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Table 2 All studies included in the review

From: Understanding the experiences of hikikomori through the lens of the CHIME framework: connectedness, hope and optimism, identity, meaning in life, and empowerment; systematic review

Author(s)
(year)
Participants
(N)
Mean age, ethnicity, and gender
(mean years ± SD), (Male vs Female)
Instruments used Key findings
Intervention studies
Lee et al. [3] Socially Withdrawn Youth (N = 41), Middle/High School Students (N = 239) 16.4 ± 3.5, 16.3 ± 1.5
Korean
31, 10
Only data on clinical withdrawal characteristics were extracted
Global Assessment Functioning Scores (GAF) (Continuous scale; scored 0–100)
 Higher score = Higher level of day-to-day functioning
 Score of 41–50 = any serious impairment in school/work/social functioning
 Score of 51–60 = moderate difficulty in school/work/social functioning
Minimum duration of social withdrawal identified as 3 months
Internet usage (Mean hours ± SD): 5.20 ± 3.40
Overall GAF Scores for all participants before and after the home visitation psychotherapy intervention (Mean ± SD):
 Pre 44.6 ± 11.1 to post 53.4 ± 13.2, p < 0.001
48.8% of socially withdrawn youth showed no change in GAF scores post intervention
Malagón-Amor et al. [39] Socially Withdrawn Adults (N = 190) 39.1 ± 18.1
Spanish
136, 54
Self-developed questionnaire assessing social network of relationships
Sociodemographic data and clinical history were extracted from the patients’ files
No statistically significant difference in social networks at the following time points:
 4 months: p = 0.200
 8 months: p = 0.947
 12 months: p = 0.991
Chan [75] Hidden Youth (N = 502) 12–21 years
Chinese
384, 118
Self-developed questionnaire assessing participation in therapeutic activities
Empowerment Scale per Rogers et al. (28-Likert items; scored 20–80)
  Higher score = levels of empowerment
Psychological Capital Questionnaire (24-Likert items; scored 21–126)
 Higher score = higher psychological well-being
Relationships by Correlations and P-values of Hikikomori Play Therapy to:
 Empowerment = 0.59, p = 0.0000
 Psychosocial well-being = 0.60, p = 0.0000
Level 3 Hierarchical Regression:
 Empowerment = 9.56, p = 0.0000
 Play Therapy = 0.64, p = no statistical significance
No scale scores were reported
Law et al. [74] Youth
(N = 373)
12–29 years
Chinese
171, 202
Used a proxy checklist as per Uchida and Norasakkunit to measure social withdrawal (4-item yes/no answers) Decrease in social withdrawal by 4.61%
No scale scores reported for socially withdrawn youth
Yokoyama et al. [18] Hikikomori
(N = 5)
16–35 years
Japanese
1, 4
Self-developed survey administered post intervention C-BED intervention:
Decrease in anxiety, increase in willingness to participate post intervention
No measurement scales used in the study
Cross-sectional studies
Koyama et al. [62] Hikikomori (N = 19), Community Residence (N = 1641) 20–49 years
Japanese
14, 5
Face-to-face household survey assessing sociodemographic data, hikikomori symptoms, and psychiatric history Demographic data of males and females from Japan, age 20–49
Kondo et al. [40] Hikikomori
(N = 337)
24.2 ± 5.4
Japanese
252, 85
Psychiatrists elicited information on sociodemographic data and psychiatric history during consultations Education level (%):
 Junior High: 34.4%
 High School: 39.5%
 University/College: 25.5%
Demographic data of males and females from Japan, with a mean age of 24
Nagata et al. [64] Hikikomori (N = 27), Patients with Social Anxiety Disorder
(N = 114)
27.4 ± 7.5
Japanese
12, 15
Information on sociodemographic data and psychiatric history were elicited from retrospective clinical data Sociodemographic data on the distribution of males and females from Japan, with a mean age of 27, and with 11.7 ± 1.7 years of education; however, it was unclear whether the data on education included the preschool years
Umeda and Kawakami [63] Hikikomori (N = 15), Community Residence (N = 693) 36.3 ± 11.1, 30.1 ± 8.6
Japanese
10, 5
Face-to-face population-based survey conducted in metropolitan, urban, and rural areas of Japan assessing sociodemographic data, hikikomori symptoms, psychological history, childhood social class, parental psychological history, and childrearing practices Education level (%):
Junior High: 3.8%
High School: 71.4%
University/College: 24.8%
Demographic data on males and females from Japan, with a mean age 36
Krieg and Dickie [37] Hikikomori (N = 24), University Students (N = 59) 22.84 years, 20.59 years
Japanese
14, 10
Trait Shyness Scale (16-Likert items; scored 16–80)
Maternal Attachment Scale
 Insecure/avoidant attachment subscale (8-Likert items; scored 1–4)
 Insecure/ambivalent attachment subscale (7-Likert items; scored 1–4)
Parental Rejecting Behavior Scale
 Ignoring subscale (1-Likert item; scored 1–7)
 Threaten subscale (1-Likert item; scored 1–7)
 Lock-out subscale (1-Likert; scored 1–7)
 Composite score (Sum of subscale scores)
Peer Rejection Scale (1-Likert item; scored 1–8)
Maladjustment to School Scale
 Difficulty with adjusting to peer group work (1-Likert item; scored 1–7)
All Japanese versions. Higher score = higher disturbance/intensity
Hikikomori vs University students for various scales (Mean ± SD):
Shyness score: 52.83 ± 12.27 vs 46.89 ± 9.76
Maternal attachment
 Avoidance score: 2.21 ± 0.70 vs 2.09 ± 0.71
 Ambivalence score: 2.08 ± 0.75 vs 1.51 ± 0.51
Parental rejection score
 Locking out score: 3.58 ± 2.21 vs 3.21 ± 2.37
 Threatening loss of relationship score: 3.71 ± 1.94 vs 2.05 ± 1.61
 Ignoring score: 3.00 ± 2.09 vs 2.15 ± 1.57
 Composite score: 10.29 ± 4.44 vs 7.41 ± 4.02
Peer rejection: 3.85 ± 2.31 vs 2.41 ± 2.15
Maladjustment to school: 4.50 ± 1.62 vs 3.20 ± 1.85
Hikikomori Correlation and P-values:
 Shyness: 0.285, p < 0.05
 Ambivalent maternal attachment: 0.400, p < 0.01
 Adjustment to middle school: 0.391, p < 0.01
 Parental rejection: 0.302, p < 0.01
 Threatened loss of relationship: 0.405, p < 0.01
 Ignoring: 0.219, p < 0.05
 Peer rejection: 0.287, p < 0.01
Chan and Lo [60] Hidden Youth
(N = 588)
12–30 years
Chinese
373, 215
World Health Organization Quality of Life scale-brief (WHOQOL-BREF)
(28-Likert item; scoring 0–112)
Higher score = Higher Quality of Life
Hidden Youth QOL Correlations and P-values
 Low level of social withdrawal = 0.550, p = 0.0000
 High level of social withdrawal = -0.850, p = 0.0000
WHOQOL-BREF scores not reported
Malagón-Amor et al. [59] Hikikomori
(N = 164)
40.0 ± 18.3
Spanish
121, 43
Information on sociodemographic data and psychiatric history were elicited from clinical data on consultations Sociodemographic data on the distribution of males and females from Spain
Uchida and Norasakkunkit [58] Hikikomori (N = 114), NEET (N = 86), Employed Adults (N = 7525) 20–39 years
Japanese
NEET Hikikomori Risk Scale
 Unclear ambitions (2-items; scoring 0–12)
Higher score = Higher level of unclear ambitions
Hikikomori vs NEET vs Employed Adults (Mean ± SD)
Unclear ambitions:
5.48 ± 1.60 vs 5.05 ± 1.41 vs 4.26 ± 1.37
Frankova [61] Hikikomori (N = 35), Control group (N = 28) 18–40 years
Ukrainian
14, 21
Chaban Quality of Life Scale (10- item scale, scoring not reported, newly developed scale from Ukraine)
Higher score = Higher Quality of Life
Hikikomori (with and without psychiatric comorbidities) vs Control group
 11.7 ± 2.70; p = 0.001 and 13.7 ± 3.3; p = 0.001, vs 19.3 ± 3.50
Chauliac et al. [38] Socially Withdrawn Youth
(N = 66)
23.2 ± 4.75
French
53, 13
Data on clinical withdrawal characteristics extracted from patient records (Frequency only) Relationships maintained (%) with:
 Family: 63%
 Friends: 8%
 Family and friends: 8%
 Family and sentimental/school: 3%
 None: 19%
Going on outings (%):
 Alone: 38%
 Accompanied: 35%
 None: 27%
Poor hygiene (%):
 Yes: 33%
 No: 67%
Yuen et al. [41] Hikikomori
(N = 104)
19.02 ± 3.62
Chinese
62, 42
Self-developed questionnaire to assess sociodemographic data, daily activities, and health history
Modified Berkman–Syme Social Network Index (7 yes/no items; scored 0–7)
 Higher score = higher connectedness
Types of Daily activities (Mean hours ± SD):
Sleeping: 7.83 ± 1.99
Computer use: 5.09 ± 4.97
Tablet/mobile use: 3.11 ± 5.03
Eating: 1.90 ± 1.03
Reading comics/animations: 0.95 ± 2.38
Watching television: 0.90 ± 1.13
Other reading: 0.65 ± 2.09
Idling/Facing the wall: 0.40 ± 0.99
Social Network Index (Mean ± SD): 2.79 ± 1.80
Yong and Nomura [43] Hikikomori (N = 58), Non-Hikikomori (N = 3024) 15–39 years
Japanese
38, 20
Interpersonal difficulties assessed by 4 yes/no questions:
 Fear of meeting others (Q1)
 Anxiety about meeting familiar people (Q2)
 Anxiety about people’s impression of oneself (Q3)
 Cannot blend into groups (Q4)
Hikikomori vs non-hikikomori (% Interpersonal difficulties; p-value):
 Overall = 74.1 vs 36.0; < 0.001
 Q1 = 36.2 vs 8.1; < 0.001
 Q2 = 48.3 vs 7.1; < 0.001
 Q3 = 51.7 vs 28.3; < 0.001
 Q4 = 53.4 vs 14.6; < 0.001
Social class of hikikomori (%)
 Upper: 3.4%
 Middle: 77.6%
 Lower: 19.0%
Wu et al. [42] Socially Withdrawn Adults (N = 168), Non-Socially Withdrawn Adults (N = 258) 28.82 ± 0.60
Taiwanese
78, 90
Self-developed online survey assessing sociodemographic data, social withdrawal behavior, and psychiatric history Education:
 Bachelor Level: 90.0%
Lived in areas of (%):
 Low income: 72.6%
 Middle income: 18.5%
 High income: 3.6%
Longitudinal studies
Yuen et al. [35] Hikikomori
(N = 104)
19.02 ± 3.62
Chinese
62, 42
Chinese Interpersonal Support Evaluation List (ISEL)- Short version (12-Likert items; scored 0–48)
 Appraisal Support subscale (4-Likert items; scored 0–12)
 Belonging Support subscale (4-Likert items; scored 0–12)
 Tangible Support subscale (4-Likert items; scored 0–12)
 Self-Esteem Support subscale (4-Likert items; scored 0–12)
Higher score = higher social support
Modified Berkman–Syme Social Network Index (7 yes/no items; scored 0–7)
Higher score = higher connectedness
ISEL (Mean ± SD):
 Time points 1–3: 24.60 ± 6.30, 24.63 ± 5.99, 24.75 ± 6.89
 Appraisal Support: 6.81 ± 2.16, 6.90 ± 1.87, 7.11 ± 2.18
 Tangible Support: 6.20 ± 1.71, 6.29 ± 1.53, 6.20 ± 1.73
 Belonging Support: 6.00 ± 2.45, 5.89 ± 2.53, 6.05 ± 2.44
 Self-Esteem Support: 5.59 ± 2.08, 5.55 ± 2.14, 5.38 ± 2.39
SNI (Mean ± SD):
 Time points 1–3: 2.79 ± 1.80, 2.93 ± 2.06, to 3.09 ± 1.87
Pilot case–control studies
Katsuki et al. [65] Hikikomori (n = 22), Non-Hikikomori (N = 18) 33.14 ± 9.33, 37.94 ± 8.93
Japanese
12, 10
Rorschach Comprehensive System; 10-inkblot items, scored as per Takahashi et al. for the Japanese population and scored by a clinical psychologist
 Form Color; higher scores indicate a higher level of passive aggressiveness, a tendency to adjust one’s emotions to the environment and people, an inclination to suppress the expression of emotions when feeling shaken in social situations
SumT; total number of texture-related responses, higher scores indicate a need for and an openness to forming close emotional relationships
Hikikomori vs Non-hikikomori (Mean ± SD):
 Form Color: 2.50 ± 1.68 vs 1.39 ± 1.14, p = 0.037
 SumT: 0.50 ± 0.67 vs 0.11 ± 0.32, p = 0.033
Mixed-method studies
Chan and Lo [60] Hidden Youth
(N = 363)
21.11 ± 2.93
Chinese
244, 119
Self-developed survey assessing sociodemographic data
 Relationships with Parents Scale as per Zeng and Zeng’s (8- items; scored:?)
 Relationships with Siblings Scale as per Zeng and Zeng’s (7-items; scored:?)
 Relationships with Teachers as per Deng; Xu and Ma’s (7- items; scored:?)
 Relationships with Peers as per Deng; Xu and Ma’s (9- items; scored:?)
 Rosenberg Self-Esteem Scale (10-Likert items; scored 0–30)
  Higher score = higher self-esteem; < 15 = low self-esteem, ≥ 15 = high self- esteem
Self-esteem of Hidden Youth in Correlations and P-values with a good relationship with:
 Parents = 0.73, p = 0.0000
 Siblings = 0.66, p = 0.0000
 Teachers = 0.13, p < 0.05
 Peers = 0.16, p < 0.05
No scale scores were reported
Chan [76] Hidden Youth
(N = 502)
12–24 years
Chinese
384, 118
Self-developed questionnaire assessing sociodemographic data and uses of counselling services
World Health Organization Quality of Life scale-brief (WHOQOL-BREF) Taiwan Version (measured well-being after receiving counselling services)
Young Person’s CORE (10- Likert items; scored 0–40)
Lower score = positive results
Qualitative Semi-structured interviews assessing perceived advantages & usefulness of three forms of counseling
Total Quality of Life scores (Mean ± SD):
 Online counselling: 3.02 ± 0.43
 Offline counselling: 2.52 ± 0.27
 Integrated counselling: 3.74 ± 0.60
Young Person’s Core (Mean ± SD):
 Online counselling: 1.56 ± 1.29
 Offline counselling: 0.62 ± 0.42
 Integrated counselling: 2.59 ± 1.18
Interview results: online counselling offered platform for communication while offline counselling offered opportunity for mediation during conflicts between youth and their family
Chan [55] Hidden Youth
(N = 357)
12–30 years
Chinese
Self-constructed questionnaires assessing forms of communication and friendship levels
Miller Social Intimacy Scale as per Miller & Lefcourt (17 items; scored: 17–170)
Higher scores = higher levels of social intimacy
Qualitative semi-structured interviews assessing how youth choose usage of forms for communication
Forms of communication used:
 Public text: People you only know (100%); Friends (100%); Good friends (100%); Best friends (100%)
 Public voice: People you only know (3.2%); Friends (49.0%); Good friends (100%); Best friends (100%)
 Public camera meeting: People you only know (0%); Friends (6.0%); Good friends (91.6%); Best friends (100%)
 Private text: People you only know (3.2%); Friends (43.0%); Good friends (100%); Best friends (100%)
 Private voice: People you only know (3.2%); Friends (30.0%); Good friends (100%); Best friends (100%)
 Private camera meeting: People you only know (0%); Friends (17.0%); Good friends (92.6%); Best friends (100%)
Scores for Miller Social Intimacy Scale not reported
Case studies/series
Hattori [73] Hikikomori
(N = 35)
21.5 years
Japanese
25, 10
Clinical data extracted from clinical records and consultations Recovery time: minimum 2 years
Patient mistrust of therapist
Spent 6–12 months testing the reliability of the therapist. Psychotherapy: 50% attrition rate
Sakamoto et al. [47] Hikikomori
(N = 1)
24 years
Omani
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: confined self at home, spent the majority of time in own room, did not engage in social relationships, reversed sleep/wake cycle, and refused contact with family
Demographic data of a male from Oman, age 24
Teo [49] Hikikomori
(N = 1)
30 years
American
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: confined self at home, spent the majority of time in own room, and did not engage in social relationships. Poor hygiene practices & urinated/defecated in jars/bottles
Demographic data of a male from the United States, age 30
Suwa et al. [51] Hikikomori
(N = 1)
25 years
Japanese
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: exhausted from effort to maintain relationships, inability to relate well with others, fear in entering adult society, no confidence to cope with society, felt ashamed of himself, and feared others opinions of him being unemployed
Ovejero et al. [45] Hikikomori
(N = 1)
25 years
Spanish
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: confined self at home, spent the majority of time in own room, and did not engage in social relationships
Demographic data of a male from Spain, age 25
Teo et al. [36] Hikikomori
(N = 36)
18–49 years
American, Japanese, Korean, & Indian
29, 7
LSNS-6 (6-Likert item, scoring 0–30)
 Measuring social connectedness
 Family subscale (3-Likert items; scored 0–15)
 Friends subscale (3-Likert items; scored 0–15)
 Total overall score > 12 = social isolation
UCLA Loneliness Scale (20-Likert items, scoring 20–80)
Higher score = Higher level of loneliness
LSNS-6 Scale score (Mean ± SD):
 Overall score: 9.7 ± 5.7
 Family score: 5.4 ± 3.0
 Friends score: 4.3 ± 3.5
UCLA Loneliness Scale (Mean ± SD): 55.4 ± 10.5
Demographic data on the distribution of males and females, from across four countries; education level: 56.0% hold a bachelor’s degree or above
Ranieri [46] Hikikomori
(N = 2)
13 years
Italian
2 Females
Clinical data extracted from patient cases Exhibited the following behaviors: confined self at home, spent the majority of time in own room, did not engage in social relationships, and refused contact with family
Demographic data of two females from Italy, age 13
Psychotherapy recovery time 4 years
Kato et al. [44] Hikikomori
(N = 1)
39 years
Japanese
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: confined self at home, spent the majority of time in own room, did not engage in social relationships, avoided face-to-face contact with others, reversed sleep/wake cycle, and left home once a month to visit an outpatient clinic
Demographic data of a male from Japan, age 39
Matsuguma et al. [77] Hikikomori
(N = 1)
17 years
Japanese
1 Male
Rosenberg Self-Esteem Scale (10-Likert items; scored 0–30)
 Higher score = higher self-esteem; < 15 = low self-esteem, ≥ 15 = high self-esteem
Subjective Vitality Scale (measures feelings of alertness or being energized, scoring 0–4)
Higher score = higher vitality
 Higher score = higher vitality
Kessler Psychological Distress Scale (measures anxiety and depression, scoring 10–50)
 Lower scores = lower distress levels
Strength-based coaching intervention pre-post scores:
 Rosenberg Self-Esteem Scale: 16 to 25
 Subjective Vitality Scale: 1.8 to 3.4
 Kessler Psychological Distress Scale: 17 to 6
Ranieri [46] Hikikomori
(N = 1)
Mixed group
19 years

1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: social anxiety, mistrust in parents, inability to approach the opposite gender when interested. Demographic data of a male, age 19
Silic et al. [48] Hikikomori
(N = 1)
24 years
Croatian
1 Male
Descriptive data extracted only Exhibited the following behaviors: confined self at home, spent the majority of time in own room, did not engage in social relationships, refused contact with family, and used furniture to block entry to room to avoid contact
Demographic data of a male from Croatia, age 24
Roza et al. [72] Hikikomori
(N = 1)
35 years
Brazilian
1 Male
Clinical data extracted from a patient case Exhibited the following behaviors: confined self at home, spent the majority of time playing computer games, and did not engage in social relationships. Neglected self-care and hygiene. Demographic data of a male from Brazil, age 35
Qualitative studies
Ogino [56] Hikikomori
(N = ?)
26.7 years
Japanese
Empirical data from 20 h site contact and qualitative interviewing with hikikomori, and staff and group leaders in support group Life experiences: motivation to return to society but obstacles they could not overcome, lack a positive sense of identity; feelings of anxiety, unable to do anything, fear of failure, lacking in self-esteem or self-confidence; having lack of qualifications on resumé; difficulties to explaining themselves to people because lack of social identity; use of intervention called Free Space Wood
Kaneko [52] Hikikomori
(N = 1)
Mid-30’s
Japanese
1 Male
Empirical data of field research and qualitative interviewing Life experiences of: lack of trust in people
Wong and Ying [54] Socially Withdrawn Youth
(N = 88)
13–24 years
Chinese
67, 21
Individual and focus group qualitative interviews Life experiences: intimate relationships online, but no intention of meeting the other person; use of intervention involving social worker engagement, social workers have accompanied socially withdrawn youth to outings to providing sense of security
Recommendations: process of recovery a “yo-yo process” with setbacks of reversal in progress noted; recovery needs to be at pace of youth; a non-linear process; building trust is an important stage in their recovery process; and starting where client is at
Wong [6] Socially Withdrawn Youth
(N = 252)
13–24 years
Chinese
202, 50
Empirical data from clinical data and literature Life experiences: face-to-face interactions only with family members, mother had no face-to-face contact with child for months; use intervention of home visiting withdrawn youth, can have sudden refusal from youth to take part in social activities/face-to-face contact during social worker reengagement
Supplementary data: NEET can be considered hikikomori, but some NEET have an active social life
Recommendations: home visiting requires sensitivity and awareness, recognition when client needs privacy, sensitivity to client’s surroundings provides clues in relation to hobbies/interests which can be topics for discussion during reengage of client
Wong [70] Socially Withdrawn Youth
(N = 30)
15–24 years
Chinese
Individual and focus group qualitative interviews Life experience: sensitive name calling of “withdrawal guys or hidden youth”; self-secluding nature of hikikomori, the majority of care provided in the home; recommendations of “starts where the client is”
Tajan [11] Recovered Hikikomori
(N = 4)
29–50 years
Japanese
3, 1
One-to-one qualitative interviews Life experience: positive and inspiring relationships from meeting someone they trusted, receiving encouragement from someone they knew and liked, feeling that no one would care if they died and living like an animal
Rubinstein [71] Hikikomori
(N = ?)

Japanese
Empirical data from 50 interviews on site of support groups, hikikomori and mental illness communities with parents, children, hikikomori-related program staff and field observation Life experience: parents desired to avoid stigma and labeling of mental illness therefore chose to call their child a hikikomori, even after receiving a psychiatric diagnosis; did not claim that the hikikomori experience was pleasant
Yong and Kaneko [57] Hikikomori
(N = 5)
Proxy respondents
(N = 3)
Online forum participants
(N = 160)
One-to-one qualitative interviews and empirical data extraction from internet forum from first person and second person experiences Life experiences: cautious about establishing relationships over the Internet due to fear and inability to trust people, loss of trust in people, low self-esteem, feelings of hopelessness for future, having non-competitiveness, ineffective communication, lack a positive sense of identity and confidence, negative appraisals from others and self, negative thinking or thoughts of self, fear of social interactions, unable to secure a job, feelings of inadequacy or incompetence, complains society too demanding and unfair, felt unable to do anything, exhibits confinement at home, little social contact
Li and Wong [53] Socially Withdrawn Youth
(N = 30)
14–29 years
Chinese
22, 8
One-to-one semi-structured qualitative interviews Life experiences: lifestyle centered on confinement at home, with little social contact, losing touch with the outside world, lacking face-to-face contact with others, having no peer relationships, unable to get along with others, lack of trust in people, experienced a traumatic life event, use the Internet to find positive self-identity and positive and inspiring, having negative feelings or thoughts, boredom, sense of no longer stand staying at home, a loss of interest in computer games, some enjoying their seclusion and feeling freed from restraints and timelines
  1. vs versus, N Total number of participants, h hours, SD Standard deviation, NEET not in employment, education, or training, QOL quality of life, C-BED community based enterprise component