Prevalence and Mental Health Correlates of Non-Suicidal Self-Injury in Elementary School Children

• 28.2% of late–elementary school children reported a lifetime history of NSSI. • Most common NSSI method was scratching, with similar rates in males and females. • Children who engaged in NSSI showed consistently worse mental health symptoms. • Associations were found for self- and teacher-reports (though weaker for teachers). • Associations were stronger when children endorsed multiple NSSI methods. Non-suicidal self-injury (NSSI) is relatively common in adolescence and associated with mental health symptoms, yet the prevalence of NSSI and mental health correlates in childhood remain poorly understood. Objective : Document the lifetime prevalence of NSSI in elementary-school children and concurrent associations with self- and teacher-reported mental health symptoms and peer problems. Cross sectional analysis of 859 children (mean age=10.9 years; n=419 males) from 33 elementary schools in Quebec, Canada who completed a self-report measure of NSSI (5-item Self-Mutilation subscale; Self Harm Inventory) and self- and teacher-report measures of concurrent mental health, including depressive symptoms (Children’s Depression Inventory–Short-Form; self-reported only), emotional distress, withdrawal, impulsive/hyperactive/inattentive behaviors, disruptive behaviors, prosocial behaviors, and peer relationship difficulties (victimization) (Social Behavior Questionnaire). Mental health symptoms were transformed into z-scores. Lifetime prevalence of NSSI (any method, at least once) was 28.2%, with no sex differences between males (26.7%) and females (29.4%) (p=.403), with scratching being the most frequently reported method (17.2%). Children reporting NSSI had significantly poorer mental health across indicators examined in both self- and teacher reports, although associations were generally smaller for teacher-reported symptoms. To illustrate, for 1 standard deviation increase in self-reported symptom scores, odds of NSSI were 2.31 times higher for depressive symptoms (95% CI 1.82–2.92), and 1.70 times higher for peer victimization (95% CI 1.46–1.99). Associations were stronger among children endorsing multiple NSSI methods compared to those reporting only one. NSSI (especially scratching) is present in late childhood and associated with worse mental health symptoms and peer problems.