A family study of autism: cognitive patterns and levels in parents and siblings

J Child Psychol Psychiatry. 1997 Sep;38(6):667-83. doi: 10.1111/j.1469-7610.1997.tb01694.x.


First-degree relatives of 99 autism probands and of 36 Down's syndrome controls were assessed with standardised tests of intellectual functioning, reading, and spelling. Higher mean verbal IQ scores, and discrepancies in favour of verbal scores, were characteristic of autism relatives. No consistent differences were found on performance scales, reading, and spelling tests. Among autism relatives, siblings affected with the broad phenotype of autism had significantly lower IQ scores and poorer reading and spelling performances than unaffected siblings. However, the small size of the cognitive difference and the lack of a distinctive cognitive profile indicates that standardised cognitive measures used in this study are unlikely to improve the operationalised definition of the broad phenotype of autism. The slightly superior verbal performance of relatives in the autism group might represent some form of heterozygote advantage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Autistic Disorder / diagnosis
  • Autistic Disorder / genetics*
  • Autistic Disorder / psychology
  • Child
  • Cognition Disorders / diagnosis
  • Cognition Disorders / genetics*
  • Cognition Disorders / psychology
  • Down Syndrome / diagnosis
  • Down Syndrome / genetics
  • Down Syndrome / psychology
  • Female
  • Genetic Carrier Screening
  • Humans
  • Intelligence / genetics*
  • Male
  • Phenotype
  • Prognosis
  • Sibling Relations