By Dr. Hanna Sahlin, Ph.D. student at the Karolinska Institutet, Stockholm, Sweden
In short, what is the study about?
There has long been a debate on whether individuals who engage in non-fatal deliberate self-harm (e.g., cutting oneself or overdosing) are more prone to aggression towards others. Self-harm linked to aggression toward others has been found in suicide attempters and in individuals who have died by suicide but has not been so extensively studied in individuals engaging in non-fatal deliberate self-harm. As self-harm is a growing public health problem, more knowledge on correlates and adverse outcomes associated with self-harm is of importance.
There are unique opportunities in Sweden to conduct epidemiological research, as we have comprehensive population and health data registers including all Swedish citizens. This study examined the association between non-fatal deliberate self-harm and violent crime by linking several nationwide population-based registries, such as the Total Population Register, the National Patient Register and The National Crime Register. We followed all living Swedish citizens born between 1982 and 1998 from their 15th birthday until the end of follow-up (31st December 2013) to see if they had been treated for non-fatal self-harm (ICD-10 diagnosis; as registered in the National Patient Register) and/or convicted of a violent crime (as registered in the National Crime Register).
What would be the most important take-home messages from the study?
We found that among individuals who had received care for self-harm, there were five times increased crude risk (hazard) of being convicted of a violent crime, compared to when not having received treatment for self-harm. Also, when we reversed our analyses, we found an equally increased risk of self-harm if one had been convicted of a violent crime. After controlling for relevant psychiatric comorbidities and socioeconomic status, an almost doubled risk of violent crime conviction remained among men and women who had received care for deliberate self-harm compared to individuals not exposed to such care.
This confirms that there is an association between being violent toward oneself and being violent towards others. However, it is important to notice that our study did not find any evidence suggesting that self-harm behaviors cause violent criminality. What we do believe is that these behaviors are somehow related. Therefore, we conclude that the engagement in violence towards oneself and towards others share an underlying vulnerability to impulsive and aggressive behaviors.
How are these findings important in practice?
Primarily we want guidelines, assessment, and treatment of self-harming and violent individuals to consider this association. Clinicians responsible for treating self-harming individuals (the majority of which are females if the setting is within psychiatric care) need to assess proneness to violence among their patients. Also, clinicians working within forensic or substance abuse settings (where it is more common for men to receive treatment) need to ask their patients about self-harm and assess self-harming behaviors among violence-prone or aggressive individuals. Unfortunately, harming oneself and harming others are behaviors patients often want to hide from their treatment providers, as both behaviors may be met by judgments from others, and are associated with shame and stigma. Therefore, by including assessments of self-harm and violence in a non-judgmental and professional manner, we may help patients reduce stigma and receive help to target both these behaviors.
Other Notable Studies
We hope this study will inspire research addressing the “how”, “why” and “when” of this association, i.e. under which conditions these behaviors co-occur and how they best can be treated. Treatments involving emotion regulation strategies have shown great promise regarding self-harm, and examining whether it would be beneficial to extend the treatment agenda to include aggressive behaviors as well would be of importance.
There are several studies of relevance to this study. I have selected a few that may further an understanding of the findings; Hawton et al (2014) which describes the prevalence of self-harm and suicidal behaviors in the forensic system in the UK1, and Gvion and Apter’s (2011) review on the association between suicidal behaviors and aggression2, and O’Donnell et al. (2015) on previous findings on self-harm and aggression3.
Link to the Primary Paper
Sahlin, H. et al. (2017). Association between deliberate self-harm and violent criminality. JAMA Psychiatry, 74(6), 615-621. DOI: 10.1001/jamapsychiatry.2017.0338
- Hawton KKE, Linsell L, Adeniji T, Sariaslan A, Fazel S. Self-harm in prisons in England and Wales: an epidemiological study of prevalence, risk factors, clustering, and subsequent suicide. Lancet. 2014 Mar 29;383(9923):1147–54.
- Gvion Y, Apter A. Aggression, impulsivity, and suicide behavior: a review of the literature. Arch Suicide Res. 2011;15(2):93–112.
- O’Donnell O, House A, Waterman M. The co-occurrence of aggression and self-harm: systematic literature review. J Affect Disord. 2015 Apr 1;175:325–50.