Dysthymic disorder contributes to oppositional defiant behaviour in children with Attention Deficit Hyperactivity Disorder, combined type (ADHD-CT).

BACKGROUND

The specific relationships between oppositional defiant disorder (ODD), ADHD-CT, dysthymic disorder (DD) and anxiety disorders symptoms have not been studied in children with ADHD-CT. The relationship to DD is important because DD is common, has an earlier age of onset, is associated with significant morbidity and with increased rates of treatment non-responsiveness when comorbid with major depressive disorder and/or ADHD-CT.

METHODS

200 clinically referred children with ADHD-CT, without comorbid major depressive disorder, were identified. "ODD", "ADHD-CT", "DD" and "anxiety disorders" symptoms were defined by composite measures of (1) semi-structured clinical interview and (2) parent and/or child standardized questionnaires. Standard multiple regression was used to examine how well "ADHD-CT", "DD" and "anxiety disorders" symptoms predict "ODD" symptoms.

RESULTS

Only "ADHD-CT" (15% of the variance) and "DD" (8% of the variance) symptoms made independent significant contributions to the prediction of "ODD" symptoms.

LIMITATIONS

The study's sample size did not allow "ODD" and "conduct disorder" symptoms to be analysed separately.

CONCLUSIONS

The association of DD with ODD may reflect a unique contribution of DD to ODD in children, whether ADHD-CT is present or not, or only when ADHD-CT is present.