It never ceases to amaze me how rarely it is explicitly stated that abused ADD children most likely were abused by ADD family members or ADD friends who were themselves likely abused by ADD family members or friends who were themselves abused by ADD family members or friends, ad infinitum. ADD is a family problem, not just an individual's problem. Perhaps it should be made a family diagnosis, rather than an individual diagnosis. It should come as no surprise that "nearly one in four members of the ADHD group had reported some form of trauma by adolescence, compared to 11 percent in the non-ADHD control group,"

The statement "In the United States, we have a large contingent of kids being diagnosed with ADHD. At the same time, 10 to 20 percent of U.S. kids are abused or neglected. But we have very limited understanding of the overlap between these two groups," seems somewhat akin to looking for zebras when you hear the sound of hooves.  There seems to me to be a very clear overlap resulting from heritability which is not to say there may well be some cases of symptoms resulting from trauma misdiagnosed as ADD or at least not getting adequate attention to the trauma that exacerbates the symptoms. When you treat the child, consider that you might possibly also need to treat the sibs, the parents, the grandparents. And ask about trauma when you diagnose ADD.