The goal of this clinical trial is to learn if a combination of varenicline and accelerated Transcranial Magnetic Stimulation (aTMS) works to help adults quit using nicotine products. Researchers will compare varenicline + active aTMS to varenicline + sham (inactive) aTMS to see the effect of aTMS on reaching abstinence. The main question it aims to answer is: Does receiving active aTMS + varenicline lead to higher abstinence rates and lower nicotine craving?

Participants will be asked to:

• Complete 2 brain MRI scans
• Take varenicline every day for 12 weeks
• Quit using nicotine products at the end of the second week of varenicline
• Complete 5 consecutive days (Monday-Friday, uninterrupted) of TMS treatments
• Complete 12 brief, weekly follow-up visits
• Complete a brief daily survey each day that they take the study drug

This is a 12-week randomized parallel design, double-blind, 2-arm clinical trial consisting of a combination of circuit-targeted TMS and varenicline in 30 adults aged 18-65 with nicotine use disorder who would like to reduce or stop nicotine use.

Eligible participants will complete a baseline assessment of questionnaires and laboratory assessments. They will be randomized to receive varenicline and either active or sham TMS. Participants will be randomized at their baseline scan visit, during which they will undergo urinalysis, an fMRI scan, and a task and questionnaire battery. At this visit, participants will receive the study medication and will be instructed to take it for 12 weeks titrated to 1mg twice daily over seven days.

Shortly after, participants will complete a TMS treatment preparation visit during which the treatment target is located and stimulation intensity of the TMS is determined. This target is used in the subsequent TMS Treatment Week consisting of 5 consecutive days of 5 TMS treatments per day. Participants' quit date will be set for the Saturday following their TMS treatments. The week after completing their TMS treatments, they will return for a second imaging visit identical to the baseline scan.

Each week of the varenicline treatment period, participants will complete weekly follow-ups with study staff, either virtually or in-person, to determine nicotine use and complete questionnaires regarding their substance use in the past week, depression, and anxiety. Six of these visits will include brief sessions of nicotine use cessation counseling with a trained study staff member.

Inclusion Criteria:

• Age ≥ 18 and ≤65;
• The ability to give written, informed consent;
• Fluency in English;
• Reported interest in quitting nicotine vaping or smoking within the next month;
• Nicotine dependence, as defined by a score of ≥4 on the 10-question E-cigarette Dependence Inventory (ECDI) or Fagerström Test for Nicotine Dependence (FTND);
• Smoke or vape nicotine daily for at least the past 90 days, as confirmed by self-report and timeline follow-back methods;
• Saliva cotinine >30ng/mL;

Exclusion Criteria:

• Pregnancy or breastfeeding;
• Use of smoking cessation pharmacotherapy in the past month;
• Unwilling to abstain during the study from using smoking cessation aids other than those provided by the study;
• Prior adverse drug reaction to varenicline;
• Receiving or planning to receive other TMS treatments or investigational drugs during course of participation
• Contraindications to TMS (including seizures, metallic implants, severe existing tinnitus, etc.);
• Contraindications to MRI (including presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia);
• Inpatient psychiatric hospitalization or suicide attempts in the past six months, or recent active suicidal ideation or suicidal behavior identified at enrollment or baseline visits;
• History of seizures and/or history of TBI subtypes associated with elevated seizure risk (e.g. penetrating injury and intraparenchymal hemorrhage)
• History of unstable neurological illness or major medical illness, such as epilepsy or renal impairment, in the past six months, unless clearly resolved;
• In the opinion of the investigators, evidence of active problem substance use severe enough to compromise ability to safely participate;
• In the opinion of the investigators, unable to safely participate in this study and/or provide reliable data (e.g., claustrophobia, unable to tolerate TMS or MRI procedures, etc.).