Metabolomic Profiles Indicate Early Parkinson's disease

A test that profiles molecular biomarkers in blood could become the first accurate diagnostic test for Parkinson's disease.

According to the U.S. National Parkinson Foundation, an estimated 1.5 million Americans suffer from Parkinson's and 60,000 new cases of that neurodegenerative disease are diagnosed each year. Currently, diagnosis depends on the patient's clinical symptoms, and screens are at best are only 90% accurate. This means that at least 10% of patients with symptoms resembling Parkinson's disease but suffering from other conditions are not receiving appropriate treatment.

Scientists from the Weill Cornell Medical College (New York, NY, USA) and colleagues studied patients with Parkinson's and found that they exhibit changes in dozens of small molecules in serum. These "metabolomic” alterations form a unique pattern in people with Parkinson's disease. A report of the study appeared in the February 2008, issue of the journal Brain.

The team compared blood samples from 66 patients with Parkinson's disease against 25 healthy controls (most of whom were the patients' spouses). The metabolomic analysis included over 2,000 small molecules found in the blood.

"We discovered a clear differentiation between the metabolomic profiles of the Parkinson's disease patients versus those of the controls,” noted study senior author Dr. M. Flint Beal, chairman of neurology at Weill Cornell Medical College, "No one molecule was definitive, but a pattern of about 160 compounds emerged that was highly specific to Parkinson's patients.”

The significance of many individual compounds to the disease remains unknown and it will be the focus of future study. However, changes in a few well-known metabolites linked to oxidative stress were clearly linked to Parkinson's disease. These included low levels of the antioxidant uric acid; an increase in blood levels of another antioxidant, glutathione; and increased levels of a marker for oxidative damage called 8-hydroxydeoxyguanosine (8-OHdG).

"Together, these and other compounds were arranged into a metabolomic pattern that identified Parkinson's disease with great accuracy,” said Dr. Beal. He stressed that more work needs to be done to validate the finding, and a test that might be used routinely by doctors is still a few years away.

"We are currently enlarging the sample size and studying people at serial intervals, to see if this test might also serve as a benchmark for disease progression,” Dr. Beal added. "We are also looking at people who carry a gene for a familial form of Parkinson's, but who do not have the illness now. We hope to track them over time to see if this metabolomic profile is predictive of disease onset.”

If those data prove as promising as this early trial, an early-detection blood test for Parkinson's disease could someday become a reality. According to Dr. Beal, "That would be a big step forward for both the treatment and the study of this devastating illness.”


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Weill Cornell Medical College