Can retinal thickness predict cognitive progression in Parkinson's patients?

In a study published in the journal NPJ Parkinson's Disease, researchers investigated whether the retinal thickness could predict cognitive progression in Parkinson's patients.

Parkinson's disease, a progressive neurodegenerative disorder, has long been associated with the dysfunction of dopamine-producing neurons in the brain. However, emerging research suggests that the involvement of blood vessels in the pathogenesis of Parkinson's may hold crucial insights into understanding and treating this debilitating condition.

In Parkinson's disease, changes in the retina, including thinning and alterations in blood vessels, may occur and could serve as a biomarker for the disease. These changes reflect underlying brain degeneration and may be detected using non-invasive imaging techniques like optical coherence tomography. Understanding retinal progression could improve the diagnosis and management of Parkinson's.

In the study, researchers used optical coherence tomography to measure the thickness of the innermost layer of the retina in Parkinson's patients. This tool is commonly used in eye tests because it provides detailed and accurate measurements. They looked at how this retinal layer changed over six years, comparing people with and without Parkinson's disease.

The results showed that the innermost retinal layer is thinner in Parkinson's patients. They noticed that during the early stages of the disease, the most significant nerve damage is seen in the retina. As the disease progresses, the nerve damage stabilizes even though the retinal layer remains thin. Interestingly, retinal thinning and cognitive decline don't happen at the same time. First, changes in the retina are noticeable, then over time, patients experience worsening cognitive and motor symptoms.

The findings concluded the slower retinal layer thickness loss is associated with faster cognitive decline; this slowness is linked to greater severity of the disease.

Reference: Murueta-Goyena, A., Romero-Bascones, D., Teijeira-Portas, S. et al. Association of retinal neurodegeneration with the progression of cognitive decline in Parkinson’s disease. npj Parkinson’s Dis. 10, 26 (2024)