Paul T. Shattuck, professor of social work at Washington University in St. Louis, said U.S. parents pay an average of $774 each year on therapies, rehabilitation and specialty medical care for their special needs children.

Shattuck and his co-author, Susan L. Parish of the University of North Carolina at Chapel Hill, found that wealthier states tend to have lower out-of-pocket medical expenses. "At the low end, families in Massachusetts paid an average of $560 for out-of-pocket medical expenses," Shattuck said in a release. "At the high end, families in Georgia shouldered an average of $970 in additional care expenses."

He said the study programs like Medicaid and the State Children's Health Insurance Program may not be going far enough to help families with children with special needs.