Adolescents who self-harm are more likely to commit violent crime if they also exhibit low self-control and have been maltreated, according to the results of a study published in the American Journal of Psychiatry.

Self-harm is a major health concern among adolescents and a leading risk factor for suicide. However, not all who self-harm also harm others. Researchers set out to investigate antecedents, clinical features, and life characteristics to differentiate adolescents who self-harm only from those who also commit violent crimes (“dual harmers”).

Leah S. Richmond-Rakerd, PhD, from the department of psychology and neuroscience, Duke University, Durham, North Carolina, and colleagues analyzed data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a United Kingdom cohort of 2232 twins born in 1994 and 1995, to identify risk factors for self-harm and violent offending. Of the total participants in the original study, there were data available for 2049 participants for both self-harm and violent crime. The researchers assessed self-harm through interviews at age 18 and violent offending through using a computer questionnaire at age 18 and reviewing police records from ages 10 through 22.

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The odds ratio (OR) for committing violent crime in those who self-harm was 3.50, even after accounting for familial risk factors. Twins who self-harmed were more likely to commit violent crime than their co-twins who did not self-harm. The OR for dizygotic twins was 2.57, whereas for monozygotic twins it was 4.00. This suggested that familial risk factors, either genetic or environmental, could not entirely explain the relationship between self-harm and violent offending.

Primary childhood risk factors that distinguished dual harmers from self-only harmers were low self-control, with an OR of 1.82, and maltreatment, with an OR of 2.46. In contrast, a higher IQ predicted decreased odds of being a dual vs a self-only harmer (OR, 0.98). However, the prevalence of childhood depression or anxiety did not differ between self-only harmers and dual harmers.

Dual harmers were also more likely to engage in activities with greater lethality, such as hanging or drowning, or more aggressive acts such as hitting oneself or banging one’s head against a wall. They also were more likely to have higher rates of psychotic symptoms and substance dependence, were more resistant to change, and had more emotional and interpersonal lability.

Researchers called for improvements in adolescent mental health services and connecting vulnerable adolescents with delinquency-reduction programs that target self-control, prevention of maltreatment and victimization, and improvement in children’s self-regulation.

The study was limited by the use of a twins-only population and by a follow-up that ended early young adulthood.

Reference

Richmond-Rakerd LS, Caspi A, Areseneault L, et al. Adolescents who self-harm and commit violent crime: testing early-life predictors of dual harm in a longitudinal cohort study [published online January 4, 2019]. Am J Psychiatry. doi: 10.1176/appi.ajp.2018.18060740