This is WHY some smokers may never be able to quit their deadly habit
THERE'S no denying it, quitting smoking is hard.
But, addiction experts now believe for some the feat could be almost impossible - and their brains are to blame.
They have identified a circuit in the brain that appears to predict if a smoker will successfully quit.
People who have stronger communication in the crucial circuit are more likely to stub their habit out for good, scientists at the Medical University of South Carolina found.
They hope their findings will pave the way for new treatments to help people quit.
Smoking causes around 90 per cent of lung cancers, and increases the risk of cancer of the mouth, bladder, kidney, liver, stomach and pancreas.
It also damages your heart, increasing the chance you'll suffer a heart attack, stroke as well as lung condition pneumonia and chronic obstructive pulmonary disease (COPD).
Dr Brett Froeliger said: "This work helps scientists understand why some smokers have a harder time quitting.
"Individual differences in brain biology are important."
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He said over time smoking becomes an automatic behaviour.
"A pack-a day smoker places a cigarette in their mouth a few hundred times a day over years, so they have many trials of experience," he said.
This kind of automated behaviour is stopped by a circuit in the brain called an inhibitory control network.
But the scientists found this circuit malfunctions in the brain's of some smokers.
Dr Froeliger's team examined the circuit in 81 smokers taking part in a 10-week programme to quit smoking.
About half of the smokers quit over the 10-week period.
Brain scans showed those who were successful had stronger connectivity in the inhibitory control networks before they tried to quit.
This work helps scientists understand why some smokers have a harder time quitting. Individual differences in brain biology are important
Dr Brett Froeliger
In another experiment, scientists measured brain activity in 26 smokers who had not committed to quitting.
Each smoker was given an open pack of cigarettes, a lighter and an ashtray.
They were paid one dollar for every six minutes they didn't smoke - up to an hour.
The idea was to give a small incentive to help them resist the urge to smoke.
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Similar to the first test, the findings showed those people with better activity in the inhibitory control networks the longer they could resist the urge to smoke.
Dr Froeliger and his team hope therapies that support this brain pathway could help smokers who are trying to stub out their deadly habit.
The findings, published in JAMA Psychiatry, add to evidence that shows difference in a person's biological make-up can explain why some smokers have more success than others when trying to quit.
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