Externalizing symptoms and suicidal behaviour in adolescents; a 17 years population based longitudinal study

Background: Hyperactive/inattentive symptoms (HI-s) are associated with suicidal behaviour in clinical studies, but there is still a lack of population-based longitudinal investigations on the developmental aspects of this association. Moreover, it is unclear whether the association is similar for boys and girls. Aims: To test the association between the HI-s during childhood and suicidal ideation and attempt during adolescence, and to investigate sex differences. Methods: 1407 children from the Québec Longitudinal Study of Child Development were followed up from 5 months to 17 years of age. We used teacher-reports of HI-s from 6 to 12 years, and self-report of suicidal ideation and attempt at 13, 15, and 17 years. Results: We identified 3 HI-s trajectories: low (boys: 32.2%, girls: 48.7%), moderate (boys: 44.6%; girls: 42.2%) and high (boys: 23.2%; girls: 9.1%). Compared to boys on a low trajectory, boys on a moderate trajectory were at higher risk for suicidal ideation (OR = 4.2, 95% CI = 1.2-14.8), and boys on a high trajectory were at higher risk for suicide attempts (OR: 4.5, 95%CI: 1.1-17.9). Girls on moderate or high HI-s trajectories were not at higher risk for suicidal ideation or attempts than girls on low trajectories. Conclusions: For boys, but not for girls, moderate-to-high HI-s increased the suicidal risk in adolescence. Interventions with preadolescent and adolescent boys showing HI-s symptoms should include a suicide prevention component. Population level suicide prevention for adolescents should particularly target boys with a history of HI-s problems.