Psychometric assessment of first-degree relatives of 62 autistic probands in Utah

Abstract

The Wechsler Intelligence Scales, Wide Range Achievement Test, and the Shipley-Hartford Test were administered to 122 parents and 153 siblings of 62 autistic probands in Utah. Scores were distributed as expected within the published normative ranges for each scale. Parents' scores correlated with those of their nonautistic children, but neither parents' nor siblings' scores correlated with the IQ level of the autistic probands. These results do not confirm prior reports from England and the United States of a high rate of cognitive and learning problems in the siblings of autistic individuals, nor the aggregation of such problems in the siblings of probands with high or low levels of cognitive function.

The Broader Autism Phenotype and Its Implications on the Etiology and Treatment of Autism Spectrum Disorders

“…However, later reports suggested that these cognitive deficits may instead have been markers of intellectual disability rather than autism per se as they were generally present in relatives of individuals with ASD and intellectual disability, but not in relatives of children with ASD with normal intelligence [47]. Since then, the majority of studies have failed to document increased rates of cognitive dysfunction in relatives, regardless of the intelligence level of the affected child [11, 17, 48]. …”

“…Given these variable intelligence levels, researchers have examined intellectual functioning in relatives of children with ASD. Although early reports suggested below average intellectual functioning and cognitive disabilities in ASD siblings [45, 46], many subsequent studies have failed to support these initial findings [11, 17, 48]. Full scale IQ in ASD parents and siblings has since been found to be in the average to high average range in most research studies (e.g., [11, 42, 48, 73–75]).…”

“…Child gender also does not appear to be related to the degree of expression of the BAP in relatives [12, 55]. Cognitive ability of children with ASD is unrelated to the degree of expression of the BAP in parents [13, 17, 21, 48]. However, Szatmari and colleagues [55] reported that social and communication impairments were more common in immediate and extended relatives of affected children with IQs above versus below 60.…”

Pragmatic Language and School Related Linguistic Abilities in Siblings of Children with Autism

“…For example, Plumet et al (1995) found that siblings (aged 13–35 years) of female probands with autism achieved significantly lower scores than siblings of female probands with Down syndrome on measures of repetition, reading, spelling, vocabulary, phonological knowledge, and short-term verbal memory. Yet, others found no differences on language measures such as reading, spelling (Folstein et al 1999; Freeman et al 1989), phonological processing (Bishop et al 2004), and receptive and expressive language (Pilowsky et al 2003) between SIBS-A and different comparison groups or published norms. Moreover, SIBS-A scored higher on cognitive, language and reading abilities measures than siblings of children with specific language impairment (Lindgren et al 2009).…”