What are the most addictive drugs? This question seems simple, but the answer depends on whom you ask. From the points of view different researchers, the potential for a drug to be addictive can be judged in terms of the harm it causes, the street value of the drug, the extent to which the drug activates the brain’s dopamine system, how pleasurable people report the drug to be, the degree to which the drug causes withdrawal symptoms, and how easily a person trying the drug will become hooked.
There are other facets to measuring the addictive potential of a drug, too, and there are even researchers who argue that no drug is always addictive. Given the varied view of researchers, then, one way of ranking addictive drugs is to ask expert panels. In 2007, David Nutt and his colleagues asked addiction experts to do exactly that – with some interesting findings.
Nicotine is the main addictive ingredient of tobacco. When somebody smokes a cigarette, nicotine is rapidly absorbed by the lungs and delivered to the brain. While Nutt et al’s expert panels rated nicotine (tobacco) as only the 12th most addictive substance, there are reasons to believe that nicotine is a very powerful addictive drug.
More than two-thirds of Americans who tried smoking reported becoming dependent during their life. In 2002 the WHO estimated there were more than 1 billion smokers and it has been estimated that tobacco will kill more than 8m people annually by 2030. Laboratory animals have the good sense not to smoke. However, rats will press a button to receive nicotine directly into their bloodstream – and this causes dopamine levels in the brain’s reward system to rise by about 25-40%.