A method that is generally used to perform ophthalmological tests could also be used to monitor the neurodegeneration that occurs in Parkinson’s patients, as revealed by a study carried out by researchers from the UPV/EHU and Biobizkaia, who have observed that it is retinal neurodegeneration likely precedes cognitive decline.
When Parkinson’s or another neurodegenerative pathology is diagnosed, patients often ask what will happen to them and how their disease will manifest, but neurologists have difficulty answering their questions because “the evolution of patients is usually very varied: some do not experience changes with as the years go by, while others end up with dementia or in a wheelchair,” explains Ane Murueta-Goyena, researcher in the Department of Neurosciences at the UPV/EHU.
Identifying Parkinson’s patients at risk of cognitive impairment is a crucial challenge to offer more effective treatments and advance clinical studies. Ane Murueta-Goyena, in collaboration with Biobizkaia researchers, has explored whether the visual system could predict the patient’s future cognitive decline, using retinal thickness as an indicator.
Monitor neurodegeneration associated with Parkinson’s
The retina is a membrane located at the back of the eye and linked to the nervous system that is made up of multiple layers. The researchers measured the thickness of the inner layer of the retina in a group of Parkinson’s patients using optical coherence tomography, a precise and repeatable measuring instrument often used in ophthalmological examinations.
This study was carried out during the period 2015-2021 and compared the evolution of this layer in people with and without Parkinson’s disease. Furthermore, analysis of retinal images from patients in a UK hospital corroborated these results, which have been published in NPJ Parkinson’s Disease.
Slower thinning of the retinal layer is associated with more rapid cognitive decline, indicating greater severity of Parkinson’s disease.
The findings revealed that the retinal layer is significantly thinner in patients with Parkinson’s. Furthermore, it has been observed that the most significant neurodegeneration occurs in the initial phases of the disease in the retina and, once the layer becomes extremely thin, the neurodegenerative process stabilizes. Retinal thinning and cognitive decline do not occur at the same time.
The initial changes in the retina are more noticeable and, as time passes, the patients’ cognitive and motor deterioration becomes more evident – adds Murueta-Goya. In other words, slower thinning of the retinal layer is associated with more rapid cognitive decline, indicating greater disease severity.
The researcher emphasized the relevance of these discoveries: “We have obtained information about the progression of the disease and, in addition, the tool we propose is non-invasive and is available in all hospitals.” The results must be validated internationally and “by slightly improving the resolution of the technology, we will be closer to validating the method to monitor the neurodegeneration that occurs in Parkinson’s disease.” Murueta-Goyena also mentioned that the research continues with another cohort of patients and highlighted that financing is key to the progress of these studies.
Source: UPV/EHU and Biobizkaia
