Hikikomori: psychopathology and differential diagnosis of a condition with epidemic diffusion

Case report: hikikomori syndrome in Italy and its link with autistic traits and internet gaming disorder

During the last few decades, a growing field of literature is focusing on hikikomori, a phenomenon described as a form of pathological social withdrawal or social isolation that lasts for more than 6 months leading to significant functional impairment and/or distress. Despite initially considered a culture-bound syndrome, hikikomori syndrome later gained a wider recognition in different countries, ranging from an attempt to take refuge in an idealistic world, when society success' standards are not reached, to a maladaptive coping strategy complicating several psychiatric illnesses such as anxiety disorders, major depression, internet addiction, internet gaming disorder (IGD) and autism spectrum disorder (ASD). In this framework, difficulties in social interaction, in problem solving strategies and socio-emotional reciprocity, may lead to social withdrawal and hikikomori-like behaviors. In this work, we described two cases of patients where the presence of underlying autism spectrum may have represented a sign of vulnerability towards the development of a possible full-blown case of hikikomori with IGD.

Exploring Hikikomori-like idiom of distress a year into the SARS-CoV-2 pandemic in Oman: Factorial validity of the 25-item Hikikomori Questionnaire, prevalence and associated factors

BACKGROUND

Existing literature that examines the Hikikomori-like idiom of distress (HLID) initially labelled this phenomenon as a culture-bound syndrome. However, the increasing number of reports from other parts of the world suggest that HLID could instead be a culture-reactive idiom of distress, originating from biopsychosocial disequilibrium and cultural upheaval. The impact of imposed social withdrawal due to the Coronavirus 2 severe acute respiratory syndrome (SARS-CoV-2) pandemic on the growing prevalence of HLID has not yet been adequately explored. Aims: The first objective is to examine the factorial validity of the 25-item Hikikomori Questionnaire (HQ-25) in Oman. Second, we aimed to investigate the prevalence of HLID following the lifting of SARS-COV-2 restrictions in the Arabian Gulf country of Oman. The third related objective is to examine factors associated with the variation of HLID.

METHODS

This cross-sectional online survey was widely distributed across the diverse socio-demographic population residing in Oman. After the validation of the questionnaire and the factorial validity, the Arabic version of HQ-25 was used to explore the prevalence and factors associated with HLID.

RESULTS

A total of 1529 participants were included in the study (response rate = 76.5%), of whom 44% (n = 673) expressed HLID. We randomly split it into half, one for exploratory factor analysis (EFA) (n = 764) and the other half for confirmatory factor analysis (CFA) (n = 765). From the EFA results, a three-factor model was found for the Omani version of HQ-25, which represented 52.87% of the variance with good internal reliability (Overall Cronbach's: 0.92; Socialisation: 0.92; Isolation: 0.84; Emotional support: 0.73). The CFA results report acceptable goodness-of-fit indices (χ2/df = 17.92, p < .001; CFI = 0.90; TLI = 0.95; RMSEA = 0.04, 95% CI 0.02-0.07; SRMR = 0.05) of the three-factor model of the collected samples. All 1529 data were used in the respondents. The results of the logistic regression showed that married marital status (OR = 1.51, 95% CI: 1.12-2.03, p = 0.007), older age (OR = 0.97, 95% CI: 0.95-0.99, p = 0.008), living in an urban area (OR = 0.71, 95% CI: 0.56-0.91, p = 0.006), unemployed occupational status (OR = 1.72, 95% CI: 1.30-2.88, p < .001), screen time (7+ hours vs. <4 hours: OR = 4.50, 95% CI: 3.16-6.41, p < .001; 4-7 hours vs. <4 hours: OR = 2.10, 95% CI: 1.61-2.70, p < .001), history of mental illness (OR = 3.70, 95% CI: 2.29-5.91, p < .001), and adverse childhood experiences (OR = 2.60, 95% CI: 2.03-3.20, p < .001) were significant risk factors for HLID.

CONCLUSION

The factorial validity of the HQ-25 performed in this study appears to mirror the previously reported 3-factor structures. Some of the associated factors appear to support and, conversely, dissent from the findings of previous studies. These are discussed in terms of the attributions of the SARS-COV-2 pandemic, demographic trends in Oman, and sociocultural factors specific to the region of interest.

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.

Physical health risks of middle-aged people with low social independence: fatal diseases in men, and little attendance to cancer screenings in both sexes

Background

The existence of social withdrawal (Hikikomori), which meets the conditions "not attending school", "not working", and "isolated at home for more than 6 months", is gradually being discovered by the world, and their mental health and healing is being highlighted. However, there are very few Hikikomori-related surveys searching their physical health, as it is generally believed that most Hikikomori are adolescents. Middle-aged Hikikomori are also found outside Japan, and their physical health is more important, because Hikikomori have difficulty managing their health due to the socially isolated circumstances and lack of sociability. Although "isolated at home for more than 6 months" could not be used, we extracted a group with low social independence with reference to Hikikomori-related surveys. We estimate that people with low social independence have similar characteristics and problems to Hikikomori, because they share many causes for the problem of difficulty in managing their own health. People with low social independence were identified, and their physical health, such as smoking and drinking status, consultation rates of various diseases, and how often they attend cancer screenings, was analyzed.

Methods

We extracted middle-aged people with low social independence and a control group from the national survey in Japan and stratified them by sex and age. Their health risks were assessed by univariate analysis. Criteria for the experimental group were set with reference to Hikikomori-related surveys. Criteria for the control group included "aged 40-69", "living with parents", "not receiving care for disabilities", and "working".

Results

Low-social-independent men had higher consultation rates for diabetes, stroke or cerebral hemorrhage, myocardial infarction or angina, gastric and duodenum diseases, kidney disease, anemia, and depression, while lower consultation rates for dyslipidemia and hypertension. The tendency of non-smoking and non-drinking was found among them. They seldom attended cancer screenings. Low-social-independent women had higher consultation rates for liver and gallbladder diseases, other digestive diseases, kidney diseases, anemia, osteoporosis, and depression. The tendency of non-drinking was the same as men. More heavy smokers were found among those aged 40-49 years, with no significant differences in other age groups. They seldom attended cancer screenings, as well as men.

Conclusions

In terms of current physical health, low-social-independent men have more fatal diseases. Both sexes with low social independence seldom attend cancer screenings and have an increased risk of developing progressive cancer in the future. At least in terms of non-smoking and non-drinking, they live healthier lives than the control group, and what makes low-social-independent men have various fatal diseases is still unclear.

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.

Psychometric Properties of the Italian Version of the 25-Item Hikikomori Questionnaire for Adolescents

Hikikomori is a form of social withdrawal that is commonly described as having an onset during adolescence, a life stage when other psychiatric problems can also emerge. This study aimed to adapt the 25-item Hikikomori Questionnaire (HQ-25) for the Italian adolescent population, examining its psychometric properties; associations between hikikomori and psychoticism, depression, anxiety, problematic internet use (PIU), psychotic-like experiences (PLEs), to confirm convergent validity of the HQ-25; and the interaction effect between symptoms of hikikomori and PIU in predicting PLEs. Two-hundred and twenty-one adolescents participated in the study. Measures included the HQ-25, the Psychoticism subscale of the Personality Inventory for the Diagnostic and Statistical Manual of Mental Disorders, the Depression and Anxiety subscales of the Brief Symptom Inventory, the Internet Disorder Scale, and the Brief Prodromal Questionnaire. Data showed a satisfactory fit for a three-factor model for the HQ-25 that is consistent with the original study on the HQ-25. Three factors (socialization, isolation, and emotional support) were associated with psychopathology measures. Six participants reported lifetime history of hikikomori. Symptoms of hikikomori and PIU did not interact in predicting PLEs. This is the first study to validate the HQ-25 in a population of adolescents. Findings provide initial evidence of the adequate psychometric properties of the Italian version of the HQ-25 for adolescents.

Preliminary study of the social withdrawal (hikikomori) spectrum in French adolescents: focusing on the differences in pathology and related factors compared with Japanese adolescents

BACKGROUND

Social withdrawal (hikikomori) has become an internationally recognized phenomenon, but its pathology and related factors are not yet fully known. We previously conducted a statistical case-control study on adolescent patients with hikikomori in Japan, which revealed the non-specificity of pathology in patients with hikikomori. Further, environmental factors, such as the lack of communication between parents and Internet overuse, were found to be significant predictors of hikikomori severity. Here, we aimed to conduct a similar preliminary case-control study in France and to compare the results with those from the study conducted in Japan.

METHODS

Parents of middle school students who underwent psychiatric outpatient treatment for hikikomori (n = 10) and control group parents (n = 115) completed the Child Behavior Checklist to evaluate their child's psychopathological characteristics and the Parental Assessment of Environment and Hikikomori Severity Scales, as in our previous study in Japan. We compared the descriptive statistics and intergroup differences in France with those from the previous study conducted in Japan. In the multiple regression analysis to find predictors of hikikomori severity in French and also Japanese subjects, the same dependent and independent variables were chosen for the present study (both differed from the previous study). These were used in order to make accurate intercountry comparisons.

RESULTS

The comparisons revealed no differences in the pathology of hikikomori between Japan and France. Specifically, both studies found similarly increased scores for all symptom scales, with no specific bias. However, the statistical predictors of hikikomori severity in France (lack of communication between parents and child and lack of communication with the community) differed from those in Japan (lack of communication between parents).

CONCLUSION

Hikikomori in Japan and France could be considered essentially the same phenomenon; moreover, our findings demonstrated the universal non-specificity and unbiasedness of the hikikomori pathology. This suggests that hikikomori is not a single clinical category with a specific psychopathology; instead, it is a common phenotype with various underlying pathologies. However, different strategies may be required in each country to prevent the onset and progression of hikikomori.