Dopamine spikes from unpredictable events. “Games of chance” are just such events, so it isn’t surprising that gambling boosts dopamine the same way drugs do.1

Dr. David Zald, at Vanderbilt University, scanned subjects’ brains while playing a computer game simulating gambling. In some cases, subjects were guaranteed to win with every fourth play; for others, winning was unpredictable. Dr. Zald found large increases in dopamine activity only when winning was  unexpected.2

The inherent unpredictability involved in gambling sets the stage for the brain to experience repeated dopamine highs, which can be addictive.3

fMRIs of compulsive slot-machine players showed they had less blood flow to their Limbic “Reward” systems compared to a control group, indicating they had more sluggish reward networks. They compensate by boosting dopamine through gambling.4 Similarly, in gambling addicts the striatum, a key part of the Reward System, was less active on winning than in a control group, as if the addicts experienced winning as no reward at all, compared to the control group.5

Addicted gamblers also experience withdrawal when they stop. Howard Shaffer, director of Cambridge Health Alliance’s division on addictions, says: “When addicted gamblers cut back, they experience withdrawal symptoms that look like stimulant withdrawal. They get depressed, they’re irritable and they have trouble sleeping. And if they gamble again, they can make the symptoms go away for the short run.”6

Incredibly, medications which boost dopamine can cause compulsive gambling. Parkinson’s disease results from a severe dopamine shortage caused by the death of dopamine-producing cells in mid-brain structures that are involved in bodily movement. Some Parkinson’s disease patients who received drug therapy to increase their dopamine levels developed gambling problems.7 An August 2003 study published in Neurology, looked at 1,884 patients who were treated in a single year with dopamine-boosting therapy. Nine of the patients were found to have gambling problems presenting financial hardship. The overall rate of compulsive gambling was 0.05 percent. However, of the 529 taking the Parkinson’s drug implicated in gambling problems, thirty times as many (1.5 percent) developed gambling problems.8

One patient, a 52-year-old who had only occasionally gambled before taking the Parkinson’s medication, became a compulsive player, losing $100,000 in casinos. A month after discontinuing the drug, his gambling stopped and his wife said she had her “old husband back.”9 Another patient who developed a compulsion to play slot machines said he saw a report on the strange side-effect of the medication on the Internet and had a “eureka!” moment. His desire to gamble vanished three days after he stopped taking the drug.10

A February 2007 study found that younger people who developed Parkinson’s and who were classified psychologically as “novelty-seekers,” or had a family history of alcoholism, were more likely to develop gambling problems from taking Parkinson’s drugs than others. The research found the likelihood of a gambling problem on taking the drugs was not related to dose, suggesting it resulted from an underlying genetic trait.11

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1. Hijacking the Brain Circuits With Nickel Slot Machines, New York Times, February 19, 2002.
2. What’s the Lure of the Edge? It’s All In Their Heads, New York Times, June 20, 2005.
3. Brain Experts Now Follow the Money, New York Times, June 17, 2003.4. Random Samples, Science Magazine, January 21, 2005.
5. An Anti-Addiction Pill? New York Times Magazine, June 25, 2006.
6. An Anti-Addiction Pill? New York Times Magazine, June 25, 2006.
7. Parkinson’s Drug May Trigger Compulsions, Wall Street Journal, July 12, 2005.
8. Studies Shed Light On Parkinson’s Drugs and Gambling, Las Vegas Press, April 3, 2006.
9. Parkinson’s Drug May Trigger Compulsions, Wall Street Journal, July 12, 2005.
10. Parkinson’s Treatment and the Urge to Gamble, New York Times, July 12, 2005.
11. Parkinson’s Disease Medications and Characteristics of Increased Risk For Compulsive Gambling Linked,, February 15, 2007.


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