A Closer Look at Early Autism Symptoms that Emerge in Infancy

Date: 
January 12, 2011

For the first time, researchers have been able to directly observe how the earliest signs of autism emerge in a prospective study of infants who were later diagnosed with autism. Before this type of study, our understanding of the early symptoms of autism relied either on parents' recollection or home videotapes. Many parents have expressed concerns about their infant well before a formal diagnosis could be made. But, it has been difficult to systematically study what symptoms show up during the infant period.

Sally Ozonoff, Ph.D., and her colleagues at UC Davis have been following a large group of infants who are at risk for autism because they have an older sibling with autism, making careful observations at 6, 12, 18, 24, and 36 months of age. This report focuses on a subgroup of 25 high risk infants who later developed autism who were compared to 25 low risk infants. Dr. Ozonoff and colleagues found that infants who later developed autism did not show any observable symptoms at 6 months of age. At this early age, the infants were making eye contact, vocalizing and smiling at others. Between 6 and 12 months of age, however, these infants gradually lost their social skills. By 12 months of age, they were clearly different than the low risk infants who continued to gain in their language and social skills. Although this gradual loss of social skills can be viewed as a type of regression, most parents did not report that their child had regressed, perhaps because the loss of skills was so gradual. The researchers also assessed whether the infants lost skills in other areas, such as visual skills. They found that the loss was specific to the area of social communication.

This study provides us with a closer look at the first observable symptoms of early onset autism. The results suggest that it should be possible to detect autism symptoms before one year of age, at least for children with early onset autism. Screening tools should focus on the social communication skills that infants display between 6-12 months, such as looking, vocalizing, and smiling at others. Dr. Ozonoff noted that it might be necessary to screen infants several times because the loss of skills can be very gradual. By paying attention to these early social communication skills during a well-baby check-up, pediatricians may someday be able to refer infants at risk for autism for interventions that can help promote the development of these skills. Autism Speaks is currently funding several clinical trials aimed at developing interventions that can be used with infants and toddlers with autism.


1.Ozonoff S,Iosif AM,Baguio F,Cook IC,Hill MM,Hutman T,Rogers SJ,Rozga A,Sangha S, Sigman M, Steinfeld MB, Young GS. (2010) A prospective study of the emergence of early behavioral signs of autism.J Am Acad Child Adolesc Psychiatry. Mar;49(3):256-66.e1-2.

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