Slot Drug Treatment for Pathological Gambling

From the green towers of Connecticut casinos to the popular television show Who Wants to Be a Millionaire, the culture of gambling is everywhere. Yet for a small proportion of people, this activity can become compulsive and potentially dangerous, with estimates suggesting the lifetime prevalence of pathological gambling (PG) at 0.2%-2%. Despite its ubiquity, little research has focused on understanding what drives this type of addictive behavior or how it might be treated. Now, a team of Yale researchers has found that blocking a dopamine receptor can reduce gambling-type behaviors in rats, hinting at a potential treatment for PG. fomototo login

Gambling is an intrinsically irrational activity, with the odds stacked against the player. As a result, the vast majority of people who engage in recreational gambling do not experience any negative consequences (Breen and Zimmerman, 2002; Harrigan, 2008). In contrast, a smaller but highly vulnerable group develops pathological gambling, which can have serious psychological and financial costs and can lead to other substance use disorders such as cocaine addiction.

In humans, studies suggest that the behavioral expression of reward expectancy is enhanced following a near-miss trial on a slot machine (Kassinove and Schare, 2001). This effect has been shown to increase motivation to continue gambling even after losing several rounds (Frank and Claus, 2006). Moreover, this response is modulated by dopamine via its D2 receptors.

To investigate whether the same mechanism that enhances this near-miss effect could also facilitate betting in a slot machine task, we administered the psychostimulant amphetamine or the D2 receptor antagonist haloperidol to a cohort of low and high impulsivity pathological gamblers. We found that amphetamine increased the probability of erroneous collect responses on loss trials but not on win trials, and that this drug effect was specific to the near-miss trial condition. In contrast, the D2 receptor antagonist reduced the number of erroneous collect responses in both low and high impulsivity pathological gamblers.

Amphetamine, like haloperidol, did not have consistent clinical benefits on actual gambling in either impulsivity groups, but modafinil did have significant effects. In particular, it reduced mean bet size in both HI and LI pathological gamblers, which may help to limit gambling-related losses. In addition, it improved the correlation between payoff and bet size on successive trials in a slot-machine task, an important feature of instrumental learning that is thought to underlie aspects of slot-machine gambling (Reid, 1986; Griffiths, 1991).

Together these data support the notion that the near-miss effect on a slot machine task heightens a gambler's incentive to continue gambling by increasing reward expectancy following a bad decision. This process is similar to the so-called 'incentive sensitization' that occurs in drug addiction, whereby environmental stimuli associated with drug-taking come to exert a strong incentive salience despite their dwindling pleasure value, promoting relapse and craving after periods of abstinence (Robinson and Berridge, 1993). Further, our findings demonstrate that a manipulation of dopamine can disrupt this incentive-sensitization process.