Watch the video of 2 students, 1 with ADHD. You will notice differences.
Some differences are directly related to ADHD. Others are the result of secondary characteristics. In special education these are characteristics of a student that result not from the disability but from how the disability plays out in an academic and other settings. For example, a student with a speech impediment may be very timid and anxious in situation in which he or she may need to speak.
In math a major secondary characteristic is math anxiety. This is a performance issue vs an ability issue and it must be addressed as a legitimate obstacle for the student. I work with graduate students who still suffer math anxiety years later.