Instead of pushing a needle into your spine and drawing out fluid to test for Parkinson’s, doctors might be able to simply stick a needle in your arm and draw blood.

Researchers say a particular protein can tell them whether you have Parkinson’s disease or one of a group of “atypical parkinsonian disorders” that look like Parkinson’s but are not — such as multiple system atrophy. But according to their study in Neurology, testing the spinal fluid through a lumbar puncture is complicated and makes patients uneasy, “reducing the clinical usefulness of these [previous] findings.” They came up with a solution: a blood test.

Read: Device Can Smell Parkinson’s On Your Breath

Telling between Parkinson’s and atypical parkinsonism can be difficult because they often have overlapping symptoms, but properly diagnosing a patient is crucial for proper care. “Early and correct diagnosis is vital to identify the patients who would benefit from certain disease-specific treatments,” the study says. The biomarker doctors are now searching for in blood is called neurofilament light chain protein, and it appears in higher levels in people with one of the latter conditions.

“It is a component of nerve cells and can be detected in the blood stream and spinal fluid when nerve cells die,” the American Academy of Neurology explained in a statement.

The findings suggest its levels in the blood could be as accurate as its levels in spinal fluid in distinguishing between diseases, both in their early and later stages, after the researchers tested the blood of more than 500 people, including those with Parkinson’s, those with atypical parkinsonism, and healthy subjects.

“Lower concentrations of the nerve protein in the blood of those with Parkinson’s may be due to less damage to nerve fibers compared to those with atypical parkinsonism disorders,” study author Dr. Oskar Hansson, of Sweden’s Lund University, said in the AAN 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.”

The Neurology study notes that the neurofilament light chain protein also appears in higher levels in neurological conditions like stroke and traumatic brain injury and in other neurodegenerative conditions, such as ALS and dementia, so this could be a step toward better diagnosis of those ailments as well.

Source: Hansson O, Janelidze S, Hall S, et al. Blood-based NfL: A biomarker for differential diagnosis of parkinsonian disorder. Neurology. 2017.

See also:

Concussions Speed Up Brain Disease

How Fast Will Neurodegeneration Happen?