If you have a disabled adult child, there may be many services available to him or her that will help reduce the financial burden for you and give your child the independence that she or he needs and deserves. Your child may be eligible for SSI. You apply for this through the Social Security Administration, and you can do it on line by going to http://www.ssa.gov/
If in Ohio, and maybe in other states as well, your child may be eligible for services through the local board of developmental disabilities. There is one for every county. The state web page for ohio is http://dodd.ohio.gov/ The list of county boards and other related links can be found at http://dodd.ohio.gov/contacts/countyboards1.htm
With regard to support, keep in mind that if your child is disabled, then you may be entitled to receive long term child support indefinitely beyond the traditional age of 18 under the Castle case. The citation for that case is Castle v. Castle (1984), 15 Ohio St.3d 279 Here is a comprehensive article that explains it in great detail. http://www.divorcesource.com/research/dl/childsupport/97oct188.shtml
There are many more things that can be done with adult disabled children, but these resources are a great way to get started. In addition, as with any disability issue, it is a good idea to look at the Ohio State Legal Rights website to understand your legal rights. Here is the cite to that:
Hope some of this helps. As always, feel free to call me if you need more information.