The primary characteristic of attention deficit hyperactivity disorder (ADHD) is a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or a child’s development.
The problems occur usually in two or more areas of a person’s life: home, work, school, and social relationships. ADHD is also referred to as attention deficit disorder (ADD) when hyperactivity or impulsivity is not present.
Attention deficit disorder begins in childhood. The symptoms of inattention and hyperactivity need to show themselves in a manner and degree which is inconsistent with the child’s current developmental level. That is, the child’s behavior is significantly more inattentive or hyperactive than that of his or her peers of a similar age.
Several symptoms must be present before age 12 (which is why ADHD is classified as a neurodevelopmental disorder, even if not diagnosed until adulthood). In the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), symptoms were required before age 7. Now the age of 12 is seen as an acceptable criterion because it is often difficult for adults to look retrospectively and establish a precise age of onset for a child. Indeed, adult recall of childhood symptoms tends to be unreliable. Thus, the DSM-5 has added some leeway to the age cut-off.