According to the definition of the International Society for the Study of Self Injury, NSSI is a self-inflicted damage of body tissue made deliberately without suicidal intent that is culturally unacceptable (1). Common forms of NSSI include cutting, burning, scratching, peeling of the skin, and hitting (2). Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has included NSSI in the section of disorders that requires further research studies and has provided research diagnostic criteria for NSSI (3).
NSSI is considered a serious mental health problem, especially among the youth, which has been reported in 13-24% of the general population and in about 35% of college students (4) (5). In a study conducted on 2,130 adolescents, the prevalence of NSSI, was reported as 6.7% (6). Also, the overall prevalence rate in the community varies between 7 and 47% (7) (8) (9). The Global Burden of Disease Study (2015) by measuring the disability-adjusted life year (DALY), reported the rate of self-injury as 471.1 per 100,000 persons (10). NSSI is associated with a wide range of negative outcomes including mental health problems, mood disorders, anxiety, substance abuse, psychotic and personality disorders as well as committing suicide (11) (12) (13) (14) (15) (16) (17) (18) (19) (20).
Longitudinal studies show that lack of proper emotion regulation leads to self-injury behaviors.
Emotion regulation has often been noted as the most important reason for NSSI in most studies (21) (22). Self-injury explanatory models suggest that this behavior is an abnormal external way of regulating and modulating unpleasant emotions. In a study, odds ratio (OR) of the relationship between NSSI and emotional disorders was reported as 1.75 (95% CI= 1.49, 2.06) (23) (24). In Gratz and Roemer study (25), the correlation between emotion dysregulation and self-injury was reported as 0.20 in women and 0.26 in men. Research has repeatedly shown that both in the general community and in clinical settings, self-injury behaviors occur more commonly in people who have difficulties in emotion regulation (26) (27) (28). However, most studies have not measured the relationship between emotion dysregulation and self-injury.
One of the most comprehensive definitions of emotion regulation considers this as a multidimensional structure that includes: A) awareness, recognition, and acceptance of emotions; B) ability to avoid impulsive behaviors and behave in line with desirable goals while experiencing negative emotions; C) modifiable use of strategies in different situations to manage the intensity or duration of emotional responses so that the individual can achieve individual goals and situational demands; D) desire to experience negative emotions as part of pursuing meaningful activities in life (25) (29) (30).
Perez, Lorca, and Marco study (26) showed that NSSI has relationship with lack of emotional clarity (r= 0.7), rejection of emotion (r= 0.41, P< 0.01), and interference with goal-directed behavior (r= 0.4, P< 0.01). Also it should be noted that regarding the relationship between self-injury and emotion dysregulation is that self-assessment studies have supported this relation (31) and have shown high levels of negative emotion in such individuals (20). For instance, Glenn, Blumenthal, Klonsky et al. (32) reported that patients with a history of NSSI reported higher emotional sensitivity using the Emotional Reactivity Scale (mean= 16.48) compared to those without such history (mean of 10.090, P= 0.004). Also, Bresin (33) showed that in a 14-day period, subjects with NSSI showed more negative emotion and fewer positive emotions than the group without NSSI. In Tuna and Gençöz study (34), subjects with history of NSSI had less self-compassion using the self-compassion scale (mean= 62.62, p<.001) and more difficulties in emotion regulation using the difficulties in emotion regulation scale (mean=95.88, p<.001).
But diary, experimental, neuropsychological, and longitudinal studies (35) (36) (37) (38) (32) (39) (36) often failed to demonstrate this pattern (28) (40). For example, Longitudinal study of Franklin, Puzia, Lee et al. (41) found that early self-assessment of emotional reaction significantly distinguishes NSSI from non-NSSI, but does not predict NSSI occurrence over the next six months. Fox (40) states that although emotional dysregulation is not a strong predictor of NSSI in the future, it is a significant risk factor in short time (e.g., during the following month). Also, there is controversy regarding the relationship between different types of emotion regulation strategies (42), such as cognitive reappraisal (43) (44), problem solving, avoidance, suppression (43) (45) and NSSI.
In two review articles (46) (47) and in several systematic reviews the relationship between NSSI and emotion regulation has been examined. Some studies have demonstrated approximately related to the relationship between NSSI and emotion regulation (48) (49) (50) (51) (52) (23) (53) (54) (55) (56) (39) (57) (58) (59). As far as we know, Others are completely related to the relationship between NSSI and emotion regulation (60) (61) (62) (63) (64) (65) (66) (67).
Dixon-Gordon, Harrison, and Roesch (50) stated that although environmental control is the most prominent function of NSSI in relational studies, emotion regulation seems to be the primary motivation for performing this high-risk behavior. However, controversy exists regarding different strategies of emotion regulation. In this regard, Brereton and McGlinchey (61) reported a significant relationship between NSSI with emotion dysregulation, experiential avoidance/suppression. However, another study (68) noted that accepting emotions can lead to self-injury behaviors. Also, Jutengren, Kerr, and Stattin (69), reported a partial relationship between experiential avoidance and self-injury. These mixed findings highlight the importance of further studies to explore the relationship between experiential avoidance and self-injury, especially in adolescence. Wolff, Thompson, Thomas et al. (64) reported a significant association between emotion dysregulation and NSSI (pooled OR of 3.03, 95%CI= 2.56, 3.59). In this study, the subscales of emotion dysregulation including impulse control problems, non-acceptance of emotional responses, limited access to emotion regulation strategies, and problems with goal-related behavior were more strongly associated with NSSI. On the other hand, lack of knowledge/emotional clarity and cognitive aspects of emotion dysregulation had less significant, but still positive with NSSI. In another systematic review, Cleare, Gumley, and O’Connor (62) concluded that self-compassion and self-forgiveness were associated with lower levels of NSSI. Several studies also suggested that self-compassion and self-forgiveness weaken the relationship between negative life events and self-injury. However, Suh and Jeong (60) reported a small effect size between self-compassion and NSSI. In addition, McHugh, Chun Lee, Hermens et al. (63) examined the relationship between impulsivity and self-injury in young patients (with an average age less than 30 year) and concluded that some aspects of impulsivity are related to suicidal behavior in young adults. Therefore, it is suggested that subsequent studies should examine the relationship between different subtypes of impulsivity and self-injury. All in all, by reviewing of the findings of these studies, considering the diversity of emotion regulation strategies and emotion dysregulation and mixed results, it seems necessary to conduct a comprehensive study on this topic.
To the best of our knowledge, there are 8 systematic review and meta-analysis studies focused completely on the relationship between the emotion dysregulation and emotion regulation strategies and NSSI (61) (62) (66) (67) (63) (65) (64) (60). Only two of them used the priori principle. All of these studies imposed language restrictions. Most of them did not include grey literature as a source for searching the primary studies or used limited grey literature. In limited numbers of these reviews, all these three steps including selection, quality assessment, and data extraction were duplicated (i.e., repeated twice which is recommended by guidelines for conducting a robust systematic review). In addition, a limited range of search key terms were used.
Therefore, given the importance of this research topic in psychology and the conflicting results regarding the effect that study design and its approach can have on the relationship between emotion regulation and NSSI and moreover the conflicting results on some types of emotion regulation strategies with NSSI mentioned earlier, we intend to comprehensively examine the relationship between emotion regulation strategies and NSSI. In this systematic review and meta-analysis, we will try to include grey literature and wider range of search key terms and duplicating selection, quality assessment, and data extraction with the objective to overcome some of the limitations of previous reviews. Additionally, if possible, we will be trying to explore the relationship between emotion regulation and NSSI based on study type and design, emotion regulation strategies, and other variables by performing subgroup analysis. In addition, the evaluation of possible heterogeneity among the primary studies and finding its potential causes will be performed.
The primary objective of this review study is to investigate the relationship between emotion regulation strategies and non-suicidal self-injury (NSSI).
Secondary objectives are:
To investigate the relationship between emotion regulation strategies and NSSI based on study approach (cross-sectional, retrospective, and longitudinal).
To investigate the relationship between emotion regulation strategies and NSSI based on gender.
To investigate the relationship between emotion regulation strategies and NSSI based on age groups.
To assess heterogeneity in the results of the primary studies and to examine the potential causes.
To investigate the relationship between emotion regulation strategies and NSSI based on different types of emotion regulation strategies.
To investigate the relationship between emotion regulation strategies and NSSI based on various tools used in the primary studies to measure emotion regulation strategies.