title: Early lexical development and risk of verbal and nonverbal cognitive delay at school age.
abstract: OBJECTIVE
  To characterise the relationship between preschool lexical delay and language comprehension and nonverbal intelligence at school age.
  
  
  METHODS
  The mothers of 2724 children completed the MacArthur Communicative Development Inventory when their child reached 1.5 years and the Language Development Survey and the Parent Report of Children's Ability at 2.5 years. When the children were 6 years old, we assessed vocabulary comprehension and nonverbal intelligence using Dutch batteries for language and nonverbal intelligence.
  
  
  RESULTS
  Demographic factors explained 9.9% of the variance in vocabulary comprehension and 8.7% of the variance in nonverbal intelligence at 6 years. Male gender, low maternal education and non-Western ethnic background predicted vocabulary comprehension delay at 6 years. Lexical development at 1.5 and 2.5 years explained only 3.8% of the variance in language comprehension at the age of six. Late onset expressive vocabulary delay increased the risk of language comprehension and nonverbal intelligence delay at 6 years (OR=2.31, 95% CI: 1.62-3.29 and OR=1.74, 95% CI: 1.17-2.58, respectively).
  
  
  CONCLUSIONS
  Sociodemographic factors are important predictors of delays in language and nonverbal abilities as children enter school. In contrast, early expressive lexical delays, in particular before the age of two, have limited predictive power for language delays at the age of six.
authors.affiliation: The Generation R Study, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Child and Adolescent Psychiatry/Psychology, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, the Netherlands.
authors.forename: Akhgar
authors.initials: A
authors.lastname: Ghassabian
authors.forename: Leslie
authors.initials: L
authors.lastname: Rescorla
authors.forename: Jens
authors.initials: J
authors.lastname: Henrichs
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Frank C
authors.initials: FC
authors.lastname: Verhulst
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D003071:Cognition; D005260:Female; D006801:Humans; D007223:Infant; D007360:Intelligence; D007802:Language; D007804:Language Development; D016014:Linear Models; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D012959:Socioeconomic Factors
keywords: Intelligence; Lexical delay; Longitudinal; Nonverbal; Predictors; Preschool