A comparison of the cognitive deficits in reading disability and attention-deficit/hyperactivity disorder.
This study used a nonreferred sample of twins to contrast the performance of individuals with reading disability (RD; n = 93), attention-deficit/hyperactivity disorder (ADHD; n = 52), RD and ADHD (n = 48), and neither RD nor ADHD (n = 121) on measures of phoneme awareness (PA) and executive functioning (EF). Exploratory factor analysis of the EF measures yielded underlying factors of working memory, inhibition, and set shifting. Results revealed that ADHD was associated with inhibition deficits, whereas RD was associated with significant deficits on measures of PA and verbal working memory. The RD + ADHD group was most impaired on virtually all measures, providing evidence against the phenocopy hypothesis as an explanation for comorbidity between RD and ADHD.
Institute for Behavioral Genetics, Campus Box 447, University of Colorado at Boulder, Boulder, Colorado 80309, USA. willcutt@colorado.edu
E G
EG
Willcutt
B F
BF
Pennington
R
R
Boada
J S
JS
Ogline
R A
RA
Tunick
N A
NA
Chhabildas
R K
RK
Olson
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000523:psychology*; D002648:Child; D003071:Cognition; D004410:Dyslexia / Q000150:complications / Q000523:psychology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009483:Neuropsychological Tests; D010700:Phonetics; D011932:Reading