Objectives We aimed to determine whether chronic nicotine use, alcohol consumption, and gambling alters brain glucose metabolism.

Methods We 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).

Results This 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.

Conclusion Tobacco 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.

The authors have declared no competing interest.

No funding

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Institutional Review Board of Changwon Samsung Hospital approved the study protocol and the need for informed consent to participate was waived due to the retrospective study design.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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Yes

Seunghyeon Shin (1st author), forladounaver.com

Keunyoung Kim, nmpnuhgmail.com

Jihyun Kim, march4900hanmail.net

DATA AVAILABILITY The data that support the findings of this study are available from the corresponding author upon request.

FUNDING No

CONFLICT OF INTEREST No conflict of interest

Ethics approval The Institutional Review Board approved the study protocol.

Patient consent statement The IRB waived the need for informed consent to participate due to the retrospective study design.

Permission to reproduce material from other sources No materials reproduced from other sources

Clinical trial registration Not available (retrospective study)

All data produced in the present study are available upon reasonable request to the authors