Multimodal Cue Exposure Therapy for Smoking Cessation

At two sites (Boston University and the University of Texas at Austin, under the MPI direction of Drs. Otto and Smits) the investigators propose to randomly assign 240 adult smokers who have achieved short-term abstinence following open treatment with a 4 session cognitive-behavior therapy program combined with medication (nicotine patch, varenicline, or bupropion, selected openly) to (1) d-cycloserine augmentation of multimodal cue exposure therapy (CET), or (2) placebo augmentation of multimodal CET. This Stage II project is designed to: (1) evaluate the short-term and long-term efficacy of the experimental intervention, (2) further test putative mechanisms of change, (3) explore possible moderator effects of theoretically-relevant variables, and (4) use innovative, multimodal CET strategies. Putative mediators and smoking abstinence will be assessed during the intervention period and up to 6 months following the quit attempt.

This study utilizes on open phase of 4-sessions of cognitive-behavior therapy for smoking cessation that is combined with open pharmacotherapy (selected by participants in collaboration with the study medical team: nicotine patch, varenicline, or bupropion). Session topics include educational (e.g., health risks of smoking, effectiveness of different treatment approaches), motivational enhancement (e.g., identifying personally relevant benefits of quitting, and costs of continuing to smoke), and cognitive-behavioral elements (e.g., identifying smoking triggers, developing coping strategies for these triggers, planning for high risk situations, relapse prevention). The study therapists will also make a supportive phone call on the day of the quit attempt, with repeated check-in calls over the quit window (i.e., weeks 4-6) as needed for individuals having difficulties reaching abstinence. Participants who fail to achieve smoking cessation during the quit period window will be referred for clinical treatment as desired in the center the study is conducted in or an alternative site.

Following successful smoking abstinence at Week 0 (Week 0 is defined by 24 hr abstinence within a two-week grace period of the target date), participants will be randomized to the study drug condition (50 mg DCS or matching placebo) combined with cue-exposure therapy (CET). CET is manualized and will have four modalities: (1) exposure to slides of smoking (pictorial), (2) exposure to emotions and imagined situations that most reliably trigger an urge to smoke (emotional/imaginal), (3) exposure to a participant's own cigarettes and pack (in vivo),70 and (4) personalized and immersive 360° VR exposure (participants select the VR scene-e.g., break time outside work, evening party, car ride that best corresponds to their highest craving situation). CET sessions are scheduled for the quit week, one week later, and again 8 weeks later. Smoking cessation assessments continue across 24 weeks of follow-up.

Eligibility Criteria:
Inclusion Criteria: (open phase)

* daily smoker for at least one year, smoking an average of at least 10 cigarettes per day, and motivated to quit smoking (\>5 on a 10 point scale)
* had reactivity to in vivo smoking cues (an increase of two points or maximal score of 10 on a 10 point visual analogue craving scale \[VAS\]) following no smoking for a minimum of two hours
* medical clearance to participate in the protocol

Exclusion Criteria:

* use of other tobacco products
* current unstable medical illness (i.e. deemed as at high risk of significant worsening by study intervention procedures by study physician; e.g. heart disease, chronic obstructive pulmonary disease, or seizure disorders - assessed during telephone prescreen and initial assessment), seizure disorder, pregnancy, breastfeeding, or use of isoniazid or ethionamide
* lifetime history of psychotic disorders or uncontrolled bipolar disorder, by DSM-5 criteria as assessed by the MIni International Neuropsychiatric Interview
* substance use disorder other than nicotine or caffeine active in the past 6 months, or excessive concurrent alcohol use as defined by self-report of an average of \>21 standardized drinks per week for males or \>14 standardized drinks per week for females
* elevated suicide risk as determined by clinician interview
* current use of any psychotropic medications or pharmacotherapy or psychotherapy for smoking cessation not provided by the investigators during the quit attempt
* known hypersensitivity to DCS
* insufficient command of the English language or inability to understand study procedures and participate in the informed consent process

To progress to the randomized phase:

* participants must achieve a 24 hour abstinence period