(SACRAMENTO, Calif.) A study of the development of autism in infants, comparing the behavior of the siblings of children diagnosed with autism to that of babies developing normally, has found that the nascent symptoms of the condition a lack of shared eye contact, smiling and communicative babbling are not present at 6 months, but emerge gradually and only become apparent during the latter part of the first year of life.
Researchers conducted the study over five years by painstakingly counting each instance of smiling, babbling and eye contact during examinations until the children were 3. They found that by 12 months the two groups' development had diverged significantly. Intentional social and communicative behavior among children developing normally increased while among infants later diagnosed with autism it decreased dramatically. The study is published online early and will appear in the March issue of the Journal of the American Academy of Child & Adolescent Psychiatry.
"This study provides an answer to when the first behavioral signs of autism become evident," said Sally Ozonoff, the study's lead author, a professor of psychiatry and behavioral sciences and a researcher with the UC Davis MIND Institute. "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."
Autism is a pervasive developmental disorder of deficits in social skills and communication, as well as in repetitive and restricted behaviors, with onset occurring prior to age 3. Abnormal brain development, probably beginning prenatally, is known to be fundamental to the behaviors that characterize autism. Current estimates place the condition's incidence at
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University of California - Davis - Health System