International Meeting for Autism Research (London, May 15-17, 2008): Developmental trajectories in siblings of children with autism: Cognition and language from 4 months to 7 years

Thursday, May 15, 2008

Champagne Terrace/Bordeaux (Novotel London West)

9:30 AM

I. Gamliel , School of Education, The Hebrew University of Jerusalem, Jerusalem, Israel

N. Yirmiya , Department of Psychology and School of Education, The Hebrew University of Jerusalem, Israel

D. H. Jaffe , School of Public Health, The Hebrew University of Jerusalem, Israel

M. Sigman , Departments of Psychiatry and Psychology, UCLA

Background: Some siblings of children with autism (SIBS-A) are characterized by the broad autism phenotype (BAP), which involves milder but qualitatively similar difficulties.

Objectives: To compare the cognitive and language skills of SIBS-A and siblings of typically developing children (SIBS-TD) from 4 months to 7 years, using growth curve analyses.

Methods: A longitudinal cohort study sample of siblings tested at ages 4, 14, 24, 36, and 54 months and 7 years (n = 41). At 7 years, 15 of the 37 SIBS-A were identified with BAP-related difficulties using parents' report and/or scores of at least 1.5 standard deviations below average on the cognitive and/or language measures (i.e., WISC-III, CELF-III). Between and within group differences were assessed with growth curve models using MLwiN repeated measures analysis for the 4-54 months data.

Results: The cognitive scores (4-54 months) of SIBS-A-BP (identified by parents' report and/or tests scores) were significantly lower (on average by 8 points) compared to SIBS-TD. However, the growth curves over time were not significantly different between SIBS-A and SIBS-TD groups. The language scores (4-54 months) of SIBS-A-BP (identified by parents' report and/or tests scores, and only by parents' report) were significantly lower (on average by 10 to 21 points) compared to SIBS-A-nonBP and SIBS-TD. The growth curve of SIBS-A-BP (identified by parents' report) indicated that these siblings developed differently than SIBS-A-nonBP and SIBS-TD. Similarly, language scores (4-54 months) of SIBS-A-nonBP (identified by test scores) were significantly lower (on average by 9 points) and their language development differed compared to SIBS-TD.

Conclusions: Language is a major area of difficulty for SIBS-A during the pre-school years. As a group, SIBS-A identified at age 7 years with BAP-related difficulties manifested lower cognitive and language abilities as well as different developmental trajectories during the pre-school years (4-54 months).

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