Shared Etiology of Phonological Memory and Vocabulary Deficits in School-Age Children PurposeThe goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children.MethodChildren with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045 twin pairs ... Article
Article  |   August 01, 2013
Shared Etiology of Phonological Memory and Vocabulary Deficits in School-Age Children
 
Author Affiliations & Notes
  • Robin L. Peterson
    University of Denver, CO
  • Bruce F. Pennington
    University of Denver, CO
  • Stefan Samuelsson
    Linköping University, Sweden
  • Brian Byrne
    Linköping University, Sweden
  • Richard K. Olson
    Linköping University, Sweden
  • Correspondence to Robin L. Peterson: robin.peterson@du.edu
  • Editor: Janna Oetting
    Editor: Janna Oetting×
  • Associate Editor: Susan Rvachew
    Associate Editor: Susan Rvachew×
Article Information
Development / Special Populations / Genetic & Congenital Disorders / Attention, Memory & Executive Functions / Speech, Voice & Prosody / Language
Article   |   August 01, 2013
Shared Etiology of Phonological Memory and Vocabulary Deficits in School-Age Children
Journal of Speech, Language, and Hearing Research, August 2013, Vol. 56, 1249-1259. doi:10.1044/1092-4388(2012/12-0185)
History: Received June 17, 2012 , Revised September 27, 2012 , Accepted November 13, 2012
 
Journal of Speech, Language, and Hearing Research, August 2013, Vol. 56, 1249-1259. doi:10.1044/1092-4388(2012/12-0185)
History: Received June 17, 2012; Revised September 27, 2012; Accepted November 13, 2012

PurposeThe goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children.

MethodChildren with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045 twin pairs (between the ages of 5 and 8 years) from the United States, Australia, and Scandinavia. The authors applied the DeFries-Fulker (DeFries & Fulker, 1985, 1988) regression method to determine whether problems in PM and vocabulary tend to co-occur because of overlapping genes, overlapping environmental risk factors, or both.

ResultsAmong children with isolated PM deficits, the authors found significant bivariate heritability of PM and vocabulary weaknesses both within and across time. However, when probands were selected for a vocabulary deficit, there was no evidence for bivariate heritability. In this case, it appears that the PM–vocabulary relationship is caused by common shared environmental experiences.

ConclusionsThe findings are consistent with previous research on the heritability of specific language impairment and suggest that there are etiologic subgroups of children with low vocabulary for different reasons, 1 being more influenced by genes and another being more influenced by environment.

Acknowledgments
Funding was provided by Australian Research Council Grants DP0663498 and DP0770805; National Institute for Child Health and Human Development Grants HD27802, HD38526, and HD49027; and grants from the Research Councils of Norway and Sweden. We thank the Colorado and Australian Twin Registries, our testers, and the children and parents involved.
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