We focused the Seminar on existing meta-analyses on treatments and undertook a Medline (PubMed) search for articles that were not covered by the meta-analyses, with a primary focus on drug treatments. Search terms included “smoking cessation”, “tobacco cessation”, “nicotine replacement therapy” (“smoking cessation” and “nicotine gum”, “nicotine patch”, “nicotine lozenge”, “nicotine nasal spray”, “nicotine inhaler” or “sublingual nicotine”), “smoking cessation” and “antidepressants”,
SeminarTobacco addiction
Introduction
Lung cancer was confirmed to be caused by cigarette smoking over 50 years ago, and since then several other diseases have been added to the list of diseases caused by smoking and involuntary exposure to cigarette smoke.1, 2 However, the worldwide production and consumption of cigarettes has continued to increase unabated during this period. There are about 1·2 billion smokers in the world, half of whom will die from diseases caused by smoking.3 Smoking causes 5 million deaths per year, and if present trends continue, 10 million smokers per year are projected to die by 2025. The prevalence varies greatly, from less than 5% to more than 55% in different countries. It also varies greatly between men and women, so prevalence in both sexes needs to be examined separately.
On the basis of analyses of the WHO and American Cancer Society database, table 1 shows the distribution of prevalence of smoking in men and women in different countries of the world. These prevalence rates are not strictly comparable—samples might not be representative of the population of the country, they may refer to different time periods, the definitions of smoking might be different (eg, smoking at least one cigarette a day for a specified time vs smoking at least 100 cigarettes in a lifetime), and even age cut-offs might differ. Despite restrictions, they are the best data available.
More men smoke than do women. In men, prevalence seems to be moderate to low in industrialised countries and in sub-Saharan Africa. Prevalence seems generally high in eastern Europe and Asia. About 45% of the worldwide population lives in countries where the prevalence of smoking in men is greater than 45%, and about 92% of the population lives where prevalence in men is more than 25%. By contrast, only about 10% of the female population worldwide lives in a country where the prevalence is greater than 24%. The prevalence in women is low in some of the most highly populated countries of the world (China, India, Indonesia, and Nigeria) and in most countries of Asia, whereas high prevalence is reported from several industrialised countries.
The main determinant to substantially reduce the accelerated increase of morbidity or mortality related to tobacco in the short term would be if smokers were able to quit smoking.4 This Seminar will provide descriptions for the diagnosis of tobacco addiction, the biobehavioural basis for this addiction, and evidence-based treatments.
Section snippets
Diagnosis
The 1988 US Surgeon General's report—The Health Consequences of Smoking: Nicotine Addiction5—described three major conclusions: cigarettes and other forms of tobacco are addictive, nicotine is the drug that causes this addiction, and the pharmacological and behavioural processes that determine tobacco addiction are similar to those that determine addiction to drugs such as heroin and cocaine. The primary difference between nicotine addiction and addiction to other drugs is the absence of
Pathophysiology
Nicotine, when inhaled, enters the lungs where a large surface area of small airways and alveoli exists, undergoes dissolution in pulmonary fluid at a high pH, is transported to the heart, and then immediately passes to the brain.16, 17 The rapid rate of nicotine absorption and high amounts of nicotine attained in the brain from smoking are two crucial factors that promote and sustain nicotine addiction.18 The rate of nicotine metabolism can also greatly affect the circulating concentrations of
Susceptibility
Apart from the effect of nicotine on the brain, the experience of nicotine withdrawal, and the associative learning processes, other factors contribute to whether tobacco use is started or sustained. These factors include the environmental culture (access and availability of tobacco products, bans on tobacco use, cost, social acceptability, and modelling [eg, parental or peer smoking]) and the characteristics of the individual (eg, genes, comorbid psychiatry disorders, and personality
Treatments
Treatments are targeted towards dealing with the physical addiction to nicotine, the psychological reliance on the effects of nicotine, and the behavioural aspects of tobacco use. Several meta-analyses and public-health guidelines have described evidence-based treatment approaches.69, 70, 71
Future directions: novel drugs and pharmacogenetics
Although available pharmacotherapies can improve success rates, the absolute cessation rate remains fairly low at around 20%. Several other drugs have undergone clinical trials and many others that target specific neurotransmitters or metabolic enzymes (eg, GABAergic drug or monoamine oxidase inhibitors) or specific nicotinic receptor subtypes (eg, α7) are undergoing development or testing in phase I or II trials. Two drugs are noteworthy because of their novel mechanism of action or target
Conclusion
Nicotine or tobacco addiction should be treated as a chronic disorder. Treatment can need persistent efforts to try to assist tobacco users in their attempts at quitting. Relapse should be seen as a probable event. In smokers who quit without treatment, the proportion who can achieve abstinence for at least 1 week is 25–51% and at least 3 months is 10–20%. By 6 months, only 3–5% have achieved longlasting abstinence.137 Treatment can improve these outcomes. Treatment can include the use of
Search strategy and selection criteria
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