Nicotine Addiction 

Tobacco was first introduced into European society by Hernandez de Toledo in the sixteenth century. The Spaniard discovered the plant while exploring the Yucatan peninsula in 1520. The explorer sent specimens of the plant to Spain and Portugal. Jean Nicot of Portugal received the tobacco plant from Hernandez and eventually sent it to the Queen. For his efforts, the new world species was given the name nicotiana. Sir Walter Raleigh brought tobacco from Virginia to England in 1586, introducing the British to the new recreation called smoking. The exact origin of the word tobacco is lost in time. Some historians suggest the word tobacco refers to the Island of Tobago, or from Tabaco, which was a Mexican Province.^[1]

Almost immediately after its introduction into Western civilizations, tobacco attracted controversy. Its use was attacked for many reasons, some equating its use with the social problems associated with narcotics while others complained about the hygienic aspects of spit tobacco. Modern concerns about tobacco focus principally on its health-impairing qualities.

Cigarette smoking is a major preventable cause of disease worldwide, and it is the major cause of premature death in North America. In 1912, Adler first suggested that inhalation of cigarette smoke might be a cause of lung cancer. Since then, knowledge about the adverse health effects of smoking has accumulated. The important causes of mortality are atherosclerotic vascular disease, cancer, and chronic obstructive pulmonary disease (COPD). Smoking also can contribute to other diseases, eg, histiocytosis X, respiratory bronchiolitis, obstructive sleep apnea, idiopathic pneumothorax, low birth weight, and perinatal mortality.

Tobacco addiction, the second-leading cause of death in the world, is a culprit for approximately 5 million deaths each year or 1 in 10 adult deaths. Currently, about 1.3 billion smokers live in the world; most (84%) live in developing countries.^[2] With the present smoking trends, tobacco will kill 10 million people each year by 2020.^[3] Through direct healthcare costs and loss of productivity from death and illness, tobacco will cost governments an estimated US $200 billion per year. A third of these costs will be borne by the developing countries. Many factors have led to increased global smoking rates. These include trade liberalization; direct foreign investment; global marketing; transnational tobacco advertising, promotion, and sponsorship; and international tobacco smuggling.

Research investigating why people smoke has shown that smoking behavior is multifaceted. Factors influencing smoking initiation differ from those of smoking behavior maintenance. Nicotine dependence, genetic factors, and psychosocial factors influence maintenance of smoking behavior.

Nicotine meets the criteria of a highly addictive drug. Nicotine is a potent psychoactive drug that induces euphoria, serves as a reinforcer of its use, and leads to nicotine withdrawal syndrome when it is absent. As an addictive drug, nicotine has 2 very potent issues: it is a stimulant and it is also a depressant. For example, one smoker talked too lovingly about her cigarettes who are called her "best friend." They got her going in the morning, and they chilled her out during the day.

Nicotine in cigarette smoke affects mood and performance and is the source of addiction to tobacco. While cigarette manufacturers have publicly denied that nicotine is an addictive drug, recent documents disclose that they have known and used the addictive properties of nicotine since the 1950s. Unfortunately, this misinformation led to the false belief that nicotine use is a habit and not an addiction.

All health care professionals should be aware of the risks of tobacco smoking, understand tobacco addiction, and assist patients with smoking cessation.

In their 2010 guidelines, the American Heart Association-American Stroke Association (AHA-ASA) highly recommended that smokers consider smoking cessation because of the direct correlation between smoking and both ischemic stroke and SAH. Clinicians should provide counseling, nicotine replacement, and oral smoking cessation medications as options. Avoiding exposure to environmental tobacco smoke is reasonable.^[4]

Case study

A young adult man met his primary care physician for the first time, during which his prior military history came to light. The young man recalled the anxiety he experienced when he received his military orders for deployment to Iraq. Prior to the notice of deployment, he smoked cigarettes only occasionally, maybe 1 or 2 cigarettes a day. As the time for deployment approached, he started smoking more cigarettes and by the time he arrived in Iraq was up to a full pack a day. Throughout the 12-month deployment, he steadily increased his smoking with peak consumption of nearly 40 cigarettes a day. The soldier suffered several significant combat-related traumas resulting in mild physical injuries.

Upon return to the United States, the soldier completed his military obligation and left the service. Although still experiencing some lingering physical and emotional pain from his tour of duty, the former soldier was improving except in one area. His use of tobacco products stubbornly persisted, despite efforts to quit. The 2 packs of cigarettes a day was not only expensive, it was no longer enjoyable. When closely questioned he admitted that only the first cigarette of the day was truly enjoyable. His wife was complaining that the expensive habit was creating an unnecessary financial strain on their meager resources.

Despite his apparent willingness to consider quitting the use of tobacco, the former soldier also readily admitted he was frightened by the prospect. He recognized that his unresolved, but currently under treatment, emotional issues from the war offered a reason not to tackle another problem at this time. The doctor appreciated this frank disclosure but took issue with the patient’s conclusion. The patient appeared motivated, probably contemplating change, but needed an additional boost to consider a smoking cessation program.

At this point, the doctor decided to discuss co-occurring disorders by explaining the common association of a mental disorder with substance misuse. The doctor further explained how tobacco use, at least in the beginning, helped the former soldier cope with anxiety. After the traumas suffered in the war, the patient developed posttraumatic stress disorder (PTSD). The continued use of tobacco made it difficult to distinguish the symptoms of nicotine dependence from PTSD, and it delayed recovery from the emotional disorder.

The doctor asked the patient to mull this information over and consider a smoking cessation program. As the doctor further proposed, various medications could alleviate nicotine withdrawal symptoms or reduce tobacco cravings. Medications, when combined with a behavioral strategy, offered the safest and surest route to a tobacco-free life. The patient and the doctor continued to address the issue over a few more visits, including a conjoint meeting with the wife, before he decided to give up smoking. With the doctor’s help, he successfully completed a 3-month smoking cessation program.

Nicotine exerts its neurophysiologic action principally through the brain's reward center. This neuroanatomical complex, otherwise known as the mesolimbic dopamine system, stretches from the ventral tegmental area to the basal forebrain. The nucleus accumbens, a dopamine-rich area, is an intersection where all addictive behaviors meet. The release of dopamine at this site promotes pleasure and reinforces the associated behaviors, such as the use of alcohol and drugs, to replicate the positive experience. Other factors may also promote nicotine dependence such as nicotine's reduction in the monamine oxidase inhibitor enzyme. This enzyme is involved in the metabolism of catecholamines, to include dopamine. The net affect would be a lingering presence of the stimulating dopamine at the nucleus accumbens.^[5]

A closer inspection of nicotine's neurophysiology reveals a much more complex system. In particular, researchers continue to study the brain's neuronal nicotinic acetylcholine receptors (nAChRs).The nAChRs are a central component involved in nicotine's widespread influence on brain chemistry. Researchers have identified nAChR subtypes, most prominently labeled as alpha and beta subunits. The alpha-4 and beta-2 subunits are the most widely expressed in the brain. Acting through the nAChRs, nicotine influences glutamate, GABA, acetylcholine, dopamine, norepinephrine, and serotonin.^[6]

Nicotine also releases corticosteroids and endorphins that act on various receptors in the brain. Nicotine use results in more efficient processing of information and reduction of fatigue. In addition, nicotine has a sedative action, reduces anxiety, and induces euphoria. Nicotine effects are related to absolute blood levels and to the rate of increase in drug concentration at receptors.

Nicotine stimulates the hypothalamic-pituitary axis; this, in turn, stimulates the endocrine system. Continually increasing dose levels of nicotine are necessary to maintain the stimulating effects. With regards to dependence, some experts rank nicotine ahead of alcohol, cocaine, and heroin. A teenager who smokes as few as 4 cigarettes might develop a lifelong addiction to nicotine.

Small rapid doses of nicotine produce alertness and arousal, as opposed to long drawn-out doses, which induce relaxation and sedation. Nicotine has a pronounced effect on the major stress hormones. Nicotine stimulates hypothalamic corticotropin-releasing factor (CRF), and it increases levels of endorphins, adrenocorticotropic hormone (ACTH), and arginine vasopressin in a dose-related manner. Corticosteroids also are released in proportion to plasma nicotine concentration.

Nicotine alters the bioavailability of dopamine and serotonin and causes a sharp increase in heart rate and blood pressure. Nicotine acts on brain reward mechanisms, indirectly through endogenous opioid activity and directly through dopamine pathways.

The association between depression and smoking is well established. A lifetime history of major depression is more than twice as common in people who smoke compared to people who do not smoke. A history of major depressive disorder (MDD) is associated with a decreased ability to quit smoking and an increased likelihood of smoking relapse. As shown by the National Institute on Alcohol Abuse and Alcoholism's National Epidemiologic Survey on Alcohol and Related Conditions, current daily smokers with lifetime MDD and current MDD were more likely to report a continuation of smoking than those without a diagnosis of MDD. Former daily smokers with current MDD were also less likely to report continued abstinence.^[7] In subjects with a history of major depression, smoking may be an attempt to decrease negative affect, and following a quit attempt, they are likely to experience greater symptoms of nicotine withdrawal compared to smokers without a history of depression. Therefore, in patients who areattempting to quit smoking, inquiring about present or past symptoms of depression and anxiety is advisable, and specific therapy may be indicated.

Frequency

United States

In 1965, 52% of men and 34% of women were cigarette smokers. Presently, the incidence of cigarette smoking has decreased to 28% and 24%, respectively. The incidence of smoking is highest in blacks, blue-collar workers, less-educated persons, and persons in the lower socioeconomic strata.

• The trend is decreasing in more educated persons. Forty percent of men with less than 12 years of education, 35.9% of high school graduates, and 17.4% of college graduates smoke. Of women, 30.7% with less than 12 years of education, 29.6% of high school graduates, and 15.1% of college graduates smoke.
• Economic status also is related to smoking behavior. Of men with an income of $10,000-20,000 per year, 36.3% smoke, as opposed to 23.2% of men who make $50,000 or more per year. Of women who had a family income of $20,000 or less per year, 29.8% smoke, as opposed to 19.5% who make $50,000 or more per year.
• In 1983, a comparison was made between white-collar workers, of whom 27.9% smoked, and blue-collar workers, of whom 42.7% smoked.
• Twenty-five percent of pregnant women who smoke quit during pregnancy; yet 80% resume smoking after childbirth.
• Surveys show that 20% of teenage girls smoke and 15% of teenage boys smoke.

International

Worldwide, approximately 1.1 billion people smoke. In China, more than 70% of men older than 25 years smoke. Smoking is more prevalent in developing countries and is continuing to increase. Prevalence of smoking in North America is decreasing, currently approximately 25% of North Americans smoke.

Mortality/Morbidity

The health consequences of this addiction are enormous. Tobacco smoking is responsible for 1 of every 5 deaths and is the most common cause of cancer-related deaths in the United States. Children smoke 1.1 billion packs of cigarettes yearly. This accounts for more than $200 billion in future health care costs.

Tobacco accounts for more than 85% of all deaths due to lung cancer. Approximately 10 million people in the United States have died from causes attributed to smoking since the Surgeon General's first report in 1964; 2 million of these were from lung cancer alone. Furthermore, tobacco also has been identified as the leading cause of emphysema, COPD, bronchitis, and heart disease.

• Laryngeal cancer is uncommon; however, in 1988, it accounted for 1.1% of cancer-related deaths in men and 0.3% of cancer-related deaths in women. Oral cancer accounted for approximately 2.1% of male cancer-related deaths and 1.2% of female cancer-related deaths in 1988. Cigarette smoking and tobacco chewing are major causes of this disease. Esophageal cancer accounted for 2.6% of male cancer-related deaths and 1% of female cancer-related deaths. Approximately 50% of overall esophageal cancer mortality is due to cigarette smoking.
• Bladder cancer accounted for 2.4% of male cancer-related deaths and 1.3% of female cancer-related deaths in 1988; approximately one third of these deaths were related to cigarette smoking. Pancreatic cancer accounted for approximately 5% of cancer-related deaths in 1990; one third of these deaths were associated with cigarette smoking. Kidney cancer accounted for 2.3% of male cancer-related deaths and 1.8% of female cancer-related deaths. Smoking has been established as an independent risk factor for uterine cervical cancer. Anal cancer in both heterosexual men and women also was due largely to cigarette smoking. Interactions between viral factors and tobacco exposure increase cancer risk.
• Nonsmokers exposed to environmental tobacco smoke have a significantly higher risk of developing cancers and pulmonary diseases. Concentrations of toxins and carcinogens are higher in sidestream smoke. Children exposed to secondhand smoke develop a variety of respiratory disorders and morbidity.

Race

The smoking rate in the United States is higher among blacks than whites and is steadily increasing in Hispanics. In 1987, 39% of the black male population were smokers, compared to 30.5% of white men; 28% of black women were smokers, as opposed to 26.7% of white women. In addition, 30% of Hispanic men and 18% of Hispanic women were smokers.

Sex

In the United States, approximately 28% of men and 24% of women smoke.

Age

Studies reveal that the average age of first-time smokers is 14.5 years and the average age of daily smokers is 17.7 years. Approximately 20% of high school seniors smoke.

Adolescents and tobacco use

Early onset of tobacco use contributes to greater rates of addiction, making adolescence a particularly vulnerable age. Specific neurobiological factors may contribute to adolescent vulnerability.^[8] In a study by Bandiera et al, an association between the effects of secondhand smoke and various mental disorders in children and adolescents was reported.^[9]

The 2012 US Surgeon General’s report concluded that prevention efforts must focus on both adolescents and young adults because among adults who become daily smokers, nearly all first use of cigarettes occurs by age 18 years (88%), with 99% of first use by age 26 years.^[10]

The Surgeon General’s report also states that tobacco use among adolescents and young adults has substantially decreased, especially since 1998. However, a leveling off has been observed over the past few years, particularly since 2007. Some groups have demonstrated increases in the prevalence of tobacco use, such as smokeless tobacco use among white males. Some groups of young people continue to smoke more than others, notably American Indians and Alaska Natives but also whites and Hispanics. With the introduction of new tobacco products and the promotion of smokeless tobacco products, use of multiple tobacco products is common. Among tobacco users, more than 50% of white and Hispanic high-school males and nearly 50% of Hispanic high-school females use more than one product.