Insula reactivity to negative stimuli is associated with daily cigarette use: A preliminary investigation using the Human Connectome Database

Background: Individuals who smoke more cigarettes per day are at greater risk for developing smoking related illness and have more difficulty quitting. Withdrawal-related negative mood is one factor thought to motivate drug use. However, heavy smokers are generally more sensitive to negative affect, not just negative emotion stemming from withdrawal. One possibility is that individual differences in how the brain processes negative stimuli may impact smoking use. Given the wealth of data implicating the insula in nicotine dependence and affective processing we hypothesize that the number of cigarettes an individual smokes per day will relate to insula reactivity to negative stimuli. Methods: A functional magnetic resonance imaging (fMRI) emotional processing task collected by the Human Connectome Project was assessed in 21 daily tobacco smokers who reported smoking between 5 and 20 cigarettes per day. The number of cigarettes smoked per day was correlated with right and left anterior insula reactivity to faces expressing a negative emotion relative to a control. This anterior insula region of interest has been associated with treatment outcome and smoking cue-reactivity in our prior work. Results: Those who smoked more daily cigarettes showed greater right insula reactivity to negative stimuli (r=0.564, p=0.008). Left insula reactivity was not associated with cigarettes smoked per day. Conclusion: Smokers who use more cigarettes per day have greater insula reactivity to negative stimuli, furthering the field's understanding of the insula's involvement in nicotine use. This preliminary work also suggests a mechanism contributing to higher rates of daily smoking. (C) 2015 Elsevier Ireland Ltd. All rights reserved.