• Rate of 7-day point prevalence abstinence at the end of the relapse prevention phase (study week 53) in the extended duration pharmacotherapy group vs. the placebo group [ Time Frame: 53 weeks ] [ Designated as safety issue: No ]
  

• Safety and tolerability of extended duration pharmacotherapy when added to antipsychotic medications in schizophrenia patients who have recently quit smoking [ Time Frame: 53 weeks ] [ Designated as safety issue: Yes ]
  
• Effect of treatment with varenicline versus placebo on health-related quality of life indices in recently abstinent smokers with schizophrenia or bipolar disorder [ Time Frame: 53 weeks ] [ Designated as safety issue: No ]
  

Participants will be moderate to heavy smokers, aged 18-70, who have smoked an average of ≥10 cigarettes/day for the past year and who have not quit during the past year for a period >1 month.

During a 12-week open phase smoking cessation program, eligible subjects will be given active varenicline in addition to a 13-session weekly cognitive behavioral therapy program for smoking cessation. Dr. Evins (Principal Investigator) or a co-investigator will meet with subjects individually at Baseline of the Smoking Cessation Program to assess their medical eligibility for varenicline. A chart review will also be conducted by a research physician or psychiatrist.

Dr. Evins or another prescribing co-investigator will write a prescription for varenicline for each medically eligible subject. Subjects will receive their study medication at the end of each weekly group meeting. Any subject who experiences a serious side effect to the medication will meet with Dr. Evins or another medical co-investigator individually.

Subjects will set quit dates between the fourth and fifth CBT session weeks. Self-reports and exhaled carbon monoxide (CO) levels will be used to assess smoking status. Those subjects who have been abstinent for ≥2 weeks at the end of the 12th session group will be eligible for a 40-week relapse prevention program. After enrolling in the Relapse Prevention Program, subjects will be randomized to receive varenicline or placebos in addition to CBT for relapse prevention.

At Week 12 (the week before the end of the Smoking Cessation Program), Dr. Evins or another prescribing co-investigator will write prescriptions for subjects eligible for the randomized Relapse Prevention phase (i.e. successful quitters); these prescriptions will be sent to the Massachusetts General Hospital Research Pharmacy, where they will be filled according to the randomization code that the a research pharmacist will create.

When subjects come for the CBT orientation group session of the Relapse Prevention Program (Week 13), they will receive a 1-month supply of varenicline or placebo pill. During this randomized Relapse Prevention phase, medication compliance will be assessed at every group meeting by pill-count. Subjects will be asked about medication compliance and side effects at each group by the CBT group leaders and staff.

Any subject who experiences a serious side effect to the medication will meet with Dr. Evins or another medical co-investigator individually. In addition, Dr. Evins or a medical co-investigator will review the adverse events forms for each subject every week. Again, self-report and CO levels will be used to monitor smoking status.

Before and during both the open and randomized relapse prevention phases, subjects will be periodically assessed for cognitive performance, clinical characteristics, and adverse events in order to evaluate effects of withdrawal, predictors of cessation and relapse, and medication side effects. Following the completion of the 40-week relapse prevention phase, 3 follow-up assessments will be performed over a 3-month period to evaluate smoking status, cognitive functioning, and clinical effects.