Smoking Severity and Functional MRI Results In Schizophrenia: A Case-Series

Objective: Although the majority of patients with schizophrenia smoke, assessment of smoking severity is usually ignored in functional magnetic resonance imaging (fMRI) studies. The aim of this study was to identify whether smoking severity was associated with changes in neural activation in patients with schizophrenia and alcohol use disorder. Methods: Seven smokers with schizophrenia and alcohol use disorder who were enrolled in a smoking cessation pilot study underwent fMRI at baseline. Executive function was assessed with the multi-source interference task (MSIT); working memory was assessed using the N-back task. Smoking severity was measured using serum cotinine and nicotine levels and the Fagerstrom Test for Nicotine Dependence. Results: During the multi-source interference task (MSIT) task, we observed significant neural activation in left and right precuneus, left and right inferior parietal lobule, left superior frontal gyrus and the right insula. After including serum cotinine level as a covariate, the left precuneus and the left superior frontal gyrus was no longer significantly activated. During the working memory (N-back) task we observed significant neural activation in the right precuneus and superior parietal lobule, the right inferior parietal lobule and the right middle frontal gyrus. After including serum cotinine level as a covariate, the right middle frontal gyrus was no longer significantly activated. Conclusion: These preliminary results suggest that smoking severity may influence neural activation in the frontal lobe and left precuneus in patients with schizophrenia and alcohol use disorder. Measuring serum cotinine level may improve reliability and diagnostic value of fMRI studies.