Typically, doctors rely on a spinal fluid test to differentiate between patients with Parkinson’s disease and those with an atypical parkinsonism disorder (APD). However, a blood test may be just as accurate when determining whether a patient’s symptoms are caused by Parkinson’s or an APD, according to a study published by the American Academy of Neurology.
Atypical parkinsonism disorders like multiple system atrophy, corticobasal degeneration, and progressive supranuclear palsy are often hard to diagnose, as their symptoms are similar to those of Parkinson’s disease. However, it is crucial to receive a proper diagnosis early for the best treatment, not to mention the fact that treatment methods differ between Parkinson’s and the ADPs. Because spinal fluid tests are invasive and painful, they are not as simple as a blood test, so diagnosing ADPs is more complicated.
However, study author Oskar Hansson found “that concentrations of a nerve protein in the blood can discriminate between these diseases as accurately as concentrations of that same protein in spinal fluid.”
The study looked at 504 people in three different study groups. Two groups, one in England and one in Sweden, were comprised of healthy people and people who have had Parkinson’s or APDs for four to six years. The third study group was full of people who had one of the diseases for three years or less. Hansson found that the blood test was as accurate as the spinal fluid test—it was able to diagnose if someone had an APD or Parkinson’s in both early-stage patients and those who had the condition for longer than four or more years.
In patients who had Parkinson’s, the protein levels were around 10 picograms per milliliter, whereas those with an APD had levels of 20 picograms or higher. Hansson believes that the “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.”
The new study will pave the way for more accurate diagnoses in patients suspected of having Parkinson’s or an APD. The APDs progress faster and have a higher mortality rate than Parkinson’s, so identifying them quickly is extremely important. One drawback of the nerve protein test is that it can only tell if a patient has Parkinson’s or an APD—it is unable to specify which APD the patient has. Thankfully, it is easier to differentiate between the different APDs based on other symptoms.