Are attentional-hyperactivity deficits unidimensional or multidimensional syndromes? Empirical findings from a...

Factor analysis on teacher ratings of symptoms in a probability community sample of children aged 6 to 16 years (N = 614) yielded two factors: Inattention and Hyperactivity-Impulsivity. Subsequent cluster analyses on the scores of factorially derived scales for a subsample of 170 children with a diagnosis of attention deficit disorder with (ADDH) and without hyperactivity (ADDWO), or normals, resulted in five clusters that accounted for 88% of the variance. The existence of these clusters was confirmed using external validating criteria. The data support a bidimensional conceptualization of attention deficit disorder with hyperactivity, one dimension consisting of symptoms of inattention and another of symptoms of hyperactivity-impulsivity. The data also suggests that a condition very similar to the DSM-III-R description of undifferentiated attention-deficit disorder also exists as a distinct entity.