Psychiatric Comorbidity and Response to Two Doses of Methylphenidate in Children with Attention Deficit Disorder

In a large, heterogeneous sample (N = 182) of children with attention deficit disorder (ADD), the prevalences of additional DSM-III diagnoses were determined using the Diagnostic Interview for Children and Adolescents (DICA). More than half the children had additional DSM-III psychiatric diagnoses. Oppositional disorder and anxiety/mood disorders were the most frequent diagnoses. White male children with ADD were selected into four contrast groups based on comorbidity: ADD children with no additional diagnosis (neither), with anxiety or depression (ANX/DEP), with oppositional or conduct disorder (OPP/CON), and with both ANX/DEP and OPP/CON diagnoses (both). ADD children who had both ANX/DEP and OPP/CON were significantly more improved on a high dose (0.6 mg/kg bid) than a low dose (0.3 mg/kg bid), but ADD boys in the other diagnostic groups responded as well to both doses.

There was no evidence that ADD children with comorbid emotional or disruptive behavior disorders respond any less well to psychostimulants than other ADD children. However, there is a concern for those children who have the comorbid combination of (1) ADD, (2) an additional externalizing disorder (disruptive behavior disorder), and (3) an internalizing disorder (a mood or anxiety disorder). These children may not respond to low clinical doses of psychostimulants, but may respond well at higher doses. Children's self-ratings on the DICA may provide important clinical data concerning stimulant dosing which are not provided by teacher or parent ratings. We found no evidence that ADD children with comorbid emotional disorders respond any less well to a psychostimulant than ADD children without emotional comorbidity.