The moderating role of neighborhood social cohesion in the mediation effects of the loneliness between acculturation stress and post-traumatic growth among female North Korean defectors

Loneliness negatively predicts post-traumatic growth (PTG) among North Korean defectors (NKD), one of the representative groups of refugees. Additionally, evidence also suggests that females, who account for 70% of NKDs entering South Korea, are vulnerable not only to past trauma but also to the current acculturation stress and loneliness affected by neighborhood social cohesion. This study explores whether the mediating effect of loneliness on the relationship between acculturation stress and PTG was moderated by the neighborhood social cohesion among female NKDs. In this study, the data of 166 female NKDs who completed an online survey regarding acculturation stress, PTG, loneliness, and neighborhood social cohesion were used. Moderated mediation analysis was conducted using SPSS PROCESS macro program. Loneliness was associated with PTG (B = − 1.896, p < 0.001), and mediated the association between acculturation stress and PTG (indirect effect = − 0.278, 95% LLCI − 0.403, 95% ULCI − 0.166). Neighborhood social cohesion moderated the mediation effect of loneliness on the association between acculturation stress and PTG (B = − 0.016, 95% LLCI 0.001, 95% ULCI 0.035). The indirect effect of acculturation stress on PTG through loneliness was notably high for those with low neighborhood social cohesion. Therefore, increasing neighborhood social cohesion would reduce loneliness caused by acculturation stress and support the positive growth among female NKDs. This represents the most effective approach to aiding female NKDs in achieving growth, even after suffering trauma.

By the year 2021, approximately 33,000 North Korean defectors (NKDs), a group that characterizes refugees and immigrants, had entered South Korea, driven by reasons such as seeking freedom from the oppressive regime's surveillance and control, facing food shortages, and striving to provide their families with better living conditions, of which more than 70% comprise females 1 .The prevalence of female NKDs has notably increased, surpassing that of male 2 as they have comparatively easier movement between regions and access to border areas in neighboring countries such as China 3 .Generally, NKDs have been exposed to extreme trauma such as witnessing other's deaths, experiencing life-threatening poverty, inhuman treatment, and the fear of repatriation to North Korea in the process of escaping from North Korea.Additionally, female NKDs are exposed to even

Measures
Post-traumatic growth PTG was measured using the Korean version of Post Traumatic Growth Inventory (PTGI), which assesses the degree of growth after traumatic experiences.The initial PTGI consisted of 21 items that were grouped into five factors (personal strength, new possibilities, improved relationships, spiritual growth, and appreciation for life) 13 .The Korean version of PTGI was ultimately revised to 16 items grouped into four factors (changes in selfperception, increase in interpersonal depth, finding new possibilities, and the increase in spiritual interest) after conducting a factor analysis 43 .The 16 items of the scale are rated on a 6-point Likert scale ranging from 0 to 5. The total score is calculated by summing all item scores.The possible score range is 0-80 points, with higher scores indicating more positive post-traumatic changes.The internal consistency of the scale was high in this study (Cronbach's α = 0.932).

Acculturation stress
Acculturation stress was assessed using the Acculturation Stress Scale that was adapted for NKDs 44 .The 33 items of the Acculturation Stress Scale-NKD assess stress from perceived discrimination (six items), homesickness (four items), perceived hate (five items), fear (four items), culture shock (three items), guilt (two items), and nonspecific concerns (nine items) on a 4-point scale from 1 (strongly disagree) to 4 (strongly agree).The total score is calculated by summing all item scores; higher scores indicate greater acculturation stress.The internal consistency of the scale was high in this study (Cronbach's α = 0.933).

Loneliness
Loneliness was measured using the 6-item Revised UCLA Loneliness Scale (RULS-6), revised by Neto in 2014 and validated by Wongparkarn in 2020 25,45,46 .The RULS-6 assesses self-perceived loneliness through feelings experienced in six situations, using a 4 point scale ranging from 1 (strongly disagree) to 4 (strongly agree).Higher total scores indicate higher degrees of loneliness.The internal consistency of the scale was high in this study (Cronbach's α = 0.843).

Neighborhood social cohesion
Neighborhood social cohesion was assessed using the Neighborhood-Level Cohesion and Disorder Scale 47 .The original scale comprised two dimensions with eight items.We used the four items of the social cohesion dimension from the original measurement to confirm the level of neighborhood-level cohesion surrounding the participants (e.g., "I really feel part of this area; most people in this area can be trusted; most people in this area are friendly; if you were in trouble, there are lots of people in this area who would help you").Higher total scores indicate higher levels of neighborhood social cohesion.Internal consistency of the scale was high in this study (Cronbach's α = 0.822).
We also collected data of demographic characteristics to describe female NKD, namely age, marital status, education in North Korea, religion, employment status, monthly income in South Korea, living with family, the year of escape from North Korea, years spent in South Korea, and duration of stay in any third country.

Data analysis
Descriptive statistics (such as means, standard deviations, frequencies, and percentiles) were used to summarize participants' characteristics.Bivariate relationships between continuous variables were evaluated using Pearson's correlation coefficient.We performed a moderated mediation analysis using the SPSS PROCESS macro, version 4.0 (Model 7) 48 .Loneliness was considered as a mediator between acculturation stress and PTG, while neighborhood social cohesion was considered as a moderator between acculturation stress and loneliness.We examined direct, indirect, and interaction effects using bias-corrected bootstrapping in a regression 48 after controlling for covariates identified as factors related to PTG in a previous research 14 , such as religion, living with family, years spent in South Korea, education in North Korea, monthly income in South Korea, and employment status.All data analyses were performed using SPSS 26

Sample characteristics
The mean age of female NKD was 36.8 years (SD = 10.3), and 45.8% were married.Most lived with family (78.3%) and had received an education higher than junior college in North Korea (28.3%).They were predominately religious (55.4%) and employed in South Korea (58.4%), with a monthly income of less than 2000 US Dollars (59.0%).The average duration of their emigration from North Korea was 14.1 years (SD = 6.3) as of 2020.Furthermore, 54.2% and 28.5% of the participants had been staying in South Korea for ≥ 10 and < 5 years, respectively.In addition, 39.8% had stayed in third countries for ≤ 1 year before arriving in South Korea (Table 1).

Acculturation stress, loneliness, neighborhood social cohesion, and PTG
The  1).The bivariate correlation analysis showed that acculturation stress had a significant positive relationship with loneliness (r = 0.619, p < 0.001) and negative relationships with PTG (r = − 0.227, p = 0.003) and neighborhood social cohesion (r = − 0.422, p < 0.001).Loneliness also had negative relationships with PTG (r = − 0.501, p < 0.001) and neighborhood social cohesion (r = − 0.364, p < 0.001).Finally, there was a positive relationship between PTG and neighborhood social cohesion (r = 0.353, p < 0.001) (Table 2).The mediation analysis confirmed the statistical significance of the total effect of acculturation stress on PTG (total effect = − 0.203, p = 0.003, 95% LLCI − 0.333, ULCI − 0.072).There waw no significant direct effect of acculturation stress on the PTG, but acculturation stress indirectly associated with PTG through loneliness (indirect effect = − 0.278, 95% LLCI − 0.403, ULCI − 0.166) (Table 3) (Fig. 1).It means that female NKDs who reported higher levels of acculturation stress also experienced greater feeling of loneliness, which, in turn, were associated with lower levels of PTG after controlling covariates, such as religion, living with family, years spent in South Korea, education in North Korea, monthly income in South Korea, employment status 14  www.nature.com/scientificreports/ We found significant moderation effect of neighborhood social cohesion in the association between acculturation stress and loneliness (Fig. 2).The strength of the positive association between acculturation stress and loneliness was strongest among female NKDs who reported low neighborhood social cohesion.In contrast, for those who reported high level of neighborhood social cohesion, the strength of the association was comparatively weaker.
The mediation effect of loneliness in the relationship was founded to be significantly moderated by the levels of neighborhood social cohesion (moderated mediation effect = 0.016, 95% LLCI 0.001, ULCI 0.035).Among female NKDs, the indirect effect of acculturation stress on PTG through loneliness was notably high for those who reported low levels of neighborhood social cohesion (indirect effect = − 0.325, 95% LLCI − 0.472, ULCI − 0.192).In contrast, the indirect effect of acculturation stress on PTG through loneliness was considerably low

Discussion
In this study, we showed that significant mediating role of loneliness between acculturation stress and PTG.Moreover, we found that neighborhood social cohesion played a crucial moderating role in the mediation effect of loneliness in the association between acculturation stress and PTG in female NKDs.This study provides insight into the potential of community-based approaches to support female NKDs who, as refugees and immigrants, experience acculturation stress and loneliness in South Korea.As anticipated, acculturation stress was strongly associated with loneliness in female NKDs.Similar to the current results, a study on Portuguese immigrants in Luxembourg also reported acculturation stress, specifically cultural identity conflict as a strong predictor of perceived loneliness 49 .Female NKDs who reported higher levels of acculturation stress also experienced greater feeling of loneliness, which, in turn, were associated with lower levels of PTG in this study.However, there exists contradictory research findings on the relationship between loneliness and PTG.For instance, a study involving war veterans revealed that higher levels of PTG could paradoxically correlate with increased feelings of loneliness, explained by increased realization of a civilian-military gap.Moreover, the study found that higher level of PTG consistently predicted higher loneliness over time whereas loneliness didn't predict PTG in war veterans 50 .Yet, the experiences of war veterans and NKDs can lead to different forms of loneliness.War veterans may feel a sense of loneliness due to their changed subjective views of reality and the emotional gap between them and civilians caused by the traumatic experiences of war when they return to their original community.On the other hand, North Korean defectors experience loneliness in a new society where they lack social networks, as they have traumatic experiences and are separated from their familiar social connections.Both groups face distinct paths to experiencing loneliness based on their unique backgrounds and challenges.Understanding and respecting these differences is crucial to resolve the relationship between loneliness and PTG.
Contrary to our initial expectations, acculturation stress does not exert a direct impact on PTG among female NKDs.Female NKDs may undergo acculturation stress and PTG in different ways from male NKDs or other refugee populations due to the unique traumatic events they have endured and the challenges they face.Prior research indicates that female NKDs frequently encounter gender-specific forms of trauma, including sexual violence, which may result in additional challenges as they adapt to a new culture and society 3,5 .For the cultural adaptation of refugees and immigrants, language issues have been reported as the most significant source of acculturation stress.In a study focused on Koran American immigrant populations, findings indicated that women experienced greater levels of acculturation stress compared to men, with less proficient in English than men 51 .While the acculturation of refugees and immigrants often involves language-related issues that contribute significantly to acculturation stress, this scenario might differ for female NKDs, who share the Korean language.Nevertheless, the additional burden of traditional caregiving responsibilities typically assigned to women, coupled with economical responsibilities due to the easier job opportunities than men in new societies 3,52 , seems to have contributed to an increased sense of loneliness for female NKDs who lack social resources and networks 30 .In particular, South Korean society is known for experiencing higher levels of loneliness when individuals do not belong to similar groups or lack a sense of community cohesion 53,54 .Particularly, during the process of raising children, female NKDs often encounter emotional challenges due to inadequate understanding of the highly competitive and academically driven educational environment, weak connections with other fellow parents, and www.nature.com/scientificreports/ a lack of support resources 55 .Consequently, it is crucial to carefully account for the distinctive experiences of female NKDs when interpreting the present data.
To the best of our knowledge, this is the first study to reveal a notable moderating effect of neighborhood social cohesion on the relationship between acculturation stress and loneliness.Low neighborhood social cohesion amplified the positive link between acculturation stress and loneliness for female NKDs, while high cohesion weakened this association.Our study suggests that female NKDs could benefit significantly from social support within local and neighboring communities.Increasing the level of neighborhood social cohesion emerged as a key strategy to improve several dimensions of refugee life through improving daily activities, psychological states, and other health-related indicators 35,56 .To advance neighborhood social cohesion, the cooperation of community resources, informal networks, and multidisciplinary expert groups including psychiatry, nursing, and psychology is required 57 .In particular, based on understanding the characteristics of the original community culture, establishing a direct social network through multidisciplinary cooperation was identified as an important step in building community for new refugees in Canada 58 .Similarly, female NKDs acquired psychological comfort through exchange with their local or neighboring communities and the associated social support 42 .A potential source of social support may be informal networks of family, friends, and neighbors.These individuals may offer practical assistance such as help with transportation or housing, as well as emotional support and a sense of belonging.In a qualitative research, NKDs initially acquired an emotional belonging and stability through forming the relationship with South Koreans 59 .Local religious or faith-based communities also may provide a supportive environment for female NKDs.Studies of the adaptation patterns of female NKDs to South Korean society have also shown that they cope with adaptation through the formation of internal communities as one of their strategies 17 .
For stable adaptation and growth as a member of the South Korean society for female NKDs, an interventional approach is needed to enhance neighborhood social cohesion with external neighbors or communities that form part of their own internal network resources.Even after intensive South Korean social adaptation program led by the Ministry of Unification in the early days of entry 17 , it is necessary to focus on forming a human network to bond with neighbors and communities during each settlement period 60 .The community-based organizations or support groups would provide a safe and supportive space for individuals to share their experiences and connect with others who have similar backgrounds.These groups may provide emotional support, practical assistance, and opportunities for socialization and community involvement.Therefore, it is crucial to develop programs and strategies that leverage the strengths of female NKDs and foster an environment where they can coexist and support one another in connection with community in religious organization, workplace, and school 60 .This can be achieved by harnessing the knowledge, assistance, and leadership skills of female NKDs who have undergone similar experiences 24 .Additionally, establishing an easily accessible mental health system capable of identifying and promptly addressing feelings of loneliness and other psychological issues among female NKDs is essential 61 .Facilitating emotional connections with new neighbors or communities can greatly contribute to the adaptation and personal growth of female NKDs in South Korea.Overall, there are many potential sources of social support for female NKDs, and the specific types of support that may be most beneficial may vary depending on individual needs and preferences.It is important for interventions and support programs to be tailored to the specific needs of this population and to take into account their unique experiences and challenges.
Although the findings of this research are valuable, this study has some limitations.First, the use of a crosssectional approach in this study restricts the ability to establish causal relationships between acculturation stress, loneliness, and PTG over time.To address this, future research should adopt a longitudinal design to capture temporal associations accurately.Second, while the study focused on female NKDs in South Korea, the relatively small sample size of 166 participants might limit the generalizability of findings.A more diverse participant pool, including female NKDs from different geographical contexts (e.g.China, South East countries etc.), is necessary to broaden the study's applicability.Lastly, relying solely on quantitative methods might not fully capture the intricate aspects of PTG among female NKDs.A more comprehensive understanding can be achieved by incorporating qualitative methods, allowing for a deeper exploration of intrinsic factors like resilience and coping strategies.
In conclusion, our research emphasizes the importance of neighborhood social cohesion and its interplay with loneliness in shaping the relationship between acculturation stress and PTG among female NKDs.Cultivating a sense of neighborhood social cohesion holds a key role in alleviating the loneliness triggered by acculturation stress and in fostering the process of personal growth for female NKDs.This approach would stand as a potent avenue to empower female NKDs, enabling them to navigate growth and surmount the enduring impact of past traumas effectively.

Figure 1 .
Figure 1.The moderation effect of neighborhood social cohesion in the mediation effect of loneliness between acculturation stress and post-traumatic growth in female North Korean defectors.

Figure 2 .
Figure 2. The moderated effect of neighborhood social cohesion on the association between acculturation stress and loneliness.

Table 1 .
. Characteristics and PTG comparison according to demographic characteristics of female North Korean defectors (N = 166).§PTG = Post-traumatic growth.

Table 3 .
Moderated mediation effect of neighborhood social cohesion and loneliness on the association between acculturation stress and PTG with (Model 7 and Model 4).§Covariates were religion, living with family, years spent in South Korea, education in North Korea, monthly income in South Korea, employment status.PTG Post-traumatic growth, SE Standard error, LLCI Lower bound of confidence interval, ULCI Upper bound of confidence interval.