Psychometric differentiation of conduct disorder and attention deficit disorder with hyperactivity.

Using a retrospective chart review procedure, children diagnosed as having attention deficit disorder with hyperactivity (ADDH), conduct disorder (CD), and ADDH+CD, as defined by DSM-III, were compared on measures of cognitive and academic functioning as well as on a continuous performance test (CPT). The groups did not differ in age or IQ, but children in the ADDH and ADDH+CD groups missed significantly more target stimuli on the CPT and performed significantly poorer on measures of academic achievement than did the pure CD group. However, poor CPT performance was not accounted for by learning problems. These findings in clinically referred patient groups are consistent with dimensional and epidemiological studies that suggest that ADDH may be a cognitively based disorder, whereas CD children are characterized by behavioral symptoms with fewer cognitive and learning deficits.