Simple ophthalmic examinations can detect Parkinson’s disease years before the first focal point appears, which could revolutionize the treatment schedule for millions of patients around the world.
Researchers at Laval University found that the retina (photosensitive tissue on the back of the eye) responded differently to light stimulation in early Parkinson’s disease, even before classical motor symptoms occurred.
“When a person consults a doctor for motor problems such as tremors, the disease has been around for several years, and the affected neurons have been involved in an irreversible regression process,” explained study leader Martin Lévesque.
The groundbreaking study, published in May’s disease neurobiology, found different electrical patterns found in the retina of newly diagnosed patients and mouse models of disease. This “retinal signature” can be used as a biomarker for early detection.
Using electronic simulations – a non-invasive technique that measures the electrical response of the retina to light flashes – the team tested 20 people diagnosed with Parkinson’s disease over the past five years and tested them in 20 healthy age-matched controls.
“We placed the electrodes on the lower eyelids of each participant and recorded their retinal responses to a range of flashes of varying intensity, frequency and color,” Lévesque noted. “The results we obtained for Parkinson’s patients had obvious signatures with those in the control group.”
Most interestingly, studies have shown that the gender specificity of retinal responses varies greatly. Female participants with Parkinson’s disease showed more significant changes in certain retinal measurements compared to men, which could provide new insights into how diseases manifest differently among genders.
The team observed that bipolar cells-neurons that transmit signals from photoreceptors to ganglion cells within the retina showed reduced activity with early Parkinson’s disease. In mouse models, they even detected abnormal accumulation of alpha-synuclein associated with Parkinson’s disease in the retina.
“The retina is a direct extension of the central nervous system and thus provides a noninvasive way to explore the brain,” Lévesque explained. This connection makes the eyes a potential “window” to brain health.
Victoria Soto Linan, lead author and doctoral student of the study, showed that retinal screening could become a routine part of health care for patients over 50 years of age. “By detecting the disease early, we can provide interventions to prevent the degeneration of neurons involved in Parkinson’s campus,” she said.
In addition to early detection, researchers believe their technology could provide a way to monitor disease progression and treatment effects. As neurologists increasingly seek biomarkers that can track Parkinson’s disease before symptoms begin, this accessible screening method has special promise.
Currently, Parkinson’s disease affects more than 10 million people worldwide, with most diagnoses occurring after a large number of neurodegeneratives. The early stages of the disease can begin 10-15 years before classical symptoms appear, thus giving similar early detection tools potential translation into therapeutic outcomes.
These findings add to the growing evidence that the eye may provide important insights into neurological diseases, and similar approaches have been explored in Alzheimer’s, multiple sclerosis and other diseases. As our population ages, this non-invasive screening tool may become increasingly valuable due to early intervention.
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