Despite being well-known in the medical arena, diagnosing Parkinson’s disease correctly can be quite challenging since symptoms of this disease are often confused with other similar neurological diseases. Now, researchers from the Lund University in Sweden have developed a simple blood test that can differentiate true Parkinson’s disorder (PD) from atypical parkinsonian disorders (APD).
Parkinson’s disease is characterized by progressive neurodegeneration, causing severe impairments in movement. Most often, the disease is associated with uncontrolled tremors; however, patients can also suffer from muscle stiffness and the difficulty moving or speaking. Because the disease is progressive, symptoms worsen over time. There are no cures, but medications can improve some of the symptoms, especially if the disease is diagnosed at early stages.
Unfortunately, there are other neurological disorders that mimic the symptoms of Parkinson’s disease, making it difficult for physicians to diagnose by examination alone. "This can be very challenging, especially during the early stages of the diseases and if the responsible doctor is not a neurologist specialized in movement disorders," said Dr. Oskar Hansson, an associate professor at Lund University in Sweden, and the study’s lead author.
Hansson stresses the importance of distinguishing Parkinson’s disease from atypical parkinsonian disorders, as the wrong diagnosis could delay treatment and worsen the outcome. In particular, people with APD "usually have a much worse prognosis, with faster disease progression, (with) more disabling symptoms,” Hansson said. Furthermore, people with APD don’t respond to dopamine-targeted therapies usually prescribed for Parkinson’s disease. Thus, correct diagnosis is key.
The new blood test relies on detection of a biomarker known as neurofilament light chain (NfL). This protein is shed into the spinal fluid when nerve cells die. Hansson and colleagues investigated whether NfL can also be picked up in blood, samples which would be much less invasive to acquire as compared to a spinal tap for spinal fluid.
In a cohort of 244 people, some with Parkinson’s disease, some with atypical parkinsonian disorder, and some healthy controls, the team found differences in the levels of NfL in blood. Particularly, people with atypical parkinsonian disorder had the highest level of NfL, followed by people with Parkinson’s disease. The difference is enough, the team says, to help doctors distinguish between the two diseases with higher confidence.
Hansson and his colleages believe the blood test will soon be "in the diagnostic work-up of patients with parkinsonism by most doctors who are not very specialized with these movement disorders." As misdiagnosis for this disease may be extremely costly for patients and family members, he hopes the test will improve diagnosis as well as outcome for the patients.
Additional sources: CNN