There is a growing body of literature supporting the hypothesis that the prevalence of problem and pathological gamblers in the general population increases with access to gambling opportunities.23 Access to gambling opportunities includes: physical proximity to gaming facilities (i.e., casinos, sports betting facilities such as racetracks, and slots, VLTs, etc., located within casinos) and increased availability of gaming (i.e., number of lotteries, the expansion of internet gambling). Participating in casino gambling, in particular, has been found to be a high risk factor for becoming a pathological gambler.32 There is some evidence that, within Ontario, persons who participate in casino games and VLTs located within casinos have higher rates of problem gambling than those who participate in other forms of gaming.10 A 2010 study by Afifi et al concluded that women were more likely to gamble if it was legally available and therefore the increase of legal forms of gambling results in an increase in women gamblers.33 Specifically, they studied 13 types of gambling and found that Canadian women who gambled using VLTs within casinos or who participated in other casino games had the second and third highest odds of being a problem gambler, respectively.33
Increased proximity to gambling opportunities has been repeatedly linked to an increase in the prevalence of problem and pathological gambling.1;6;9;12;34-36 Research in the United States has shown that there is a higher prevalence of problem gambling in areas within 80km of casinos,1;6 with the likelihood of being a pathological or problem gambler being twice the average for persons living within these regions.6 Similarly, a study by Welte et al found that the presence of a casino within 10 miles of a person's home was associated with problem and pathological gambling; specifically, their results found the odds of being a problem or pathological gambler increased by 90%.9 In New Zealand, Pearce et al found that after adjusting for possible confounders, the quartile of the population with the closest access to any type of gambling outlet had odds 2.05 times that of the quartile with the furthest access to gambling outlets of being a problem gambler.34 A study of Ontario university students found a statistically significant difference between the number of problem gamblers at universities closer to a casino than to universities further from a casino.36 Another Ontario study found exposure to gambling facilities (in this case commercial or charity casinos, or slot facilities at racetracks) had a modest but statistically significant effect on the prevalence of problem gamblers.12 These observations are not consistent across all studies; some have found no association between the availability of casinos and the prevalence of problem and pathological gamblers.9
The legalization of gambling and proliferation of casinos around the globe has resulted in numerous natural experiments. In Minnesota between 1990 and 1994, the legalization of the lottery and a large increase in the number of casinos resulted in an increase in the rate of pathological and problem gambling from 2.5% to 4.4%.37 A similar trend was observed in New Zealand where increased usage (62%) of a gambling hotline occurred after the opening of a new casino.38 Cox et al concluded in their study that "the rapid and prolific expansion of new forms of legalized gambling ... would be associated with a considerable health cost".35(p213).