This study will test the hypothesis that a medication called tolcapone (Brand Name: Tasmar) will help reduce cognitive problems that smokers experience when they quit. This study will also determine whether the benefits of this medication differ depending on a smokers' genetic background.
Tolcapone, an FDA-approved treatment for Parkinson's disease, improves cognitive performance in healthy controls with COMT val/val genotypes, putatively by increasing prefrontal dopamine levels. We propose a within-subject double-blind cross-over neuroimaging study of short-term (11 days) treatment with tolcapone (vs. placebo). Thirty chronic smokers (15 with val/val genotypes and 15 with val/met or met/met genotypes) will undergo blood oxygenation level dependent (BOLD) fMRI during the two medication periods: 1. after 24 hours of monitored abstinence while on tolcapone, and 2. after 24 hours of monitored abstinence while on placebo (medication order counterbalanced with at least a 10-day washout). The BOLD fMRI data will be acquired while subjects perform a working memory task (Fractal N-back), a sustained attention task (Continuous Performance Task; CPT), and a response inhibition task (Go/No-Go). The primary outcome is medication effects (within subject) on task-related BOLD activation after 24 hours of abstinence. Changes in behavioral performance and subjective symptoms will be examined in relation to brain activity changes. The proposed study will provide a critical mechanistic understanding of the role of COMT in abstinence-induced cognitive symptoms that promote smoking relapse. Information obtained in this study may further establish cognitive performance measures as endophenotypes for nicotine dependence.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
218
Participants will be asked to take study medication each day for both 11-day study medication periods. The study medication assignments for each participant in this project is randomized and counterbalanced. This means that approximately 50% of participants will take tolcapone during the first medication period, followed by the placebo in the second medication period. Alternatively, approximately 50% of participants will take the placebo during the first medication period, followed by tolcapone during the second medication period.
Participants will be asked to take study medication each day for both 11-day study medication periods. The study medication assignments for each participant in this project is randomized and counterbalanced. This means that approximately 50% of participants will take tolcapone during the first medication period, followed by the placebo in the second medication period. Alternatively, approximately 50% of participants will take the placebo during the first medication period, followed by tolcapone during the second medication period.
University of Pennsylvania
Philadelphia, Pennsylvania, United States
Measure of Brain Activity: Blood Oxygen Level Dependent (BOLD) fMRI Signal Change During the "N-back" Working Memory Task (Brain Region: Right Dorsolateral Prefrontal Cortex; Right DLPFC)
Subjects completed two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each period, after at least 24 hours of smoking abstinence, subjects had an fMRI scan to measure changes in brain activity that occur during a memory test. The subjects completed a commonly used working memory test referred to as the "N-back". This test presented complex geometric figures on a projection screen for 0.5 seconds; each figure is separated by 2.5 seconds of black screen. There were 4 conditions requiring increasing memory demands: 0-back, 1-back, 2-back, \& 3-back. Subjects had to respond to the target geometric figure that was separated by 0, 1, 2, or 3 figures before it is repeated. Between each condition, there was a brief rest period. To identify brain signal change, we calculated the difference in the amount of brain activity detected by the fMRI scan for each condition compared to the rest periods. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Measure of Brain Activity: Blood Oxygen Level Dependent (BOLD) fMRI Signal Change During the "N-back" Working Memory Task (Brain Region: Left Dorsolateral Prefrontal Cortex; Left DLPFC)
Subjects completed two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each period, after at least 24 hours of smoking abstinence, subjects had an fMRI scan to measure changes in brain activity that occur during a memory test. The subjects completed a commonly used working memory test referred to as the "N-back". This test presented complex geometric figures on a projection screen for 0.5 seconds; each figure is separated by 2.5 seconds of black screen. There were 4 conditions requiring increasing memory demands: 0-back, 1-back, 2-back, \& 3-back. Subjects had to respond to the target geometric figure that was separated by 0, 1, 2, or 3 figures before it is repeated. Between each condition, there was a brief rest period. To identify brain signal change, we calculated the difference in the amount of brain activity detected by the fMRI scan for each condition compared to the rest periods. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
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Measure of Brain Activity: Blood Oxygen Level Dependent (BOLD) fMRI Signal Change During the "N-back" Working Memory Task (Brain Region: Dorsal Cingulate/Medial Prefrontal Cortex; MF/CG)
Subjects completed two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each period, after at least 24 hours of smoking abstinence, subjects had an fMRI scan to measure changes in brain activity that occur during a memory test. The subjects completed a commonly used working memory test referred to as the "N-back". This test presented complex geometric figures on a projection screen for 0.5 seconds; each figure is separated by 2.5 seconds of black screen. There were 4 conditions requiring increasing memory demands: 0-back, 1-back, 2-back, \& 3-back. Subjects had to respond to the target geometric figure that was separated by 0, 1, 2, or 3 figures before it is repeated. Between each condition, there was a brief rest period. To identify brain signal change, we calculated the difference in the amount of brain activity detected by the fMRI scan for each condition compared to the rest periods. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Measure of Brain Activity: Blood Oxygen Level Dependent (BOLD) fMRI Signal Change During the "N-back" Working Memory Task (Brain Region: Posterior Cingulate Cortex; PCC)
Subjects completed two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each period, after at least 24 hours of smoking abstinence, subjects had an fMRI scan to measure changes in brain activity that occur during a memory test. The subjects completed a commonly used working memory test referred to as the "N-back". This test presented complex geometric figures on a projection screen for 0.5 seconds; each figure is separated by 2.5 seconds of black screen. There were 4 conditions requiring increasing memory demands: 0-back, 1-back, 2-back, \& 3-back. Subjects had to respond to the target geometric figure that was separated by 0, 1, 2, or 3 figures before it is repeated. Between each condition, there was a brief rest period. To identify brain signal change, we calculated the difference in the amount of brain activity detected by the fMRI scan for each condition compared to the rest periods. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Measure of Brain Activity: Blood Oxygen Level Dependent (BOLD) fMRI Signal Change During the "N-back" Working Memory Task (Brain Region: Ventromedial Prefrontal Cortex; vmPFC)
Subjects completed two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each period, after at least 24 hours of smoking abstinence, subjects had an fMRI scan to measure changes in brain activity that occur during a memory test. The subjects completed a commonly used working memory test referred to as the "N-back". This test presented complex geometric figures on a projection screen for 0.5 seconds; each figure is separated by 2.5 seconds of black screen. There were 4 conditions requiring increasing memory demands: 0-back, 1-back, 2-back, \& 3-back. Subjects had to respond to the target geometric figure that was separated by 0, 1, 2, or 3 figures before it is repeated. Between each condition, there was a brief rest period. To identify brain signal change, we calculated the difference in the amount of brain activity detected by the fMRI scan for each condition compared to the rest periods. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Cognitive Performance: Accuracy
Subjects underwent two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each study medication period, after at least 24 hours of smoking abstinence, subjects completed an fMRI brain scan. During these fMRI scan sessions, participants completed computer tasks that were designed to test working memory and attention. These tasks were similar to computer games, in that participants would push a button in response to the pictures they see. Specifically, we tested whether subjects, while taking tolcapone, would display increased accuracy during the N-back working memory task compared to their performance while they took the placebo. We measured accuracy by counting the absolute number of true positives scored (the number each subject got correct during the task). This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Cognitive Performance: Reaction Time
Subjects underwent two, 11-day study medication periods (one taking active tolcapone; one taking placebo). On Day 8 of each study medication period, after at least 24 hours of smoking abstinence, subjects completed an fMRI brain scan. During these fMRI scan sessions, participants completed computer tasks that were designed to test working memory and attention. These tasks were similar to computer games, in that participants would push a button in response to the pictures they see. Specifically, we tested whether subjects, while taking tolcapone, would display increased average reaction time (in milliseconds) during the N-back working memory task compared to their performance while they took the placebo. This was a within-subject analysis.
Time frame: At fMRI scan sessions - Days 8 and 29
Subjective Symptoms: Smoking Behavior
In order to determine if tolcapone (vs. placebo) would affect subject smoking behavior, we collected the daily number of cigarettes each subject smoked from Days 1 through 7 during each study medication period. This allowed us to calculate the average number of daily cigarettes smoked, across all subjects, during each study medication period (i.e., the average number of cigarettes/day smoked while all subjects took tolcapone and the average number of cigarettes/day smoked while all subjects took placebo). Then, we statistically assessed if there was a significant difference between these averages.
Time frame: Days 1 through 7 of each study period
Subjective Symptoms: Cigarette Craving
Subjective symptoms were assessed during each in-person session throughout each study medication period. During each visit, we asked subjects to complete the Questionnaire for Smoking Urges-Brief (QSU-B). Specifically, subjects completed the QSU-B at day 5, day 8 (fMRI scanning session 1), day 26 (day 5 of study medication period 2), and day 29 (day 8 of study medication period 2; fMRI scanning session 2). The range of possible scores on the QSU-B is 10-70, with higher values indicating an increased craving for cigarettes. This range of scores represent a "total" score; there are no subscales. While the QSU-B was collected at all in-person sessions, we only analyzed the scores collected from the fMRI scanning sessions of each period (day 8 and day 29). To analyze, we averaged the total scores across all 20 subjects from each fMRI scanning session and statistically analyzed for significant differences between these two averages. This was a within-subject analysis.
Time frame: Day 8 (fMRI scanning session) of each study period
Subjective Symptoms: Withdrawal Symptoms
Subjective symptoms were assessed during each in-person session throughout each study medication period. During each visit, we asked subjects to complete the Minnesota Nicotine Withdrawal Scale - Revised version (MNWS). The scale assesses eight DSM-IV items of nicotine withdrawal. The range of possible total scores on the MNWS is 0-60, with higher values indicating an increased nicotine withdrawal. This range of scores represent a "total" score; there are no subscales. The MNWS-N (right now/at the moment) was assessed during each fMRI scanning session visit (Day 8). To assess if tolcapone (vs. placebo) affect withdrawal symptoms, we statistically analyzed the average of the total MNWS scores across, all 20 subjects, for each study medication period. Specifically, we analyzed for significant differences between reported withdrawal symptoms while taking tolcapone vs. taking placebo.
Time frame: Day 8 of each study period