A new review study suggests that people smoking cigarettes are more likely to develop schizophrenia. The findings imply that nicotine in cigarette smoke may be altering the brain.
Schizophrenia is a long-term mental disorder that usually appears in late teens or early twenties but can emerge in any time in life. Some of the symptoms include delusions, loss of personality (flat affect), confusion, agitation, social withdrawal, psychosis and strange behavior. About one in every 100 people worldwide has the illness and they are all at high risk of committing suicide, according to the CDC,
Earlier studies suggest that schizophrenia is caused by genetic and environmental factors. However, a new analysis made by researchers at King's College London identified smoking as the possible contributor of the mental disorder. The team looked at the data of 61 different studies involving a total of 288,000 participants. Five percent of the participants smoked cigarettes.
The analysis revealed that 57 percent of the smoking participants developed schizophrenia during the follow-up period. The rate is three times higher compared to the non-smokers.
The researchers believe that the nicotine found in the cigarettes is altering the levels of the brain chemical dopamine.
"Excess dopamine is the best biological explanation we have for psychotic illnesses," Robin Murray, study co-author a professor of psychiatric research at King's College London, told Reuters. "It's possible that nicotine exposure, by increasing the release of dopamine, causes psychosis to develop."
The researchers admitted that further research is needed to prove the link. They failed to take into account other factors such as cannabis use which also trigger psychotic illness.
"It's very difficult to establish causation [with this style of study], what we're hoping that this does is really open our eyes to the possibility that tobacco could be a causative agent in psychosis, and we hope this will then lead to other research and clinical trials that would help to provide firmer evidence," James MacCabe, from the Institute of Psychiatry, Psychology and Neuroscience at King's, told the BBC.
The study was published in the July 9 issue of the Lancet Psychiatry.
