Researchers have now linked gambling addiction, compulsive shopping, sexual addiction and various other impulse control disorders to medications prescribed for Parkinson\u2019s disease and restless leg syndrome. The evidence for this relationship was presented in the October edition of the journal JAMA Internal Medicine, and the depth of the connection runs far deeper than anyone imagined. All pharmaceutical drugs have side effects, some of them extreme or dangerous. While it is rare for prescription medications to cause new forms of mental illness to materialize as if from thin air, some drugs do possess the ability to affect the human brain quite profoundly, regardless of past mental health history. This includes medications called dopamine receptor agonists. These chemicals provide a therapeutic effect by replicating the actions of the neurotransmitter dopamine when shortages exist in the brain. Dopamine helps to regulate movement and emotional response and is strongly associated with feelings of pleasure. In its absence, important neural pathways can become severely compromised. Parkinson\u2019s disease is a degenerative condition that kills off the brain cells that manufacture this vital neurotransmitter, slowly starving dopamine receptors to death. By stepping in to bind with these neglected neurological outposts, dopamine receptor agonists can sometimes restore lost functioning in the brains of Parkinson\u2019s patients. Unfortunately, just as shortages of dopamine can cause disturbing effects, so too can a sudden influx of chemicals that mimic its actions. It appears this sets up a dynamic that can eventually cause impulse control disorders like gambling addiction to manifest. Like Two Peas in a Pod: Adverse Drug Effects and Impulse Control Disorders Analyzing adverse drug reaction reports collected by the U.S. Food and Drug Administration, researchers associated with the Safe Medication Practices in Alexandria, Virginia, Harvard Medical School and the McLaughlin Centre for Population Health Risk Assessment in Ottawa, Ontario, found 1,580 cases of compulsive or addictive behavior blamed on the consumption of pharmaceuticals. Poring over the data, the scientists were alarmed to discover that 710 of the people reporting adverse effects (45 percent of the total) had taken dopamine receptor agonists. The drugs were typically taken for Parkinson\u2019s disease, but occasionally for restless leg syndrome, which also responds to these medications. Of this group, 410 individuals had taken a drug known called pramipexole, which is sold under the brand names Mirapex, Mirapexin and Sifrol. Coming in second with 188 adverse reactions was the dopamine receptor agonist ropinirole, which is marketed as Requip, Repreve, Ronirol or Adartrel. Next on the list with 37 hits was the drug aripiprazole (sold as Abilify), an antipsychotic listed as a partial agonist for dopamine receptors. Significantly, each of these drugs is known to specifically target one receptor subtype known as D3. This neurochemical docking station has been researched frequently and tied to drug addiction in other studies. Illicit drugs tend to play havoc with the body\u2019s dopamine manufacturing system, leading to boom-or-bust cycles of over- and underproduction that ultimately create cravings and dependency. An overstimulated D3 receptor starts the process by intensifying the experience of pleasure associated with drug consumption, and there is every reason to believe that it does the same thing in cases where impulse control is lost following the use of certain pharmaceutical medications. A person with a hyper-activated D3 receptor may repeat pleasurable behaviors continuously until his or her actions become non-voluntary and entirely compulsive. As they reanimate the body\u2019s atrophied dopamine production system, Parkinson\u2019s drugs recreate the actions of stimulants like cocaine and methamphetamine. Unlike these illicit substances, however, these medications are not addictive. They only lay the groundwork for the invasion of true addictive\/compulsive disorders, such as uncontrollable shopping or compulsive gambling. Gambling on Pharmaceuticals Among the original group of 1,580 who suffered impulse control problems after consuming pharmaceuticals, almost 40 percent developed a serious and life-disrupting gambling disorder. Another 12 percent increased their gambling activity substantially without falling victim to addiction. This means more than half the people filing relevant drug reaction complaints with the FDA were infected by a sudden urge to gamble. When a pharmaceutical side effect is this common, doctors prescribing these drugs have a responsibility to do extensive follow-ups with their patients to make sure they aren\u2019t having difficulties controlling their gambling behavior\u2014or any other type of compulsive behavior, for that matter. Thanks to the publicity this JAMA Internal Medicine article is generating, it is safe to assume this will happen more often in the future.