A Prospective Study of Autistic-Like Traits in Unaffected Siblings of Probands With Autism Spectrum Disorder

Archives of general psychiatry (Impact Factor: 13.75). 09/2012; 70(1):1-7. DOI: 10.1001/2013.jamapsychiatry.1
Source: PubMed

ABSTRACT CONTEXT The presence of autistic-like traits in relatives of individuals with autism spectrum disorder (ASD) is well recognized, but, to our knowledge, the emergence of these traits early in development has not been studied. OBJECTIVE To prospectively investigate the emergence of autistic-like traits in unaffected (no ASD diagnosis) infant siblings of probands diagnosed as having ASD. DESIGN Two groups of children unaffected with ASD were assessed prospectively-siblings of probands diagnosed as having ASD (high risk [HR]) and control subjects with no family history of ASD (low risk [LR]). Scores on a measure of autistic-like traits at 12 months of age were used in a cluster analysis of the entire sample. SETTING A prospective study of infant siblings of probands with ASD from 3 diagnostic centers in Canada. PARTICIPANTS The study included 170 HR and 90 LR children, none of whom was diagnosed as having ASD at age 3 years. MAIN OUTCOME MEASURES The Autism Observation Scale for Infants was used to measure autistic-like traits and derive clusters at 12 months of age. Clusters were compared on ASD symptoms, cognitive abilities, and social-emotional difficulties at age 3 years. RESULTS Two clusters were identified. Cluster 1 (n = 37; 14.2% of total sample) had significantly higher levels of autistic-like traits compared with cluster 2. Within cluster 1, 33 children came from the siblings (19.4% of HR group) and only 4 came from the control subjects (4.5% of LR group). At age 3 years, children from cluster 1 had more social-communication impairment (effect size > 0.70; P < .001), lower cognitive abilities (effect size = -0.59; P < .005), and more internalizing problems (effect size = 0.55; P = .01). Compared with control subjects, HR siblings had a relative risk of 4.3 (95% CI,1.6-11.9) for membership in cluster 1. CONCLUSIONS Study findings suggest the emergence of autistic-like traits resembling a broader autism phenotype by 12 months of age in approximately 19% of HR siblings who did not meet ASD diagnostic criteria at age 3 years.

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    • "In addition, no differences were found between 7-and 13-month-old children from these groups in terms of performance in tasks related to gaze following (Bedford et al., 2012). A study by Georgiades et al. (2013) revealed no deficits in the area of pragmatic language among 12-month-old infants. "
    01/2014; DOI:10.5114/hpr.2015.48306
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    • "The BAP refers to subclinical differences in traits and abilities seen in family members of individuals with ASD (Gerdts & Bernier, 2011). Patterns similar to those observed in this study have been reported at 12 months among high-risk siblings without an eventual ASD diagnosis who were over-represented in clusters of infants exhibiting difficulties on the Autism Observation Scale for Infants (AOSI), which includes measures of affective response, coordination of gaze and action, and social-communicative behaviors (Georgiades et al., 2013). Differences in anticipatory smiling and related behaviors between high-risk siblings (including those without ASD) and low-risk siblings suggests the possibility that difficulties communicating preexisting positive affect to a social partner may characterize the early BAP. "
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    ABSTRACT: First-degree relatives of persons with an autism spectrum disorder (ASD) are at increased risk for ASD-related characteristics. As little is known about the early expression of these characteristics, this study characterizes the non-ASD outcomes of 3-year-old high-risk (HR) siblings of children with ASD. Two groups of children without ASD participated: 507 HR siblings and 324 low-risk (LR) control subjects (no known relatives with ASD). Children were enrolled at a mean age of 8 months, and outcomes were assessed at 3 years. Outcome measures were Autism Diagnostic Observation Schedule (ADOS) calibrated severity scores, and Mullen Verbal and Non-Verbal Developmental Quotients (DQ). At 3 years, HR siblings without an ASD outcome exhibited higher mean ADOS severity scores and lower verbal and non-verbal DQs than LR controls. HR siblings were over-represented (21% HR versus 7% LR) in latent classes characterized by elevated ADOS severity and/or low to low-average DQs. The remaining HR siblings without ASD outcomes (79%) belonged to classes in which they were not differentially represented with respect to LR siblings. Having removed a previously identified 18.7% of HR siblings with ASD outcomes from all analyses, HR siblings nevertheless exhibited higher mean levels of ASD severity and lower levels of developmental functioning than LR children. However, the latent class membership of four-fifths of the HR siblings was not significantly different from that of LR control subjects. One-fifth of HR siblings belonged to classes characterized by higher ASD severity and/or lower levels of developmental functioning. This empirically derived characterization of an early-emerging pattern of difficulties in a minority of 3-year-old HR siblings suggests the importance of developmental surveillance and early intervention for these children.
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