The health risks of smoking are well-documented but now scientists have revealed that it can massively increase your risk of mental illness.
Lighting up can more than double your chances of developing depression as well as causing bipolar disorder or even schizophrenia.
In fact, smokers are 250 percent more likely to end up hospitalized with a mental illness than non-smokers.
Researchers weren’t sure whether smoking caused depression or whether depressed people smoke, but now they have discovered it is definitely smoking that does it.
New figures from Aarhus University show that smoking increases the risk of developing depression by more than 100 percent but you can reduce the risk significantly if you quit.
Thanks to cigarette packets displaying shocking picture of diseased lungs and rotting teeth we are all aware of the risks, especially of cancer.
But smoking causing mental illness is less well known.
Professor Doug Speed from the Center for Quantitative Genetics and Genomics at the Danish University said: “The numbers speak for themselves. Smoking does cause mental illness.
“Although it’s not the only cause, smoking increases the risk of being hospitalized with a mental illness by 250 percent.
“Smoking typically comes before the mental illness. In fact, a long time before.
“On average, people from the data set began smoking at the age of 17, while they were typically not admitted to hospital with a mental disorder until after the age of 30.”
The team studied data from 350,000 people from the UK Biobank which is enough data to clean their figures from other possible effects leading to mental illness.
The genetic data was paired with a lot of other health information and answers provided by the participants regarding their lifestyle.
They fed the data into a computer and began looking for patterns.
Prof. Speed said: “Previous research hasn’t really considered that there may be a temporal dimension at play.
“People typically start to smoke before the age of 20, but aren’t admitted to hospital with a mental disorder until they’re between 30 and 60 on average.
“Smoking typically comes before the mental illness. In fact, a long time before.
“On average, people from the data set began smoking at the age of 17, while they were typically not admitted to hospital with a mental disorder until after the age of 30.”
As many as 90 percent of the people in the data set who were still smokers or former smokers started before the age of 20.
The likelihood that you will start smoking later in life is therefore quite small.
Prof Speed added: “When we looked at the many smokers in the database, we found a number of recurring genetic variants.
“By looking at twin studies, in which the twins had the same genes but grew up in separate homes, we could see that their genes could explain 43 percent of the risk of becoming a smoker.
“There are a number of genetic variants that we can refer to as ‘smoking-related genes’.
“The people in the data set who carried the smoking-related genes but did not smoke were less likely to develop mental disorders compared to those who carried the genes and smoked.
“Because the genetic variants also seem to be linked with the risk of mental illness, this used to be a bit blurry.
“But in this study, we demonstrate that it’s probable that the risk of starting to smoke causes the risk of developing mental disorders to increase due to the ‘smoking-related genes’.
“Another explanation could be that smoking causes inflammation in the brain, which in the long term can damage parts of the brain and lead to various mental disorders. But as I said: We don’t know for sure as yet.”
Statistically, smoking seems to cause mental disorders such as depression, bipolar disorder and schizophrenia.
Yet despite this latest study, the researchers have no explanation as to why, only a number of theories.
Prof. Speed continued: “We still need to find the biological mechanism that causes smoking to induce mental disorders.
“One theory is that nicotine inhibits absorption of the neurotransmitter serotonin in the brain, and we know that people with depression don’t produce enough serotonin.”
When you smoke a single cigarette, nicotine activates the production of serotonin in the brain.
This is one of the things that makes you feel relaxed after smoking but if you continue to smoke, nicotine will have the opposite effect inhibiting serotonin which can make you anxious, upset and unstable.
Prof. Speed said: “Another explanation could be that smoking causes inflammation in the brain, which in the long term can damage parts of the brain and lead to various mental disorders.
“But as I said: We don’t know for sure as yet.”
The study, published in the journal Acta Psychiatrica Scandinavica, recommends raising the smoking age limit to 20 as people rarely pick up the habit after that age.
Produced in association with SWNS Talker
