Scientists find key biomarker of Parkinson's disease in the retina

Jun 8 2018

A research involving scientists from the University of Alicante and the United States notes that the accumulation of a protein known as alpha-synuclein in the retina is a key Parkinson's biomarker that could help detect the degree of severity of the disease.

The work has been published this month in Movement Disorders, a prestigious a worldwide journal in the field of clinical neurology edited by the International Association of Parkinson's and Movement Disorders, and is part of a broader scientific project funded by the Michael J. Fox Foundation.

The main researcher of this project, which started last February is Dr. Nicolás Cuenca, coordinator of the research group Visual System Neurobiology and Neurodegenerative Retinal Diseases Therapy at the University of Alicante. The main researcher of this project, which started last February, is Dr. Nicolas Cuenca, coordinator of the research group Visual System Neurobiology and Neurodegenerative Retinal Diseases Therapy at the University of Alicante (UA)

This worldwide novel work has been conducted with retinas from deceased Parkinson's patients, donated to Sun Banner, a center dedicated to the study of this disease and Alzheimer's, and sent to the UA to be studied by Cuenca and also by the predoctoral researcher at the University of Alicante Isabel Ortuño Lizarán.

Cuenca and Ortuño Lizarán explain, in an interview with EFE, that they have studied in detail the alpha-synuclein protein as one of the main pathological marks that are usually analyzed to determine Parkinson's disease, a neurodegenerative disease that affects seven and ten million people in the world.

Parkinson's patients present as a characteristic sign of this disease an accumulation of the aforementioned protein in the brain, forming a structure called Lewy bodies, and this number increases as the disease progresses.

Cuenca and Ortuño Lizarán emphasize that the scientific relevance of their work is based on the fact that, for the first time, they have identified Lewy bodies in retinas of people with Parkinson's disease. This is the result of the study of the retinas sent by the Banner Sun Health Research Institute from deceased Parkinson's patients, whose clinical and pathological data of the brain are collected in this American institute.

Also, researchers have found a correlation: the greater the amount of alpha-synuclein in the retina, the more Parkinson's motor and clinical disturbances, thus, the more serious the condition.

The accumulation of this protein in the retina forming Lewy bodies is similar to that found in the brain in Parkinson's patients. "That is why we believe that alpha-synuclein is a helpful biomarker for Parkinson's; it can show the degree of severity of the disease and reflects, in some way, what is happening in the brain," Cuenca added.

Ortuño Lizarán stated that currently there is no technique applied in medicine to detect alpha-synuclein in the retina of a living person. The work reveals a second finding in that this protein does not only appears in patients diagnosed with Parkinson's, but also in some who did not present their usual motor symptoms (tremors and slowness of movement) although their brains were already affected by this disease.

According to Ortuño, this indicates that alpha-synuclein can also be an early biomarker, which could help detect Parkinson's before the clinical symptoms appear.

One aspect of this research work, which is not included in the journal Movement Disorders, is that, other than the accumulation of the alpha-synuclein protein, another relevant process that occurs in the brain of Parkinson's patients is observed in the retina: death of dopaminergic cells (found both in retina and brain).

Parkinson's disease is characterized by the degeneration of dopaminergic neurons, which release dopamine, a key neurotransmitter for motor function, and people who suffer from this disease often experience visual disturbances.

Both researchers emphasize that retina represents the ideal place to study Parkinson's, Alzheimer's and multiple sclerosis as it is an extension of the brain and part of the central nervous system.