The Japanese term Hikikomori was used for the first time by Saito in 1998 [1]. This term designates the extreme, voluntary, and prolonged (6 months or more) withdrawal of adolescents and young adults to their home, avoiding social contacts, school, or professional activities [1,2]. In the literature, this term is usually translated as “social withdrawal” but also as “youth social withdrawal,” “housebound syndrome,” or “claustration syndrome.” In Japan, the term Hikikomori refers to both the phenomenon and the person affected by this withdrawal. Currently, the term Hikikomori is applied to individuals who do not leave their rooms or homes, and to individuals who are able to go out locally or for their hobbies but most often stay home [3]. In the lit-Print ISSN 1738-3684 / On-line ISSN 1976-3026 OPEN ACCESS erature, there is a distinction between “primary Hikikomori,” which presents no comorbidity, a “pure” form of social withdrawal, and “secondary Hikikomori,” which occurs due to a known mental disorder [4].

The first prevalence study was performed in Japan, where, in 2006, lifetime prevalence was estimated at 1.2% [5]. Hikikomori has now been identified in many other countries, such as Hong Kong, Spain, France, India, Korea, Ukraine, and the United States [6-10], and can be conceptualized as a “culturally boundless syndrome of modern society [11].” Despite heterogeneous results across studies, there are several common Hikikomori characteristics: onset around the age of 20 years with a largely male predominance [5,12], urban area living [6], and mostly occuring in high-income, developed countries, with a strong maternal presence [12-14]. Previous studies have reported that most Hikikomori who seek treatment in a health care centers have also suffered from a psychiatric disorder during their lifetime [5,15-17]. Nevertheless, whether it is the psychiatric disorders that generate the social withdrawal or whether the social withdrawal is the cause of the psychiatric disorders remains unclear [18].

Beyond psychiatric comorbidities, several studies have investigated the psychological functioning of individuals with Hikikomori, especially looking at personality. Some studies that evaluated personality disorders found a strong relationship between Hikikomori and avoidant personality disorder [19] or passive-aggressive personality disorder [20]. Other studies that focused on personality traits found difficulties in identifying and verbalizing emotions among individuals with Hikikomori [10,21]. Indeed, people with Hikikomori are more likely to express emotions indirectly and expect others to implicitly understand their feelings and thoughts [20]. More recently, Amendola et al. [22] found a strong relationship between Hikikomori and overall personality dysfunction. Nevertheless, only a few studies have investigated personality traits and none have done so according to the most dominant framework for measuring them: the Big Five personality traits. Indeed, the Big Five Inventory is one of the tools most widely used internationally to assess dimensions of personality.

Family relationships and their involvement in social withdrawal have been a subject of high interest in research on Hikikomori. However, the results have been heterogeneous regarding the presence or not of dysfunctional family functioning as a cause or consequence of Hikikomori [12,23]. Insecure attachments, especially avoidant and ambivalent attachment, have been associated with Hikikomori [24], highlighting vulnerability to situations of rejection. Indeed, social withdrawal often comes as a consequence of difficult socializing experiences, perceived as failures and avoided thereafter. Social withdrawal can also be linked to rejection of social success ideals [25] or to traumatic experiences such as school bullying or sexual abuse [26], thus instilling fear and distrust of the outside world amongst these individuals.

Experiences of failure, loneliness, and worthlessness are currently known suicide motives in Hikikomori [27]. Hikikomori can be seen as an expression of contemporary suffering on entering adulthood due to social and family pressures on youth in which the requirements for success are high [14]. Thus, some investigators have proposed that Hikikomori may be a (maladaptive) strategy to cope with the stress caused by social judgment [18]. Although the behavioral repertoire of families who cope with individuals with Hikikomori have been investigated [28], only one study has evaluated the different adjustment strategies used by the Hikikomori themselves. Thus, Nonaka and Sakai [29] found that Hikikomori was associated with the use of instrumental support and behavioral disengagement coping strategies. As highlighted by the authors, these findings need to be replicated in cultures outside of Japan to clarify whether there are cultural specificities in the psychological functioning of Hikikomori.

Thus, the aim of the present study was to explore the relationships between personality dimensions, coping strategies, and social withdrawal while controlling for the presence of depression and anxiety. Given that social withdrawal may be a sign of depression itself and may be seen as a marker of anxiety, and that the period during which the current study took place during the coronavirus disease-2019 (COVID-19) pandemic was associated with an increase in anxiety and depression due in part to isolation from others [30], it was important to control for the possible effect of psychological distress.

Descriptive data for the whole sample are presented in Table 1. The proportion of females and males in our two samples was equivalent, but the Hikikomori group was significantly younger than the control group (F(1)=5.44, p=0.021, d=0.54). Participants of the Hikikomori group were significantly more alone than those in the control group (φc=0.24, p=0.005) and less involved in social participation (φc=0.41, p<0.001).

The Hikikomori group had higher depression and anxiety scores than the control group did, with a large effect size (F(1)=54.74, p<0.001, d=1.10 and F(1)=53.08, p<0.001, d=1.14, respectively). None of the control group had a score of probable or severe depression or anxiety (Table 2).

Regarding personality dimensions, participants from the control group had significantly higher extraversion (F(1)=56.15; p<0.001; d=1.52), assertiveness (F(1)=33.06; p<0.001; d=1.24), energy level (F(1)=75.37; p<0.001; d=1.68), agreeableness (F(1)=4.97; p=0.027; d=0.46), compassion (F(1)=15.01; p< 0.001; d=0.78), conscientiousness (F(1)=15.69; p<0.001; d=0.81), responsibility (F(1)=23.41; p<0.001; d=0.99), openness (F(1)=4.45; p=0.037; d=0.46), and creative imagination (F(1)=5.05; p=0.026; d=0.47) scores than did those from the Hikikomori group, with effect size ranging from medium to large. In contrast, participants from the Hikikomori group had higher neuroticism (F(1)=16.65; p<0.001; d=0.89) and anxiety (F(1)=20.05; p<0.001; d=1.41) scores than did those from the control group, with a large effect size.

Regarding coping, participants from the Hikikomori group had significantly lower scores on the problem-focused coping dimensions, especially active coping (F(1)=11.69; p=0.001; d=0.73) and instrumental support (F(1)=18.73; p<0.001; d=1.00). They also had significantly lower scores on some emotion-focused coping dimensions: emotional support (F(1)=10.19; p=0.002; d=0.66), positive reframing (F(1)=15.55; p=0.014; d=0.87), acceptance (F(1)=9.91; p=0.002; d=0.67), humor (F(1)=5.55; p=0.020; d=0.54), and venting (F(1)=14.89; p<0.001; d=0.88). Finally, regarding the dysfunctional coping dimension, participants from the Hikikomori group had higher scores on self-blame (F(1)=8.29; p=0.005; d=0.56) and behavioral disengagement (F(1)=34.52; p<0.001; d=1.06) than did those from the control group.

Two factors were positively associated with Hikikomori (Table 3), being alone (OR=14.75, p=0.047) and depression (OR=1.94, p=0.030), respectively. In contrast, Hikikomori was negatively associated with extraversion (OR=0.04, p=0.013) and instrumental support (OR=0.11, p=0.011).

To date, only a few studies have investigated the personality dimensions of Hikikomori and only one has explored coping strategies. The aim of this study was to explore the relationships between Hikikomori, personality, and coping while taking into account depression and anxiety.

Our Hikikomori sample had an equal proportion of male and female participants, in contrast to the male predominance highlighted in several previous studies [5,12]. Furthermore, our results showed that sex is not a risk factor associated with being Hikikomori, in line with a recent study that found a similar proportion of Hikikomori men and women [38]. Another interesting result was that even though individuals of the Hikikomori group were less involved in social participation than the control group, some of them did work. Thus, as in previous studies [9,10,38,39], some Hikikomori prefer to avoid social participation but are engaged in it by obligation, mostly for financial reasons.

Our results on personality dimensions showed higher neuroticism scores in the Hikikomori group, especially on the anxiety facet. This result is in line with the self-reported case study of Chong and Chan [40] that suggested that having an introverted personality plays a crucial role in a person becoming Hikikomori. Previous studies have found a relationship between neuroticism and a negative attitude toward events [41] that have interpersonal consequences. Indeed, individuals with high neuroticism scores tend to be less satisfied with their relationships overall [42-46] and have higher social deprivation [47]. Regarding relationships, intrapersonal theories [48] suggest that neurotic individuals “think in ways that lead to more negative perceptions of their interpersonal experiences, regardless of the objective quality of those experiences [49].” Personality shapes individuals’ perceptions of the world around them [50]; thus, the general tendency of neurotic individuals to experience negative emotions [51], especially in the interpersonal domain, could lead to avoidance of social situations and relationships (i.e., Hikikomori). Consequently, it is not surprising that extraversion was negatively associated with Hikikomori. Indeed, previous studies have demonstrated the influences of individuals’ personality on their environment and vice versa (individuals influence their environment and are, in return, influenced by their environment). For example, extraverted individuals may create a positive social environment through their own positive demeanor and may then be positively reinforced by their environment for their extraverted personality [52], because they are appreciated for it. Thus, in agreement with the state-effect model [53], one hypothesis is that the lack of contact with the environment (i.e., the lack of extraversion, extraversion which is negatively associated with Hikikomori in our study) may cause short-term personality changes as a result of their current Hikikomori disorder (i.e., Hikikomori have higher neuroticism scores but this personality dimension is not associated with Hikikomori). A longitudinal study is necessary to confirm this hypothesis.

Participants from the Hikikomori group also had significantly higher depression scores, and depression was positively associated with the risk of being Hikikomori. This result is similar to that of a previous study in which individuals who were reported to be lonely, isolated, or neurotic—as well as any combination thereof—were more depressed than were those who did not have these characteristics; the individuals in that study also had higher social deprivation [48]. Our results are similar to other studies that have highlighted a strong relationship between depression and both loneliness [54-56] and neuroticism [57,58]. In our study, being alone was highly associated with being Hikikomori (it increased the risk by almost 15 times).

Compared with members of the control group, Hikikomori used significantly more dysfunctional coping strategies, especially self-blame and behavioral disengagement, and less problem-focused and emotion-focused coping strategies. In the qualitative study of Yong and Kaneko [59], social withdrawal appeared to be a passive way of coping with existing problems. This coping type could be seen as a “specific adaptation to contemporary competitive social changes and the human relationships these changes produce [59].” It may be a way of creating a safe place where events are more predictable and less challenging. Taken together, our results confirm that neurotic individuals are “prone to cope more poorly than others with stress,” as posited by Costa and McCrae [51].

As in previous studies that found a relationship between ineffective coping styles and poorer mental health [60], Hikikomori tend to criticize themselves for a perceived sense of responsibility for the situation (self-blame) and tend to withdraw when faced with a stressful situation (behavioral disengagement). This is in line with a study on social anxiety in which frequent engagement in dysfunctional coping strategies was associated with higher degrees of social anxiety and related social impairment [61]. Thus, as suggested by Tran and Haaga [62] for social anxiety, Hikikomori cope with their anxiety by fleeing stressful situations. Nevertheless, in agreement with the results of Nonaka and Sakai’s study [29], only instrumental support was negatively associated with Hikikomori. According to the selfesteem and identity models, social support has an impact on self-esteem which contributes to less psychological distress [61]. Nevertheless, the inclination to use social support is linked to personality [61]. For example, individuals with poor social abilities will have difficulty accepting help without feeling inferior. Given the strong effect of self-esteem on depression [63] and the relationship between depression and Hikikomori in our study, it seems necessary to better understand the links between these variables.