In the present study, the relationship between implicit identification and the severity of self-injury in adolescent patients with a diagnosis of NSSI was investigated. The result showed that, apart from borderline personality, implicit identification with self-harm had an independent influence on the severity of NSSI in these patients. Adolescent with stronger implicit identification with self-injury, in addition to more pronounced inclinations towards borderline personality, faces high risk of severe NSSI.
Despite the increasing incidence of NSSI among adolescents and the growing concern it has generated, its underlying mechanism remains undefined, making preventive measures against it difficult to implement. Previous research suggests that various factors, including individual characteristics (such as age, gender, personality traits, mood disorders, and mental health problems), social factors (such as school environment, internet use), and family factors (such as family structure, parenting styles, and upbringing), are associated with the mechanism of NSSI, and that NSSI may be the product of a combination of factors[4, 5, 24, 25].
Previous research has identified depression and anxiety as risk factors for NSSI. A survey conducted by ElaPolek et al. on individuals aged 14–26 in the general population found that those with higher levels of anxiety had a 3–7 times greater risk of suffering from NSSI compared to those with low anxiety levels[26]. However, this association has not been verified in further research[27]. Consistent with previous research, the present study found that the level of anxiety was significantly higher in the group with severe NSSI as compared to the group with mild NSSI[28]. However, the multiple variable logistic regression analysis revealed that the effect of total anxiety score on self-harm severity was no longer significant. This is consistent with Eikelenboom M et al.'s conclusion that anxiety is not correlated with NSSI[27]. The correlation between anxiety and NSSI may be moderated by underlying factors.
The correlation between borderline personality and NSSI is relatively well established and has been widely confirmed in previous research[29]. Recent research indicates that borderline personality is as stable in adolescents as it is in adults[30]. Early intervention for adolescents with borderline personality disorder is crucial in preventing self-harm and suicide. Additionally, this study highlights the importance of screening for borderline personality disorder in adolescent patients with a clinical diagnosis of NSSI.
Previous assessments of risk factors for NSSI have typically relied on self-reports by individuals, and the accuracy is often poor for some individuals who deliberately conceal their true thoughts or have poor self-awareness[31–33]. As a result, some experts propose that the combination of explicit measures based on subjects' self-reports and implicit measures of NSSI attitudes may be more conducive to accurate assessment of the influencing factors of NSSI[34–36]. Multiple studies have demonstrated that the NSSI adolescent population has a significantly stronger identification with self-harming behavior than their non-NSSI peers[22, 23, 37]. The present study found that although all adolescents were diagnosed with NSSI, there were differences in their implicit identification with NSSI. Some even received negative D scores, reflecting the complex psychological mechanisms underlying NSSI. After categorizing the patients based on the severity of their NSSI, it was found that the D scores of the severe NSSI group were significantly higher than those of the mild NSSI group. The effect on NSSI severity remained significant after adjustment in logistic regression analysis. However, in a study that examined both explicit and implicit identification with the stigma of NSSI, Marilyn L et al reported that explicit identification were associated with the severity of NSSI, whereas implicit identification were not, which was in contrast to the findings of the present study[38].The difference in results between these two studies may be due to the fact that the participants in their study were ordinary college students. NSSI was defined as having committed at least one self-injurious act, which made the conditions for inclusion liberal. In contrast, the participants in this study were all patients with NSSI who were interviewed by psychiatrists and accurately diagnosed according to DSM-5 diagnostic criteria. Therefore, the conclusions drawn may be representative of the real clinical situation. In addition, it is important to note that the participants in the current study were adolescents, whereas the participants in the previous study were adults, resulting in significant differences in psychological maturity between the two populations. Therefore, the discrepancies between the results of the two studies reflect differences in the psychological mechanisms of the NSSI population at different ages.
The Cognitive Emotion Theory model of NSSI suggests that it can serve as a strategy for regulating emotions. Whether or not a person will engage in self-harm lies in the individual's outcome anticipation and self-efficacy expectations. If an individual anticipates a positive outcome from NSSI, they may engage in it to avoid risk or regulate their mood during emotional disturbances. As the individual's anticipation is achieved, his risk of engaging in repeated NSSI increases significantly, as does the frequency and severity of NSSI[39]. It may explain the association between the D-score and the severity of NSSI.
The present study has several limitations. Firstly, the results of the study may be potentially biased due to the limited sample size and cross-sectional design. Secondly, this study only included adolescents with NSSI who attended to the psychiatric outpatient clinic, and the severity of their symptoms and the degree of attention paid to their condition by their families tends to differ markedly from that of the general population of adolescents with NSSI. Therefore, due to the selective bias of the study population, the potential risk of generalizing our results should be considered. Thirdly, there was a marked gender imbalance in the participants of the present study, and although this is consistent with the clinical reality that NSSI is more common in women, we did not investigate the potential impact of gender-specific NSSI, which needs to be investigated in the future.