b'Those with the predominantly hyperactive/impulsive type often: fidget with their hands or feet or squirm in their seatleave their seat when remaining seated is expectedmove excessively or feel restless in situations where such behavior is inappropriate have difficulty engaging in leisure activities quietly talk excessively and blurt out answers before questions have been completed have difficulty awaiting their turn and interrupt othersAs with any symptoms of mental illness, it is the degree of disruption or dysfunction that distinguishes between a diagnosable condition and what might simply be a collection of personal characteristics.Many students display behaviors such as those described above, have no difficulty managing relationships, classes and related campus activities. What causes ADHD? ADHD is not caused by dysfunctional parenting nor a lack of intelligence or discipline. Strong scientific evidence supports the conclusion that ADHD is a biologically based disorder. National Institute of Mental Health researchers using PET scans have observed significantly lower metabolic activity in regions of the brain controlling attention, social judgment,Mental Health Concerns195'