- Onset before age 12. - At least 6 months of limited attention span and/or poor impulse control.

- Characterized by hyperactivity, impulsivity, and/or inattention in multiple settings (school, home, places of worship, etc).- Normal intelligence, but commonly coexists with difficulties in school.

- Often persists into adulthood.

Treatment: stimulants (eg, methylphenidate) +/- cognitive behavioral therapy (CBT); alternatives include atomoxetine (noradrenaline uptake inhibitor), α₂-agonists (guanfacine, clonidine).