A Prospective Study of the Emergence of Early Behavioral Signs of Autism
Volume 49, Issue 3, Pages 256-266.e2 (March 2010)
Journal of the american academy of child and adolescent pscyhiatry
Sally Ozonoff, Ph.D.a, Ana-Maria Iosif, Ph.D.a, Fam Baguio, B.S.a, Ian C. Cook, Ph.D.a, Monique Moore Hill, M.S.a, Ted Hutman, Ph.D.b, Sally J. Rogers, Ph.D.a, Agata Rozga, Ph.D.b, Sarabjit Sangha, B.S.a, Marian Sigman, Ph.D.b, Mary Beth Steinfeld, M.D.a, Gregory S. Young, Ph.D.a
Accepted 30 November 2009. published online 08 February 2010.
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 development. 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.
a University of California–Davis
b University of California–Los Angeles
Correspondence to: Dr. Ozonoff, M.I.N.D. Institute, University of California Davis Health System, 2825 50th Street, Sacramento CA 95817
© 2010 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.