Dr. Flora Matheson, a research scientist at St. Michael's Hospital's Centre for Research on Inner City Health, with colleagues from the Centre for Addiction and Mental Health, conducted a review of existing literature on drug use and problem gambling. The results were published online in the journal ISRN Addiction. Dr. Matheson said that while the literature confirms a high correlation between problem gambling and substance abuse, the evidence also suggests that these people are less responsive to current treatment initiatives than other gamblers.

"Given the marginal and essentially hidden nature of this population -- street drug users with gambling problems -- unique approaches are necessary to encourage them to participate in research and treatment," she said. In their review the authors found many reports that problem gambling and substance abuse are related, or may even be one disorder, because of underlying traits such as impulsivity. A substantial body of literature indicates that both problems typically begin in adolescence or early adulthood and have common risk factors such as sexual abuse, depression and delinquency.

One study found that people with both problem gambling and substance abuse problems were more likely to have attempted suicide at some point in their lives and to have reported problems with sexual compulsivity. Another found that people with both problems also tended to engage in risky sexual behavior. And another found gambling to be a potential reinforcer of drug use, an obstacle to success in drug treatment programs and a substitute activity that increased as people stopped using drugs.

The differences between the two problems are largely the fact that long-term illicit drug use can entail serious chronic health problems and problem gambling leaves long-term financial issues in its wake. Dr. Matheson found the number of women with problem gambling is on the rise, perhaps due to changes in the availability and legal status of many gambling activities. An Australian study found that of 1,520 people seeking help for gambling-related difficulties, 46 per cent were women. Gamblers Anonymous, once an almost exclusively male organization, is seeing more women every year, she said.

Dr. Matheson, a medical sociologist, said people with substance use disorders may use gambling to support their drug habit. One study found people with substance use disorders were more likely to use those substances before or while gambling to enhance performance and to assuage the pain of losing or enhance the joy of winning.

"One attraction of drugs is the predictability of pleasure, as opposed to the uncertainty associated with gambling," she said.

Dr. Matheson said substance abuse and problem gambling are conditions that both wax and wane, and may become substitutes for one another.

"In the absence of illegal drug purchasing, and the many behaviours that go with it, gambling can provide an alternative form of excitement," she said.

"Substitution of one behavior for another has long been identified as a key issue in the field of addiction and perhaps the very notion of substitution could be studied in its own right. It could very well be that in some cases the primary addiction is not to any one behavior, but to a process where the object can be and does get replaced and alternated."