Symptom properties as a function of ADHD type: An argument for continued study of Sluggish Cognitive Tempo

Inconsistent alertness and orientation (sluggishness, drowsiness, daydreami ng) were reported to accompany Attention Deficit Disorder (ADD) without Hyp eractivity in DSM-III. Such Sluggish Cognitive Tempo items were tested in t he DSM-IV Field Trial for ADHD, but were discarded from the Inattention sym ptom list because of poor negative predictive power. Using 692 children ref erred to a pediatric subspecialty clinic for ADHD, Sluggish Tempo items wer e re-evaluated. When Hyperactivity-Impulsivity was absent (i.e., using only cases of Inattentive Type plus clinic controls), Sluggish Tempo items show ed substantially improved utility as symptoms of Inattention. Factor analys es distinguished a Sluggish Tempo factor from an Inattention factor. When D SM-IV ADHD types were compared, Inattentive Type was uniquely elevated on S luggish Tempo. These findings suggest that (a) Sluggish Tempo items are ade quate symptoms for Inattentive Type, or (b) Sluggish Tempo may distinguish two subtypes of Inattentive Type. Either conclusion is incompatible with AD HD nosology in DSM-IV.