EBD Blog

Source: Oznoff et al., 2010

In “A Prospective Study of the Emergence of Early Behavioral Signs of Autism,” Professor Sally Oznoff and colleagues found that infants who develop Autism behave differently than their typically developing peers even as early as one year of age. Writing in the Journal of the American Academy of Child & Adolescent Psychiatry, the researchers reported about a comparison of video tapes of children (n=50, half of whom had Autism) made at six-month intervals during infancy and early childhood.

The children differed markedly in social communicative behaviors and engagement, including gazes to faces, vocalizations, smiles, and overall engagement, according to ratings made by trained examiners of the videos. The two groups did not differ at 6 months of age, but by 12 and 18 months of age, differences clearly emerged. Professor Oznoff and colleagues noted that these differences indicate that, although children with Autism manifest atypical behavior earlier than parents report it, few differences are apparent during the first few months of life.

A press release about the story quotes Professor Oznoff as saying, “Contrary to what we used to think, the behavioral signs of autism appear later in the first year of life for most children with autism. Most babies are born looking relatively normal in terms of their social abilities but then, through a process of gradual decline in social responsiveness, the symptoms of autism begin to emerge between 6 and 12 months of age.”

Here’s the abstract:

Objective: To examine prospectively the emergence of behavioral signs of autism in the first years of life in infants at low and high risk for autism. Method: A prospective longitudinal design was used to compare 25 infants later diagnosed with an autism spectrum disorder (ASD) with 25 gender-matched low-risk children later determined to have typical develop- ment. Participants were evaluated at 6, 12, 18, 24, and 36 months of age. Frequencies of gaze to faces, social smiles, and directed vocalizations were coded from video and rated by examiners. Results: The frequency of gaze to faces, shared smiles, and vocalizations to others were highly comparable between groups at 6 months of age, but significantly declining trajectories over time were apparent in the group later diagnosed with ASD. Group differences were significant by 12 months of age on most variables. Although repeated evaluation documented loss of skills in most infants with ASD, most parents did not report a regression in their child’s development. Conclusions: These results suggest that behavioral signs of autism are not present at birth, as once suggested by Kanner, but emerge over time through a process of diminishment of key social communication behaviors. More children may present with a regressive course than previously thought, but parent report methods do not capture this phenomenon well. Implications for onset classification systems and clinical screening are also discussed.

Oznoff, S., Iosif, A-M., Baguio, F., Cook, I. C., Hill, M. M., Hutman, T.,…Young, G. S. (2010) A prospective study of the emergence of early behavioral signs of autism. Journal of the American Academy of Child & Adolescent Psychiatry, 49, 256-266.

Professor Oznoff and some of the other authors are associated with the Early Developmental Studies Lab at the M.I.N.D. Institute (see link under “Web Resources” in left rail) of the University of California–Davis. Link to the abstract (readers may be able to download the full article at the page to which this link points). Also, see the press release about the study and coverage (“Autism signs appear in babies’ first year, but parents don’t notice, study finds“) in the Los Angeles Times.