What proportion of smokers become addicted?

Most people who become smokers initiate smoking before the age of 18. They generally try smoking as part of experimentation, after observing their peers and family smoking and viewing tobacco advertising. It is fairly natural, when cigarette smoking can be observed so widely, for a child to think, “I wonder what that is like?”. Most kids who try smoking are not considering or expecting that they may become addicted. But it may be worth educating young people on their risks of becoming addicted. To do so we have to be clear about what we mean by “addiction”.

Nowadays the words “dependence” and “addiction” are generally used interchangeably with the same meaning. When used in relation to substance or drug use, these words refer to a situation in which the drug has come to unreasonably control a person’s behavior. The central characteristic of most definitions of drug addiction is that the individual experiences an impaired ability to reduce or end their use of the drug. In the case of cigarette smoking that characteristic is most commonly expressed as long term daily smoking despite awareness of the likelihood of serious health effects, a desire to reduce or quit, and failed attempts to reduce or quit.

In order to more clearly define, diagnose and study nicotine dependence, various diagnostic criteria have been developed, such as those of the American Psychiatric Association (DSM-IV) or the World Health Organization (ICD-10). These typically describe a list of criteria and require individuals to meet a certain number of these to meet the diagnostic threshold for “nicotine dependence”. There are 7 main DSM-IV criteria, (including things like difficulty cutting down, continued use despite it causing problems, experience of withdrawal symptoms when reducing etc) and if a smoker meets at least 3 of these they are considered to be “nicotine dependent”. Of course there is a certain artificiality about this because most people consider that nicotine addiction exists on a continuum of severity, rather than being a categorical disorder that a person either does or does not have. But these diagnostic frameworks at least give us a way of identifying those who are clearly addicted.

Last year, Drs Eric Donny and Lisa Dierker published a paper (in the journal, “Drug and Alcohol Dependence”) that aimed to identify what proportion of smokers in the general population met strict DSM-IV criteria for nicotine dependence. Their study was based on direct interviews with a large, representative sample of non-institutionalized adults in the United States in 2001-2. From that sample they focused on the 8,213 who were daily smokers in the past year. This sample included people who smoked anything from 1 to over 40 cigarettes per day, and people who had smoked for less than one to over 50 years.

The study found, not surprisingly, that the greater the number of cigarettes per day the person smoked, the greater the chance that they would meet strict diagnostic criteria for having become nicotine dependent. Whereas under 50% of those who smoked 1-5 cigarettes per day met the criteria, over 80% of those who smoked over 30 cigarettes per day met the criteria.

Unexpectedly, however, the longer the person had smoked, the less likely they were to have become dependent, particularly if the person had started smoking over 50 years ago. This finding seems very odd, and may have more to do with memory for quit attempts or attitudes to smoking among older age cohorts.

Overall, over 60% of ever daily smokers met strict diagnostic criteria for having become nicotine dependent. But almost all smokers had experienced at least one symptom of nicotine dependence. For example, 97% of “dependent” smokers had experienced difficulty cutting down their cigarette consumption, as had 72% of “non-dependent” smokers. The authors acknowledged that the differences in dependence between these two groups may be more quantitative rather than qualitative. The authors also acknowledged that certain co-occurring factors appear to make it more likely that a smoker will bcome dependent. An example they provided was a history of major depression, which is associated with approximately 100% nicotine dependence among heavy smokers.

So we can tell young people that if they take up smoking, there is an over 90% chance that they will experience some symptoms of nicotine addiction, and over a 60% chance that they will go on to meet strict diagnostic criteria for becoming addicted to nicotine.

A pdf copy of the full paper by Drs Donny and Dierner can be accessed (near the bottom of the page) at:
http://www.tern.org/Publications.htm

Labels: addiction, cigarette, cigarette smoking, dependence, jonathan foulds, nicotine

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