http://goo.gl/zfGbCH
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 thatsmokers of menthol cigarettes develop even more of these receptors than smokers of unflavoured cigarettes.