This study was conducted by researchers at Duke University Medical Center, and was designed based on past research indicating that abstinence from a drug increases motivation to use that drug (i.e. cravings) and increases perceived reward value of cues related to the drug. The authors hypothesized that "consistent with incentive motivation models of drug use, 24-h smoking abstinence would increase brain activation in response to smoking cues in regions subserving reward, motivation, and affective processes."
Participants of the study were screened for current cigarette dependence, and were tested on a day in which they smoked a typical amount of cigarettes and again on a day in which they abstained from cigarettes. Each participant completed a withdrawal questionnaire, was tested for levels of cravings, and underwent an fMRI to measure neural responses to pictorial cues (half "neutral" control picture cues, the other half pictures of people smoking).
Results of these measures showed greater neural response to the smoking cues during a period of abstinence as compared to a period of satiation (a day in which the participant smoked). The areas of the brain that had heightened responses during periods of abstinence included those areas responsible for visual sensory processing, sustained attention memory, visuospatial attention, decision-making, motor planning and execution and sensorimotor integration.
Results also showed no greater neural response to smoking cues than control cues when patients had smoked on the day of testing.
The authors conclude that: "The present findings suggest that smoking abstinence potentiates neural responding to smoking-related cues, which may reflect an increase in the incentive salience of those cues resulting from an increase in smoking motivation."
The findings of this study suggest that addiction alters brain responses to stimuli, and after a period of abstinence smoking cues trigger those areas of the brain involved in the planning and choosing of actions- such as smoking. It appears that the areas triggered in the brain also support a hypothesis that addiction progresses from voluntary to compulsive actions.
