Objective: Although many toddlers with expressive vocabulary delay ("late talkers") present with age-appropriate language skills by the time they are of school age, little is known about their broader behavioral and emotional profile. The aim of this study was to determine whether late talkers are at increased risk for behavioral and emotional problems during childhood and adolescence.
Patients and methods: Participants were from the Western Australian Pregnancy Cohort Study. Early expressive vocabulary was measured by parent report at age 2 years using the Language Development Survey. Late talkers were defined as toddlers who scored at or below the 15th percentile on the Language Development Survey for their gender but were screened not to have any other developmental delays. The Child Behavior Checklist was used to measure problem child behavior with continuous z scores and clinical thresholds at ages 2, 5, 8, 10, 14, and 17 years. Potential confounders included maternal and family sociodemographic characteristics as well as prenatal smoking and alcohol exposure.
Results: At age 2 years, late talkers (n = 142) had higher Child Behavior Checklist scores (representing poorer behavior) than control toddlers (n = 1245) in total, internalizing, and externalizing scales and higher risk for clinically significant internalizing and externalizing problems. Regression models, incorporating the confounding variables, revealed no association between late-talking status at age 2 years and behavioral and emotional problems at the 5-, 8-, 10-, 14-, and 17-year follow-ups.
Conclusions: Expressive vocabulary delay at the age of 2 years is not in itself a risk factor for later behavioral and emotional disturbances.