Changes to the visual systems of Parkinson’s patients hint at early-detection biomarkers

An image from the study. (Courtesy of Radiological Society of North America)

Researchers have identified differences between the visual systems of people newly diagnosed with Parkinson’s disease and those of healthy volunteers. The finding suggests doctors could use biomarkers tied to the visual system to spot the disease early and monitor its advance.

Writing in the journal Radiology, the researchers describe a study that enrolled 20 patients newly diagnosed with Parkinson’s and 20 age-matched healthy volunteers. The researchers then analyzed the white matter of the participants using an MRI technique. This allowed the researchers to look at the optic radiation connectivity, diffusivity and white matter concentration. 

The study found statistically significant differences between the Parkinson’s patients and healthy volunteers for each of these three metrics. The study also detected a significant change in the gray matter concentration in the visual cortices.

Those findings prompted the researchers to speculate that the changes to the visual system may happen before motor symptoms develop. If that is the case, assessments of the visual system could alert doctors to the likely onset of Parkinson’s before a patient becomes symptomatic. Such early detection could improve outcomes if used in conjunction with effective interventions.

The size of the study and the use of a technique known to deliver false positives leave questions about what can be inferred from the data, however. The team behind the study, while talking up the potential significance of the findings, are aware that the work is a long way from translating into advances that improve the detection and monitoring of Parkinson’s.

“This is just a starting point,” lead researcher Alessandro Arrigo, M.D., said in a statement. “Visual processing metrics may prove helpful in differentiating Parkinsonism disorders, following disease progression and monitoring patient response to drug treatment.”

Arrigo wants to see studies that show definitively when in the progression of Parkinson’s visual pathways degenerate and what happens to them when they do.