Cognitive, Environmental, and Linguistic Predictors of Syntax in Fragile X Syndrome and Down Syndrome PurposeTo examine which cognitive, environmental, and speech-language variables predict expressive syntax in boys with fragile X syndrome (FXS), boys with Down syndrome (DS), and typically developing (TD) boys, and whether predictive relationships differed by group.MethodWe obtained Index of Productive Syntax (Scarborough, 1990) scores for 18 boys with FXS only, 20 ... Article
Article  |   December 01, 2012
Cognitive, Environmental, and Linguistic Predictors of Syntax in Fragile X Syndrome and Down Syndrome
 
Author Affiliations & Notes
  • Gary E. Martin
    University of North Carolina at Chapel Hill
  • Joanne E. Roberts
    University of North Carolina at Chapel Hill
  • Correspondence to Bruno Estigarribia: estigarr@email.unc.edu
  • Joanne E. Roberts is now deceased.
    Joanne E. Roberts is now deceased.×
  • Editor: Janna Oetting
    Editor: Janna Oetting×
  • Associate Editor: Diane Loeb
    Associate Editor: Diane Loeb×
Article Information
Development / Special Populations / Genetic & Congenital Disorders / Attention, Memory & Executive Functions / Speech, Voice & Prosody / Language
Article   |   December 01, 2012
Cognitive, Environmental, and Linguistic Predictors of Syntax in Fragile X Syndrome and Down Syndrome
Journal of Speech, Language, and Hearing Research, December 2012, Vol. 55, 1600-1612. doi:10.1044/1092-4388(2012/10-0153)
History: Received June 7, 2010 , Revised January 20, 2011 , Accepted March 6, 2012
 
Journal of Speech, Language, and Hearing Research, December 2012, Vol. 55, 1600-1612. doi:10.1044/1092-4388(2012/10-0153)
History: Received June 7, 2010; Revised January 20, 2011; Accepted March 6, 2012
Web of Science® Times Cited: 8

PurposeTo examine which cognitive, environmental, and speech-language variables predict expressive syntax in boys with fragile X syndrome (FXS), boys with Down syndrome (DS), and typically developing (TD) boys, and whether predictive relationships differed by group.

MethodWe obtained Index of Productive Syntax (Scarborough, 1990) scores for 18 boys with FXS only, 20 boys with both FXS and an autism spectrum disorder, 27 boys with DS, and 25 younger TD boys of similar nonverbal mental age. Predictors included group (diagnosis), nonverbal cognition, phonological working memory (PWM), maternal education, speech intelligibility, and expressive vocabulary. The research questions were addressed via hierarchical linear regression.

ResultsDiagnostic group, nonverbal cognition, and PWM predicted 56% of the variance in syntactic ability, with approximately three-fourths of the predicted variance explained by group membership alone. The other factors did not contribute any additional significant variance in this final model. There was no evidence that predictor effects differed by group.

ConclusionsNonverbal cognition and PWM have an effect on expressive syntax beyond that of diagnostic group. These effects are estimated to be the same in boys with FXS, boys with DS, and TD boys. Explanations for residual variance and the relative role of different predictors are discussed.

Acknowledgments
This research was supported by National Institute of Child Health and Human Development Grants 1 R01 HD038819, 1 R01 HD044935, 1 R03 HD40640, and 5 T32 HD40127; by an Odum Institute for Research in Social Science Seed Grant to the first author; by a University Research Council Grant from the University of North Carolina at Chapel Hill to the first author; and by the Cognitive Science Program at the University of North Carolina at Chapel Hill. We thank Jan Misenheimer for her help with data entry and Kristin Cooley, Anne Harris, Cheryl Malkin, and Sabrina Smiley for their assistance with data verification and reliability.
We would also like to remember Joanne Erwick Roberts, a visionary in the field of language in fragile X syndrome, without whom this research would have never been possible.
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