Childhood externalizing, internalizing and comorbid problems: distinguishing young adults who think about suicide...

While childhood externalizing, internalizing and comorbid problems have been associated with suicidal risk, little is known about their specific associations with suicidal ideation and attempts. We examined associations between childhood externalizing, internalizing and comorbid problems and suicidal ideation (without attempts) and attempts by early adulthood, in males and females.

Participants were from the Quebec Longitudinal Study of Kindergarten Children, a population-based study of kindergarteners in Quebec from 1986 to 1988 and followed-up until 2005. We captured the co-development of teacher-rated externalizing and internalizing problems at age 6-12 using multitrajectories. Using the Diagnostic Interview Schedule administered at age 15 and 22, we identified individuals (1) who never experienced suicidal ideation/attempts, (2) experienced suicidal ideation but never attempted suicide and (3) attempted suicide.

The identified profiles were no/low problems (45%), externalizing (29%), internalizing (11%) and comorbid problems (13%). After adjusting for socioeconomic and familial characteristics, children with externalizing (OR 2.00, CI 1.39-2.88), internalizing (OR 2.34, CI 1.51-3.64) and comorbid (OR 3.29, CI 2.05-5.29) problems were at higher risk of attempting suicide (v. non-suicidal) by age 22 than those with low/no problems. Females with comorbid problems were at higher risk of attempting suicide than females with one problem. Childhood problems were not associated with suicidal ideation. Externalizing (OR 2.01, CI 1.29-3.12) and comorbid problems (OR 2.28, CI 1.29-4.03) distinguished individuals who attempted suicide from those who thought about suicide without attempting.

Childhood externalizing problems alone or combined with internalizing problems were associated with suicide attempts, but not ideation (without attempts), suggesting that these problems confer a specific risk for suicide attempts.