Project III: Validity of Subtypes of ADHD

Principal Investigator: Bruce F. Pennington

Co-investigator: Erik G. Willcutt

Goals of Project III: The overall goal of this project is to test the internal and external validity of subtypes of ADHD. To accomplish this goal, a battery of neuropsychological and psychiatric measures is administered to twins with RD, ADHD or RD+ADHD, and to unaffected control twins and their siblings. Reliability and internal validity of ADHD subtypes is assessed by examining inter-rater agreement and test-retest reliability and conducting factor and cluster analyses of the individual symptoms. Diagnostic and discriminant validity are tested by comparing subtypes on measures of functional impairment and other clinical correlates. Etiological relations among the subtypes are tested using multiple regression analysis of selected twin data and molecular genetic linkage and association analysis.