Early Detection: How a Biomarker Could Redefine Parkinson's Disease
Written by Keerti Varada
Edited by Kriti Iyer
April 5, 2024
Edited by Kriti Iyer
April 5, 2024
Research
Parkinson’s disease is a long-term neurological disorder that inhibits movement. This disorder involves a progressive loss of neurons that produce dopamine, a chemical messenger, in regions of the brain. Reduced dopamine levels affect motor functions, including balance and coordination. Related disorders, termed “Parkinsonian disorders,” share similar conditions, but may differ in their causes. Parkinsonian disorders are degenerative; they also tend to have a gradual onset, and symptoms differ from person to person, making these disorders particularly hard to diagnose.
Currently, Parkinsonian disorders are diagnosed based on clinical criteria, which can often only detect the disorder at an advanced state. However, scientists at Lund University in Sweden have recently discovered that the levels of DOPA decarboxylase (DDC) can be used to identify Parkinsonian disorders. DOPA decarboxylase is a specific protein that helps produce dopamine in the body. This correlation was demonstrated in a study involving 682 patients diagnosed with Parkinson’s disease, multiple system atrophy, Lewy body dementia, and supranuclear palsy, all of which are classified as Parkinsonian diseases. These individuals tended to have higher levels of DOPA decarboxylase.
DCC is used here as a biomarker, an indicator that can be measured for medical professionals to diagnose specific diseases. DDC is an enzyme involved in the nervous system, which consists mostly of the brain, spinal cord, and nerves, and it converts a different enzyme, L-DOPA, into dopamine. As a result, mutations in the gene that produces DDC will negatively affect the levels of chemical messengers in the body, like serotonin and dopamine. Specifically, the scientists conducting this study found a correlation concerning the levels of DDC in the cerebrospinal fluid (CSF) of the body, which surrounds the brain and spinal cord, as well as the bloodstream.
DDC levels were higher in the CSF of patients with Parkinsonian symptoms. DDC in the CSF is known as peripheral DDC, as it leaks out from the brain. It is likely that in individuals with Parkinsonian diseases, DDC leaks out from the brain into peripheral regions, such as the CSF, when the brain detects a lack of dopamine.
The study found that individuals who were taking Levodopa for their disorder also tended to have elevated levels of DDC. Levodopa is a medication that is often used as treatment for Parkinson’s disease; it contains L-DOPA, which the body can convert into dopamine, relieving symptoms. It is hypothesized that the reason for an increase of DDC production in patients taking Levodopa is due to the body recognizing the additional L-DOPA and trying to speed up the conversion of L-DOPA to dopamine by producing more of the enzyme.
Furthermore, high levels of this enzyme were notably observed in patients that had early, presymptomatic stages of Lewy body dementia. Unlike previous methods of diagnosing Parkinson’s, DDC levels can be used to detect the disorder earlier, even before an individual experiences enduring symptoms. As a result, there is hope that DOPA decarboxylase could potentially be used to identify and diagnose individuals with Parkisonian disorders before their condition becomes advanced.