The Incentive-Sensitization Model of addiction asserts that chronic exposure to addictive drugs leads to sensitization, as reflected by increased dopamine release to drug-related cues. Increased dopamine release to amphetamine in problem gambling subjects vs. controls would be consistent with, although not confirmatory of, sensitization in problem gambling. This hypothesis was tested by assessing displacement of PHNO from D2/D3 receptors following oral amphetamine. PG subjects reported greater Desire to Gamble and less Confidence to Refrain from Gambling than controls before and after the slot machine game, and stronger subjective rewarding effects of the game than controls. Results show that problem gambling subjects do not differ from healthy individuals with respect to subcortical D2/D3 receptor levels. However, problem gambling subjects display significantly greater dopamine release from a standard stimulant challenge in brain regions involved in learning and execution of habitual behaviours.
