New research showing a strong link between Parkinson's disease and low levels of "bad" cholesterol are so worrying that U.S. researchers are launching a study to look into it.
The team at the University of North Carolina is planning clinical trials involving thousands of people to see whether statin drugs, which lower low density lipoprotein, or LDL, might actually cause Parkinson's in some people.
Other research has for several years suggested that people with abnormally low levels of LDL might be at higher risk of Parkinson's.
Xuemei Huang and colleagues found that patients with low levels of LDL cholesterol are at least three and a half times more likely to develop Parkinson's disease than those with higher LDL levels.
Writing in the journal Chemistry & Industry, they said they plan a bigger study of patients taking statins, the biggest-selling drugs in the world.
"I am very concerned, which is why I am planning a 16,000-patient prospective study to examine the possible role of statins," Huang said in a statement.
Prospective study means the patients are watched for a period of time to see what diseases or conditions develop.
Huang noted some other studies showed that people with APOE2, a gene that causes naturally low cholesterol, have a higher risk of Parkinson's. Another variation of the gene, APOE4, is associated with a risk of Alzheimer's disease.
British heart experts expressed alarm about the report and said heart patients should not stop taking statins.
"We are concerned that any suggestion of a link between statins and Parkinson's disease would unnecessarily scare the millions of people benefiting from statins in the U.K.," said Dr. Peter Weissberg, medical director of the British Heart Foundation.
"There is no evidence to suggest that statins cause Parkinson's disease. There is, however, overwhelming evidence that statins save lives by preventing heart attacks and strokes."
Parkinson's is an incurable brain illness that can paralyze patients. Patients may also have difficulty walking and talking and may shake uncontrollably at times.
According to the National Institutes of Health, Parkinson's affects at least 500,000 people in the United States alone. But heart disease affects 70 million Americans, according to the U.S. Centers for Disease Control and Prevention, and kills more than 910,000 each year.