Smoking Linked to Increased Risk of Psychosis

A meta-analysis by British researchers has revealed that smoking tobacco may increase the risk of psychosis. Past research has shown that those with psychotic mental illnesses are more likely to be smokers but until now, the link was thought to be caused by sufferers using cigarettes to deal with their distress.

The study authors used data from 61 studies, including almost 290,000 participants, to form their new conclusions. They found that 57% of people treated for a first episode of psychosis were smokers before the diagnosis. Overall, psychotic patients were three times more likely to smoke than those without this type of mental illness.

So far, there are only statistical trends to indicate that smoking may increase the risk of psychosis. There is no evidence to definitively prove that tobacco contributes to the development of mental illness. However, researchers believe that smoking may play its part by impacting levels of dopamine – a chemical which affects the way the brain experiences emotion. Changes in the way the body responds to pleasure and reward can trigger serious mental disorders, such as schizophrenia.

“While it is always hard to determine the direction of causality, our findings indicate that smoking should be taken seriously as a possible risk factor for developing psychosis, and not dismissed simply as a consequence of the illness,” says Dr James MacCabe, one of the researchers who worked on the study.

Professor Sir Robin Murray, of the Institute of Psychiatry at King’s College, explains: “Excess dopamine is the best biological explanation we have for psychotic illnesses such as schizophrenia. It is possible that nicotine exposure, by increasing the release of dopamine, causes psychosis to develop.”

Experts say it will be difficult to prove that smoking raises the chances of psychotic mental illnesses. However, they also stress that there are plenty of reasons to stop smoking. Smoking increases your risk of a number of diseases, including cancer and heart disease, so a possible link to psychosis is just one more reason to avoid cigarettes.