Dad,

This is a great question.

If you look at the DSM ( Diagnostic and Statistical Manual of Mental Disorders) which is used by medical/mental health professionals to diagnose psychiatric disorders, one of the criteria in diagnosing ADHD states:

"The symptoms do not occur exclusively during the course of a pervasive developmental disorder, schizophrenia, or other psychotic disorder, and are not better accounted for by another mental disorder (e.g., mood disorder, anxiety disorder, dissociative disorder, personality disorder.)"

The DSM does not say that an individual with Down Syndrome or other developmental disorder cannot also have ADHD. What I believe it is trying to say is that ADHD is a diagnosis of exclusion, meaning...if other disorders, like PDD, mood, anxiety, etc. can explain "ADHD-like" symptoms, then they would not carry the ADHD diagnosis. For example, people with anxiety can appear to have ADHD (being distracted, hyperactive), but it is the anxiety, not a possible ADHD that explains that behavior.

Conversely, in your son's case, it certainly seems to me that he could have ADHD in addition to Down Syndrome.

Regardless of what it's called, if he has symptoms of ADHD that are affecting the quality of his life, then I don't see why he can't be treated for the ADHD unless there are medical issues that preclude such treatment.

Note, too that those with anxiety, depression and other psychiatric disorders, certainly can also have a co-morbid ADHD, which seems to be the question you are asking. Yes, people can have more than one disorder.

Hope this helps!
Terry