Attention-deficit hyperactivity disorder (ADHD) (sometimes also referred to as ADD) is a psychiatric diagnosis that interprets divergent personality traits perceived to be distracting as symptoms of a mental disorder. Characteristics sometimes interpreted as symptoms include hyperfocus, hyperactivity, forgetfulness, mood shifts, poor impulse control, and distractibility.

ADHD is commonly diagnosed among children. When diagnosed in adults, it is regarded as adult attention-deficit disorder (AADD). It is believed that approximately 30 to 70% of children diagnosed with ADHD retain the disorder as adults.