorable temperament, psychiatric conditions, adverse family processes including detrimental parenting, negative peer experiences, societal pressures, and excessive internet and digital media use, which are all placed within a comprehensive developmental psychopathology framework. We will close with a discussion of possible interventions for young people with ESW and formulate a guideline that describes (the temporal order of) various components that need to be included in such a treatment.

The impact of higher levels of autistic traits on risk of hikikomori (pathological social withdrawal) in young adults

BACKGROUND

Hikikomori is an extreme state of social withdrawal, originally identified in Japan but more recently recognised internationally. Many countries imposed restrictions during the COVID-19 pandemic which may have had a detrimental impact on those at risk of hikikomori, specifically young adults and those with high levels of autistic traits.

AIMS

To explore whether levels of autistic traits mediate the relationship between psychological wellbeing and hikikomori risk. We also looked at whether autistic traits mediated between lockdown experiences (e.g. not leaving the house) and hikikomori risk.

METHODS

646 young people (aged 16-24) from a wide range of countries completed an online questionnaire assessing psychological wellbeing, autistic traits and experiences of lockdown for this cross-sectional study.

RESULTS

Autistic traits mediated the relationship between both psychological wellbeing and hikikomori risk, as well as frequency of leaving the house during lockdown and hikikomori risk. Greater hikikomori risk was associated with poor psychological wellbeing, higher autistic traits and leaving the house less frequently during the COVID-19 pandemic.

CONCLUSIONS

These findings suggest similarities with Japanese hikikomori research and are consistent with suggestions that psychological wellbeing and COVID-19 restrictions are associated with increased hikikomori risk in young adults, and both associations are mediated by higher levels of autistic traits.

Pathological social withdrawal in autism spectrum disorder: A case control study of hikikomori in Japan

Introduction

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 ASD are associated with hikikomori.

Methods

Thirty-nine adult male patients with a diagnosis of ASD attending our outpatient clinic for neurodevelopmental disabilities were subjected to a structured interview regarding social withdrawal, various self-administered questionnaires, and blood tests. Through structured interviews, the subjects were divided into two groups: (Group 1) ASD with hikikomori condition and (Group 2) ASD without hikikomori condition. Sixteen subjects qualified as hikikomori and 23 subjects qualified as subjects without hikikomori. Age, sex, autism spectrum quotient (AQ), Autism Diagnostic Observation Schedule (ADOS), and FIQ were matched.

Results

Compared to non-hikikomori controls, hikikomori cases were likely to have stronger sensory symptoms, lower uric acid (UA) (p = 0.038), and higher rates of atopic dermatitis (p = 0.01). Cases showed more severe depressive and social anxiety symptoms based on self-rated scales: Patient Heath Questionnaire 9 (PHQ-9) (p < 0.001) and Liebowitz Social Anxiety Scale Japanese Version (LSAS-J) (p = 0.04). Tarumi's Modern-Type Depression Trait Scale (TACS-22), which measure traits of Modern-Type Depression (MTD), were significantly higher in cases (p = 0.003).

Conclusion

The present study has suggested that ASD patients with hikikomori were more likely to have higher sensory abnormalities, comorbid atopic dermatitis, lower UA, stronger depressive, and anxiety tendency. Evaluating and approaching these aspects are important for appropriate interventions in ASD with hikikomori. Further investigations should be conducted to validate our pilot findings.

An examination of the potential benefits of expert guided physical activity for supporting recovery from extreme social withdrawal: Two case reports focused on the treatment of Hikikomori

Extreme and long-term social withdrawal, first described in Japan as Hikikomori, has now become a globally recognized mental health problem. Intervention studies severely lag behind epidemiological and phenomenological research. We present two descriptive case reports of Japanese university students with Hikikomori who participated in an early phase test of a structured intervention involving physical activities that was developed and facilitated by clinicians and physical education specialists-Human Movement Consultation (HMC). The two recipients (19- and 29-years old at the start of treatment) completed approximately 40 consultation sessions delivered over 3 years consisting of a combination of outdoor workouts (i.e., walking, running, and cycling) and interpersonal sports (e.g., table tennis, badminton, and tennis). Changes in social withdrawal behavior were independently rated from clinical health records using a structured scale (the Glasgow Hikikomori Scale; GHS). Behavioral observations and scale data for both cases indicated improvements from pre-treatment levels of social withdrawal. At the end of the intervention, both had returned to normative levels of functioning. Case A returned to university and Case B secured a new job upon the completion of HMC. To help advance our understanding of treatment options, these case descriptions analyze potential change mechanisms in order to understand how HMC can support recovery from extreme social withdrawal. One key observation is that both outdoor workouts and interpersonal sports offer a non-threatening method of enabling Hikikomori to engage in interpersonal interactions. Such connections via structured activities may allow the reinstatement of social skills in a graded manner. In addition, an initial focus on physical experiences may help promote psychological and social connectedness without triggering the social fears and challenges that underlie the Hikikomori state. The findings from these two cases offer a framework to guide further research and the development of exercise-based interventions for this hidden and often neglected group.

Who are hikikomori? Demographic and clinical features of hikikomori (prolonged social withdrawal): A systematic review

OBJECTIVE

This review, which was registered with PROSPERO (CRD42021237988), aimed to systematically extract common elements in the hikikomori definition or criteria applied by researchers and examine cultural differences and chronological changes in the demographic characteristics of hikikomori individuals such as age, gender and hikikomori duration.

METHOD

For inclusion in the review, the hikikomori criteria, age and gender of the hikikomori individuals had to be specified, and the article had to be peer-reviewed and written in Japanese or English, focusing on hikikomori individuals or their families. Case studies, reviews and qualitative studies were excluded.

RESULTS

The total sample size for the 52 studies included in the review was 4744. Over 80% of the studies included the elements 'not working or attending school', 'not socializing outside one's home' and 'duration of hikikomori' in their hikikomori criteria, and many studies included the element 'staying at home on most days except solitary outings'. A cross-temporal meta-analysis showed the possibility that the age of hikikomori individuals increased chronologically (β = 0.44, B = 0.50, 95% confidence interval = [0.16, 0.84]). Comparisons weighted by sample size between Japan and other countries showed the possibility that the age of hikikomori individuals was higher (d = 0.32), the percentage of males was lower (d = 0.91) and the hikikomori duration was shorter (d = 2.06) in studies conducted in countries other than Japan. However, many of the included studies had a high risk of selection bias, and this bias may have influenced the results obtained. Thus, the results of this study may represent the researcher's perception of hikikomori rather than accurately representing the actual condition of hikikomori.

CONCLUSION

Researchers should specifically identify similarities and differences in the clinical picture of hikikomori and compare the studies to organize the findings derived from studies focusing on hikikomori.

Autistic children and adolescents with frequent restricted interest and repetitive behavior showed more difficulty in social cognition during mask-wearing during the COVID-19 pandemic: a multisite survey

BACKGROUND

The public health measures enacted in order to control the coronavirus disease (COVID-19) pandemic have caused considerable changes to daily life. For autistic children and adolescents, adapting to the "new normal," including mask-wearing, may be difficult because of their restricted interest and repetitive behavior (RRB) characteristics. We aimed to examine the relationships between RRB characteristics and the impact of mask-wearing on their social communications during the pandemic.

METHODS

We recruited participants with a clinical diagnosis of autism spectrum disorder based on DSM-5 diagnostic criteria from two outpatient clinics in Tokyo, Japan, between November 2020 and April 2021 using a convenience sampling methodology. As a result, the participants consisted of 102 children and adolescents (mean (SD) age = 11.6 (5.3)). We collected data on RRB characteristics frequency before and during the pandemic using the CoRonavIruS Health Impact Survey (CRISIS) - Adapted for Autism and Related Neurodevelopmental conditions (AFAR). We then conducted factor analyses to compute the RRB severity composite scores, which are divided into lower- (e.g., sensory seeking), and higher-order (e.g., restricted interest). We also investigated mask-wearing culture using a bespoke questionnaire, and using Spearman's rank correlation analyses, we examined the relationships between before pandemic RRB characteristics, and the impact of mask-wearing on social communications during the pandemic.

RESULTS

We found that children and adolescents who exhibited lower-order RRB before the pandemic had difficulties in going-out with mask-wearing (rho = -0.25, q = .031), more challenges with mask-wearing (rho =  - 0.34, q = .0018), and difficulty in referring to others' emotions while wearing masks (rho =  - 0.36, q = .0016). We also found an association between higher-order RRB before the pandemic and an uncomfortable sensation (rho =  - 0.42, q = .0002) and difficulties in referring to other's emotions while wearing masks (rho =  - 0.25, q = .031).

CONCLUSIONS

We revealed that various behaviors, such as sensory seeking, repetitive motor mannerisms and movements, and rituals and routines, undertaken before the pandemic could be important predictors of difficulties with mask-wearing and social communication for autistic children and adolescents during the pandemic. Caregivers and teachers wearing masks may need to provide extra support for social communication to autistic children and adolescents showing RRB characteristics frequently.

Relationship between autistic traits and social functioning in healthy individuals

AIM

Social functioning is influenced by various factors. Autistic traits could be one of the factors that affect social functioning.

METHODS

In the present study, the relationship between autistic traits and social functioning among 755 healthy individuals was analyzed. Autistic traits were assessed with the autism-spectrum quotient. Social functioning was assessed by the social functioning scale and the social activity assessment.

RESULTS

The Autism-Spectrum Quotient total score was significantly negatively correlated with the social functioning scale total and all subscales of the social functioning scale. All subscales of the Autism-Spectrum Quotient except attention to detail were significantly negatively correlated with the social functioning scale total score. However, the Autism-Spectrum Quotient was not correlated with the social activity assessment, which indicates labor functioning.

CONCLUSION

Autistic traits of healthy individuals had a negative impact on situations in real life through social functioning for daily life-sustaining. The effect was not enough to affect labor functioning as indicated by working hours in healthy individuals. These findings should also be examined in individuals with autism spectrum disorder in future studies.

Association between Self-Restraint Behavior, Stigma and Depressive Tendency in Office Workers during the COVID-19 Pandemic in Japan—Self-Restraint Behavior and Depression during the COVID-19

Background: The COVID-19 pandemic has forced people to change their lifestyles, especially with respect to restrictions on going out. Forced quarantine (i.e., lockdown) and self-restraint behavior (SRB), including self-quarantine, are suggested to induce potential negative impacts on public mental health. SRB seems to be related to governmental policies, each individual’s social background and mental condition; however, no empirical studies have been conducted. Methods: 1053 participants (mainly office workers) from epidemic areas and non-epidemic areas in Japan voluntarily conducted an online survey in June 2020. We assessed COVID-19-related aspects such as the degree of SRB, motivation for SRB, stigma, anxiety and depressive feelings due to COVID-19 by original questionnaires) and general mental health status (social anxiety by MINI-SPIN, depressive tendency by PHQ-9, depression-related personality traits by TACS-22 and resilience by TRS). Results: Regional comparison showed significant differences in SRB and social anxiety. People in epidemic areas tend to refrain from going out. Conversely, people in non-epidemic areas tend to shun the public eye. Regardless of epidemic status, proactive SRB was associated with higher motivation for SRB, higher social anxiety, higher depressive tendency, stronger COVID-19-related psychological factors and lower resilience. Moreover, people with proactive SRB in non-epidemic areas had the highest depressive tendency. Discussion: The present cross-sectional survey among office workers in Japan showed that people with proactive SRB have stronger COVID-19-related anxiety and depressive feelings, regardless of where they live. Our key finding is that people with proactive SRB in non-epidemic areas have the highest depressive tendency. Based on the present finding, we herein propose the following hypothesis: Higher levels of depressive tendency may enhance proactive SRB, which may be partly associated with higher levels of stigma, anxiety and depressive feelings related to COVID-19. Limitations: The general tendencies to avoid danger and stigma were not evaluated. Conclusions: Depressive tendency is suggested to be associated with proactive SRB against COVID-19. Intervention for depressive tendency in non-clinical settings (e.g., workplaces) may help citizens understand the infectious situation appropriately and to behave effectively during the pandemic. Further investigations should be conducted to clarify the present findings.

Future perspectives of robot psychiatry: can communication robots assist psychiatric evaluation in the COVID-19 pandemic era?

PURPOSE OF REVIEW

Direct face-to-face interview between a psychiatrist and a patient is crucial in psychiatric evaluation, however, such traditional interviews are becoming difficult to conduct because of the infection risk in the COVID-19 era. As telepsychiatry, video interviews using internet are suggested to be useful to evaluate and assist individuals with mental disorders. However, some patients especially with social phobia, depression, and autism spectrum disorder (ASD) hesitate to use even such face-to-face-like tools. Communication robots have been proposed as future assistant tools for such patients. Herein, we summarize recent advancements in robot psychiatry, and propose the benefits of communication robots in psychiatric evaluation.

RECENT FINDINGS

Recent studies have suggested that communication robots are effective in assisting people with ASD. As a pilot trial, we herein conducted semi-structured interviews to evaluate depression and hikikomori, a form of pathological social withdrawal, using a communication robot and a psychiatrist, respectively. There was almost identical evaluation between the two. Interestingly, a person with hikikomori answered that the robot was easier to disclose.

SUMMARY

Robots can reduce the burden of human resources and the infection risk in the COVID-19 era. Robot interview is expected to be implemented for future evaluation system in psychiatry.

Working with social withdrawal, or hikikomori, in Japan: From shame to pride

The term hikikomori, or social withdrawal, was first coined in the late 1980s in Japan to describe adolescents and young adults who isolated themselves at home, withdrew from most social engagement, such as work or school, and had almost no relationships with others (except family members and online contacts) for longer than 6 months. Hikikomori often results from emotional injuries such as rejection, or failures that have not been addressed or even noticed. In the current case illustration, the problem of hikikomori is depicted through a client named Ken, a 40-year-old single man who, following graduation from university, became lodged in a 15-year cycle of repeatedly finding employment, quitting within the first year, and going into reclusive isolation. Ken underwent affect-oriented integrative psychotherapy for 4 years. The importance of processing emotional pain and highlighting positive emotional experiences to build a positive sense of self in working with hikikomori will also be discussed.

Case Report: Burden of Illness in Narcolepsy Type 1: Hikikomori in a Teenage Girl

Narcolepsy type 1 (NT1) deeply impacts on quality of life, especially during adolescence, with NT1 children and adolescents that frequently report difficulties in integration with peers and decreased participation in after-school activities. Here we describe the case of NT1 teenager girl presenting with severe physical and social withdrawal, fulfilling the proposed diagnostic criteria for hikikomori, together with the classic NT1 symptoms. Social withdrawal is an overlooked phenomenon among NT1 children and adolescents that, if present, require a multidisciplinary approach and personalized interventions, but patients can benefit from NT1 pharmacological treatment.

Longitudinal association between autistic traits and affinity for hikikomori in Japanese university students

The affinity for hikikomori represents the desire to be withdrawn, as well as to entertain an empathetic attitude towards withdrawn individuals. It is composed of two subdimensions, the maladaptive desire for hikikomori, and empathy for others with hikikomori. This longitudinal study examined whether autistic traits predicted the affinity for hikikomori. At the baseline assessment, undergraduate and graduate students in Japan (N = 272) completed the Autism-Spectrum Quotient (AQ), the Affinity for Hikikomori Scale in University Students, and measures assessing academic failures and interpersonal conflicts. They also completed all measures excluding the AQ eight weeks later. Structural equation modeling indicated that difficulties in social interaction aspects of autistic traits were positively associated with academic failures at Time 2 even after controlling for academic failures at Time 1. In addition, difficulties in social interaction were positively related to the desire for hikikomori at Time 2 indirectly via academic failures at Time 2 after controlling for the desire for hikikomori at Time 1. Difficulties in social interaction were also directly associated with the increased desire for hikikomori at Time 2. These findings suggest that autistic traits, and especially difficulties in social interaction, are predictors of the maladaptive aspect of the affinity for hikikomori.

Blood metabolic signatures of hikikomori, pathological social withdrawal

Background

A severe form of pathological social withdrawal, ‘hikikomori,’ has been acknowledged in Japan, spreading worldwide, and becoming a global health issue. The pathophysiology of hikikomori has not been clarified, and its biological traits remain unexplored.

Methods

Drug-free patients with hikikomori (n = 42) and healthy controls (n = 41) were recruited. Psychological assessments for the severity of hikikomori and depression were conducted. Blood biochemical tests and plasma metabolome analysis were performed. Based on the integrated information, machine-learning models were created to discriminate cases of hikikomori from healthy controls, predict hikikomori severity, stratify the cases, and identify metabolic signatures that contribute to each model.

Results

Long-chain acylcarnitine levels were remarkably higher in patients with hikikomori; bilirubin, arginine, ornithine, and serum arginase were significantly different in male patients with hikikomori. The discriminative random forest model was highly performant, exhibiting an area under the ROC curve of 0.854 (confidential interval = 0.648–1.000). To predict hikikomori severity, a partial least squares PLS-regression model was successfully created with high linearity and practical accuracy. In addition, blood serum uric acid and plasma cholesterol esters contributed to the stratification of cases.

Conclusions

These findings reveal the blood metabolic signatures of hikikomori, which are key to elucidating the pathophysiology of hikikomori and also useful as an index for monitoring the treatment course for rehabilitation.

Prevalence and Characteristics of Social Withdrawal Tendency Among 3-24 Months in China: A Pilot Study

Background: Sustained withdrawal behavior is an obstacle for child development. The present study aimed to preliminarily evaluate the prevalence of social withdrawal tendency in young Chinese children using the Alarm Distress Baby Scale (ADBB) and describe the characteristics of socially withdrawn children. Method: This was a cross-sectional analysis as part of a prospective cohort study. A total of 114 children aged 3-24 months were included. The following instruments were administered: the Chinese version of ADBB, the Ages and Stages Questionnaire (ASQ-3), the Ages and Stages Questionnaire: Social-Emotional (ASQ:SE), and the Infant Temperamental Questionnaire. The tendency of social withdrawal in children was assessed using the ADBB. Social withdrawal was defined as an ADBB score of 5 or above. Student's t-test, χ² test, and Fisher's exact test were performed to identify the differences in maternal and child characteristics between the children with and without social withdrawal. Age-specific indicators of development in these two groups were also presented. Results: About 16.7% of the children were socially withdrawn. Compared with those without social withdrawal, children with social withdrawal were older and had higher proportions of boys (68.4 vs. 42.1%) and social-emotional development delay (63.2 vs. 0%). In age-specific analyses, social-emotional development was poorer in children with social withdrawal across all age groups from 3 to 24 months. Conclusion: Assessed by the ADBB, the prevalence of social withdrawal tendency in young Chinese children was similar to that reported in the European population; children with social withdrawal tended to have poorer social-emotional development. Further research with larger sample sizes is needed to validate the scale and confirm these findings.