If the stress is from the coursework, then perhaps the curriculum can be adjusted. See Teaching Gifted Kids in the Regular Classroom by Susan Winebrenner (recently updated and in paperback). If the stress is being caused by peer relations, then an elementary guidance counselor could intervene with the kids to work on some peer skills. If the stress is from some internal source, then professional counseling is definitely recommended to help the child. If the problem is between the teacher and the student, I tend to state that it's more beneficial for the child, if at all possible, to adjust to the situation as they will always encounter "another Ms. Smith" somewhere down their educational road!
These are, of course, general guidelines, but I base them on lots of experience. I am not aware of specific research on classroom changes for gifted children. I hope you find this information helpful.