Comorbid externalising behaviour in AD/HD: Evidence for a distinct pathological entity in adolescence

Authors

Sharnel Perera, Swinburne University of Technology
David Crewther, Swinburne University of Technology
Rodney Croft, University of WollongongFollow
Hannah Keage, Flinders University
Daniel Hermens, University of Sydney
C Richard Clark, Flinders University

RIS ID

67640

Publication Details

Perera, S., Crewther, D., Croft, R., Keage, H., Hermens, D. & Clark, C. Richard. (2012). Comorbid externalising behaviour in AD/HD: Evidence for a distinct pathological entity in adolescence. PLoS One, 7 (9), 1-12.

Abstract

While the profiling of subtypes of Attention Deficit Hyperactivity Disorder (AD/HD) have been the subject of considerable scrutiny, both psychometrically and psychophysiologically, little attention has been paid to the effect of diagnoses comorbid with AD/HD on such profiles. This is despite the greater than 80% prevalence of comorbidity under the DSM-IV-TR diagnostic definitions. Here we investigate the event related potential (ERP) and psychometric profiles of Controls, AD/HD, and comorbid AD/HD (particularly AD/HD+ODD/CD) groups on six neurocognitive tasks thought to probe the constructs of selective and sustained attention, response inhibition and executive function. Data from 29 parameters extracted from a child group (age range 6 to 12; 52 Controls and 64 AD/HD) and from an adolescent group (age range 13 to 17; 79 Controls and 88 AD/HD) were reduced via a Principal Components Analysis, the 6 significant eigenvectors then used as determinants of cluster membership via a Two-Step Cluster Analysis. Two clusters were found in the analysis of the adolescent age group - a cluster dominated by Control and AD/HD participants without comorbidity, while the second cluster was dominated by AD/HD participants with externalising comorbidity (largely oppositional defiant/conduct disorder ODD/CD). A similar segregation within the child age group was not found. Further analysis of these objectively determined clusters in terms of their clinical diagnoses indicates a significant effect of ODD/CD comorbidity on a concurrent AD/HD diagnosis. We conclude that comorbid externalising behaviour in AD/HD constitutes a distinct pathological entity in adolescence.