Strangely enough, I first heard about this last night on a teaser for Fox News at 10, DC's most ridiculously sensationalist news program. But hey! It's actually interesting: a study has found that some drugs prescribed for Parkinson's Disease can prompt compulsive gambling behavior; some subjects also indulged excessively in alcohol, sex and food.

It's too early to say for sure, but there's an obvious explanation that presents itself. Parkinson's is primarily a deficit in the dopamine-related systems in the brain. Dopamine is important for motor function, but it's best known as the key neurotransmitter in the brain's system of rewards. The proverbial rats that'll push an electrode-stimulating button until they starve to death? That electrode is wired into their dopaminergic neurons in the nucleus accumbens. And cocaine and methamphetamine are dopamine agonists (meaning they increase the system's activity). It's the feel good neurotransmitter! (I guess that'd make serotonin the feel-good-about-yourself neurotransmitter.)

So why do these drugs induce excessive gambling instead of excessive consumption of the drug? A strong possibility is that their mechanism of action relies on potentiating dopaminergic activity. The drug doesn't replace dopamine, but it makes it more effective. So when patients participate in activities that naturally light up their brains' reward centers, they get a bigger kick than they normally would. Let's just hope the folks conducting the study keep their subjects away from the crack.