Attention-deficit/hyperactivity disorder (ADHD) is one of the most common mental disorders affecting children. ADHD also affects many adults. Symptoms of ADHD include inattention (not being able to keep focus), hyperactivity (excess movement that is not fitting to the setting) and impulsivity (hasty acts that occur in the moment without thought). An estimated 8.4 percent of children and 2.5 percent of adults have ADHD. ADHD is often first identified in school-aged children when it leads to disruption in the classroom or problems with school and work. It can also affect adults. It is more common among boys than girls.
ADHD is diagnosed as one of three types: inattentive type, hyperactive/impulsive type or combined type.