The menthol in menthol cigarettes could be making people more addicted to nicotine (Image: Getty)

It’s a fresh problem. People who smoke menthol cigarettes often smoke more frequently and can be less likely to quit – and it could be because fresh-tasting menthol is changing their brains to more sensitive to nicotine.

How menthol enhances nicotine addiction has been something of a mystery. Now, Brandon Henderson at the California Institute of Technology in Pasadena and his colleagues have shown that exposing mice to menthol alone causes them to develop more nicotinic receptors, the parts of the brain that are targeted by nicotine.

Menthol can be used medically to relieve minor throat irritations, and menthol-flavoured cigarettes were first introduced in the 1920s. But smokers of menthol cigarettes can be less likely to quit. In one study of giving up smoking, 50 per cent of unflavoured-cigarette smokers were able to quit, while menthol smokers showed quitting rates as low as 23 per cent, depending on ethnicity.


Over time, smokers of both menthol and unflavoured cigarettes acquire more receptors for nicotine, particularly in neurons involved in the body’s neural pathways for reward and motivation. And research last year showed that smokers of menthol cigarettes develop even more of these receptors than smokers of unflavoured cigarettes.

More than a flavour

To understand how menthol may be altering the brain, Henderson’s team exposed mice to either menthol with nicotine, or menthol alone. They found that, even without nicotine, menthol increased the numbers of brain nicotinic receptors. They saw a 78 per cent increase in one particular brain region – the ventral tegmental area – which is involved in the dopamine signalling pathway that mediates in addiction.

“This data shows that menthol is not merely a flavour additive as many of us have believed in the past,” said Henderson, when he presented his findings at the 2014 Annual Meeting of the Society for Neuroscience in Washington DC, last month.

If the effect is the same in humans, this would help explain why menthol smokers have a harder time quitting than those who smoke non-menthol cigarettes.

“We had no idea whether people who chose menthol cigarettes had a higher likelihood of tobacco addiction, or whether menthol had specific effects on the brain,” says Marina Picciotto at the Yale University School of Medicine. She says these findings suggest that menthol enhances the addictive properties of the nicotine.

Menthol-flavour cigarettes are due to be banned in the EU from 2022, and the US Food and Drug Administration is considering taking similar measures .