Attention Deficit Hyperactivity Disorder (ADHD) is diagnosed in 2 to 5 percent of children between the ages of 6 and 16; approximately 80 percent are boys. The typical symptoms of distractibility, hyperactivity and agitation occur at all ages, even in adults who have the condition, but with considerable disparity. Children often seem forgetful or impatient, tend to disturb others and have a hard time observing limits. Poor impulse control manifests itself in rash decision-making, irrational actions and rapid mood swings. The child acts before thinking. And yet, ADHD children often behave perfectly normally in new situations, particularly in those of short duration that involve direct contact with individuals or are pleasurable or exciting, like watching TV or playing games. Precursor behaviours such as a difficult temperament or sleep and appetite disorders have often been found in children younger than 3 who were later detected to have ADHD, but no definite diagnosis can be made in those first three years. Physical restlessness often diminishes in teenagers, but attention failure continues and can often become associated with aggressive or anti-social behaviour and emotional problems, as well as a tendency towards drug abuse.