Int. J. Environ. Res. Public Health 2012, 9 208 intervention [46]. Everyday practice shows that many alcoholics consider that quitting tobacco to be far more difficult to quit than alcohol. Likewise, polydrug abusers often consider that tobacco would be the last substance they would be able to quit. It is also the case that, of all abused substances, nicotine is the one where the risk of developing a dependence syndrome is the highest after first exposure [1,47,48]. Even this leaves us problems, as the authors themselves use conflicting language [47]: “Over 80% of those who had used tobacco six or more times met dependence criteria…It appears that tobacco readily produces dependence (perhaps more so than most other substances), yet it does not progress to severe levels of dependence as readily as cocaine, heroin and most other drugs. Though it easily causes compulsive use, tolerance, and withdrawal, tobacco may be less likely to get “out of control” and progress to severe dependence than most other drugs”. Perhaps the biggest difficult is that, with addiction, there are several dimensions. These include the swiftness with which an addiction takes hold, the severity or otherwise of deleterious effects, the time course of their development, whether they are balanced by any possible beneficial effects, how many are affected, and how easy it is for an addiction to be broken. In all of these dimensions, tobacco addiction rates high. It is a strong addiction, being of rapid onset and hard to break, as evidenced by the large amount of good quality evidence of low placebo response rates in cessation trials, and of major public health concern because of its negative effects on health in a large number of people. Acknowledgments This work was funded by Pfizer. Conflict of Interest This work had its genesis in discussions between RAM and Pfizer personnel about how addictions might be differentiated. That resulted in a piece of commissioned work relating to the use of placebo. The authors were free to publish the results of any research if they chose, free of any constraints by Pfizer, which had no role in design, planning, or execution of the study, or in writing the manuscript. RAM is funded by NIHR Biomedical Research Centre Programme, and has received research funding from Pfizer. HJA has received sponsorship to attend scientific meetings, speaker honorariums and consultancy fees from Pfizer, McNeil, GlaxoSmithKline, Pierre-Fabre Santé, Sanofi-Aventis, and Merck-Lipha. References 1. Lopez-Quintero, C.; Cobos, J.P.; Hasin, D.S.; Okuda, M.; Wang, S.; Grant, B.F.; Blanco, C. Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug Alcohol Depend. 2010, 115, 120-130.