Nicotine addiction Flashcards

Question

outline nicotine's plasma concentration

Answer 1

- Each cigarette delivers 1.2-2.9mg of nicotine. - A typical pack-a-day smoker absorbs 20-40mg of nicotine each day. - Half-life is ~ 2hours. - During a typical day, nicotine accumulates over 6-8 hours (3-4 half-lives). - The increment is 5-30ng/ml after each cigarette (depending on how the cigarette is smoked). - More frequent smoking reduces fluctuations in nicotine plasma concentration. - The plateau (10-50ng/ml) is usually reached in the early afternoon.

Answer 2

To alleviate the symptoms of withdrawal, smokers re-dose themselves throughout the day. This figure depicts the typical nicotine addiction cycle a cigarette smoker experiences on a daily basis. • The jagged line represents venous plasma concentrations of nicotine as a cigarette is smoked every 40 minutes from 8 am to 9 pm. • The upper solid line indicates the threshold concentration for nicotine to produce pleasure or arousal. • The lower solid line indicates the concentrations at which symptoms of abstinence (i.e., withdrawal symptoms) from nicotine occur. • The shaded area represents the zone of nicotine concentrations (neutral zone) in which the smoker is comfortable without experiencing either pleasure/arousal or abstinence symptoms.

Answer 3

Cessation of smoking overnight allows resensitization of drug responses (i.e., loss of tolerance). Most dependent smokers tend to smoke a certain number of cigarettes per day (usually more than 10) and tend to consume 10–40 mg of nicotine per day to achieve the desired effects of cigarette smoking and minimize the symptoms of nicotine withdrawal.

Answer 4

Tobacco users tend to carefully titrate, or regulate, their tobacco intake to maintain a relatively constant level of nicotine in the body, in order to… • Prevent withdrawal symptoms. • Maintain pleasure/arousal. • Modulate mood (e.g., to handle stress or anxiety). Although many tobacco users might not think about it consciously, they are able to alter nicotine delivery in a number of ways, including • By smoking or dipping more frequently. • By smoking more intensely (e.g., inhaling deeper or longer, smoking cigarette down to the filter). • By obstructing the vents (with fingers or lips) on “light” cigarettes, thereby increasing the amount of nicotine delivered to the lung.

Answer 5

- Nicotine plasma concentration significantly drops overnight, which leads to withdrawal symptoms in the morning in chronic smokers. - Withdrawal onset is usually within a few hours after last cigarette. - Nicotine withdrawal syndrome includes: mood changes, dysphoria, depressive mood, irritability, frustration or anger, anxiety, restlessness, difficulty concentrating, impaired attention, hunger, increased appetite or weight gain, craving. First morning cigarette produces the most pleasurable effect… • After an overnight abstinence, more receptors become available for activation. • It also relieves withdrawal symptoms. The earlier the smoker begins to smoke after waking in the morning the more severe the dependence. If abstinence continues, withdrawal symptoms peak at 24-48 hours and gradually subside over several weeks. Some symptoms persist for months… • Mild depression, dysphoria and anhedonia.

Answer 6

Nicotine is a powerful drug capable of inducing a variety of pharmacologic effects, including an alteration in brain chemistry. However, tobacco addiction is more than just a brain disease. It is a complex process involving the interplay of many factors (pharmacologic, environmental, and physiologic) that influence an individual’s decision to use tobacco. As such, treatment of addiction requires a multifaceted approach. - environmental factors - social interactions - pharmacologic factors - physiologic factors

Answer 7

* Tobacco industry advertising: For years, the tobacco industry has engineered major marketing plans to design more addictive cigarettes and to defy the public regarding the hazards of smoking. Their multibillion-dollar marketing effort is an important contributor to tobacco use. * Conditioned stimuli: All drug-taking behavior is learned, a result of conditioning. Drug-taking behavior is reinforced by the consequences of the pharmacologic actions of the drug. At the same time, smokers begin to associate specific moods, situations, or environmental factors with nicotine’s reward effects. The association between such cues and anticipated drug effects and the resulting urge to smoke is another type of conditioning. For example, people often smoke cigarettes in specific situations, such as after a meal or with coffee or alcoholic beverages. The association between smoking and these other events, repeated many times, causes the environmental situations to become powerful cues for the urge to smoke. A nondrug example of this type of conditioning is the desire to eat popcorn at the movies. * Other aspects of smoking (e.g., manipulation of smoking materials, taste, smell, feel of smoke in the throat) become associated with the pleasurable effects of smoking. Even unpleasant moods can become conditioned cues for smoking. For example, a smoker may learn that not having a cigarette provokes irritability, a common nicotine withdrawal symptom. Smoking a cigarette relieves withdrawal symptoms. After repeated similar experiences, a smoker may come to regard irritability from any source, such as stress or frustration, as a cue for smoking.

Answer 8

Having family or peer-group members who smoke increases the likelihood of tobacco use and, therefore, addiction. Among adolescents, peer pressure is often a reason for initiating tobacco use.

Answer 9

As discussed previously, there is a pharmacologic basis for a nicotine-dependent individual’s decision to use tobacco.

Answer 10

Experts now believe that some individuals have a genetic predisposition for nicotine addiction. Additionally, the impact of coexisting medical conditions (especially psychiatric conditions) increases an individual’s likelihood of using and becoming dependent on tobacco.

Answer 11

Heritability ~50% (range 28-84%). Effect of gene polymorphisms… • People with defective alleles of CYP2A6 gene have slow metabolism of nicotine and lower rates of smoking and tobacco dependence. • People with CHRNA4 gene polymorphism (gene coding for α4 subunit of the nicotinic Ach receptor) have higher rates of tobacco dependence.

Answer 12

Remarkably, alpha-5 subunit knockdown in MHb did not alter the rewarding effects of nicotine but abolished the inhibitory effects of higher nicotine doses on brain reward systems. Increased nicotine intake in α5 knockout mice… - Nicotine intake has bell-shaped concentration curve. - Up-phase represents rewarding component, unaffected by deletion of a5. - Down phase reflects the aversive effects of higher doses of nicotine, significantly greater responses in a5 KO.

Answer 13

- People with psychiatric disorders and substance use disorders have 2-4 times higher rates of smoking (range 41% and 67% respectively) than the general population. - 40-88% of patients with schizophrenia smoke. - Higher rates of depression in smokers. - Higher rate of smoking in substance abusers. - Suggests common mechanism underlying nicotine addiction and other psychiatric disorders.

Answer 14

Possibly reduces symptom severity in schizophrenia (self-medication hypothesis)… • There is deficient endogenous central nicotinic neurotransmission in schizophrenia, which causes a disruption of sensory gating (a possible mechanism for delusions). • Exogenous nicotine partly compensates for this deficiency. • Schizophrenic patients smoke larger amounts of cigarettes per day and extract more nicotine from them – significant health risk. • Therapeutic use of safe forms of nicotine in schizophrenia has been proposed. Reduces risk of Parkinson’s disease... • Benefit correlates with the intensity and duration of smoking. • Does not appear to be due to publication bias. Does it reduce prevalence of Alzheimer’s disease? • After controlling for tobacco industry affiliation, smoking has been found to increase the risk of Alzheimer’s disease, RR -1.72.

Answer 15

Tobacco dependence is a chronic brain disease and is a condition that requires a two-prong approach for maximal treatment effectiveness. Prolonged tobacco use of tobacco results in tobacco dependence, which is characterized as a physiological dependence (addiction to nicotine) and behavioral habit of using tobacco. Addiction can be treated with FDA-approved medications for smoking cessation, and the behavioral habit can be treated through behavior change programs, such as individualized counseling and group or online cessation programs. Physiological: the addiction to nicotine...treatment: medications for cessation Behavioral: the habit of using tobacco...treatment: behaviour change program