Attention Deficit Hyperactivity Disorder
(ADHD) (ADD)
Medical Author: Dennis S. Phillips, MD, and John Mersch, MD, FAAP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
What is attention deficit hyperactivity disorder (ADHD)?
ADHD refers to a chronic disorder that initially manifests in childhood and
is characterized by hyperactivity, impulsivity, and/or inattention. Not all of
those affected by ADHD manifest all three behavioral categories. These symptoms
can lead to difficulty in academic, emotional, and social functioning. The
diagnosis is established by satisfying specific criteria and may be associated
with other neurological, significant behavioral, and/or developmental/learning
disabilities. Therapy may consider the use of medication, behavioral therapy, and
adjustments in day-to-day lifestyle activities.
Studies in the United States indicates approximately 8%-10% of
children satisfy diagnostic criteria for ADHD. ADHD is, therefore, one of the
most common disorders of childhood. ADHD occurs two to four times more commonly
in boys than girls (male to female ratio 4:1 for the predominantly hyperactive
type vs. 2:1 for the predominantly inattentive type). While previously believed
to be "outgrown" by adulthood, current opinion indicates that many children will
continue throughout life with symptoms that may affect both occupational and
social functioning.
What is the cause of ADHD?
The cause of ADHD has not been fully defined. One theory springs from observations regarding variation in functional brain imagining studies between those with and without symptoms. Similar variations have been shown in studies of the structure of the brain of affected and non-affected individuals. Animal studies have demonstrated differences in the chemistry of brain transmitters involved with judgment, impulse control, alertness, planning, and mental flexibility.
A genetic predisposition has been demonstrated in (identical) twin and sibling studies. If one identical twin is diagnosed with ADHD, there is at 92% probability of diagnosis with the twin sibling. When comparing nonidentical twin sibling subjects, the probability falls to 33%. (Overall population incidence is 8%-10% in the U.S., as described above.)
Next: What are the symptoms of ADHD? »
 |
 |
From the Doctors at MedicineNet.com  |
|
Specialty RSS
