Smokers ‘three times more likely to be psychotic’ than non-smokers

Smoking tobacco, already known to cause cancer and stroke, may be also be a contributor to mental illness, a new study suggests. Researchers at King’s College London have found that people who suffer from psychosis are about three times more likely to be smokers. Although the association between smoking cigarettes and psychosis - particularly schizophrenia - has been acknowledged before, little attention has been directed towards the possibility that cigarettes themselves may increase the risk of psychosis. The study also showed that daily smokers became psychotic around a year earlier than non-smokers.

These findings call into question the self-medication hypothesis by suggesting that smoking may have a causal role in psychosis.

Conclusion from King’s College London scientists

The report stresses it does not conclusively prove that smoking causes psychosis, saying further research must be done. But the results did suggest that smoking “should be taken seriously as a possible risk factor for developing psychosis and not dismissed simply as a consequence of the illness,” they wrote. The researchers theorised that changes in the brain’s dopamine system may explain the association. Dopamine is a chemical messenger that helps control the brain’s reward and pleasure centres. “It is possible that nicotine exposure, by increasing the release of dopamine, causes psychosis to develop,” said psychiatric professor Robin Murray.

Tthere is overwhelming evidence that nicotine use through tobacco smoking is one of the most dangerous drug problems in the world.

Dr Michael Bloomfield, clinical lecturer in psychiatry at University College London