COGNITIVE LANGUAGE DEVELOPMENT AND BIRTH ORDER IN NON AFFECTED SIBLINGS OF CHILDREN WITH AUTISM

Abstract

The study aims  to explore cognitive and language development in siblings of children with autism, and to compare younger and older siblings on all the measures. 36 siblings of children with autism, between the ages of 2 years, 6 months and 15 years (x=8.67; SD=3.91) were assessed using the PPVT for the receptive language abilities, the WPPSI-III or WISC-III as an estimation of IQ, the VABS as a measure of adaptive functioning, and SCQ was used to assess autism-related symptoms. 72% (n=26) of the children were older than the affected sibling, whereas 28% (n=10) were younger. PPVT scores were below normal limits. On the contrary, IQ scores for the total sample were regarded as average. In contrast, their adaptive functioning was within normal limits. Younger siblings had poorer performance on the PPVT and on the communication sub-domain of the VABS when compared to older siblings. Siblings of children with autism might exhibit abnormal language development, which could be considered as features of the broader-autism phenotype. Although it has also been suggested that birth order could affect the language development of the unaffected siblings, the relationship between these variables remains unclear. These findings offer additional support for a familial association between autism and language abnormalities.