It is not controversial to state that smoking tobacco is a serious health risk with long-term consequences for an individual's health. According to the Centers for Disease Control and Prevention (CDC), nearly 440,000 people in the United States die from a smoking-attributable illness each year, which amounts to 5.6 million years of potential life lost and $92 billion in lost productivity. Smoking is known as the number one cause of preventable death and not only afflicts individual users, but also has detrimental health effects for innocent bystanders. What is often lost in the deluge of statistics, however, is the biology behind the effects of smoking cigarettes and illness. Surprisingly, smoking cigarettes has health benefits, yet it should be noted that these do not outweigh the systemically harmful effects to the human body.
With every puff of a cigarette, one receives acute doses of tar and carbon monoxide, the major contributors to the enormous increased risk of cardiovascular and lung disease associated with smoking. Each draw of a cigarette also yields a dose of nicotine, a neurologically active factor that is most often cited as the addictive agent in cigarettes. Nicotine often is given a bad name because of its addictive properties in conjunction with the ill effects of tar and carbon monoxide. Nicotine, however, like most agents that act on the central nervous system, has positive effects as well as negative effects.
In the body, nicotine binds to a class of receptors known as cholinergic receptors. In fact, one of the two constituents of this receptor class, the nicotinic cholinergic receptor, was named specifically because nicotine can activate the receptor (the other is the muscarinic receptors). Nicotinic cholinergic receptor activation results in a number of molecular and physiological effects including increased release of the neurotransmitter dopamine and to a lesser extent norepinephrine, increased cognitive arousal and heart rate, as reported in the Journal of Neurobiology. Considering that dopamine is intimately involved in reward pathways, it is not unexpected that nicotine has addictive properties.
The positive health effects of nicotine originate from its physiological effects. Many studies have demonstrated a correlation between smoking and decreased risks of both Parkinson's and Alzheimer's disease according to Fratiglioni et al. Nicotine, primarily through its effects on dopamine, has direct application to Parkinson's as the symptoms of the disease stem from a loss of dopamine producing neurons in a region of the brain called the substantia-nigra. Further, it is likely that the cognitive arousal results in neuronal activation, providing protection against Alzheimer's disease through a "use it or lose it" phenomenon. Speer et al. showed that smoking even reduces the risk of preeclampsia during pregnancy, likely through reduced adhesion molecule expression.
What truly makes the phenomenon of smoking interesting is that it has a positive impact upon mental illness. To support that correlation, many researchers, including Lasser et al. , have found that cigarette use is higher in select mentally-ill populations. Given that nicotine may reduce the sensation of pain, increase temporary attention resources through arousal and decrease anxiety possibly through desensitization of the stress response, cigarette smoking may be a form of self-medication for mild mental illness. In fact, there is evidence to suggest that smoking may ameliorate some of the positive symptoms of schizophrenia according to Sacco et al. . The act of smoking may itself be a treatment for our own mental maladies as slow breathing may reduce perceived levels of stress and anxiety, in addition to the biological effects of nicotine. One should not smoke, but the positive cognitive effects of smoking may help explain why it is still a prevalent phenomenon despite the very dangerous health risks involved.
Michael can be reached atmichaelmcduffie@cavalierdaily.com.
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