Varenicline for Nicotine Dependence Among Those With HIV/AIDS

Inclusion Criteria 1. 18 years of age or older who self-report smoking at least 5 cigarettes (menthol and non-menthol) per day, on average. 2. Diagnosed with HIV infection and exhibiting viral load of \< 1000 copies/mL and CD4+ counts of \> 200 cells/mm3 within 6 months prior to enrollment. 3. Able to use varenicline safely, based on a medical evaluation including medical history and physical examination, and psychiatric evaluation. 4. Residing in the geographic area for at least 7 months. 5. Women of childbearing potential (based on medical history and physical exam) must consent to use a medically accepted method of birth control (e.g., condoms and spermicide, oral contraceptive, Depo-Provera injection, contraceptive patch, tubal ligation) or abstain from sexual intercourse during the time they are taking study medication and for at least one month after the medication period ends. 6. If current or past diagnosis of bipolar disorder (I, II, or NOS), eligible if: 1. No psychotic features 2. MADRS: total score \< 8 (past 4 weeks), suicidal item score \< 1 (past 4 weeks) 3. Y-MRS: total score \< 8 (past 4 weeks), irritability, speech content, disruptive, or aggressive behavior items score \< 3 (past 4 weeks) 4. No psychiatric hospitalization or Emergency Room visits for psychiatric issues in the past 6 months 5. No aggressive or violent acts or behavior in the past 6 months 7. Able to communicate fluently in English. 8. Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the combined consent/HIPAA form. Exclusion Criteria: Smoking Behavior 1. Current enrollment or plans to enroll in another smoking cessation program in the next 7 months. 2. Regular (daily) use of chewing tobacco, snuff, snus, cigars, cigarillos, or pipes. 3. Current use or plans to use nicotine substitutes (gum, patch, lozenge, e-cigarette) or smoking cessation treatments in the next 7 months. 1. Note: Once participants are found eligible for the study, they are told they should refrain from using any nicotine replacement therapy (NRT) for the duration of the study. If a subject reports an isolated (non-daily) instance of NRT use during the study, they may be permitted to continue. Alcohol/Drug Exclusion Criteria 1. Current untreated and unstable diagnosis of substance abuse or dependence (eligible if past use and if receiving treatment and stable for \>30 days). 2. Positive urine drug screen (for cocaine and/or methamphetamines) at the Intake Session. 3. Breath Alcohol Concentration (BrAC) assessment greater than or equal to 0.01 at the Intake Session. Medication Exclusion Criteria Current use or recent discontinuation (within last 14 days) of the following medications: 1. Other smoking cessation medications (e.g. Zyban, Wellbutrin, Wellbutrin SR, Chantix) a. Note: Once participants are found eligible for the study, they are instructed to only use the smoking cessation medication provided to them by the study staff. If a subject reports an isolated (non-daily) instance of using a non-study smoking cessation medication, the study physician and PI will evaluate the situation and determine if it is safe for the subject to continue participation. 2. Anti-psychotic medications. Medical Exclusion Criteria 1. Women who are pregnant, planning a pregnancy within the next 7 months, or lactating. 2. Current diagnosis of unstable and untreated major depression, as determined by self-report \& MINI (eligible if stable for \>30 days). 3. Current or past diagnosis of psychotic disorder, as determined by self-report or MINI. 4. Any suicide risk score on MINI, current suicidal ideation on Columbia scale, or self-reported lifetime suicide attempt. 5. History of heart disease, stroke or MI, unstable angina, or tachycardia (if stable, requires Study Physician approval). 6. Uncontrolled hypertension (SBP \>160 or DBP \>100). a. Note: If a participant presents with blood pressure greater than 160/100 at sessions occurring on Week 0 (Pre-Quit) or at any other point during the treatment period, they will not be provided with/able to continue on medication unless the study physician grants approval. 7. History of kidney or liver failure. 8. Abnormal ECG (unless approved by study physician). 9. Estimated creatinine clearance \<50 mL/min, within 6 months prior to enrollment. 10. AST and/or ALT results greater than 2 times the upper limit of normal, within 6 months prior to enrollment. 11. Any impairment (physical, neurological, visual) preventing cognitive task performance. 12. Previous allergic reaction to varenicline. General Exclusion Criteria 1. Any medical condition or concomitant medication that could compromise subject safety or treatment, as determined by the Principal Investigator and/or Study Physician. 2. Inability to provide informed consent or complete any of the study tasks as determined by the Principal Investigator and/or Study Physician.