The Boston Globe has an article on the curious side effects of Requip, a drug manufactured by GlaxoSmithKline to treat Restless Leg Syndrome (RLS) and Parkinson’s Disease. Jonah Lehrer, an editor for SEED magazine, describes a high school English teacher who became a compulsive gambler after taking the drug.
“At first, the drug was like a miracle,” Klinestiver says. “All my movement problems just disappeared.”
Over time, however, Klinestiver needed higher and higher doses of the drug in order to ease her symptoms. That’s when she became a gambling addict. Although she’d never been interested in gambling before, Klinestiver was suddenly obsessed with slot machines. Every day, she would drive to the local dog racing track and play slots until 3:30 in the morning. After a year of addictive gambling, Klinestiver lost more than $200,000.
Ropinirole, the active ingredient in Requip, is an agonist for D2 and D3 dopamine receptors. Another D3 dopamine agonist called pramipexole is the active ingredient in Mirapex, another RLS/Parkinson’s medication manufactured by Pfizer. This medication has also been linked with compulsive behaviors such as gambling, overeating and heightened sex drive.
Lehrer’s article also provides a nice summary of Wolfram Schultz’s theory of dopamine and reward. Whereas dopamine was once thought to serve as the brain’s pleasure currency, researchers are now turning to a more complex picture in which dopamine signals expectations of pleasure. Altering dopaminergic signaling could induce gambling because this activity involves so much randomness that the brain is constantly surprised by the distribution of gains and losses.