Are behavioral addictions less common than addictions to substances?

In general, behavioral expressions of addiction, such as gambling, are less prevalent than addiction to substances. It is likely that this is the case because behaviors don't alter your state of mind as powerfully or as consistently as drugs. However, the less-common behaviors haven't been as well studied. In 2011, researchers from the University of Southern California published a review of 83 studies, each involving at least 500 subjects; this study examined the prevalence of 11 different expressions of addiction (tobacco, alcohol, illegal drugs, eating, gambling, Internet use, love, sex, exercise, work, and shopping). They found that most of the forms of behavioral addiction studied -- eating, gambling, Internet use, love, sex, and exercise -- each occurred in about 2% to 3% of the population. Addiction to substances (alcohol, cigarettes, and illicit drugs) had prevalence rates between 5% and 15%, as did two behavioral expressions of addiction (work and shopping). However, other research suggests that the rate of shopping addiction is closer to 2% to 3%.