Smoking can triple the chances of developing psychosis, scientists say in a new study.
Earlier, the fact that people with psychotic mental illnesses are more likely to be smokers was put down to other factors, such as self-medication or obtaining relief from distress.
But now researchers believe something in tobacco might actually be responsible – as well as genetic and environmental influences, irishexaminer.com reports.
Dr James MacCabe, a member of the team from King’s College London, said: “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.”
By making 61 observational studies of 15,000 people who smoked and 273,000 who didn’t, the team found 57% of people treated for a first episode of psychosis were smokers.
The study also showed that daily smokers became psychotic around a year earlier than non-smokers.
But it also acknowledged the relationship between cause and effect is difficult to prove – with another potential theory being a possible link between smoking and excess dopamine, a brain chemical that plays a role in transmitting nerve signals. A proven link has already been found between cannabis use and psychosis in genetically vulnerable people.
