Article/Report  |   December 2007
Late Language Emergence at 24 Months: An Epidemiological Study of Prevalence, Predictors, and Covariates
 
Author Affiliations & Notes
  • Stephen R. Zubrick
    Curtin University of Technology, Telethon Institute for Child Health Research
  • Catherine L. Taylor
    Curtin University of Technology, Telethon Institute for Child Health Research
  • Mabel L. Rice
    University of Kansas
  • David W. Slegers
    University of Kansas
  • Contact author: Mabel Rice, Dole Center, 1000 Sunnyside Avenue, Room 3031, University of Kansas, Lawrence, KS 66045-7555. E-mail: mabel@ku.edu.
Article Information
Special Populations / Research Issues, Methods & Evidence-Based Practice / Language Disorders / Language
Article/Report   |   December 2007
Late Language Emergence at 24 Months: An Epidemiological Study of Prevalence, Predictors, and Covariates
Journal of Speech, Language, and Hearing Research, December 2007, Vol. 50, 1562-1592. doi:10.1044/1092-4388(2007/106)
History: Received August 29, 2006 , Revised January 16, 2007 , Accepted March 2, 2007
 
Journal of Speech, Language, and Hearing Research, December 2007, Vol. 50, 1562-1592. doi:10.1044/1092-4388(2007/106)
History: Received August 29, 2006; Revised January 16, 2007; Accepted March 2, 2007
Web of Science® Times Cited: 83

Purpose: The primary objectives of this study were to determine the prevalence of late language emergence (LLE) and to investigate the predictive status of maternal, family, and child variables.

Method: This is a prospective cohort study of 1,766 epidemiologically ascertained 24-month-old singleton children. The framework was an ecological model of child development encompassing a wide range of maternal, family, and child variables. Data were obtained using a postal questionnaire. Item analyses of the 6-item Communication scale of the Ages and Stages Questionnaire (ASQ; D. Bricker & J. Squires, 1999; J. Squires & D. Bricker, 1993; J. Squires, D. Bricker, & L. Potter, 1997; J. Squires, L. Potter, & D. Bricker, 1999) yielded a composite score encompassing comprehension as well as production items. One SD below the mean yielded good separation of affected from unaffected children. Analyses of bivariate relationships with maternal, family, and child variables were carried out, followed by multivariate logistic regression to predict LLE group membership.

Results: 13.4% of the sample showed LLE via the ASQ criterion, with 19.1% using the single item of “combining words.” Risk for LLE at 24 months was not associated with particular strata of parental educational levels, socioeconomic resources, parental mental health, parenting practices, or family functioning. Significant predictors included familial history of LLE, male gender, and early neurobiological growth. Covariates included psychosocial indicators.

Conclusion: Results are congruent with models of language emergence and impairment that posit a strong role for neurobiological and genetic mechanisms of onset that operate across a wide variation in maternal and family characteristics.

Acknowledgments
This work was funded by grants from the Health Promotion Foundation of Western Australia and from Grants RO1DC05226, P30DC005803, and P30HD002528 from the National Institutes of Health. The RASCALS study was originally created by Jennifer Kurinczuk, who provided details of the original sampling plan. Thanks to Meryl Biggs, Kaye Moore, and Deborah Parsons for help in maintaining the cohort and collection of data. We appreciate statistical consultation by Janet Marquis and Jonathan Templin. We especially thank the children and families who participated in the RASCALS study.
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