Language Impairment in Younger Siblings of Children with ASD: Stability and Predictors

Background:  

Language impairment is common in ASD, yet some show typical language functioning at school-age.  In addition, early language delay has been reported in Non-ASD siblings of children with ASD (sibs-Non-ASD).  

Objectives:  

To define:

1. stability of early language delay in sibs-ASD and sibs-Non-ASD.
2. very early predictors of later language impairment in younger siblings of children with ASD.

Methods:  

Participants were 132 younger siblings of children with ASD enrolled in a prospective, longitudinal study.  Outcome classification of ASD (n=25) versus Non-ASD (n=107) was determined at age 36 months.  Language assessments were conducted at ages 14, 24, and 36 months using the Mullen Scales of Early Learning (MSEL; Mullen, 1995) Receptive (RL) and Expressive Language (EL) scales, and at 4 to 8 years using the Test of Oral Language Development-P3 (TOLD-P3; Newcomer & Hammill, 1997).  Early language delay was defined as scoring > 1.5 standard deviations below the test mean on the MSEL RL or EL scale.  The ‘gold standard’ language delay classification was defined by scores of >1.5 standard deviations below the test mean on any TOLD-P3 subtest at school-age.  Children with ASD were only included in analyses if they completed the TOLD-P3.

To define early predictors of school-age language impairment, we examined frequency of initiation of joint attention (IJA) and inventory of gestures using the Communication and Symbolic Behavior Scales Developmental Profile  (CSBS; Wetherby & Prizant, 2002), MSEL Visual Reception (VR) and RL and EL T scores, and ADOS-G Communication algorithm score (Lord et al., 1999) at age 14 months.  

Results:  

At 14 months, 68% of the ASD group and 38% of the Non-ASD group had language delay.  By school-age, 58% and 14% of the ASD and Non-ASD groups, respectively, had language delay. 

In the ASD group, 66% of 14-month-olds with language delay also met TOLD-P3 criteria for language delay at school-age.  Sensitivity (.71) of language delay on the MSEL improved marginally by age 36 months.  In contrast, specificity of language delay on the MSEL at age 14 months was very poor (.30).  By age 24 months, specificity reached .70, and was maintained at that level through age 36 months in the ASD group.

            For the Non-ASD group at 14 months, sensitivity and specificity of language delay classification per the MSEL were .53 and .64, respectively.  Sensitivity continued to drop through age 36 months (.21 and .14 at 24 and 36 months, respectively), while specificity reached a high level (.91) by 24 months, and was sustained through 36 months (.98). 

At age 14 months, VR and IJA scores were the best predictors of language impairment at school-age (X²= 9.96; p = .002), explaining 25% of the variance.  The individual outcome classification rate was moderate to high (83.5%), with good sensitivity (.75) and specificity (.84). 

Conclusions:  

Early language delay is transient in many Non-ASD-sibs-A.  Some ASD-sibs-A acquired early language milestones but exhibited delays in later syntactic and semantic development.  Nonverbal cognition and joint attention are better early predictors of school-age language delay than early language skills in sibs-A.