Smoking Could Raise Mental Illness Risk: Study

News ID: 796221 Service: Science
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TEHRAN (Tasnim) – Scientists have suggested that smoking may be a factor for developing psychotic illnesses like schizophrenia.

The analysis by researchers from Kings College London, which was published in the Lancet Psychiatry journal, found that people who suffer from psychosis are three times more likely to smoke than the rest.

While this association is nothing new, little research has been conducted into whether smoking could actually be a causal factor for psychosis.

Researchers from Kings College London conducted an analysis of 61 studies comprising data on 15,000 smokers and 2, 73,000 nonsmokers.

Analysing data, conducted around the world between 1980 and 2014, the team found that 57% of people first diagnosed with psychosis were smokers. The researchers also found that daily smokers developed psychotic illness around a year earlier than non-smokers.

They also found that daily smokers who went on to develop psychosis did so on average a year earlier than smokers who developed the illnesses.

It has long been hypothesized that higher smoking rates among psychosis sufferers could be explained by people seeking relief from boredom or distress, or self-medicating against the symptoms or side-effects of antipsychotic medication.

But if this were so, researchers would expect smoking rates to increase only after people had developed psychosis.

However, the findings failed to prove its causation, with the researchers saying that some of the studies they looked at did not take into account possible confounding factors, such as whether smokers were also regular cannabis users, something psychotic illness is associated with. Researchers suggested a possible explanation for the link could be smoking's impact on levels of the chemical dopamine in the brain, which also plays a role in psychotic illness.

However, Dr James McCabe, clinical lecturer in psychosis studies at the King's Institute of Psychiatry , Psychology and Neuroscience said smoking should be "taken seriously as a possible risk factor" for psychosis and not "dismissed as a consequence of the illness".

Robin Murray , professor of psychiatric research at the IoPPN said: "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."

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