title: Causal effects on child language development: A review of studies in communication sciences and disorders.
abstract: We reviewed recent studies published across key journals within the field of communication sciences and disorders (CSD) to survey what causal influences on child language development were being considered. Specifically, we reviewed a total of 2921 abstracts published within the following journals between 2003 and 2013: Language, Speech, and Hearing Services in Schools (LSHSS); American Journal of Speech-Language Pathology (AJSLP); Journal of Speech, Language, and Hearing Research (JSLHR); Journal of Communication Disorders (JCD); and the International Journal of Language and Communication Disorders (IJLCD). Of the 346 eligible articles that addressed causal factors on child language development across the five journals, 11% were categorized as Genetic (37/346), 83% (287/346) were categorized as Environmental, and 6% (22/346) were categorized as Mixed. The bulk of studies addressing environmental influences focused on therapist intervention (154/296=52%), family/caregiver linguistic input (65/296=22%), or family/caregiver qualities (39/296=13%). A more in-depth review of all eligible studies published in 2013 (n=34) revealed that family/caregiver qualities served as the most commonly controlled environmental factor (e.g., SES) and only 3 studies explicitly noted the possibility of gene-environment interplay. This review highlighted the need to expand the research base for the field of CSD to include a broader range of environmental influences on child language development (e.g., diet, toxin exposure, stress) and to consider more directly the complex and dynamic interplay between genetic and environmental effects.
  
  
  OBJECTIVE
  Readers will be able to highlight causal factors on child language development that have been studied over the past decade in CSD and recognize additional influences worthy of consideration. In addition, readers will become familiar with basic tenets of developmental systems theory, including the complex interplay between genetic and environmental factors that shapes child development.
authors.affiliation: Department of Speech & Hearing Science, University of Illinois, 901 S. Sixth Street, Champaign, IL 61820, United States. Electronic address: clarerogers93@gmail.com.
authors.forename: Clare R
authors.initials: CR
authors.lastname: Rogers
authors.affiliation: School of Molecular & Cellular Biology, University of Illinois, 393 Morrill Hall, 505 South Goodwin Avenue, Urbana, IL 61801, United States.
authors.forename: Karissa L
authors.initials: KL
authors.lastname: Nulty
authors.affiliation: Department of Speech & Hearing Science, University of Illinois, 901 S. Sixth Street, Champaign, IL 61820, United States; Neuroscience Program, Beckman Institute, 405 N. Mathews Avenue, Urbana, IL 61801, United States.
authors.forename: Mariana Aparicio
authors.initials: MA
authors.lastname: Betancourt
authors.affiliation: Department of Speech & Hearing Science, University of Illinois, 901 S. Sixth Street, Champaign, IL 61820, United States.
authors.forename: Laura S
authors.initials: LS
authors.lastname: DeThorne
mesh_terms: D002648:Child; D002663:Child Language; D003142:Communication; D003147:Communication Disorders / Q000209:etiology; D059647:Gene-Environment Interaction; D006801:Humans; D007804:Language Development; D012931:Social Environment
keywords: Causal factors; Child language development; Developmental systems theory; Ecological developmental biology; Environment; Epigenetics; Genetics