Theresa R. Cerulli, MD: The other challenge in diagnosing ADHD [attention-deficit/hyperactivity disorder] is that the comorbid psychiatric conditions are so high. If you have ADHD, 75% of the time there’s a comorbid condition with it. In other words, straightforward ADHD exists alone in only 25% of your patients with ADHD. Seventy-five percent of the time there’s a comorbid psychiatric condition, and 60% of the time there are 2 or more comorbid psychiatric conditions with ADHD.