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Discover 20,142 clinical trials near Baltimore, Maryland. Find research studies in your area.
Showing 14681-14700 of 20,142 trials
NCT01036126
Background: \- Relapse to drug abuse often happens in the presence of stimuli that are associated with previous drug use, also known as cues. Drug-taking behavior appears to be partly controlled by such cues. Some research suggests that cue-induced craving states are responsible for drug use and relapse, but other research suggests that cues can control drug taking without conscious craving or even awareness. Researchers are interested in using functional magnetic resonance imaging (fMRI) to study how individuals respond to drug-related cues and how these cues affect craving on a conscious or unconscious level. Objectives: \- To determine how drug-related stimuli (cues) affect thinking, information processing, and body reactions in current drug users. Eligibility: \- Individuals between 18 and 50 years of age who are dependent on either tobacco or crack-cocaine, or are healthy volunteers who are not dependent on either drug. Design: * The study will require two sessions, a training session and a testing session, that will take place within 48 hours of each other. Between the two test sessions, participants may not consume alcohol, tobacco, or illegal drugs, and must restrict caffeine consumption. * During the first session, participants will complete questionnaires about tobacco/cocaine use and craving, and will be trained on the tasks to be performed in the MRI scanner. * During the second session, participants will perform concentration tasks and look at pictures, some of which will be tobacco/cocaine related. Body reactions such as heart rate, pupil dilation, and sweating will be measured during this session. Some participants will have actual MRI scanning, while others will have mock MRI scanning. * After the MRI session, participants will complete questionnaires about craving and responses to the scan.
NCT01035632
Background: \- Relapse following cigarette abstinence remains a common problem for smokers who are attempting to quit. Most research has focused on the acute withdrawal phase that occurs within the first 48 hours to 1 week after quitting; however, more information is needed on the experiences of smokers in longer durations of abstinence. Objectives: * To study the effects of long-term smoking abstinence. * To study the effects of cigarette-related cues on craving in longer periods of smoking abstinence. Eligibility: \- Individuals at least 18 years of age who are current smokers (at least 10 cigarettes per day) and who want to quit but are not currently attempting to quit. Design: * Participants will be randomly assigned to abstain from all nicotine use for 7, 14, or 35 days. A fourth group of participants will also abstain for 35 days, but will undergo more testing sessions than the other groups. * All participants will have an initial orientation session in which they will complete questionnaires about their smoking habits and will respond to smoking-related cues to provide information about their cravings. * Participants will visit the clinic daily during their abstinence period, and provide urine and breath samples to test for tobacco use. Participants will receive compensation for every day that they do not use tobacco. * On the end day of the abstinence period, participants will return to the clinic, provide urine and breath samples, and undergo testing of their responses to smoking-related cues. Participants in the fourth group will have these tests on Days 7, 14, and 35 of abstinence; other participants will have the tests only once, at the end of their abstinence period. * After the required abstinence period, participants will enter a 5-day step-down period. They will continue to report to the clinic for breath and urine testing, and they will receive payments for abstinence that decrease in value across days. * After the step-down period, for the final 12 days of the study, participants will report to the clinic every 3 days to give urine and breath samples and to report the number of cigarettes smoked.