By Amy Norton
Researchers said the finding doesn't prove statins are to blame. But, they added, the findings undercut the notion that statins might help protect against Parkinson's.
Where does that idea come from? Past research has shown that people with high cholesterol tend to have a lower risk of Parkinson's, explained Dr. Xuemei Huang, a professor of neurology at Penn State College of Medicine.
Since many of those people are treated with statins, that led to speculation that the drugs -- rather than high cholesterol itself -- might be protective.
But so far, studies have come to mixed conclusions, according to Huang. Some have tied statins to a lower Parkinson's risk, while others have found either no connection or an increased risk.
Enter the new study. Using medical records from over 4,600 U.S. adults -- with and without Parkinson's -- Huang's team found that statin users had a higher risk of being diagnosed with the neurological disease.
When the researchers dug deeper, they found that certain statins -- those that are fat-soluble, rather than water-soluble -- were tied to Parkinson's risk.
That's notable, according to Huang, because only fat-soluble statins can cross from the blood into the brain. Fat-soluble statins include drugs such as atorvastatin (Lipitor), fluvastatin (Lescol) and simvastatin (Zocor).
"This doesn't mean that statins are causing Parkinson's," Huang noted.
But, Huang said, the findings raise an important question: Could some statins hasten the progression of someone who is in the early, symptom-free stages of Parkinson's?
The study uncovered hints that could be the case, according to Huang. People on statins faced an increased risk of a Parkinson's diagnosis within 2.5 years of starting the drugs, but those odds dipped thereafter.
A neurologist who was not involved in the study said the connection between statins and Parkinson's has been controversial.
"We can't really make any conclusions," said Dr. Olga Waln, who specializes in treating movement disorders at Houston Methodist, in Texas.
"I would not encourage anyone to stop taking a statin that they're using to prevent cardiovascular disease," Waln said. "I also wouldn't encourage anyone to use a statin to help prevent Parkinson's."
Parkinson's is a movement disorder that affects nearly 1 million people in the United States alone, according to the Parkinson's Disease Foundation.
The root cause is unclear, but as the disease progresses, the brain loses cells that produce dopamine -- a chemical that regulates movement. As a result, people suffer symptoms such as tremors, stiff limbs, and balance and coordination problems that gradually worsen over time.
High cholesterol has been tied to a reduced risk of Parkinson's, but no one yet knows why, Huang said.
The current findings are based on records from a large health insurance claims database. Huang's team focused on more than 2,300 patients recently diagnosed with Parkinson's; they compared each with a patient the same age and gender who didn't have the disorder.
Overall, the study found, there was a connection between past statin use and a higher likelihood of being diagnosed with Parkinson's. Specifically, people who'd used a fat-soluble statin had 58 percent higher odds, versus people who'd never used a statin.
Waln said the findings on fat-soluble statins are "very interesting," since the drugs can cross the blood-brain barrier.
"This warrants further investigation," she said.
What's needed, according to Waln, are "prospective" studies -- which follow a group of people over time, rather than reviewing medical records.
Huang said she could only speculate as to how statins might hasten Parkinson's progression -- if that is, in fact, the case. But she noted that statins may lower not only cholesterol, but also a compound called coenzyme Q10. This compound produces energy for cells, and there is evidence it may help protect nerve cells.
For now, Huang said, "Heart disease and stroke prevention are the priority."
So, people at increased risk of those common, potentially deadly diseases should stick with their statins, she said.
However, Huang added, people who worry about Parkinson's because of a family history might want to ask their doctor some questions.
"Let's say your mom and grandmother had Parkinson's, but you don't have a family history of heart attack or stroke," Huang said. "You might ask more questions about the benefits and risks of taking a statin."
The findings were published in June issue of the journal Movement Disorders.