The proposed project will initiate the first longitudinal twin study of reading disability and conduct novel analyses of the genetic and environmental etiologies of stability and change in reading difficulties. To accomplish these objectives, an extensive psychometric test battery, as well as behavioral questionnaires and interviews, will be administered to a sample of 50 pairs of identical twins and 50 pairs of fraternal twins in which at least one member of each pair is reading disabled, to their siblings, and to a comparison sample of 50 pairs of identical twins and 50 pairs of fraternal twins with no history of reading deficits, all of whom previously participated in the Colorado Learning Disabilities Research Center CLDRC). Resulting data will be analyzed in conjunction with data previously collected in the CLDRC to provide the first longitudinal assessment of the genetic and environmental etiologies of reading deficits and subtypes of reading disability at two ages, as well as their longitudinal stability and comorbidity with ADHD. These data will also be used to test novel hypotheses about the longitudinal covariation of reading difficulties with measures of other psychopathology, reading, language and perceptual processes and specific cognitive abilities. Univariate and bivariate QTL analyses of reading deficits and ADHD, reading component processes and other psychopathology will also be conducted.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-SNEM-2 (01))
Program Officer
Cooper, Judith
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
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Indirect Cost
University of Colorado at Boulder
Other Domestic Higher Education
United States
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Wadsworth, Sally J; DeFries, John C; Willcutt, Erik G et al. (2015) The Colorado Longitudinal Twin Study of Reading Difficulties and ADHD: Etiologies of Comorbidity and Stability. Twin Res Hum Genet 18:755-61
Willcutt, Erik G; Chhabildas, Nomita; Kinnear, Mikaela et al. (2014) The internal and external validity of sluggish cognitive tempo and its relation with DSM-IV ADHD. J Abnorm Child Psychol 42:21-35
Willcutt, Erik G; Petrill, Stephen A; Wu, Sarah et al. (2013) Comorbidity between reading disability and math disability: concurrent psychopathology, functional impairment, and neuropsychological functioning. J Learn Disabil 46:500-16
Willcutt, Erik G; Boada, Richard; Riddle, Margaret W et al. (2011) Colorado Learning Difficulties Questionnaire: validation of a parent-report screening measure. Psychol Assess 23:778-91
Astrom, Raven L; Wadsworth, Sally J; Olson, Richard K et al. (2011) DeFries-Fulker analysis of longitudinal reading performance data from twin pairs ascertained for reading difficulties and from their nontwin siblings. Behav Genet 41:660-7
Willcutt, Erik G; Pennington, Bruce F; Duncan, Laramie et al. (2010) Understanding the complex etiologies of developmental disorders: behavioral and molecular genetic approaches. J Dev Behav Pediatr 31:533-44
Hawke, Jesse L; Stallings, Michael C; Wadsworth, Sally J et al. (2008) DeFries-Fulker and Pearson-Aitken model-fitting analyses of reading performance data from selected and unselected twin pairs. Behav Genet 38:101-7
Wadsworth, Sally J; DeFries, John C; Olson, Richard K et al. (2007) Colorado longitudinal twin study of reading disability. Ann Dyslexia 57:139-60
Friend, Angela; DeFries, John C; Wadsworth, Sally J et al. (2007) Genetic and environmental influences on word recognition and spelling deficits as a function of age. Behav Genet 37:477-86
Astrom, Raven L; Wadsworth, Sally J; DeFries, John C (2007) Etiology of the stability of reading difficulties: the longitudinal twin study of reading disabilities. Twin Res Hum Genet 10:434-9

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