Researchers with the University of California regularly examined a group of babies, some considered to be high risk for Autism, and others who were not.
They monitored the babies' smiling, babbling and eye contact during each exam until they were three years old.
They found the symptoms of autism began to emerge between six and 12 months of age. By six months, most of the infants who developed Autism showed declines in social communication. Then, after 6 months, their eye contact, social smiling and responsiveness declined as well.
Meanwhile, researchers in a different Autism study may have found a way to improve the social behaviors of highly functioning Autistic children.
Previous research has shown that some Autistic children are deficient in Oxytocin, a hormone linked to social behaviors and emotions.
In a new study, 13 patients with high-functioning Autism did a better job responding to social cues when they were given Oxytocin.
Researchers say more studies need to be done to see if the hormone could help these children long-term.