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Martin Zack, Centre for Addiction and Mental Health
Constantine Poulos, Centre for Addiction and Mental Health
Categories: · Neurological/biological factors · Treatment ·
| Type of Award | Amount Approved | Project Status |
|---|---|---|
| Level III | $162,636.00 | Completed |
ABSTRACT
In a previous study we used the psychostimulant drug, d-amphetamine as a prime in an investigation of problem gamblers. This study provided supportive evidence that gambling activity involves psychostimulant-like dopaminergic effects in problem gamblers. In the current study, we sought to further isolate the role of dopamine in problem gambling (PG) by using a low dose of the selective dopamine antagonist, haloperidol. The results, while preliminary, are remarkable. In a laboratory-based study, haloperidol significantly increased the pleasurable reinforcing effects of an actual slot machine gambling episode and the motivation to continue gambling in problem gamblers (N = 18). In other words, decreased dopamine transmission achieved by partial receptor blockade increases the abuse liability of gambling activity in problem gamblers. Taken together with our previous findings, the evidence implies that gambling activity could serve to restore a deficit in dopamine function in some problem gamblers.
Several studies have shown that Impulsivity and Boredom Proneness are separate neurocognitive dimensions and that each constitutes a major risk factor for PG. Recent research using the glutamate enhancer, modafinil, indicates a beneficial effect of the drug on each of these critical dimensions. Through a neurochemical cascade, modafinil has been found to increase tonic dopamine function without the pronounced spike of dopamine in limbic structures that is characteristic of conventional psychostimulant drugs. As such, modafinil has been shown to have minimal abuse liability.
This study investigated the effects of 200-mg acute oral modafinil in a placebo-controlled, double-blind fully counterbalanced design. All subjects were problem gamblers, as defined by scores > 5 on the SOGS and DSM-IV checklist for PG. They were stratified into High vs. Low levels of Impulsivity and Boredom Proneness based on previous published means for problem gamblers.
Each subject underwent two procedurally identical test sessions (placebo vs. modafinil). On each session, subjects engaged in an actual gambling episode on a slot machine game in a mock-bar laboratory. Bet size per trial over the course of the gambling episode provided an ecologically valid measure of gambling intensity.
Modified visual analogue scales (VAS) assessed the pleasurable reinforcing effects of the gambling episode and motivation to gamble before and after the game. The Lexical Salience Task assessed automatically activated gambling-related cognitions. The ARCI, a standard measure of subjective drug effects, assessed the effects of modafinil throughout the test session. The Stop Signal Task provided a behavioral index of state impulsivity. A modified VAS assessed ratings of current boredom proneness during the test sessions.
KNOWLEDGE TRANSLATION ACTIVITIES BY THE AUTHORS ASSOCIATED WITH THIS RESEARCH:
Zack, M., & Poulos, C.X. (2009). Parallel roles for dopamine in pathological gambling and psychostimulant addiction. Current Drug Abuse Reviews, 2, 11-25.
Zack, M., & Poulos, C.X. (2008). Effects of the atypical stimulant modafinil on a brief gambling episode in pathological gamblers with high versus low impulsivity. Journal of Psychopharmacology Jun 26. [Epub ahead of print]
Attached presentations:
1. “Medications” - given at the symposium on clinical management of PG, sponsored by the CAMH Problem Gambling Project, Jan/09), and subsequently at Dalhousie, Department of Psychology (Apr 09).
2. “Modafinil” - given at the Sleep Disorders Unit of the Toronto Western Hospital (Jan/09)
| File Name | Type | Size |
|---|---|---|
| Full Report | 246kb | |
| Research Summary | 41kb | |
| French Language | 52kb | |
| Presentation | 2Mb | |
| Presentation | 276kb |