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Blood Test Shows Ability to Differentiate Parkinson's From Similar Diseases

NEW YORK (360Dx) – A new blood test can be as accurate as a spinal fluid test in determining whether symptoms are caused by Parkinson's disease or other similar disorders, a study reported on Wednesday.

Researchers from London and Sweden investigated 504 people and found that a nerve protein called neurofilament light chain protein in blood can discriminate between Parkinson's and atypical parkinsonian disorders (APD) as accurately as concentrations of the same protein in spinal fluid.

"Our findings are exciting because when Parkinson's or an atypical parkinsonism disorder is suspected, one simple blood test will help a physician to give their patient a more accurate diagnosis," Oskar Hansson of Lund University and one of the study's authors, said in a statement. "These atypical parkinsonism disorders are rare, but they generally progress much faster and are more likely to be the cause of death than Parkinson's disease, so it's important for patients and their families to receive the best care possible and to plan for their future needs."

APDs include multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration. In the early stages of disease, differentiating Parkinson's from APDs is challenging because symptoms overlap. Yet early accurate diagnosis is important because expectations concerning progression and the potential benefit from different treatment differ between Parkinson's and APD.

For the research described in Neurology, the researchers looked at three patient groups. Two groups, one in London and one in Sweden, comprised healthy people and people who had been living with Parkinson's or APDs for an average of four to six years.

A third group of people had been living with the diseases for up to three years. In total, 244 people had Parkinson's, 88 had multiple system dystrophy, 70 had progressive supranuclear palsy, 23 had corticobasal degeneration, and 79 were healthy and were used as controls.

Hansson and his colleagues found that the blood test was as accurate as spinal fluid test at diagnosing whether a patient had Parkinson's or an APD, both in in early stage disease and in later disease. They found that the levels of neurofilament light chain protein were higher in people with APDs, while people who had Parkinson's or who were healthy had lower levels of the protein.

In the Swedish group, the average protein level was about 10 picograms per milliliter. Patients with multiple system atrophy averaged about 20 pg/ml, while patients with progressive supranuclear palsy averaged about 25 pg/ml. Those with corticobasal degeneration averaged around 27 pg/ml.

The blood test had a sensitivity of 82 percent and a specificity of 91 percent for the Swedish group. For those in the early stages of disease, sensitivity was 70 percent while specificity was 80 percent.

The researchers said that a limitation of the test is that it cannot distinguish between different APDs, though doctors can look for other symptoms in order to do so.