Symptoms of ADHD must be present by the age of six, although diagnosis may not occur until adolescence or adulthood. ADHD has three types:

A. Predominantly Inattentive type: this type has at least six of the following symptoms: Difficulty sustaining attention; not listening when spoken to; not following through on instructions or finishing tasks easily; being easily distracted by external stimuli; often forgetful; loosing things necessary for tasks; and avoiding work and school activities.

B. Predominantly hyperactive type: Fidgets and squirms; leaves seat in classroom; runs about or climbs excessively or has feelings of restlessness; has difficulty playing or engaging in leisure activities; often on the go or acts if driven by a motor; often talks excessively. 

Impulsive symptoms are: blurts out answers before questions have been completed; has difficulty awaiting his turn; frequently interrupts or intrudes on others. 

C. Combined type: Is diagnosed when both symptoms of hyperactivity-impulsivity and symptoms of inattention are both present.

Although ADHD has its onset in childhood, it often persists into adolescence and adulthood, and can be diagnosed in adulthood.

Treatment of all three types of ADHD: includes medications which are usually forms of amphetamines; behavior therapy and talk therapy to reduce the self-esteem problems created by negative interpersonal reactions from others. ADHD can usually be diagnosed through psychological or psychiatric interview of behavior and symptoms.