ADD and ADHD refer to attention-deficit disorder and attention-deficit hyperactivity disorder, respectively. Both are common mental disorders that manifest primarily in children, according to the National Institute of Mental Health. Common symptoms for both disorders include restlessness, difficulty in focusing or staying organized, and impulsivity. Those with an ADHD diagnosis also exhibit a difficulty in sitting still or engaging in quiet activities. Some debate exists as to the accuracy of an ADHD or ADD diagnosis as an actual disorder.
Refer to someone as having attention-deficit disorder or attention-deficit hyperactivity disorder only if the information is relevant to the story and if a licensed medical professional has formally diagnosed the person. Use attention-deficit disorder or attention-deficit hyperactivity disorder upon first reference; ADD and ADHD are acceptable for each disorder on second reference, respectively.