Is there a blood test for Parkinson's disease?

3/10/24, 7 mins reading

The simple answer is: no so far.

Parkinson’s disease diagnosis

The diagnosis of Parkinson’s disease has been heavily relying on clinical symptoms especially motor symptoms in conjunction with physical examination, image testing, family history, and other factors. There are no blood screenings or tests at the moment that allow doctors to make a definitive diagnosis.

Why blood tests are important?

There are two reasons why blood tests are so important. 1) First of all, a blood test, if possible, would provide clinicians with a more accurate diagnosis. Currently, a clinical diagnosis based on symptoms is only 80% accurate. A definitive diagnosis of PD relies on a post-mortem brain examination. Blood tests would be helpful to minimize misdiagnosis from other disorders such as Lewis body dementia and other Parkinsonian disorders. 2) Secondly, accurate blood tests would allow clinicians to diagnose, identify, and treat Parkinson’s disorder patients in their early stages or before symptom presentation, which is particularly crucial since there is no cure for PD, and early intervention or treatments will tremendously improve the living standard and extend the life expectancy for PD patients.

Updates on blood testing

There have been studies that tried to find biomarkers from CSF, serum, genetics, and imaging. One study has reviewed and laid out the items that are currently being investigated around the world. Here in this blog, we will be discussing and focusing on blood tests in serum and genetics.

• Serum In addition, a group from Oxford University has conducted another study and found that serum L1CAM-positive extracellular vesicle (L1EV)-associated α-synuclein can be used as a biomarker to identify potential Parkinson’s disease patients with an 80% accuracy. Again, the study was a cross-section, and further investigations from other populations and communities are needed. The serum items that are currently being investigated as biomarkers include Alpha-synuclein, Neurofilament light chain, Glial fibrillary acidic protein, Amyloid and tau, General inflammatory markers, MiRNAs and other smnRNAs.

• Genetics A recent study conducted by a group from Duke University has identified a buildup of mitochondrial DNA(mtDNA) damage in PD neuronal culture and animal models, as well as in human PD postmortem brain tissue using polymerase chain reaction(PCR). The study also found that the level of mtDNA in peripheral blood is increased in those with PD-associated leucine-rich repeat kinase 2 (LRRK2) G2019S mutation compared to the age-matched control group. This mtDNA damage could be potentially used as a biomarker in the future. Although the findings from this study appear promising, the mitochondrial DNA damage is not unique to Parkinson’s disease and further studies are needed to verify its effect in a more diverse and larger population. Genes under investigation currently as biomarkers include PARK, GBA1 and MAPT, DJ-1, Leucine-rich repeat kinase 2 (LRRK2), GBA, SNCA-AS1, APOE, BIN1, and TMEM175

We will continue to provide updates on this subject.