Impulsivity has been variously defined as behavior without adequate thought, the tendency to act with less forethought than do most individuals of equal ability and knowledge, or a predisposition toward rapid, unplanned reactions to internal or external stimuli without regard to the negative consequences of these reactions.

Impulsivity is associated with many different psychiatric disorders including mania, personality disorders and substance abuse disorders. However, there is significant disagreement among researchers regarding the definition and credibility of impulsivity and how it should be measured, if at all.

The onset for impulsivity for teens is usually between the ages of 12 and 13 and may be associated with lack of inhibition control in the brain. If at age 15-16 lack of impulse control suddenly appears, this is thought to be late onset and usually will correct itself around ages 18-19. Late onset impulse control is usually due to peer pressure. It is important to define where your teen falls on this spectrum to determine the type of care or supervision that may be needed.