An ability to detect Parkinson's before it imparts irreparable damage on the brain would be a game changer when it comes to treatment options. This has inspired the development of blood tests and biosensors with the potential to pick up on the disease's early biomarkers, and now new research has raised the prospect of a simple, low-cost eye test to catch the disease before it evolves into telltale symptoms like tremors and muscle stiffness.
Working with rats, researchers at University College London (UCL) experimented with a new imaging technique called DARC, or the detection of apoptosing retinal cells. Currently in clinical trials, DARC uses a fluorescent dye to visualize cells in the retina that are sick or dying, explains Francesca Cordeiro, a Professor of Retinal Neurodegeneration and Glaucoma Studies at UCL.
"The changes can be seen as tagged cells appearing as white fluorescent spots on the retina," she tells New Atlas. "The number of these spots is an indicator of active disease."
Applying the imaging technique to the animal models, the researchers found that it could reveal changes in the retina that seem to precede the disease's more obvious symptoms, which generally start to appear once more than 70 percent of the brain's dopamine-producing cells are destroyed.
"Our study has suggested in an experimental model of Parkinson's that the changes identified by DARC occur early in the disease process, before the changes of dying dopaminergic cells in the brain," says Cordeiro. "They also highlight the fact that changes in the retina can be used as an indicator of successful treatment, before changes are seen in the brain."
Treatment options for Parkinson's include a number of drugs designed to boost levels of dopamine in the brain, and some possible future solutions include brain-zapping headsets and other portable devices, but the UCL team treated their animal models with an anti-diabetic drug called Rosiglitazone after detecting the changes to their retinas. Following the treatment, the researchers observed clear evidence of reduced cell death in the retina and a protective effect on the brain.
Like with a lot of advances in our understanding of specific neurodegenerative diseases, the UCL team's findings could have some widespread ramifications. The DARC method has already undergone testing in humans with glaucoma, with trials due to kick off soon for Alzheimer's, with the researchers hopeful that it could facilitate earlier diagnoses of these conditions too.
"Nerve cell death is a feature of all neurodegenerative diseases," explains Cordeiro. "As the eye is connected to the brain, changes in the retina reflect those in the brain. Glaucoma and Alzheimer's therefore would have changes in nerve cell death, although they would be different in their distribution pattern and this pattern needs validation in the clinical trials."
The findings have the researchers hopeful that it may soon be possible to intervene at much earlier stages of Parkinson's disease, which affects a million people in the US and seven million people worldwide. It is currently working to patent the technology.
The research was published in the journal Acta Neuropathologica Communications.
Source: University College London