To evaluate the effect of comorbid psychiatric disorders (PD) on the association between childhood ADHD and suicidality and the effect of gender on the association between PDs and suicidality among adults with childhood ADHD.

Subjects were recruited from a birth cohort of all children born 1976–1982 remaining in Rochester, MN after five years of age. Participating subjects with research-identified childhood ADHD (n = 232; mean age 27.0 years; 72% men) and non-ADHD controls (n = 335; mean age 28.6 years; 63% men) were administered a structured psychiatric interview (MINI International Neuropsychiatric Interview) to assess suicidality and psychiatric comorbidities.

Compared to controls, ADHD cases were significantly more likely to meet criteria for suicidality [odds ratio (OR) = 2.7, 95% CI 1.7–4.5]. Although this association was not moderated by the presence of PDs (P = 0.63 for interaction effect), the association between ADHD and suicidality was partially mediated by the presence of PDs [OR decreased from 2.7 to 2.1 (95% CI 1.2–3.5)]. Among adults with childhood ADHD, there was no significant moderating effect of gender on the association between suicidality and PD (P = 0.26 for interaction effect). However, the odds of suicidality was 6.1 (95% CI, 2.3–15.9) times higher among males with both externalizing and internalizing PDs compared to males with no disorders; among females the corresponding odds ratio was 3.4 (95% CI, 0.7–16.6).

Childhood ADHD is significantly associated with adult suicidal risk. Among those with ADHD, associations between suicidality and comorbid psychiatric disorders are more apparent in men among those with comorbid externalizing and internalizing disorders.

The authors have not supplied their declaration of competing interest.