Motivational and cognitive inhibitory control in recreational cannabis users.

Substance use disorders have been associated with impaired decision making and increased impulsive behavior. Lack of inhibitory control may underlie such higher order cognitive difficulties and behavior problems. This study examined inhibitory control in 53 recreational cannabis users and 48 controls. Inhibitory control was tested with two computer tasks, one with a motivational component and one without such a component. Impulsive behavior was assessed using the Barratt Impulsiveness Scale. Results showed that the recreational cannabis users had poorer motivational inhibition (i.e., were more inclined to "gamble") than controls. There were no group differences in the cognitive inhibition task. Cannabis users also reported more impulsive behavior in daily life. This behavior was related to response style in the motivational inhibition task, but not to performance in the cognitive inhibition task. It is concluded that, among recreational cannabis users, lack of inhibitory control depends on contextual or situational factors-that is, it becomes evident only when situations or tasks involve a motivational component.