Psychiatry Research ∎ (∎∎∎∎) ∎∎∎–∎∎∎

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Letter to the Editor

Psychopathology associated with social withdrawal: Idiopathic and comorbid presentations To the Editors: Social withdrawal is a significant concern among psychiatrists and researchers as it presents in a variety of psychiatric disorders and impedes recovery from mental illness. One form of social withdrawal that has been most commonly described in Japan is hikikomori. It is characterized by persistently reclusive behavior and has a lifetime prevalence of 1–2% in East Asian countries (Koyama et al., 2010; Teo and Gaw, 2010; Wong et al., 2014). Substantial debate exists over whether hikikomori is a unique psychiatric condition or a cultural concept of distress that reflects other underlying psychopathology. However, prior studies have been limited by lack of validated diagnostic interviews, unclear operationalization of hikikomori, and data collection solely in Japan. In this study across two cultures, we aimed to determine what co-morbid psychiatric diagnoses are associated with hikikomori and if idiopathic (or “primary”) hikikomori exists. Eligibility and recruitment of participants have been reported in detail elsewhere (Teo et al., 2015). In brief, participants with social withdrawal were recruited from psychiatric hospitals and clinics in Japan and online advertisements in the U.S. This study presents results from the 22 participants who completed all diagnostic assessments, 11 each from Japan and the U.S. This study was approved by the institutional review boards of each site, and all participants provided written informed consent. To assess for hikikomori, we conducted an interview following criteria adapted from our earlier proposed definition (Teo and Gaw, 2010). We operationalized hikikomori as at least 6 months of (1) spending most of the day and nearly every day at home; (2) avoiding social situations, such as attending school or going to a workplace; (3) avoiding social relationships, such as friendships or contact with family members; and (4) significant distress or impairment due to social isolation. Diagnoses of psychiatric disorders were determined by the Structured Clinical Interview for the DSM Disorders (SCID). Participants completed both the SCID-I (Patient Version) with Psychotic Screen, which assessed for 36 Axis I diagnoses, and the SCID-II, which included the nine Axis II personality disorders, according to Diagnostic and Statistical Manual-IV-Text Revision criteria. In addition, we included a self-report measure, the Internet Addiction Test (IAT). The IAT consists of 20 items with a total score range from 20 to 100; suggested cutoffs are available for signs of mild/ typical (20–49), moderate (50–79), or severe (80–100) internet use. Given the small sample size, statistical analysis was limited to descriptive statistics, comparison of means by a t-test, and comparison of proportions by a chi-square test. Participants were on average 29 years old (S.D.¼6.4), 77% (n¼17) were male, 41% (n¼9) graduated from a 2- or 4-year college, and the mean duration of their longest period of social withdrawal was 0165-1781/Published by Elsevier Ireland Ltd.

2.7 years (S.D.¼2.4). As shown in Table 1, the five most common lifetime psychiatric diagnoses in this sample were avoidant personality disorder (41%, n¼9), major depressive disorder (32%, n¼7), paranoid personality disorder (32%, n¼7), posttraumatic stress disorder (27%, n¼ 6), and social anxiety disorder (27%, n¼6). The majority of participants, 68% (n¼15), fulfilled criteria for multiple psychiatric diagnoses: 59% (n¼13) had three or more, and 9% (n¼2) had two diagnoses. Another 9% (n¼2) had a single diagnosis. Twenty-three percent (n¼ 5) did not meet the criteria for diagnosis of any psychiatric disorder contained in the SCID-I and SCID-II. All of these participants were from Japan. Compared with Japanese participants, U.S. participants were more likely to have a mood disorder

Table 1 Lifetime psychiatric diagnoses in participants with a history of hikikomori (n¼ 22). Diagnosis

Japan n

United States n

Total n


4 2 2 1 2 1 2

5 5 5 5 4 3 2

9 7 7 6 6 4 4

41 32 32 27 27 18 18

0 0 0 2 2 0 0 2 0 0 0 0 0

4 3 3 1 1 2 2 0 2 1 1 1 1

4 3 3 3 3 2 2 2 2 1 1 1 1

18 14 14 14 14 9 9 9 9 5 5 5 5

Avoidant personality disorder Major depressive disorder Paranoid personality disorder Posttraumatic stress disorder Social anxiety disorder Dysthymic disorder (current only) Obsessive–compulsive personality disorder Specific phobia Alcohol abuse or dependence Cannabis abuse or dependence Obsessive–compulsive disorder Panic disorder Binge eating disorder Bipolar disorder, type I Dependent personality disorder Schizoid personality disorder Antisocial personality disorder Agoraphobia without panic disorder Borderline personality disorder Depressive disorder not otherwise specified Generalized anxiety disorder (current only) Narcissistic personality disorder Other bipolar disorder Schizotypal personality disorder Stimulant abuse or dependence Substance-induced anxiety disorder





1 0 1 0 0

0 1 0 1 1

1 1 1 1 1

5 5 5 5 5

Multiple psychiatric diagnoses No psychiatric diagnoses

4 5

11 0

15 5

68 23

Percentages total more than 100% as participants may have more than 1 disorder. Participants were evaluated for a current or past (unless otherwise specified) history of 45 Axis I and Axis II psychiatric disorders using the SCID-I and SCID-II and according to Diagnostic and Statistical Manual-IV-Text Revision criteria. Diagnoses with a frequency of zero are excluded.


Letter to the Editor / Psychiatry Research ∎ (∎∎∎∎) ∎∎∎–∎∎∎

(po0.01), substance use disorder (p¼0.04), and anxiety disorder (p¼0.02). The mean score for the IAT in our overall sample was 39 (S.D.¼23). Scores were slightly higher among U.S. subjects (mean¼43, S.D.¼21) than Japanese subjects (mean¼35, S.D.¼25), but this difference was not statistically significant (p¼0.41). Nearly 60% of the sample (n¼13) scored in the lowest category, nine (41%) in the moderate category (only one of whom was in the group with no SCID-I and SCID-II diagnoses), and none in the severe category. Taken together, the results suggest individuals with hikikomori commonly have a history of psychiatric comorbidity, but idiopathic hikikomori also exists. Two possible explanations for our finding of idiopathic hikikomori only among Japanese participants are that (1) Japanese preferentially self-report symptoms of social withdrawal over other psychiatric symptoms and (2) some features of Japanese culture promote the development of hikikomori in the absence of other diagnosable psychiatric conditions (Teo et al., 2014). Study limitations include small sample size, potential for selection bias and observer bias, lack of formal assessment for autism spectrum disorders, and inability to determine whether hikikomori preceded onset of psychiatric disorders. We suggest that a future population-based study could (1) help establish the relative prevalence of idiopathic versus co-morbid hikikomori and (2) determine how frequently the onset of hikikomori pre-dates other psychiatric disorders. Acknowledgments and disclosures This study was supported by grants to Dr. Kato from the Japan Society for the Promotion of Science (KAKENHI 26713039) and World Psychiatric Association, as well as a grant to Drs. Kato, Tateno, and Teo from the Pfizer Health Research Foundation. Drs. Saha and Teo were supported by the Department of Veterans Affairs. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the United States government. All authors report no competing interests.

Teo, A.R., Gaw, A.C., 2010. Hikikomori, a Japanese culture-bound syndrome of social withdrawal? The Journal of Nervous and Mental Disease 198 (6), 444–449. Teo, A.R., Stufflebam, K., Kato, T.A., 2014. The intersection of culture and solitude: the hikikomori phenomenon in Japan. In: Coplan, R.J., Bowker, J.C. (Eds.), A Handbook of Solitude: Psychological Perspectives on Social Isolation, Social Withdrawal, and Being Alone. Wiley-Blackwell, Oxford, pp. 445–460. Wong, P.W., Li, T.M., Chan, M., Law, Y., Chau, M., Cheng, C., Fu, K., Bacon-Shone, J., Yip, P.S., 2014. The prevalence and correlates of severe social withdrawal (hikikomori) in Hong Kong: a cross-sectional telephone-based survey study. The International Journal of Social Psychiatry 24, 0020764014543711, electronic publication.

Alan R. Teo n, Somnath Saha VA Portland Health Care System and Oregon Health & Science University, Portland, OR, USA E-mail address: [email protected] (A.R. Teo) Kyle Stufflebam University of Chicago, Chicago, IL, USA Michael D. Fetters Japanese Family Health Program and Department of Family Medicine, University of Michigan, Ann Arbor, MI, USA Masaru Tateno Department of Neuropsychiatry, Sapporo Medical University, Sapporo, Japan Shigenobu Kanba Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan Takahiro A. Kato Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan

References Koyama, A., Miyake, Y., Kawakami, N., Tsuchiya, M., Tachimori, H., Takeshima, T., 2010. Lifetime prevalence, psychiatric comorbidity and demographic correlates of “hikikomori” in a community population in Japan. Psychiatry Research 176 (1), 69–74. Teo, A.R., Fetters, M.D., Stufflebam, K., Tateno, M., Balhara, Y., Choi, T.Y., Kanba, S., Mathews, C.A., Kato, T.A., 2015. Identification of the hikikomori syndrome of social withdrawal: psychosocial features and treatment preferences in four countries. International Journal of Social Psychiatry 61 (1), 64–72.

n Corresponding author. 3710 SW US Veterans Hospital Road (R&D 66), Portland, OR 97239-2964, USA. Tel.: þ1 503 220 8262x52461.

Psychopathology associated with social withdrawal: Idiopathic and comorbid presentations.

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