 They are frequently accident-prone, reckless and impulsive, and may thoughtlessly (rather than defiantly) break rules.Cognitive impairment and delayed language and motor development are more common in this group than in the general population; and they may experience low self-esteem and engage in dis-social behavior as a consequence of the disorder.While hyperkinetic children are commonly incautious and unreserved with adults, they might be isolated and unpopular with other children.