Some experts see little harm in a responsible physician using A.D.H.D. medications to help a struggling student. Others — even among the many like Dr. Rappaport who praise the use of stimulants as treatment for classic A.D.H.D. — fear that doctors are exposing children to unwarranted physical and psychological risks. Reported side effects of the drugs have included growth suppression, increased blood pressure and, in rare cases, psychotic episodes.