"Many are simply going to whatever interests them or attempting to escape unpleasant circumstances, without understanding that they could be harmed or that they should stay with their families [or] teachers," she said.
Wandering added to the parents' already high stress levels and many parents felt little support to help them manage their children's impulsive behavior, the study found.
"Taking vacations or even simple outings to restaurants or stores are fraught with worry and stress for many of our families, and as a consequence some become socially isolated, further increasing their stress and decreasing their social support," said Warner.
Currently there are no national standards for responding to missing children with autism. The Amber Alert system, which focuses on child abduction, does not cover children with autism who wander.
"Once a child goes missing, there needs to be a way to initiate a search," said Law. "Each minute that goes by without that child being recovered, the chances of a serious outcome goes up tremendously."
McIlwain uses stories to teach Connor about staying safe. They have put stop sign photos on their door as a visual cue, and installed alarms on doors and window.
Many parents like McIlwain have also found success in GPS-like tracking devices worn on the wrist or ankle, originally used as a way to locate dementia patients who wander off. When activated by the caregiver, the device generates a 911 call so the individual can be located quickly.
"Still, no measures are 100 percent effective, and parents of children with ASD must be extremely vigilant, which is draining," said Warner.
Many medical centers offer training for parents and their autistic children on preventing elopement. Children are taught signals to stop, go and stay, while parents are taught what to do if a child wanders.
Even parents who are not worried their child will take off should still learn ways to prevent and prepare, many experts said.
"Future research should focus on 'best practices' to prevent elopement, and the public also needs to become aware that children with ASD do elope, and it is not due to bad parenting," said Pauline Filipek, professor of pediatrics in the division of child and adolescent neurology at the University of Texas Health Science Center in Houston.
ABC News' Lauren Hughes M.D., contributed to this report
For more information on wandering, visit www.awaare.org