According to the researchers who conducted the study, the figures show that smoking doubles the risk of developing depression, schizophrenia and bipolar disorder, for example.
“The numbers speak for themselves very clearly. Smoking causes mental illness. It’s not the only cause, but smoking increases the risk of hospitalization for mental illness by 250 per cent,” explains Professor Doug Speed from the Center for Quantitative Genetics and Genome Research. at Aarhus University.
Scientists have so far disagreed about the relationship: Do we get depression or other mental illnesses because of smoking? Or do we smoke to suppress underlying mental illness?
But the new study found that smoking usually precedes the development of mental illness.
“So smoking predates mental illness. By a long time, too. The people included in the dataset started smoking at an average age of 17, whereas they were usually entered with mental illness only in their 30s,” explains Doug Speed.
Researchers do not have an exact explanation for why smoking increases the risk of mental illness.
“We haven’t found the biological mechanism that causes smoking to lead to mental illness. One theory is that nicotine blocks the reuptake of the neurotransmitter serotonin into the brain. We know that people who suffer from depression, for example, produce very little serotonin.” explains Dog Speed.
When you smoke a single cigarette, nicotine primarily activates the production of serotonin in the brain. It can have a relaxing effect.
But if you continue to smoke, nicotine can have the opposite effect and instead inhibit serotonin production.
This can make you anxious, sad, and unstable, according to the researchers.
“Extreme tv maven. Beer fanatic. Friendly bacon fan. Communicator. Wannabe travel expert.”