Behavioral inhibition and activation in posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is characterized by anxiety symptoms and impulsivity and aggression, which are thought to represent examples of excessive behavioral inhibition and activation, respectively. PTSD and traumatized control subjects performed the Stop-Signal Task to assess behavioral activation and inhibition simultaneously. PTSD subjects showed no evidence of the generally increased behavioral inhibition expected to accompany anxiety, but exhibited progressively decreased behavioral activation during acquisition of the task. However, when behavior was facilitated using monetary rewards, both PTSD and traumatized control subjects showed increases in behavioral activation, whereas PTSD subjects also showed significant disinhibition. These findings argue against PTSD patients being chronically inhibited and unresponsive to rewards, and the presence of disinhibition accompanying behavioral activation in these subjects may explain the impulsivity and aggression associated with PTSD.