Models and determinants of vocabulary growth from kindergarten to adulthood.
BACKGROUND
Increasing evidence suggests that childhood language problems persist into early adulthood. Nevertheless, little is known about how individual and environmental characteristics influence the language growth of individuals identified with speech/language problems.


METHODS
Individual growth curve models were utilised to examine how speech/language impairment and environmental variables (socioeconomic status, family separation, and maternal factors) influence vocabulary development from age 5 to 25. Participants were taken from a community sample of children initially diagnosed with speech/language problems at age 5 and their sex- and age-matched controls.


RESULTS
The language impaired group had significantly poorer receptive vocabulary than the speech impaired and control groups throughout the 20-year period. Family income was a significant predictor of vocabulary growth when considered separately, but ceased to be a predictor when language impairment status was taken into account. Maternal education and family separation were determinants of vocabulary at age 5, over and above language impairment status.


CONCLUSIONS
Language impairment is a significant risk factor for vocabulary development from childhood to adulthood. Individuals with speech impairment were less impaired on receptive vocabulary than individuals with language impairment. Further investigation into maternal and familial risk factors may provide targets for early intervention with children at risk for language impairment.
Beitchman
Joseph H
JH
Centre for Addiction and Mental Health, Toronto, Canada. Joe_Beitchman@camh.net
Jiang
Hedy
H
Koyama
Emiko
E
Johnson
Carla J
CJ
Escobar
Michael
M
Atkinson
Leslie
L
Brownlie
E B
EB
Vida
Ron
R
D000293:Adolescent; D000328:Adult; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D004522:Educational Status; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000175:diagnosis* / Q000209:etiology; D008137:Longitudinal Studies; D008297:Male; D009035:Mothers; D012016:Reference Values; D012307:Risk Factors; D015406:Single Parent; D012931:Social Environment; D012959:Socioeconomic Factors; D013064:Speech Disorders / Q000175:diagnosis / Q000209:etiology; D014825:Vocabulary