Biological factors of smoking
The biological factors involved in smoking relate to how the brain responds to nicotine. When a person smokes, a dose of nicotine reaches the brain within about ten seconds. At first, nicotine improves mood and concentration, decreases anger and stress, relaxes muscles and reduces appetite.
Regular doses of nicotine lead to changes in the brain, which then lead to nicotine withdrawal symptoms when the supply of nicotine decreases. Smoking temporarily reduces these withdrawal symptoms and can therefore reinforce the habit.
This cycle is how most smokers become nicotine dependent.
Social and psychological factors also play a part in keeping smokers smoking. Although many young people experiment with cigarettes, other factors influence whether someone will go on to become a regular smoker. These include having friends or relatives who smoke and their parents’ attitude to smoking. As young people become adults, they are more likely to smoke if they misuse alcohol or drugs or live in poverty. These factors make it more likely that someone will encounter stress. Most adults say that they smoke because of habit or routine and/or because it helps them relax and cope with stress.
Smoking and stress
The idea that people smoke cigarettes to help ease the signs and symptoms of stress is known as ‘self-medication’. Stress is very common, affecting us when we feel unable to cope with unwelcome pressure. It can cause physical symptoms like headaches or breathlessness as well as making people feel irritable, anxious or low. These feelings can alter our behavior and feeling stressed often makes people drink alcohol or smoke more than usual. Long term stress is also related to anxiety and depression.
Smoking and anxiety
Research into smoking and stress has shown that instead of helping people to relax, smoking actually increases anxiety and tension. Nicotine creates an immediate sense of relaxation so people smoke in the belief that it reduces stress and anxiety. This feeling of relaxation is temporary and soon gives way to withdrawal symptoms and increased cravings. Smoking reduces nicotine withdrawal symptoms, which are similar to the symptoms of anxiety, but it does not reduce anxiety or deal with the underlying causes.
Smoking and depression
In the UK, smoking rates among adults with depression are about twice as high as among adults without depression. People with depression have particular difficulty when they try to stop smoking and have more severe withdrawal symptoms during attempts to give up. Nicotine stimulates the release of the chemical dopamine in the brain. Dopamine is involved in triggering positive feelings. It is often found to be low in people with depression, who may then use cigarettes as a way of temporarily increasing their dopamine supply. However, smoking encourages the brain to switch off its own mechanism for making dopamine so in the long term the supply decreases, which in turn prompts people to smoke more.
Most people start to smoke before they show signs of depression so it is unclear whether smoking leads to depression or depression encourages people to start smoking. The most likely explanation is that there is a complex relationship between the two.
Smoking and schizophrenia
People with schizophrenia are three times more likely to smoke than other people and they tend to smoke more heavily. One of the most common explanations of this is that people with schizophrenia use smoking to control or manage some of the symptoms associated with their illness and to reduce some of the side effects of their medication. A recent study has shown that there could be a causal link between smoking and schizophrenia. However, there are various factors which may increase the risk for developing schizophrenia and further research is needed to fully understand the link and causal pathway.