We answered a similar question a couple years ago, so we pulled it out of storage, dusted if off, and here it is again.
Slot machines – video poker in particular – have been described as the crack cocaine of gambling. The analogy, while somewhat pejorative, is not without substance. Cocaine was once primarily an expensive "status" drug, whose high price tag precluded mass usage. Similarly, before the advent of slot machines, casino gambling (as opposed to sports betting and other forms of wagering) was generally something of an elitist and highly male affair, with urban casinos (as opposed to the riverboats, which were less upscale) often consisting of salons and private members-only clubs of the dress-code and velvet-drape variety still found throughout Europe.
While the advent of cheap and plentiful crack democratized cocaine usage, so slot machines accepting denominations as low as pennies, housed in large, respectable, but anonymous casinos, have opened up gambling to everyone, particularly women. Solitary and, in the case of slots (not video poker), requiring little to no skill, electronic games are far less intimidating than table games. The lack of social interaction makes it easier to lose track of time and become "lost" in the game, which for some can become a mind-numbing form of escapism.
And the parallel doesn't end with accessibility. The purity of crack and the fact that it's smoked rather than snorted means not only that the high is faster and more intense, but also that the feeling of euphoria is shorter-lived and the following depression and risk of an ensuing cycle of addiction all the stronger. Similarly, problem gamblers who regularly play slots and video poker appear to progress into pathological gambling much faster than those who only gamble at, say, horse racing, or other forms of gambling that do not have such an immediate rate of gratification.
The factors that influence what seems to be a strong relationship between gambling machines (particularly all forms of video gaming) and problem gambling are still not well understood, but anecdotal reports indicate that one risk factor may be the speed of play. In other words, the faster the wager-to-response time with a game, the more likely players may be to develop problems with that particular game. It's common for pathological gamblers to explain that it's the rush of being "in action" that's addictive, rather than the winning (which is often perceived as a good thing not in itself, but only in that it prolongs the ability to stay in action). Unlike betting on a football game where the outcome remains unknown for hours, or sitting at a full blackjack table where you have to wait your turn to play, slots and video poker rapidly and repeatedly deliver lots of little "highs," and that's what seems to get many people hooked.
There's also a physiological dimension to gambling addiction that's not fully understood, but which has been highlighted by the recent discovery of a seemingly bizarre correlation between people being treated for Parkinson's disease (and other conditions, including Restless Leg Syndrome) and various forms of compulsive behavior, including the sudden onset of gambling addiction in people who might never have gambled before in their lives. Parkinson's is a degenerative disorder marked by the death of particular brain cells; it’s primarily treated by drugs that restore or improve neurochemical signaling systems that are dependent on the neurotransmitter dopamine. Dopamine influences balance and movement, but also mood, behavior, and the sensation of reward. The disease is treated with dopamine agonists, which bind to the dopamine receptors in the brain, and it seems that it's the possible over-stimulation of this part of the brain that can lead to more impulsive behaviors and produce a feeling of euphoria from activities that might have been of no interest or even undesirable before, such as gambling or alcohol consumption.
