ACE Project I - The Development of the Siblings of Children with Autism: A Longitudinal Study

The major aim of this study is to identify group differences in early life in children who are at risk of autism and autism spectrum disorder because they have an older sibling who has been diagnosed with autism. The study is taking place at two sites: the Center for Autism Research and Treatment at UCLA and the MIND Institute at UC Davis. As of June 2006, 230 siblings of autistic children (109 at UCLA and 121 at UC Davis) and 131 infant siblings without a family history of autism (63 at UCLA and 68 at UC Davis) have been recruited and tested every 6 months, starting at 6, 12, or 18 months and continuing until 36 months of age. We propose to recruit an additional 100 infant siblings of children with autism at UCLA and to extend the follow-up of the current sample to 5-years of age.

The characteristics of the children selected for study were chosen on two grounds, either because:

• these characteristics and skills are known to be important for the development of typical children or
• because these characteristics and skills reliably separate children with autism from children with other kinds of delay.

Examples of the first class of assessments are the observations of interactions between the 6-month-olds and their mothers that are video-taped and coded in terms of synchrony and emotional responsiveness. Also at 6 months, habituation and discrimination of emotions and patterns of gaze directed to slides of faces showing emotions are studied with an eye tracking monitor so that the children's speed of processing, capacity to discriminate emotions, and focus on the eyes can be measured. Examples of the second class of characteristics are assessments of communication development including both nonverbal communication and spoken language; imitation; emotional responsiveness; and patterns of pretend play. At 18 months, biological samples (either blood or buccal swabs) are collected from the infant, affected sibling, and parents to be used in Project II. At 18, 24, and 36 months, the ADOS is administered to all subjects so that some form of diagnosis can be made.

This study of infant siblings has sufficient power to compare five different subgroups in terms of their earlier and subsequent behaviors. These subgroups consist of infants with full autism, infants with autism spectrum disorder, infants with language delays, unaffected siblings of children with autism, and infants without a family history of autism. The identification of early deficits and the characterization of trajectories of development will be evaluated so that we will have a fuller awareness of early development of autism and both behavioral and genetic information critical to moving diagnosis to earlier ages.