Children who have a sibling with a disability are more prone than other kids to having troubles with relationships, behavior, schoolwork or recreational activities, according to a new survey of parents.

The study could not explain why the siblings of disabled kids were more likely to have problems functioning socially or emotionally than kids without a special needs brother or sister. But Anthony Goudie, the report's lead author, said he's convinced it has to do with the family situation.

"That's driven by the disproportionate or increased financial strain and stress within these households, the psychological stress...and the emotional stress on caregivers and parents, and the amount of time they have to spend devoting to the child with a disability," said Goudie, who is an assistant professor at the University of Arkansas for Medical Sciences and Arkansas Children's Hospital in Little Rock.

Goudie said the findings are important because the functional problems for which the non-disabled siblings appear to be at increased risk have been tied to higher odds of mental illnesses, such as depression and anxiety disorders, that require treatment.

His study is perhaps the largest to date looking at the day-to-day difficulties for siblings of kids with a disability.

Earlier research included fewer children or focused only on one type of disability in siblings, Goudie told Reuters Health.

In some of those cases, the results showed that kids with a disabled sibling do just fine, while other studies found the children fare worse socially, behaviorally and emotionally than kids without a disabled child in their family.

For a better sense of how well siblings of disabled kids function, Goudie and his colleagues collected data from a large survey of parents that asked about their children's behavior, relationships, school performance, activities and emotions.

There were 13 questions, each to be answered on a scale of 1 to 4, with 1 being no problem in functioning and 4 being the most impaired.

The researchers considered a child whose total score was higher than 16 out of 52 to have a "significant functional impairment."

Nearly 250 children with a disabled sibling were included in the study, and the researchers compared their functioning to more than 6,500 children from families without any disabled children.

A disability was not defined by specific conditions but by limitations - such as difficulty breathing, swallowing, using language - that made a child unable to do the things children of the same age typically do.

Goudie's group found that about 10 percent of children without disabled siblings scored above 16, and therefore had worrisome functional impairments.

In contrast, 24 percent of kids who had a sibling with a disability scored above 16, the team reports in the journal Pediatrics.

Debra Lobato, the director of Child Psychology at Rhode Island Hospital/Hasbro Children's Hospital in Providence, said the results are not surprising.

One explanation is that they might stem, in part, from parents overstating their children's problems, she said.

Parents who have a child with a disability are often under more stress, and may have a heightened concern for their other children.

"It's possible that their own experience colors how they see their healthy, typical kids doing," said Lobato, who was not involved in the new study.

The other explanation for the results is that these siblings do indeed fare worse than kids who don't have a disabled child in the family, she said.

"The kids are living under more stress. Not everybody breaks under the stress, but there's a significant number who find this to be a very difficult situation," Lobato told Reuters Health.

Goudie said the findings can be used to help parents and health care providers be aware that siblings are at a higher risk for developing functional problems.

"The importance of identifying (functional problems) in a group of kids is that if we can identify mental health issues at an early age, we can intervene at an early age and have greater success in remedying the situation," he said.

Lobato said group support for siblings of children with a disability can help them deal with the challenges that go along with living in a family with a child who has special needs.

She added that doctors who treat children with disabilities should consider a family check-up to screen siblings for emotional, behavior and psychological problems.

"Check in annually, how are the other kids doing? And if you picked up kids early on who had some needs, then you can address them early," she said. "My experience is a small amount of intervention early with siblings goes a long way."