First discovered by Dr. James Parkinson, Parkinson's disease results from a dopamine depletion from a destruction of specific cells in the brain. Patients with Parkinson's disease have problems moving, with symptoms that include tremors, a stooped position, muscle aches, rigid muscles, shuffling movement and problems walking. A lack of facial expression can also occur. MedlinePlus, a service of the US National Library of Medicine and the National Institutes of Health, explains that the disease can leave patients disabled.
One treatment option for Parkinson's disease is medication, though the beneficial effects can lessen over time. Some of the medications for Parkinson's disease work by increasing dopamine levels in the brain, which improve symptoms. The MayoClinic.com points out that levodopa, a precursor to dopamine, is the most effective Parkinson's disease medication. Dopamine is too large to cross the blood-brain-barrier, which prevents material from crossing over into the brain. But levadopa is a small enough molecule to cross over. Once in the brain, levadopa converts to dopamine. Doctors may combine levodopa with carbidopa, a drug that prevents levadopa from converting into dopamine before crossing the blood-brain-barrier. Another dopamine medication for Parkinson's disease is dopamine agonists, like pramipexole and ropinirole. Dopamine agonists mimic the effects of dopamine, which also reduce Parkinson's disease symptoms.
But while these dopamine-affecting drugs can help with the symptoms of Parkinson's disease, they can cause serious side effects. In a new study published in the Archives of Neurology, researchers found that these medications can increase compulsive behaviors in Parkinson's disease patients. The study included 3,090 patients with Parkinson's disease. HealthDay News reported that 13.6 percent of patients had impulse control disorders. Of the Parkinson's disease patients with compulsive behaviors, 5.7 percent of patients compulsively shopped; 5 percent of patients gambled; 4.3 percent of patients binge ate; 3.5 percent of patients had compulsive sexual behaviors; and about 4 percent of patients had two or more of these compulsive behaviors.
The researchers pointed out that certain factors increase patients' risk of having compulsive behaviors. For example, the compulsive behaviors are more common in dopamine agonist users. Patients who take levadopa for their symptoms may also display problems controlling their behaviors. Other risk factors identified during the study include cigarette use, living in the U.S., a family history of gambling, and being younger or unmarried. The authors of the study noted that larger studies on the link between dopamine agonists and compulsive behaviors are needed.