Article

Journal of Abnormal Child Psychology

, Volume 42, Issue 1, pp 21-35

The Internal and External Validity of Sluggish Cognitive Tempo and its Relation with DSM–IV ADHD

  • Erik G. WillcuttAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado Email author 
  • , Nomita ChhabildasAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado
  • , Mikaela KinnearAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado
  • , John C. DeFriesAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado
  • , Richard K. OlsonAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado
  • , Daniel R. LeopoldAffiliated withDepartment of Psychology and Neuroscience, UCB 345, University of Colorado
  • , Janice M. KeenanAffiliated withUniversity of Denver
  • , Bruce F. PenningtonAffiliated withUniversity of Denver

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Studies of subtypes of DSM-IV attention-deficit/hyperactivity disorder (ADHD) have provided inconsistent support for the discriminant validity of the combined type (ADHD-C) and predominantly inattentive type (ADHD-I). A large sample of children and adolescents with ADHD (N = 410) and a comparison group without ADHD (N = 311) were used to test the internal and external validity of sluggish cognitive tempo (SCT), a dimension characterized by low energy and sleepy and sluggish behavior. SCT scores were then incorporated in analyses of ADHD subtypes to test whether the discriminant validity of ADHD-C and ADHD-I could be improved by including SCT symptoms as part of the criteria for ADHD-I. Factor analyses of parent and teacher ratings indicated that six SCT items loaded on a factor separate from symptoms of ADHD and other psychopathology, providing important support for the internal validity of SCT. The external validity of SCT was supported by significant associations between SCT and measures of functional impairment and neuropsychological functioning when symptoms of ADHD and other psychopathology were controlled. However, contrary to initial predictions, high levels of SCT did not identify a subgroup of ADHD-I that was clearly distinct from ADHD-C. Instead, the current results suggest that DSM-IV inattention and SCT are separate but correlated symptom dimensions that are each independently associated with important aspects of functional impairment and neuropsychological functioning.

Keywords

ADHD Sluggish tempo Subtypes DSM-IV Inattention Hyperactivity-impulsivity