(Credit:YouTube/Kennedy Krieger Institute)

(CBS News) Autism experts frequently tout the importance of children getting diagnosed early, since studies have shown early invention leads to better outcomes later in life. A new study shows that a simple diagnostic test that checks how a child controls his or her head posture might provide another clue for pediatricians and parents.

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Typically, red flags that might lead to an autism diagnosis are issues with social and communicative traits, such as avoiding eye contact or not playing with others. but Dr. Rebecca Landa, the study’s author and director of the Center for Autism and Related Disorders at Kennedy Krieger Institute in Baltimore, says certain disruptions in a child’s motor development may provide important clues.

For the study, researchers assessed infants in a simple “pull-to-sit” task that measures posture control by firmly – yet carefully – pulling a child’s arms from a position of lying flat on his/her side back into a sitting position (as seen in the videos below). Typically infants achieve this type of posture control by the time they are four months old.

In one experiment, researchers gave this task to 40 infants who were considered to be genetically high-risk for the disorder because a sibling has autism. They researchers were looking specifically at “head lag” – the inability to control head posture – at 6, 14, 24 and 30 months of age.

The researchers found 90 percent of subjects eventually diagnosed with autism exhibited head lags as infants, and 54 percent of kids who met social and communication delays criteria exhibited head lag, while 35 percent of children who did not meet that criteria exhibited the lag.

In a second experiment, Landa and her team examined only six month olds at a single point in time to check for head lag, and found 75 percent of the high risk infants displayed head lag compared with 33 percent of low-risk infants, further emphasizing that head lag is more common in infants that may develop autism.

Landa’s study is to be presented at the International Meeting for Autism Research on may 17 in Toronto.

“While previous research shows that motor impairments are linked to social and communication deficits in older children with autism, the field is just starting to examine this in younger children,” she said in an Institute news release. “Our initial research suggests that motor delays may have an important impact on child development.”

If some parents try the test at home and are worried, Landa emphasized to the Baltimore Sun that a head lag at six months does not mean a child is definitely going to have autism, but rather is a potential sign that a pediatrician should explore further. baltimoresun.com/health/blog/bal-poh-autism-test-for-infants,0,1502094.story

“We don’t want to scare parents,” she said. “If I go to the doctor because I’m having problems with balance, he’s not going to assume I have a brain tumor. when a baby shows a head lag there are so many other things it can be. but this is a very real indicator of something wrong with development and easy things can be done to help.”

Dr. Alycia Halladay, director of environmental research for the advocacy and research group Autism Speaks, told WebMD that the findings are “intriguing” but a head lag’s diagnostic value remains uncertain.

“The first step is to replicate these outcomes in larger studies in multiple sites,” she said.

The study adds to recent research aimed at diagnosing autism at an early age. A recent study found differences in nerve connections seen in infants’ brain scans might signal autism, CBS News medical correspondent Dr. Jon LaPook reported.

About 1 in 88 children has autism, according to recent government estimates.

This video from the Kennedy Krieger Institute shows a typical neck/head development at four months:

This video shows an example of a head lag: