An early sign of autism could be repetitive behavior.
Researchers looked at 184 children who had a high risk of autism and pinpointed "red flags" in the children who ended up developing the condition, HealthDay reported.
The team also observed 59 children who had an average risk of developing the disorder. Forty-two of the high-risk children were diagnosed with autism by the age of two. When the children were between the ages of 12 and 24 months the parents were asked to fill out a questionnaire on repetitive behavior.
The children who developed autism tended to display repetitive behavior such as "flapping their hands or arms, rocking back and forth, or focusing obsessively on one toy," HealthDay reported.
"At one time, people thought repetitive behavior didn't really show up until preschool," Wolff said.
Repetitive behavior is seen in healthy babies "but in typically developing children, that usually peaks around the age of [six] months," lead researcher Jason Wolff of the University of North Carolina at Chapel Hill told HealthDay.
"In children who go on to develop autism, repetitive behavior is still highly prevalent or even increasing, at the age of 12 months," Wolff said.
The researcher suggested a simple "pen-and-pencil measure" could be used to screen for autism in the future, but more research will be required before the method can be relied on.
"This is a promising observation, but it needs refinement before it can be turned into something clinically useful," Andrew Adesman, chief of developmental and behavioral pediatrics at Cohen Children's Medical Center, who was not involved in the study, told HealthDay.
The technique could help medical professionals spot autism earlier. The earlier the disorder is diagnosed the earlier therapy can begin. Starting therapy earlier can lead to better outcomes.
A separate study determined electroencephalograms (EEGs) that monitor brain activity could also effectively predict autism at an early age.
