Self-harm in adolescents was associated with more than threefold higher risk of committing violent crime, data from the U.K. indicated, with certain risk factors raising the likelihood of “dual harm.”
A longitudinal study of twins found that self-harm was linked to increased risk of official cautions or convictions for violent crime (adjusted OR 3.5, 95% CI 2.61-4.70), reported Leah S. Richmond-Rakerd, PhD, of Duke University in Durham, North Carolina, and colleagues.
Four additional risk factors (low self-control, family psychiatric history, maltreatment, and childhood self-harm) boosted the probability that individuals would become “dual harmers,” the authors wrote in The American Journal of Psychiatry.
“We know that some individuals who self-harm also inflict harm on others,” Richmond-Rakerd said in a statement. “What has not been clear is whether there are early-life characteristics or experiences that increase the risk of violent offending among individuals who self-harm. Identifying these risk factors could guide interventions that prevent and reduce interpersonal violence.”
Indeed, the authors said that prior studies on the subject have focused on risk factors for self-harm among violent offenders, but only after they become “clients of the criminal justice system.”
The team examined data from the Environmental Risk (E-Risk) Longitudinal Twins Study in Great Britain. At age 18, participants were interviewed about self-harm since age 12 (“Have you ever tried to hurt yourself, to cope with stress or emotional pain?”), including methods of self-harm. Participants reported on past violent behaviors via computer questionnaire at age 18, and their criminal and police records from age 10 to 22 were obtained.
Overall, self-harm and violence data was available for 2,049 participants. Of these, 13.4% met the criteria for self-harm and 19.4% met criteria for violent crime.
Low childhood self-control (OR 1.82, 95% CI 1.35-2.45) and maltreatment (OR 2.46, 95% CI 1.10-5.51) predicted increased odds of a dual harmer versus a self-only harmer, the authors said — adding that low self-control, family psychiatric history, maltreatment, and childhood self-harm predicted dual harm relative to self-only harm with “high accuracy” (area under receiver-operating characteristic curve 0.75, 95% CI 0.69-0.82).
“Our study suggests that dual-harming adolescents have experienced self-control difficulties and been victims of violence from a young age,” said Richmond-Rakerd. “A treatment-oriented rather than punishment-oriented approach is indicated to meet these individuals’ needs.”
Examining clinical features, the authors found that “dual harmers” exhibited higher-lethality behaviors (such as hanging or drowning) and aggressive acts (such as hitting oneself with an object or banging one’s head against the wall) while self-only harmers engaged in lower-lethality methods (such as cutting or scratching).
The authors said that dual harmers were associated with a higher prevalence of psychotic symptoms (OR 2.35, 95% CI 1.11-4.95), but they were not more likely than self-only harmers to be in contact with mental health professionals. Dual harmers were also more likely to meet criteria for alcohol dependence and cannabis dependence, the authors said.
Personality-wise, the authors found that dual harmers were notable for having greater resistance to change, poorer impulse control, and more aggressive/rude behavior.
Limitations to the data, the authors said, included that it may not be generalizable to singletons and that participants were followed only to the beginning of young adulthood.
The E-Risk Study is funded by the Medical Research Council, with additional support from the National Institute of Child Health and Development (NICHD), the Jacobs Foundation, and the Avielle Foundation.
Richmond-Rakerd disclosed support from NICHD.