U. S. researchers have recently found that the earliest symptoms of autism such as lack of shared eye contact, smiling and communicative babbling – are not present at six months, and only become apparent during the latter part of the first year of life.

Published in the March issue of the Journal of the American Academy of Child and Adolescent Psychiatry, the report reveals that researchers conducted the study for over five years by painstakingly counting each instance of smiling, babbling and eye contact during examinations until the children were age 3, where they found that by the age of 12 months, the two groups' development had diverged significantly.

Lead author Sally Ozonoff, who is also a professor at Psychiatry and Behavioral Sciences and a researcher with the University of California-Davis MIND Institute, said, “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 six and 12 months of age”.

Ozonoff notes, "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".

Intentional social and communicative behavior among children developing normally increased while infants later diagnosed with autism decreased dramatically, the study said.

According to the figures of the National Autism Society, there are over half a million people in the UK with autism.