The peer factor: Nonsuicidal self-harm may spur copycats among teens

Adolescents who are aware of their friends’ self-injurious behaviours are at risk of the same tendencies and exhibit greater suicidality, according to a new study. Intervention efforts should also seek to target this peer influence effect in reducing suicidal behaviours among teens.

“It has been suggested that suicide may exert a contagion effect, whereby exposure to suicidal behaviours influences identical behaviours in others,” the researchers said, though it remains unclear whether such a phenomenon applies to nonsuicidal self-injuries (NSSIs), such as skin cutting or scratching.

To see whether NSSIs spurred the same behaviours in others, the researchers accessed the data of 1,483 adolescents, aged 14–17 years, from the 2014 cross-sectional, population-based Ontario Child Health Study. Logistic regression models were employed to determine whether the knowledge of a friend’s NSSIs correlated with similar self-tendencies.

Compared to boys, girls were nearly thrice as likely to report knowledge of a friend’s self-harm behaviours (33.7 percent vs 13.2 percent). They were also much more likely than boys to engage in NSSIs (11.4 percent vs 3.4 percent). [Acta Psychiatr Scand 2020;doi:10.1111/acps.13229]

Similarly, suicidal ideations (8.5 percent and 4.3 percent) and suicide attempts (4.8 percent vs 2.3 percent) were nearly twice as common in girls.

Statistical models verified these trends. The knowledge of a friend’s self-injurious behaviour encouraged the same self-tendencies in teens (odds ratio [OR], 2.89, 95 percent confidence interval [CI], 1.58–5.29).

Notably, this remained true and strong even after adjusting for mental disorders. The contagion effect was significant for NSSIs (OR, 2.03, 95 percent CI, 1.05–3.90), suicidal ideation (OR, 3.09, 95 percent CI, 1.50–6.30), and suicide attempts (OR, 2.87, 95 percent CI, 1.20–6.87).

Self NSSIs and suicidal behaviours did not correlate significantly with age, sex, or mental disorders.

“[O]ur results present evidence of an apparent contagion effect of NSSI in peer groups in the general population,” said the researchers, explaining that this phenomenon may happen through social learning, where even just discussing NSSIs with peers might reinforce the same behaviours and tendencies in an adolescent.

Alternatively, several papers have suggested that teens with similar attitudes, personalities, and tendencies are more likely to associate with each other. This phenomenon, called the theory of assortative relating, posits that those who are already at risk of self-injurious behaviours may cluster with other similarly at-risk people. Further studies are needed to more clearly see the mechanisms underlying the contagion effect in NSSIs. [Curr Dir Psychol Sci 1999;8:89-92; PLoS One 2014;doi:10.1371/journal.pone.0108724]

“Given the socialization effect of NSSI in adolescent friend groups, psychoeducation, such as training in resistance to peer pressure, may help protect adolescents from NSSI contagion,” the researchers said, adding that “changing social norms to reduce the normalization and acceptability of NSSI and suicidal behaviours may alleviate susceptibility to NSSI contagion effects.”

“Targeted intervention/postvention among adolescents exposed to NSSI may be effective in reducing self-harm and suicidal behaviours,” they said.