Oral nicotine pouches (ONPs) are non-combustible nicotine products that may reduce cigarette craving and smoking cue-induced brain activity, supporting their potential as harm-reduction tools for adults who smoke cigarettes. This within-subject, repeated-measures study will evaluate the acute effects of a single 6 mg oral nicotine pouch on subjective craving and prefrontal neural responses to smoking-related cues using functional near-infrared spectroscopy (fNIRS). Participants will complete assessments before and after nicotine pouch administration following overnight nicotine abstinence to characterize changes in craving and neural cue reactivity.

This study will evaluate the acute effects of oral nicotine pouch (ONP) use on subjective cigarette craving and prefrontal neural responses to smoking-related cues among adult cigarette smokers. Although oral nicotine pouches do not involve combustion or inhalation, their effects on craving relief and neural cue reactivity following nicotine abstinence remain poorly understood. Characterizing these acute responses may improve understanding of the potential role of oral nicotine pouches as lower-risk nicotine products.

This is a single-arm, within-subject, repeated-measures study consisting of one baseline screening visit and one experimental visit. During the baseline visit, informed consent will be obtained, eligibility will be confirmed, demographic and tobacco use information will be collected, nicotine dependence will be assessed, and head circumference will be measured to determine appropriate functional near-infrared spectroscopy (fNIRS) cap sizing. Participants will also receive instructions to abstain from nicotine use for at least 12 hours before the experimental visit.

At the experimental visit, overnight nicotine abstinence will be verified before participants complete baseline assessments of subjective craving and nicotine withdrawal. Participants will then complete a standardized smoking cue reactivity task while prefrontal brain activity is recorded using functional near-infrared spectroscopy (fNIRS). Following completion of the baseline task, participants will self-administer one commercially available 6 mg oral nicotine pouch and complete a standardized 25-minute absorption period. Participants will then complete an identical post-pouch cue reactivity task with simultaneous fNIRS recording, followed by post-session assessments of craving, withdrawal, subjective product effects, and product perceptions.

The smoking cue reactivity task consists of repeated presentations of smoking-related and neutral visual cues, followed by guided imagery in which participants imagine smoking a cigarette or performing a comparable neutral behavior while holding the corresponding object. The task is administered before and after nicotine pouch administration using identical procedures to permit within-subject comparisons of neural and subjective responses.

Functional near-infrared spectroscopy is a non-invasive neuroimaging technique that measures changes in oxygenated and deoxygenated hemoglobin within cortical tissue as an indirect measure of neural activity. Brain activity will be recorded continuously throughout both cue reactivity task runs using a standardized prefrontal optode montage. Participants will be monitored throughout study procedures for discomfort, and study procedures will be discontinued if requested by the participant or if study staff determine continuation is not appropriate.

Inclusion Criteria:

• Age 21 years - 55 years

• Self-reported use of cigarettes within the past 30 days

• Biochemical confirmation of cigarette use:

  o Carbon monoxide (CO) breath sample ≥10 ppm

• Fagerström Test for Nicotine Dependence (FTND) score ≥5, indicating moderate to high nicotine dependence

• Fluent in English

• Willing to try an oral nicotine pouch

• Willing to abstain from nicotine for at least 12 hours prior to each experimental session

Exclusion Criteria:

• Age younger than 21 years or older than 55 years

• Biochemical evidence inconsistent with recent cigarette use:

  o CO breath sample <10 ppm

• Expressed intent to reduce or quit nicotine use within the next 30 days

• History of medical conditions contraindicated for nicotine use (e.g., uncontrolled hypertension, recent cardiac events)

• Primary use of non-cigarette products (e.g., cigars, pipe tobacco, smokeless tobacco)

• Prior use of oral nicotine products in their lifetime

De-identified individual participant data (IPD) that underlie the results reported in any future publications (e.g., self-reported craving scores, task performance metrics, and fNIRS-derived signal outputs) will be shared. The data will be stripped of all personally identifying information in accordance with HIPAA guidelines and made available upon reasonable request for academic and research purposes. A data dictionary and codebook will be provided to facilitate reuse. Access will be granted upon request to the corresponding author.

Data will be made available within a target of 1 year after study completion.