Neural Basis of Eating Behavior in Abstinent Smokers

Tobacco use and obesity are the two leading causes of preventable deaths. Because these two behaviors share common brain reward mechanisms, reducing one behavior often leads to increases in the other behavior. Behavioral Economic and Incentive Salience models shed much light on this clinical problem. Smoking cessation produces reward dysregulation that can alter the motivational salience of other reinforcers, particularly food. After stopping smoking, smokers increase between-meal snacking, especially foods high in fat and sugar. Increases in caloric intake occur within days of quitting smoking, and are clinically significant. The investigators have also shown that smoking cessation produces working memory deficits and reduces activity in the brain's cognitive control circuits, making it even more difficult to exert self-control over temptations to eat highly rewarding foods. Thus, smokers have a double challenge: food becomes more salient and reinforcing at a time when their neurocognitive resources are compromised. Neuroimaging can identify mechanisms underlying behavior change beyond self-report and behavioral measures. The proposed functional magnetic resonance imaging (fMRI) study breaks new ground by integrating concepts and tools from the fields of behavioral economics and cognitive neuroscience to accelerate the study of mechanisms underlying PCWG. The investigators will use a previously validated within-subject crossover neuroimaging study design to examine changes in working memory, food salience (cue-induced craving), and food reinforcement processes in the brain after 4 days of smoking cessation (vs. smoking as usual). A non-smoker control group will provide insight into baseline differences from smokers (abstinent and satiated). Caloric intake, the primary outcome, will be assessed using 24-hr. food recalls during each study period. The investigators will assess three parallel pathways including: working memory, food cue reactivity, and food reinforcement at the neural and behavioral levels. This study will provide new insights about how the brain can constrain or promote the ability of smokers to prevent post cessation weight gain (PCWG) and lead to new interventions that integrate neural and behavioral framework. Support for our predictions would inform testing of novel approaches to prevent PCWG, such as computerized neurocognitive exercise training to increase DLPFC activity and shift activity away from reward sensitive brain networks.