tDCS Plus Varenicline for Smoking Cessation

Inclusion Criteria: * Be able to provide informed written consent * Stated willingness to comply with all study procedures * Age 18-85 years * Smoke ≥ 8 cigarettes per day (CPD) * Is seeking treatment for tobacco dependence * Willing to attend the required clinic appointments (Two consecutive weeks, Monday through Friday) * Otherwise healthy (i.e. not suffering from any major illness/condition that would impact their participation in the study) Exclusion Criteria: * Use of smoking cessation medication (e.g. buproprion, varenicline, NRT, cytisine) in the past 3 months * Current regular use of nicotine-containing products besides cigarettes (e.g. electronic cigarettes, etc.) * Unstable psychiatric illness that would adversely impact study participation and compliance (determined by the QI) * History of seizures/epilepsy * Lifetime history of concussions or head traumas * Current pregnancy or plans to become pregnant * Current pacemakers or implanted electrical devices * Current metal embedded in the skull * Presence of skin lesions, open wounds, or bruising at stimulation sites; or * Contraindications to varenicline use (e.g. pregnant/breastfeeding, alcohol dependence, kidney disease/renal impairment, known hypersensitivity to varenicline)