The symptoms of the disorder are hyperactivity, impulsiveness and attention deficits, also children with ADHD may have oppositional defiant disorder, conduct disorder, anxiety, depression, specific learn difficulties and sleep disorders.
Einkennin eru ofvirkni, hvatvísi og athyglisbrestur. Oft glíma einstaklingarnir einnig við mótþróaþrjóskuröskun, hegðunarröskun, kvíða eða þunglyndi, sértæka námserfiðleika, svefntruflanir o.fl..