A New Way to Test for Parkinson’s Disease

Why it’s Difficult to Get a Clear Diagnosis Early

Parkinson's disease is a degenerative disorder of the nervous system that affects movement, which currently has no cure. However, early diagnosis and treatment can significantly improve a patient's quality of life through better symptom management, more effective treatment options, and improved emotional wellbeing.

Unfortunately, getting an early diagnosis of Parkinson's disease can be challenging and not always straightforward. Here are some reasons why:

Similar symptoms to other conditions: The symptoms of Parkinson's disease can be similar to those of other conditions, such as essential tremor or multiple system atrophy. This can make it difficult for doctors to determine the underlying cause of the symptoms in some cases. Patients may be initially diagnosed with another condition, such as essential tremor, only to have their diagnosis changed later on.

Diagnostic dependence on motor symptoms: Currently the diagnosis for Parkinson's disease is based on a patient's medical history, symptoms, and neurological examination. Before motor symptoms are seen, it can be difficult for doctors to quickly diagnose the condition.

Early symptoms can be subtle: Parkinson's disease typically develops slowly over time, and early symptoms can be subtle and easily overlooked, such as a loss of smell. Patients may initially dismiss motor symptoms such as tremors or stiffness as signs of aging or stress, delaying diagnosis and treatment.

Variability of symptoms: The symptoms of Parkinson's disease can vary widely from patient to patient, both in terms of severity and type. This variability can make it challenging for doctors to recognize the disease and distinguish it from other conditions.

However, experts have recently revealed a new way to test for Parkinson’s disease before motor symptoms become apparent. Could this be a game changer for those seeking a clearer diagnosis of Parkinson’s at an earlier stage? Let’s dive in.

How the New PD Test Works

New research has confirmed that a lab test analyzing cerebrospinal fluid (CSF) for a protein called alpha-synuclein can accurately detect Parkinson’s disease, even in people without typical symptoms such as tremors.

Published in Lancet Neurology in May 2023, the study involved over 1,100 participants and found that the lab test accurately identified abnormal protein accumulations in 88% of all participants with Parkinson’s disease. This testing method, known as alpha-synuclein seed amplification assays (αSyn-SAAs) is relatively simple, requiring only a small cerebrospinal fluid sample.

Results from this new test suggest that detection of alpha-synuclein in cerebrospinal fluid may be positive earlier than brain imaging scan techniques that assess dopamine-containing neurons. In other words, it may offer hope for earlier detection and therapeutic intervention for Parkinson's disease.

What Is Alpha-Synuclein?

Why is this protein, alpha-synuclein (α-Syn), so important in the context of this test?

Because it’s a hallmark of Parkinson’s disease.

Under normal conditions, α-Syn is found in the brain and is thought to play a role in the regulation of dopamine release. But in Parkinson’s disease, abnormal aggregation – or clumping together – of α-Syn leads to the formation of Lewy bodies and Lewy neurites.

The α-Syn aggregates can lead to the death of dopamine-producing neurons, resulting in the motor symptoms of PD. Different forms of α-Syn have been identified, including monomeric, oligomeric, and fibrillar forms. Oligomeric forms of α-Syn are particularly toxic to neurons and are thought to play a key role in the development of PD.

Scientists have also found aggregated α-Syn in the esophagus, stomach, and intestines of some PD patients. Additional evidence suggests that α-Syn aggregates can travel bidirectionally via the vagus nerve, part of the gut-brain axis that connects the brain to the peripheral nervous system. While still controversial, some scientists believe that the development of Parkinson's disease for some people begins in the gut or other areas of the peripheral nervous system.

Intriguingly, α-Syn can be detected using nasal swab testing as well as skin tests of PD patients. This raises the possibility that future testing for PD using this biomarker may not require collection of cerebrospinal fluid via an invasive procedure like a lumbar puncture/spinal tap.