Self-harm is a major public health problem (1) and adolescents are particularly at risk (e.g., (2). The international lifetime estimate of self-harm among adolescents was 17% (3), and the international 12-month prevalence was 10–19% in a large review of 52 studies on self-harm (4). Girls engage more in self-harm than boys (3, 5). A study from seven different countries showed that both the lifetime and the 12- month prevalence of self-harm was three times larger among adolescent girls compared to adolescent boys (6).
Previous research suggests that bullying victimisation is a risk factor for self-harm (7) (8) (9). Yet, not all adolescents who experience bullying harm themselves. This study aims to better understand the link between bullying and self-harm.
In this study, we use a definition of self-harm from the World Health Organization (WHO)/EURO multicentre study (10), where all non-accidental medically treated self-poisoning and self-injury not resulting in death, regardless of intention, are included. Thus, self-harm are defined as: “The act of hurting oneself, with non-fatal outcome, in which an individual deliberately initiates a non-habitual behaviour that, without intervention from others, will cause self-harm or deliberately ingests a substance in excess of the prescribed or generally recognized therapeutic dosage, and which is aimed at realizing changes that the person desires via the actual or expected physical consequences” (10, 11).
Risk factors for self-harm is a complex interplay of genetic, biological, psychological- and environmental factors (1). This included the psychological factors depression, anxiety, aggression, and low self-esteem (12), and exposure to emotionally traumatic events such as sexual abuse, violence, early parental separation loss, family/parental conflicts, school academic problems and bullying (13) (14). Many studies confirm that bullying victimisation, which refers to being a victim of aggressive behaviour or intentional harm, repeatedly over time, and which involves an imbalance in power (15), is associated with self-harm (8) (5). Verbal bullying by peers, in particular, seems to have a strong association with self-harm among adolescents (16). (5) found that girls who were bullied were three times as likely to engage in self-harm as others, while bullied boys were twice as likely.
One reason for the strong association between bullying victimisation and self-harm may be that both are associated with emotional problems such as anxiety, and depression (17). Bully victimisation is linked to increased feelings of anxiety and depression, and several studies have shown that self-harm works as an affect-regulation function by decreasing negative emotions (18) (19). Thus, negative emotions may mediate the relationship between bullying victimisation and self-harm (19) (20). In addition, a large study of Irish adolescent boys showed that school-related problems, physical abuse, worries about sexual orientation and serious conflicts with parents heighten the risk of self-harm among those who were bullied (9).
Few studies, however, appear to have investigated possible protective factors for self-harm in the face of bullying. Studies that did, found that parental- and family support (9) (21) and authoritative parental style (8) moderated the relationship between self-harm and bullying. There appears to be a lack of research investigating protective factors outside of the family such as support from friends, and school well-being (including teacher support). These protective variables could potentially have a moderating effect on the relationship between self-harm and bullying behaviour.
Interestingly, studies indicate that it is not only the experience of being bullied that is associated with self-harm, but also the experience of bullying others (21). Adolescents who bully are at increased risk of aggressive and delinquent behaviours, school failures, and dropping out of school on the one hand, but also at increased risk of depression and suicidal ideation on the other (22) (23). In addition, Barker and colleagues found that bullies had an increased risk of engaging in self-harm, especially if they also had a history of being bullied, so-called “bully-victims” (22). However, little is known about the mechanisms between bullying behaviour and self-harm.
In addition, few studies have considered the protective effects of social support from parents, friends and school (including teacher support) on the relationship between bullying others and self-harm. Thus, the mechanisms behind bully victimisation, bullying others and self-harm are not fully understood.
In this study, we investigated the relationship between self-harm and 1) being bullied (“bullied”), 2) bullying others (“bullies”) and 3) both being bullied and bullying others (“bully-victims”), and which factors might explain these relationships. Further, we aimed to identify which factors that may moderate the relationship between these bullying behaviours and self-harm.
Hypotheses
We hypothesised that:
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a) Gender (being a girl), socioeconomic differences (having a poor socioeconomic background), having school behavioural problems, experiencing parental conflict and having emotional problems (depression and anxiety) would increase the risk of self-harm and the relationship between 1) being bullied (“bullied”), 2) bullying others (“bullies”) and 3) both being bullied and bullying others (“bully-victims”). Furthermore, these factors would partly explain the relationships between self-harm and the three bullying groups.
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b) Social support from parents, an authoritative parental style/parental monitoring, social support from friends, and school well-being (including teacher support) would protect against self-harm for the three bullying groups. The protective variables (social support from parents, an authoritative parental style, social support from friends, and school well-being) would moderate the relationship between the “bullied”, the “bullies”, the “bully-victims” and self-harm. We expected interaction effects between the protective variables and the three bullying groups on self-harm.