Brain regions affected by impaired control modulate responses to alcohol and smoking cues

Despite the commonly observed comorbidity of alcohol and tobacco use disorders and years of research, the mechanism underlying concurrent use of alcohol and tobacco is not yet clear. In this study, we used functional magnetic resonance imaging (fMRI) to investigate the relationship between brain responses to alcohol and smoking cues in 45 subjects with episodic drinking and regular smoking.

fMRI data were collected from two studies performing an alcohol-craving task and a smoking-craving task. First, we identified brain voxels significantly activated for both substance cues and then associated the activation of these voxels with various alcohol- and nicotine-dependence measures. Significant clusters (cluster-wise p < .05) correlated with behavioral assessments were extracted, and clusters identified from both cues were compared.

The association tests with various dependence scores showed that the loss of behavioral control subcategory in the Alcohol Dependence Scale was significantly correlated with brain activation of the posterior cingulate cortex (PCC) and right posterior insula regardless of cue types.

Our findings suggest that the PCC and right posterior insula, each playing a role in the salience network, are affected significantly by impaired control for alcohol and in turn influence brain responses to not only alcohol but also smoking cues, providing insight to neuronal mechanisms for concurrent use or comorbidity of alcohol and nicotine dependence.