Smoking cigarettes is a deadly pastime. Smoking causes cancer, heart disease, stroke, emphysema, bronchitis, vascular disease, cataracts, impotence and many other health problems.
Everybody knows this, but still people in substantial numbers continue to smoke. Why do people continue to smoke and ignore all public health anti-smoking campaigns? Obviously people find it difficult to quit and smokers are commonly viewed as being addicted to cigarettes.
I have read claims made by people who study the addictive properties of cigarettes that smoking is more addictive than a cocaine habit. I find it very difficult to accept such claims. A new report in the August 2000 edition of the science journal Neuron describes the physical mechanism through which smoking exerts its `addictive' effect.
When you inhale cigarette smoke, you breathe in thousands of chemicals, including nicotine. Nicotine is the agent that provides most of the pleasure of smoking and is the chemical that exerts the `addictive' effect. Most of the ill-health effects of smoking are caused by the other chemicals in cigarette smoke. The article in Neuron reports that brief exposure to low levels of nicotine, as little as one cigarette, can leave a lasting effect in the brain's `reward' areas. These areas exist to acknowledge and reinforce beneficial behaviours, e.g. eating when hungry by causing pleasurable feelings.
Nerve cells (neurons) in the brain communicate with each other at junction points (synapses) by passing chemical signals called neurotransmitters back and forth. The brain reward system encourages the body to repeat pleasing behaviours by releasing dopamine, the neurotransmitter associated with the pleasant feelings, in the reward areas.
Nicotine enhances the connections between one set of nerve cells that are sensitive to the drug and other nerve cells that register pleasure. Furthermore, the first exposure to nicotine induces an enduring `memory trace' that amplifies the pleasant effects of the drug and encourages a desire to repeat the exposure.
Nicotine exerts its effect by taking over pathways in the reward areas, thereby providing the same sort of reward for the harmful smoking behaviour as the system normally provides for beneficial behaviour. Nicotine alters the connections between nerve cells in a similar way to the mechanisms that underlie the creation of memory. The brain remembers that the intake of nicotine was good and it remembers the pleasant sensations it caused.
Nicotine specifically acts by binding to the synapse region of a set of neurons that send excitory signals to the neurons that release dopamine. The nicotine enhances the excitory signals transmitted to the dopamine nerve cells which then increase the release of dopamine. The brain reads the increased dopamine levels as: "This is good, do it again."
It is hoped that this detailed understanding of how nicotine exerts its effects will allow medications to be developed that will help smokers to kick the habit. However, I would guess that the chances of developing a drug that will cleanly erase the craving for nicotine with no side effects are slim. The more likely outcome is that a drug will be developed that will diminish the craving for nicotine but leave a substantial part to be played by willpower if the smoking habit is to be overcome.
I accept that nicotine exerts a chemical effect on the brain that creates a craving for the drug. However, I am not convinced that the strength of the craving is as strong as many people claim. I used to smoke but I stopped, and I know for certain I don't have a will of iron.
The climate of the times strongly emphasises the rights of the individual, but plays down the other side of the coin - our obligation to assume responsibility for our lives, to exercise self-control and to exercise parental authority. I believe that the majority of smokers could stop by exerting moderate willpower. People should be encouraged to believe this and should not be told they are slaves to an addiction.
I also believe that very many teenagers could be prevented from taking up smoking by responsible parenting. In all average situations it should simply be the house rule that no child under 18, living at home, can take up smoking.
Cigarettes are a scourge. It is estimated that they cause 70 times more deaths than all other types of drug dependence combined. We cannot afford to wait endlessly for a magic bullet to painlessly solve this problem. However, we could greatly ease it by exercising our finer faculties a little bit.
William Reville is a senior lecturer in Biochemistry and Director of Microscopy at UCC.