First-time<unk>  users develop a dependence about 32% of the time. There are approximately 976 million smokers in the world. Estimates are that half of smokers (and one-third of former smokers) are dependent based on DSM criteria, regardless of age, gender or country of origin, but this could be higher if different definitions of dependence were used. Recent data suggest that, in the United States, the rates of daily smoking and the number of cigarettes smoked per day are declining, suggesting a reduction in population-wide dependence among current smokers. However, there are different groups of people who are more likely to smoke than the average population, such as those with low education or low socio-economic status and those with mental illness. There is also evidence that among smokers, some subgroups may be more dependent than other groups. Men smoke at higher rates than do women and score higher on dependence indices; however, women may be less likely to be successful in quitting, suggesting that women may be more dependent by that criterion. There is an increased frequency of<unk>  in people with anxiety disorders. 6% of smokers who want to quit smoking each year are successful at quitting.<unk>  withdrawal is the main factor hindering smoking cessation. A 2010 World Health Organization report states, "Greater<unk>  has been shown to be associated with lower motivation to quit, difficulty in trying to quit, and failure to quit, as well as with smoking the first cigarette earlier in the day and smoking more cigarettes per day." E-cigarettes may result in starting<unk>  again. Greater<unk>  may result from dual use of traditional cigarettes and e-cigarettes. Like tobacco companies did in the last century, there is a possibility that e-cigarettes could result in a new form of dependency on<unk>  across the world.
Nicotine dependence
Exercise addiction
Cocaine dependence
Nicotine withdrawal
Alcohol dependence
Benzodiazepine dependence
Caffeine dependence
Polysubstance dependence