All parents worry about losing sight of their young kids when out in public. I’ve had that happen in a Target store (with my son) and at a playground (with my daughter), so I know first-hand how scary an experience it is.

But that fear can be amplified when your child has an autism spectrum disorder (ASD). Concerns about such a child’s ability to communicate with other people and to recognize and avoid danger can add to the mix of anxieties. Current estimates say ASDs affect 1 in 88 children.

A study published Monday morning in the journal Pediatrics helps quantify the extent to which children on the autism spectrum wander off on their own – a behavior known as “elopement.” The study’s introduction notes that anecdotal evidence suggests kids on the autism spectrum tend to elope and the experience is very stressful for their families. But, the authors write, the phenomenon has been little studied, with only a handful of cases investigated.

Researchers at the Kennedy Krieger Institute and the Johns Hopkins University School of Medicine (both in Baltimore) and several other institutions surveyed parents of 1,218 children with ASD, which encompasses autistic disorder, Asperger disorder and  pervasive development disorder.  They were asked if their child had wandered away at or after age 4 (the age at which such behavior is no longer in keeping with normal child development, the study explains), how stressful an experience that was for the family, whether the child had been at risk of physical danger while wandering and what the child’s likely reason for wandering may have been.

Nearly half (49 percent) of families reported that their child had eloped at least once. Of those families, 26 percent said the child had been gone long enough to cause concern. Nearly a quarter (24 percent) of those who wandered had been at risk of drowning, and 65 percent had been at risk of traffic injury. Most parents (56 percent) called it the most stressful experience in raising their child, and 50 percent said they had received no assistance or guidance as to how to handle their child’s wandering.

Most children (74 percent) wandered away from their own or another home; 40 percent wandered from a store, and 29 percent wandered from a school. Wandering peaked at age 5.4 years, and the risk of wandering increased with the severity of the child’s disorder.

Most parents said their child seemed to attain some kind of goal by wandering, escaping an uncomfortable situation or environment, for instance, or seeking a place where they’d be happier. Most also said their child seemed happy, joyful or purposeful when wandering, though children with Aspberger’s syndrome were more commonly described as being anxious.

The researchers also asked about siblings’ wandering behaviors; only 13 percent of the 1,076 siblings of children on the autism spectrum were said to have eloped.

The study notes: “Because participation in this study required having a living child with ASD, families of children who lost their lives while eloping were not included. It was therefore not possible to estimate the number of fatalities that occur due to elopement.”

Has your child with autism ever wandered off? How did you deal with that experience?

FYI: The American Academy of Pediatrics in September published the book Autism Spectrum Disorders: What Every Parent Needs to Know .