Association of temperament and character traits with ADHD and its comorbidities.

Background: Increasing evidence suggests that personality traits may be associated with ADHD and comorbid concerns. We investigated temperament and character traits associated with internalizing and externalizing comorbidities in adolescents with or without ADHD.

Methods: The population consisted of a subsample (n = 457) of the Northern Finland Birth Cohort 1986 (NFBC1986) that comprised 16-year-old adolescents with and without symptoms of ADHD. ADHD and psychiatric comorbidities were assessed using the Kiddie-SADS-PL and temperament and character profiles were determined with TCI-125. Outcomes were examined using Pearson's chi-square test, Analyses of Covariance and Cohen's d.

Results: The adolescents with ADHD endorsed more novelty seeking and less persistence, self-directedness, and cooperativeness than those without. Comparison of the personality traits and psychiatric comorbidities with the ADHD cases showed that comorbidities did not particularly affect the temperament and character profiles, but rather ADHD accounted for the differences between the personality traits. However, the temperament and character traits predicted externalizing and internalizing psychiatric disorders in the control group.

Conclusions: Our findings reveal unique comorbidity-related temperament factors, which may have implications for adaptive and personalizing intervention efforts.