Investigators

Richard Olson

Our research is focused on the etiology and remediation of reading disabilities. Etiological questions are being addressed by testing identical and fraternal twins as part of an NIH Center for the Study of Learning Disabilities. We have also worked on the application of computer technology to support the remediation of word-reading and related language disabilities in the schools.

Earlier research in the Center confirmed that reading-disabled children tend to have a unique deficit in the phonological decoding component of word recognition, measured by the oral reading of nonwords (e.g., tegwop, strale). The deficit in this component word-reading skill is closely related to deficits in an analytic language skill called phoneme awareness, defined as the ability to isolate and manipulate the phonemic segments of speech. Bivariate genetic analyses have indicated that there is a strong shared genetic influence on disabled readers' deficits in phonological decoding and phoneme awareness (Gayan & Olson, 2001). More recent behavioral-genetic analyses have addressed possible independent genetic influences on a second component word-reading skill called orthographic coding. One way this is measured is by having subjects quickly choose the word from two letter strings that would sound the same if sounded out (e.g., rain rane). The new analyses show clearly that there are both shared and independent genetic influences on phonological and orthographic coding skills. Thus, there may be important individual differences in disabled readers profiles of component reading skills and in their genetic etiology. Analyses of disabled readers' and their siblings' DNA have found linkage evidence for a locus on the short arm of chromosome 6 that appears to be most strongly associated with deficits in orthographic coding (Gayan et al., 1999).

Representative Publications:

1. Wadsworth SJ, DeFries JC, Olson RK, Willcutt EG.(2007). Colorado longitudinal twin study of reading disability. Annals of Dyslexia, 57(2), 139-60. | pubmed abstract |

2. Willcutt EG, Pennington BF, Olson RK, DeFries JC.(2007). Understanding comorbidity: a twin study of reading disability and attention-deficit/hyperactivity disorder. American journal of medical genetics. Part B, Neuropsychiatric genetics, 144(6), 709-14. | pubmed abstract |

3. Olson RK. (2006) Genes, environment, and dyslexia. The 2005 Norman Geschwind Memorial Lecture. Annals of Dyslexia, 56(2), 205-38. | pubmed abstract |

 

 

 

 

 

 

 

Richard Olson

Muenzinger D451B
Boulder, CO 80309-0345
phone: (303) 492-8865
fax: (303) 492-2967

email:
rolson@psych.Colorado.EDU