Why is cigarette smoking addictive?
Cigarettes contain many toxic chemicals that are drawn into your lungs each time you drag on a cigarette and can seriously damage your health. Cigarette smoking has been linked to heart disease, stroke, and cancer.
However, it is the nicotine in cigarettes that is the addictive chemical. Nicotine is a natural pesticide found in the tobacco plant. It very poisonous and one of the most addictive known drugs. When nicotine is inhaled into your lungs in cigarette smoke, it is rapidly absorbed into the blood and reaches the brain within seconds. The effects of nicotine are immediate. You will feel an adrenaline rush, as it stimulates adrenaline release from the adrenal glands. In the brain, nicotine stimulates the release of the neurotransmitter dopamine, a brain chemical that allows nerve cells to communicate. Dopamine is often referred to as the “feel good” hormone as it is released when the reward circuit is activated. Dopamine creates a feeling of pleasure and relaxation when activated by a pleasurable activity like eating or sex. The amount of dopamine released by a drug like nicotine is much greater. It creates a feeling of euphoria, leading to the desire to repeat the feeling, which soon becomes a need and is the start of an addiction.
If you continue to smoke, you will gradually need more and more nicotine to get the same effect. If you stop smoking, once you are nicotine dependent, you will suffer from unpleasant withdrawal symptoms. These include physical symptoms like sweating, tremor, increased pulse rate (tachycardia), and nausea; also, emotional symptoms like anxiety, irritability, confusion, depression, and insomnia.
How do medicines work to help you quit smoking?
Medications to help you quit smoking work by helping you break the addiction for nicotine and reducing the withdrawal symptoms while you stop smoking. They include:
Varenicline has a similar structure to nicotine. It binds to the same receptors that nicotine binds to, which are the nicotinic acetylcholine receptors. These receptors stimulate dopamine release, but varenicline produces a much weaker response so that the reward effect and the craving are both gradually reduced.
Bupropion is an antidepressant that helps break the addiction created by nicotine dependence and works by increasing the amount of dopamine in the brain without the need for nicotine. Bupropion blocks the reuptake of dopamine from the nerve cells that release it, which prolongs the time that dopamine is active in the brain.