Non-suicidal self-injury (NSSI) is defined as the deliberate direct destruction or alteration of body tissue without conscious suicidal intent[1]. In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), this diagnosis is denoted as a “ condition for further study”[2]. Globally, the lifetime prevalence of at least one episode of NSSI in adolescence is 17–18%[3] [4]. In China, a recent study reported that 33.7–51% of community youths engage in self-injurious behavior[5]. Moreover, a meta-analysis showed that individuals with mood disorders (anxiety, depression, bipolar, and related disorders) are at higher risk of NSSI compared to normal controls[6]. In an adolescent psychiatric sample, the prevalence of one-time-only NSSI behavior was as high as 60%, and the incidence of recurrent NSSI was approximately 50%[7]. A better understanding of the underlying mechanisms and risk factors for adolescent NSSI is crucial to inform prevention and intervention efforts. Although several risk factors for NSSI have been identified previously[8], there are few published studies on the effects of the external environment on adolescent NSSI. This paper attempts to explore the influence of early family environment and peer relationships on the NSSI of adolescents
Childhood trauma includes abuse and neglect by family members, especially primary caregivers[9], and has been identified as an important risk factor for the occurrence of NSSI[10] [11]. Neglect can be divided into two categories[12]: (1) physical neglect, where the basic requirements for the child’s survival are not met, such as nutrition and shelter; (2) emotional neglect, where the basic psychological needs of the child are neglected or diluted. Abuse can be divided into the following categories: (1) physical abuse, which is intentional and violent physical injury; (2) emotional abuse, which refers to verbal and other mental attacks that harm a child’s health, including attacks on self-confidence, insults, and other behaviors that hinder a child’s normal growth; (3) sexual abuse, defined as an adult using violence, inducement, or other methods to engage in any form of sexual behavior with a child[13] [14].
The interdependent parent-child relationship is a unique feature of Chinese society and family relationships play an irreplaceable role in the lives of Chinese children[15]. According to attachment theory, children function best when in a safe environment created by their parents. However, if a child does not feel safe, a child’s mind attempts to reduce the threats and create safety by fighting, fleeing, or freezing[16]. When adolescents are exposed to danger, decisions are made instantaneously by the brain; this process primarily involves conditioned responses formed during early childhood rather than complex processes performed by higher-order parts of the brain that are not fully formed until early adulthood (i.e., the prefrontal and anterior cingulate cortex, the parts of the brain responsible for language, associative, and regulatory functions)[17]. That is, the early environment also affects adolescents' coping styles and behaviors when facing risks. To sum up, childhood experiences also have a fundamental role in subsequent development that cannot be ignored[15]. Importantly, a recent meta-analysis found that adverse childhood experiences have significant independent effects on self-harm[18] [19]. Further, several studies have indicated that childhood trauma can directly or indirectly lead to the development of NSSI[20] [21]. Although there is a time lag, the association between childhood trauma and NSSI in adolescence is significant.
Peer victimization is when an individual is repeatedly and chronically bullied or victimized by one or more peers[22], including: (1) physical victimization, involving physical attacks by peers; (2) verbal victimization, involving verbal abuse by peers; (3) social victimization, involving bullying by peers in a personal relationship; and (4) property victimization, involving stealing or destruction of property by peers[23]. Individuals who have experienced peer victimization have a greater risk of NSSI[24]. In the highly developed modern society, the psychological growth of adolescents is inseparable from the establishment of social relationships with family members, peers, and teachers; peer relationships account for a large proportion of the life of adolescents[25]. The influence of peer relationships on adolescents should not be ignored. According to interpersonal suicide theory (ITS), the desire to die may increase if a sense of burden and frustrated belonging is perceived in core interpersonal interactions, and this desire then leads to self-injury and suicidal behavior Furthermore, integrative motivation-volition theory (IMV) suggests that negative life events, especially feelings that can be internalized as shame or frustration in interpersonal relationships, can lead to feelings of entrapment and subsequent suicidal thoughts and plans[26]. In a study of depressed adolescents, Vergara GA et al. reported that severe peer victimization and bullying led to NSSI[27]. Similarly, in another study, negative peer experiences were found to predict NSSI trajectories in depressed adolescents[28]. In summary, there is considerable evidence for a causal relationship between peer victimization and NSSI[29] [30].
In China, the saying goes ‘a single silk does not make a thread; a single tree does not make a forest’. Collectivism has always been a prominent characteristic of Chinese culture[31]. Even in modern society, there is a continuing cultural association between collectivism and some life domains[31]. In other words, Chinese people are more connected to the people around them, whether it is their family or friends. Several studies have reported that Chinese people have a higher level of dependency compared to people in Western countries[32]. Therefore, relationships between people are of extraordinary significance to the Chinese. Moreover, childhood trauma and peer victimization can be considered to be two different types of interpersonal trauma in adolescent life[33], both of which involve emotional and physical abuse[34] [23]. Therefore, we hypothesized that childhood trauma and peer victimization may play significant roles in adolescent emotional and behavioral problems.
Although the correlation between childhood trauma and NSSI has been well confirmed in previous studies, to date, few studies have examined the mediating factors and underlying mechanisms of this relationship[35]. One of the existing studies found that adolescents who experienced more childhood abuse were also more likely to report peer victimization. In this prospective study, females who suffered childhood trauma (child sexual abuse) were at increased risk of peer victimization. Still, there is a need to explore in more depth the intrinsic links between childhood trauma, peer victimization, and NSSI. Further, at present, the majority of studies on family relationships, friendships, and NSSI are based on Western samples; these relationships have rarely been explored in the Chinese context. Due to the differences in the construction of society and the influence of traditional culture, there may be important differences between Chinese adolescents’ perceptions of interpersonal relationships and the importance they place on them, as compared to their Western counterparts. The cultural differences between Western and Chinese societies cannot be ignored when exploring the relationships between childhood trauma, peer victimization, and NSSI. In order to explore these relationships in a Chinese sample, this study utilized structural equation modelling (SEM). SEM is a data analysis tool that combines path analysis[36] and the common factor model[37]. It can verify a conceptual model and a study’s research hypotheses by specifying relations among observed entities and hypothesized latent constructs[38]. Latent variable models allow researchers to address research questions that directly compare the viability of dimensional, categorical, and hybrid conceptions of constructs and provide greater validity and generalizability by allowing for the correction of measurement error, as compared to methods based on observed variables[39]. SEM has been widely used as a powerful analysis tool in psychiatric research.
In summary, it was hypothesized that there are links between childhood trauma, peer victimization, and NSSI. Thus, the current study explored the mediation effect of peer victimization on the relationship between childhood trauma and NSSI using SEM.