The overall aim of this project is to evaluate the effect of progressive nicotine reduction in cigarettes on smoking behavior, toxin exposure and psychiatric symptoms in smokers with comorbid mood and/or anxiety disorders.

Smokers with mood and/or anxiety disorder will smoke research cigarettes that will contain either a) nicotine content similar to their preferred usual brand of cigarettes, or b) nicotine content per cigarette that is progressively reduced from approximately 11.6 mg to 0.2 mg per cigarette over 18 weeks.

It is our hypothesis that nicotine intake will decline as a function of cigarette nicotine content in the Reduced Nicotine Content group without significant increases in tobacco smoke exposure, severity of nicotine withdrawal symptoms, mood and anxiety symptomatology or protocol non-adherence over time in the Reduced Nicotine Content group as compared with the control group.

The overall aim of this project is to evaluate the effect of progressive nicotine reduction in cigarettes on smoking behavior, toxicant exposure and psychiatric symptoms in smokers with comorbid mood and/or anxiety disorders.

To do so, we will randomly assign 200 adult smokers with a unipolar mood and/or anxiety disorder within the past year to smoke research cigarettes that will contain either a) Usual Nicotine Content (UNC): nicotine content similar to their preferred usual brand of cigarettes, or b) Reduced Nicotine Content (RNC): nicotine content per cigarette is progressively reduced from approximately 11.6 mg to 0.2 mg per cigarette over 18 weeks. All subjects will participate in baseline periods prior to double-blind randomization to assess normal smoking behavior and then to establish ability to tolerate research cigarettes prior to randomization.

A total of 280 participants will be enrolled in the study at two sites with the aim of randomizing 200 who complete the baseline phase. 100 participants will be enrolled in the randomized phase at Penn State Hershey and 100 at the Massachusetts General Hospital site. Participants will be started on the study protocol during Baseline I and Baseline II but will be removed from the study if they are not able to comply with the protocol. We expect that approximately 40 participants at each site drop out from the study prior to randomization (due to inability to comply with study protocol).

It is our hypothesis that nicotine intake, as measured by plasma cotinine concentration, will decline as a function of cigarette nicotine content in the RNC group. Further, it is our hypothesis that by gradually reducing the nicotine content of the cigarettes in a step-wise fashion, there will not be significant increases in biomarkers of tobacco smoke exposure, severity of nicotine withdrawal symptoms, mood and anxiety symptomatology or protocol non-adherence over time in the experimental group (RNC) as compared with the UNC control group.

Inclusion Criteria:

• Smoke >4 cigarettes/day for at least a year
• No quit attempt in prior month
• Not planning to quit smoking within next 6 months
• Plan to live in local area for next 8 months
• Meet diagnostic criteria for a current or lifetime Anxiety Disorder or Mood Disorder as determined by the Mini-international Neuropsychiatric Interview
• Read and write in English
• Women not pregnant or nursing and taking steps to avoid pregnancy
• Able to understand and consent to study procedures

Exclusion Criteria:

• Unstable or significant medical condition such as Chronic Obstructive Pulmonary Disease or kidney failure
• Use of non-cigarette nicotine delivery product in the past week or smoking cessation medicine in prior month
• Currently reducing or planning to reduce cigarette consumption in next month
• Uncontrolled serious psychotic illness or substance abuse or inpatient treatment for these in the past 6 months
• Current suicide risk on clinical assessment
• Aged <18 or >65
• History of difficulty providing blood samples (fainting, poor venous access)
• Unwilling to remain on one flavor of cigarette (regular or menthol) for the duration of the trial

Baseline values for outcomes reflect levels after participants were on the usual nicotine content cigarettes for 2 weeks and before they received the intervention.

All randomized participants throughout the entire 33 weeks of the trial.

Adverse events (AEs) were systematically collected at each study visit by asking participants about any changes in their physical or mental health or if they needed to seek immediate medical care at an emergency room or hospital.

The sample size was not reached due to a shortage of study cigarette inventory.