Girls with Attention Deficit Hyperactivity Disorder (ADHD) -- and their families -- often look forward to the likely decline in visible symptoms such as fidgety or disruptive behavior as they mature into young women. However, new findings caution that, as they enter adulthood, girls with histories of ADHD are more prone to internalize their struggles and feelings of failure -- a development that can manifest itself in self-injury and even attempted suicide.