Altered brain glucose metabolism in nicotine use but not in hazardous alcohol consumption or problem gambling of healthy middle-aged adults

ObjectivesWe aimed to determine whether chronic nicotine use, alcohol consumption, and gambling alters brain glucose metabolism. MethodsWe retrospectively analyzed data from 473 healthy men who participated in health checkups at Samsung Changwon Hospital Health Promotion Center during 2013 (baseline) and 2018 (follow-up). The health checks included a brain 18F-fluorodeoxyglucose positron emission tomography (PET), a questionnaire of tobacco use, the Alcohol Use Disorders Identification Test (AUDIT; Korean version), and the Problem Gambling Severity Index (PGSI). From brain PET scans, the mean uptake in regions-of-interest was scaled to the mean global cortical uptake by each individual, defining the standardized uptake value ratio. We established a model for tobacco use, AUDIT, and PGSI with regional SUVR as a dependent variable and tobacco use, AUDIT, and PGSI as predictors adjusted for age using Bayesian hierarchical modelling. Bayesian models were estimated using four Markov chains, each of which had 4,000 iterations including 1,000 warm-ups, thus totaling 12,000 post-warmup samples. The sampling parameters were slightly modified to facilitate convergence (max tree depth = 20). All data were analyzed using R (The R Foundation for Statistical Computing, Vienna, Austria). ResultsThis study included 131 healthy males (mean age at baseline and follow-up: 43.0 {+/-} 3.4, 48.1 {+/-} 3.3 years, respectively). Tobacco use was negatively associated with glucose metabolism in the caudate, thalamus, cingulate, and frontal lobe, and positively associated with the cerebellum, whereas AUDIT or PGSI were not associated. ConclusionTobacco use was associated with altered brain glucose metabolism in the caudate, thalamus, cingulate, frontal lobe, and the cerebellum. However, neither hazardous alcohol consumption, nor problem gambling showed any association with brain glucose metabolism. Our findings might provide new insights into the neural mechanisms of chronic nicotine use.