Eye Scans May Predict Parkinson’s Disease 7 Years Early: Study

Looking into someone’s eyes could tell doctors whether they are going to develop a potentially devastating neurological disease, according to new research.

Parkinson’s disease is a neurodegenerative disease that destroys the ability of the brain to produce dopamine. Dopamine is most well-known as a chemical associated with feelings of pleasure, but it is also critical for the brain’s ability to control movement. 

People with Parkinson’s lack brain cells that produce dopamine, which leads to the shakiness, stiffness, and issues with coordination that are hallmarks of the disease. 

Parkinson’s is typically diagnosed with a neurological examination and by evaluating a patient’s medical history. However, there are no blood or laboratory tests that can diagnose it with the same level of certainty as other scans can diagnose diseases like cancer. Brain imaging to see changes in dopamine-producing neurons is either costly, difficult, or not widely accepted as diagnostic tools. 

The retina, the part of the eye that converts light into signals that the brain interprets as images, has emerged as a “window into the central nervous system,” according to a research team at the University College London, in the UK. 

Technology to take pictures of the retina is much more accessible and affordable than an MRI or brain scan. The retina has dopamine-producing cells involved in helping cells communicate with each other, making it an easier way to assess the state of a patient’s ability to produce the chemical. 

In the study, published on Monday in the journal Neurology, researchers analyzed data and images from the retinas of more than 150,000 participants. Of these participants, 700 of them already had Parkinson’s disease when they had their retinas imaged, and 53 of them later developed the disease. 

They found that in people with existing Parkinson’s disease, the parts of their retinas that produce dopamine were thinner than people who did not have Parkinson’s. Additionally, these areas were also thinner in people who did not have Parkinson’s at the time of getting imaged, but who developed it later. 

The average time for these patients who would go on to develop Parkinson’s between imaging and diagnosis was a little more than 7.2 years, suggesting that these images may be a way to predict the onset of Parkinson’s before a diagnosis. 

“While we are not yet ready to predict whether an individual will develop Parkinson’s, we hope that this method could soon become a pre-screening tool for people at risk of disease,” said lead author Siegfried Wagner, M.D., in a press release.

However, treatment for Parkinson’s remains somewhat limited, and there is no cure. Currently, the main drug is levodopa, which essentially replaces dopamine that the brain can no longer produce, but there are considerable side effects. A procedure called deep-brain stimulation is another option for people who don’t respond well to medication, but it requires surgery.  

Retinal scans have also shown promise in the early detection of Alzheimer’s disease, drawing more attention to their ability to show the inner workings of the brain.