The proposed research is the competitive renewal of an NIMH MERIT award focused on the linguistic phenotype in familial dyslexia. Our earlier work has clarified both the underlying cognitive phenotype and the genetic etiology of familial dyslexia. We propose to extend that work by examining both the phenotypic and genotypic relation between dyslexia (or reading disability--RD) and phonological disorder (PD), which manifest at different ages but exhibit several intriguing commonalities. The two disorders overlap symptomatically in that some prospective studies of children with PD find they later have an elevated rate of RD and in that retrospective studies of children with RD document elevated rates of earlier PD. The underlying cognitive phenotype that is characteristic of RD, a deficit in phoneme awareness, is also found on follow-up in many cases of PD. Finally, there is evidence that each disorder is under genetic influence and that the two disorders are co-familial. In sum, there is evidence for overlap at three levels of analysis: defining symptoms, underlying cognitive processes, and familial etiology. We will test five competing explanations for this overlap: 1) that they are the same disorder in terms of both genetic etiology and cognitive phenotype, but that the symptom manifestations differ depending on severity such that PD + RD is a more severe manifestation than RD alone; 2) that they share a common etiology which acts pleiotropically to produce either PD, RD, or both in a given individual; 3) that PD and RD have distinct etiologies, but share a common cognitive phenotype (cognitive phenocopy hypothesis); 4) that PD and RD have distinct etiologies, but that PD accompanied by specific language impairment develops into a symptom phenocopy of RD (synergy hypothesis); or 5) that PD and RD have distinct etiologies, but co-occur in offspring because of assortment (RD individuals are more likely to mate with PD individuals). We will perform four principal tests to distinguish these hypotheses. Specifically, we will test 1) whether there is a common cognitive phenotype by means of a longitudinal study; 2) whether there is a common genetic etiology by means of a linkage analysis of PD families; 3) whether there is assortment by examining parents of PD and RD children; and 4) how PD, RD, and PD+RD segregate in families.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
2R01MH038820-16
Application #
2463188
Study Section
Child Psychopathology and Treatment Review Committee (CPT)
Project Start
1984-01-01
Project End
2003-05-31
Budget Start
1998-09-30
Budget End
1999-05-31
Support Year
16
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Denver
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
City
Denver
State
CO
Country
United States
Zip Code
80208
Johnson, Erin Phinney; Pennington, Bruce F; Lowenstein, Joanna H et al. (2011) Sensitivity to structure in the speech signal by children with speech sound disorder and reading disability. J Commun Disord 44:294-314
Rhee, Soo Hyun; Willcutt, Erik G; Hartman, Christie A et al. (2008) Test of alternative hypotheses explaining the comorbidity between attention-deficit/hyperactivity disorder and conduct disorder. J Abnorm Child Psychol 36:29-40
Bidwell, L Cinnamon; Willcutt, Erik G; Defries, John C et al. (2007) Testing for neuropsychological endophenotypes in siblings discordant for attention-deficit/hyperactivity disorder. Biol Psychiatry 62:991-8
Willcutt, Erik G; Pennington, Bruce F; Olson, Richard K et al. (2007) Understanding comorbidity: a twin study of reading disability and attention-deficit/hyperactivity disorder. Am J Med Genet B Neuropsychiatr Genet 144B:709-14
Pennington, Bruce F (2006) From single to multiple deficit models of developmental disorders. Cognition 101:385-413
Pennington, Bruce F; Willcutt, Erik; Rhee, Soo Hyun (2005) Analyzing comorbidity. Adv Child Dev Behav 33:263-304
Willcutt, Erik G; Doyle, Alysa E; Nigg, Joel T et al. (2005) Validity of the executive function theory of attention-deficit/hyperactivity disorder: a meta-analytic review. Biol Psychiatry 57:1336-46
Pennington, Bruce F (2005) Toward a new neuropsychological model of attention-deficit/hyperactivity disorder: subtypes and multiple deficits. Biol Psychiatry 57:1221-3
Willcutt, Erik G; Pennington, Bruce F; Olson, Richard K et al. (2005) Neuropsychological analyses of comorbidity between reading disability and attention deficit hyperactivity disorder: in search of the common deficit. Dev Neuropsychol 27:35-78
Smith, Shelley D; Pennington, Bruce F; Boada, Richard et al. (2005) Linkage of speech sound disorder to reading disability loci. J Child Psychol Psychiatry 46:1057-66

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