There are 2 clinical trials
Background: - Researchers have been studying behavioral components of nicotine addiction by looking at how drugs have a reinforcing effect, connecting the stimulation provided by the drug (nicotine) to the behavior that produces it (smoking). Based on previous studies, researchers are interested in learning more about how nicotine affects current smokers' responses to psychological tests and smoking-related cues, and in studying whether certain kinds of genetic background may affect smokers' responses to these kinds of studies. Objectives: - To compare the effect of nicotine versus denicotinized cigarettes during specific psychological tests. - To compare the effects of smoking cues versus neutral cues on craving, mood, and autonomic response. - To study the effect of genes on nicotine reinforcement and smoking-cue reactivity. Eligibility: - Individuals between 18 and 64 years of age who are current smokers (at least 10 cigarettes per day for at least 1 year) and are not currently interested in reducing their smoking or seeking treatment for tobacco dependence. Design: - Pilot session: - Participants will practice smoking using the measuring equipment that will be used in the study. - After successful practice, participants will read or listen to music for 1 hour, during which they are not allowed to smoke. - After the 1-hour period, participants will sample study cigarettes that have different levels of nicotine, and will be asked to guess whether the cigarettes are normal study cigarettes or denicotinized cigarettes. - Baseline session: - Blood, urine, and breath samples will be taken at the start of the session. - Participants will smoke part of an initial cigarette, and then will read or listen to music for 1 hour, during which they are not allowed to smoke. - After the 1-hour period, participants will give another breath sample and will complete questionnaires about mood and concentration levels. - Trial sessions: - Participants will smoke study cigarettes, and will be asked to either respond to questions about perceived nicotine levels in the cigarettes or press a lever for the chance to be rewarded with additional puffs of the cigarette. After the session, participants will give another breath sample and will complete questionnaires about mood and concentration levels. - Participants will also participate in cue-reactivity sessions to test the body's physiological response to smoking cues (a pack of cigarettes) and neutral cues (a pack of unsharpened pencils). After the session, participants will complete questionnaires on mood and concentration 15, 30, 45, and 60 minutes after the session. - At the conclusion of the last experimental session, participants will discuss the study with researchers, and may receive a referral list of smoking treatment programs.
Genetic Measures The following genetic polymorphisms will be assayed: 1) C/T rs2023239 variant of the CB1R gene, 2) the Ser/Gly rs6280 variant of DRD3 gene, and 3) variants of the CYP2A6 gene.
There is a series of well designed studies that have reported, in those with a history of anti-social behavior, that supplementation with vitamins / minerals, omega-3 fatty acids (n-3 FA), or both, reduces the incidence of aggressive behavior. Although there is evidence that all these nutrients have a role, to date the relative contribution of fatty acids and vitamins / minerals has not been considered: for example the possibility of a synergistic interaction has not yet been examined. In addition the topic has to date been studied under real-life condition, such as a prison, making the topic difficult to study. The major aim of the present study was to develop a paradigm that would allow the study of the topic in a sample from the general population without a history of anti-social behavior. Subjects received either a vitamin/mineral supplement, a fatty acid supplement, both or neither for three months, Measures of impulsivity and aggression were assessed before and after supplementation. Although in the past measures of actual behaviour have proved to be sensitive to supplementation, questionnaire measures have not. The second major objective was therefore to consider whether such phenomena can be studied in a sample without a history of anti-social behavior, using standardized, sensitive laboratory based measures and to compare these with questionnaire measures. POLYMORPHISMS AND THE RESPONSE TO MICRO-NUTRIENT SUPPLLMENTATION The data set were subsequently used to test an a priori hypothesis not related to the initial hypothesis. A meta-analysis found a consistent pattern that micro-nutrient supplementation improved mood (Long SJ, Benton D. Effects of vitamin and mineral supplementation on stress, mild psychiatric symptoms, and mood in nonclinical samples: a meta-analysis. Psychosom Med 2013; 75: 144-153). To produce evidence of possible mechanisms the extent was determined, to which the impact of micro-nutrient supplementation was influenced by a range of polymorphisms associated with neurotransmitter systems known to modulate mood. The primary outcome measure was the General Health Questionnaire, a 30-item self-report questionnaire that was developed to detect, in a community sample, those who would benefit from seeing a psychiatrist. Given the literature that relates polymorphisms to mood disorders, and the known pharmacology of anti-depressant drugs, a range of polymorphisms were chosen associated with serotonin and catecholamines. Dopamine The SNPs associated with the metabolism and functioning of dopamine were: Dopamine beta hydroxylase (DBH, rs16111115); Dopamine transporter (DAT1, rs2550946); Catechol-O-methyltransferase (COMT, rs4680, rs6269). Dopamine receptor D1 (DRD1, rs4532); Dopamine receptor D2 (DRD2, rs1079598, rs1800497); Dopamine receptor D3 (DRD3, rs6280); Dopamine receptor D4 (DRD4, rs1800955). Serotonin Ten SNPs associated with different aspects of serotonin metabolism were also considered. Rs1843809 is a SNP of the TPH2 gene that encodes Tryptophan hydroxylase. Rs1050565 is a SNP in the BLMH gene that influences the activity of 5HTT (SLC6A4), the serotonin transporter. SNPs associated with various serotonin receptors were also examined: genetic variations of the HTR1A gene (5-HT1A receptor, rs6295); HTR1B gene (5-HT1B receptor, rs6296); HTR2A gene (5-HT2A receptor, rs6311); HTR2B gene (5-HT2B receptor, rs1549339); HTR2C gene (5-hydroxytryptamine receptor 2C, rs518147); HTR3A gene (5-hydroxytryptamine receptor 3A, rs1150226); HTR3B (5-HT3B receptor, rs1672717); HTR4 gene (5-HT4 receptor, rs2278392). Adrenergic mechanisms Finally six SNPs associated with adrenergic receptors were considered: ADRA2A (adrenoceptor alpha 2A, rs553668); ADRB1 (adrenoceptor alpha B1, rs1801253); ADRB2 (adrenoceptor alpha B2, rs1042713; ADRB3 (adrenoceptor alpha B3, rs4994); SLC6AC (noradrenaline transporter, rs5569 and rs2242447). Analysis The data will be analyzed using analysis of variance with a change in GHQ from before to after supplementation as the dependent variable: Micronutrient/placebo X Polymorphism.
Dopamine receptor D1 (DRD1, rs4532); Dopamine receptor D2 (DRD2, rs1079598, rs1800497); Dopamine receptor D3 (DRD3, rs6280); Dopamine receptor D4 (DRD4, rs1800955).
Description: The GoStop Impulsivity Paradigm measures the ability to inhibit an already initiated response. A number of five digits are presented on a computer screen for 500ms followed by a 500ms blackout. A second number then appears for 500ms followed by a 500ms blackout. If the numbers are identical the mouse button has to be pressed before the second number disappeared. However, the response has to be with-held if a "Stop" signal appeared; that is the second number was identical but changed from black to red. If the two numbers were different then no response was required.Measure: Go Stop Impulsivity Paradigm Time: Change from before to after supplementation for three months
Description: This is test of the tendency to respond in an aggressive manner. A series of cartoons are presented that present an intentionally frustrating situation. The participant reports what he or she would say in that situation. Blind the responses are assessed in terms of the extent to which the responses are aggressive in matter Note that the use of two primary outcomes reflects the aim of the study to contrast performance and questionnaire measuresMeasure: Rosenzweig Picture Frustration Test Time: Change from before to after supplementation for three months
Description: The Buss-Perry Aggression Questionnaire assesses four aspects of aggressive behavior: physical aggression, verbal aggression, anger and hostility. Participants rank statements about their temperament using a 7-point Likert scale ranging from 1 (extremely uncharacteristic of me) to 7 (extremely characteristic of me).Measure: Buss Perry Aggression Scale Time: Change from before to after supplementation for three months
Description: The Perceived Stress Scale assesses the extent to which stressful thoughts and feeling had been experienced during the last month. For example: "In the last month, how often have you been upset because of something that happened unexpectedly?" The participant responded on a scale ranging from 0 = Never to 4 = Very Often. An overall score is calculated.Measure: Perceived Stress Scale Time: Change from before to after supplementation for three months
Description: A measure of the subjects ability to forgo initial reward for a later larger reward. The subject can choose to wait for a reward and get more points or alternatively respond more quickly and get fewer points sooner. The longer a subject waits the higher the reward; that the more points are earned. A mouse click began the task and a second resulted in a reward. Two counters display the most recent and cumulative reward over a 20 minute session. Subject are able to infer that responses at a faster rate earn smaller rewards.Measure: Single Key Impulsivity Paradigm Time: Change from before to after supplementation for three months
Description: Polymorphisms associated with the metabolism and receptors of dopamine and serotonin will be related to the response to micro-nutrient supplementationMeasure: General Health Questionnaire Time: Further analysis of existing data - considers changes from baseline to three months