Currently, ADHD is a diagnosis based entirely on symptoms. If you remember, the criteria include inattention, impulsiveness, and hyperactivity, but the Diagnostic and Statistical Manual of Mental Disorders doesn’t say a word about the underlying biology. What it does say is that if these same symptoms are associated with a different mental disorder, like schizophrenia, then it’s no longer ADHD. Similarly, if we see impulsivity and hyperactivity but
