ADHD is a chronic condition marked by persistent inattention, hyperactivity, and sometimes impulsivity. ADHD begins in childhood and often lasts into adulthood. About 30% to 50% of children with ADHD continue to have symptoms as adults.
Symptoms of ADHD can differ from person to person, but there are three basic types of ADHD. Each one is identified by some combination of hyperactivity, impulsivity, and inattention. When activity levels are normal or low, the type is usually called primarily inattentive. The symptoms of hyperactivity and possibly impulsiveness appear to diminish with age but are seen in the primarily hyperactive/impulsive type. The third type has some symptoms from each of the other two and is called the combined type.
Children with ADHD have trouble functioning at home and in school and often havedifficulty making and keeping friends. If left untreated, ADHD may interfere with school and work, as well as with social and emotional development.
ADHD is more common in boys, whose impulsivity and hyperactivity may be evident. Inattentiveness is a hallmark of ADHD in girls, but because they aren't often disruptive in the classroom, they may not get diagnosed.
ADHD tends to run in families. When one person is diagnosed with ADHD, there is a 25%-35% chance that another family member will also have the condition, compared to 4%-6% of the general public.
No one knows for sure whether ADHD is more common today, but it is very clear that the number of children getting diagnosed and treated for ADHD has risen over time. Some of this increase in diagnosis and treatment is due to greater awareness of the symptoms. Some experts feel that ADHD is overdiagnosed, while others feel it is underdiagnosed or undertreated.