Smoking
Conditions
Keywords
Smoking, fMRI
Brief summary
The broad objective of this proposal is to identify functional neuroanatomical correlates of impairments in response inhibition during smoking abstinence. We will measure changes in performance and regional blood oxygenation levels using functional magnetic resonance imaging (fMRI)while smokers complete tasks designed to assess decision making and response inhibition. Our primary hypothesis is that smoking abstinence will result in impaired response inhibition accompanied by decreases in blood-oxygenation-level-dependent (BOLD) fMRI signal in brain regions associated with these cognitive processes including frontal cortex and the ventral striatum. Abstinence may also result in performance-related increases in activation in brain regions associated with effortful processing including the anterior cingulate cortex in effort to compensate for deficits in other regions.
Detailed description
Participants will learn and practice a Go/No-Go reaction time task (Garavan, Hester, Murphy, Fassbender, & Kelly, 2006) that measures inhibitory and excitatory aspects of behavioral control. During the task subjects are presented with an alternating series of Xs and Ys in the center of the screen and must press a button every time they see a Go trial (the letter 'Y' or the letter 'X') while inhibiting a response when they are presented with a No-Go trial (any interruption of the X Y alternating stream, e.g., X Y Y).
Interventions
BEHAVIORALSmoking Abstinence
Smokers were scanned after having quitting smoking for 24 hours, and scanned after smoking as usual.
Sponsors
Duke University
National Institutes of Health (NIH)
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
Smoker subjects must have * smoked an average of 10 cigarettes per day for two continuous years of a brand that delivers (by Federal Trade Commission rated yields) at least 0.5 mg nicotine * have an expired air carbon monoxide reading of at least 10 ppm. * must be in general good health Non-smoker subjects must have * smoked less than 50 cigarettes in their lifetime * have not smoked in the last six months * have an expired air carbon monoxide reading of less than or equal to 5 ppm. * must be in general good health.
Exclusion criteria
* major medical condition * anything that would make participation unsafe (e.g., have pacemaker or other metallic implant) or uncomfortable (e.g., chronic pain) * psychiatric condition * suffering from claustrophobia * current alcohol or drug abuse * smokeless tobacco use, or use of nicotine replacement therapy or other smoking cessation treatment
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Signal Change in Functional Magnetic Resonance Imaging (fMRI) BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Satiated Day | 12.5 minutes of fMRI scanning following smoking as usual | Percent signal change in fMRI BOLD response in rIFC to correctly inhibited targets (as compared to control trials) during a response inhibition task following smoking as usual. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial. |
| Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Abstinent Day | 12.5 minutes of fMRI scanning following 24 hrs smoking abstinence | Percent signal change in fMRI BOLD response in rIFC to correctly inhibited targets (as compared to control trials) during a response inhibition task following not smoking for 24 hours. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial. |
| Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Abstinent Day | 12.5 minutes of fMRI scanning following 24 hrs smoking abstinence | Percent signal change in fMRI BOLD response in pre-SMA to correctly inhibited targets (as compared to control trials) during a response inhibition task following not smoking for 24 hours. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial. |
| Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Satiated Day | 12.5 minutes of fMRI scanning following smoking as usual | Percent signal change in fMRI BOLD response in pre-SMA to correctly inhibited targets (as compared to control trials) during a response inhibition task following smoking as usual. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial. |
Countries
United States
Participant flow
Recruitment details
community recruitment completed recruitment March 2009
Pre-assignment details
enrolled participants would be excluded if they were unable to meet study requirements, or had scheduling issues.
Participants by arm
| Arm | Count |
|---|---|
| Smokers Men and women ages 18-50 who smoke at least 10 cigarettes per day of a brand delivery at least 0.5 mg of nicotine for at least 2 years. | 62 |
| Total | 62 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | PI dropped, bad data | 44 |
Baseline characteristics
| Characteristic | Smokers |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 62 Participants |
| Age, Continuous | 32.5 years STANDARD_DEVIATION 10.03 |
| Region of Enrollment United States | 62 participants |
| Sex: Female, Male Female | 27 Participants |
| Sex: Female, Male Male | 35 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 18 |
| serious Total, serious adverse events | 0 / 18 |
Outcome results
Primary
Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Abstinent Day
Percent signal change in fMRI BOLD response in pre-SMA to correctly inhibited targets (as compared to control trials) during a response inhibition task following not smoking for 24 hours. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial.
Time frame: 12.5 minutes of fMRI scanning following 24 hrs smoking abstinence
Population: 18 participants completed all aspects of the study. Two participants were excluded from analyses because they reported falling asleep in the scanner and one was excluded because of an incidental finding during the scan.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Smokers | Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Abstinent Day | 0.173 percentage of signal change | Standard Deviation 0.123 |
Comparison: Within group repeated measures design. Null hypothesis is that there will be no difference in percent signal change during active task relative to baseline.p-value: <0.05Paired t-test
Primary
Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Satiated Day
Percent signal change in fMRI BOLD response in pre-SMA to correctly inhibited targets (as compared to control trials) during a response inhibition task following smoking as usual. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial.
Time frame: 12.5 minutes of fMRI scanning following smoking as usual
Population: 18 participants completed all aspects of the study. Two participants were excluded from analyses because they reported falling asleep in the scanner and one was excluded because of an incidental finding during the scan.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Smokers | Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Presupplementary Motor Area (Pre-SMA) During Task on Satiated Day | 0.169 percentage of signal change | Standard Deviation 0.17 |
Comparison: Within group repeated measures design. Null hypothesis is that there will be no difference in percent signal change during active task relative to baseline.p-value: <0.05Paired t-test
Primary
Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Abstinent Day
Percent signal change in fMRI BOLD response in rIFC to correctly inhibited targets (as compared to control trials) during a response inhibition task following not smoking for 24 hours. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial.
Time frame: 12.5 minutes of fMRI scanning following 24 hrs smoking abstinence
Population: 18 participants completed all aspects of the study. Two participants were excluded from analyses because they reported falling asleep in the scanner and one was excluded because of an incidental finding during the scan.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Smokers | Signal Change in fMRI BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Abstinent Day | 0.104 percentage of signal change | Standard Deviation 0.141 |
Comparison: Within group repeated measures design. Null hypothesis is that there will be no difference in percent signal change during active task relative to baseline.p-value: <0.05Paired t-test
Primary
Signal Change in Functional Magnetic Resonance Imaging (fMRI) BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Satiated Day
Percent signal change in fMRI BOLD response in rIFC to correctly inhibited targets (as compared to control trials) during a response inhibition task following smoking as usual. Response inhibition trials are trials in the task in which the participant must inhibit a response (not press the button)when presented with a No-Go trial. Control trials are trials in the task in which the participant must press the button when presented with a Go trial.
Time frame: 12.5 minutes of fMRI scanning following smoking as usual
Population: 18 participants completed all aspects of the study. Two participants were excluded from analyses because they reported falling asleep in the scanner and one was excluded because of an incidental finding during the scan.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Smokers | Signal Change in Functional Magnetic Resonance Imaging (fMRI) BOLD Signal Between Response Inhibition Trials and Control Trials in Right Inferior Frontal Cortex (rIFC) During Task on Satiated Day | 0.039 percentage of signal change | Standard Deviation 0.099 |
Comparison: Within group repeated measures design. Null hypothesis is that there will be no difference in percent signal change during active task relative to baseline.p-value: <0.05Paired t-test