In a new analysis that revisits links between smoking and schizophrenia, scientists say cigarettes could be a casual factor in developing psychosis.
Aggregating information from 15,000 tobacco users, 273,000 non-users, and their relative rate of psychosis, showed that cigarette smoking appeared to increase the risk.
“While it’s 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,” said James MacCabe, who co-led the research at King’s College London’s Institute of Psychiatry.
Psychosis – in which people can experience delusions, become paranoid, and even hear voices in their head – affects roughly one in a hundred people, typically developing in early adulthood.
The link between smoking and schizophrenia has been examined before, but for this study, McCabe’s team analyzed rates of smoking in people presenting with their first episode of psychosis. They found 57 per cent of them were smokers. In past studies, scientists simply had patients suffering from schizophrenia smoke, to see if it would counteract the stress – not necessarily looking for the links McCabe discovered.
Robin Murray, a professor of psychiatric research who worked with McCabe, points to the brain’s dopamine system as the cause to this casual link.
“Excess dopamine is the best biological explanation we have for psychotic illnesses,” he said. “It’s possible that nicotine exposure, by increasing the release of dopamine, causes psychosis to develop.”
As if there weren’t enough consequences to smoking cigarettes already.