There may be a new telltale sign to detect Parkinson’s disease before the symptoms become realized.

Researchers from Italy have discovered that changes in the visual systems of patients recently diagnosed with Parkinson’s disease may clue them into biomarkers for the early detection and monitoring of the disease.

“Just as the eye is a window into the body, the visual system is a window into brain disorders,” lead researcher Dr. Alessandro Arrigo, a resident in ophthalmology at the University Vita-Salute San Raffaele of Milan, said in a statement. “Although Parkinson’s disease is primarily considered a motor disorder, several studies have shown non-motor symptoms are common across all stages of the disease.

“However, these symptoms are often undiagnosed because patients are unaware of the link to the disease and, as a result, they may be under-treated.”

Parkinson’s—a neurodegenerative condition caused by neuronal loss in several brain structures—is characterized by tremors, rigidity or stiffness throughout the body and impaired balance and coordination.

Non-motor symptoms include visual alterations like an inability to perceive colors, a change in visual acuity and a decrease in blinking that can lead to dry eye.

“These non-motor Parkinson’s symptoms may precede the appearance of motor signs by more than a decade,” Arrigo said.

The researchers examined 20 newly diagnosed and not yet treated patients with MRI’s being performed on both healthy controls and the patients, who underwent imaging within four weeks of diagnosis.

The researchers used diffusion weighted imaging to asses white matter changes and voxel-based morphometry to investigate concentration changes of the brain’s gray and white matter. The participants were also given ophthalmologic examinations.

The patients with Parkinson’s had significant abnormalities within the visual system brain structures including alterations of optic radiations, a reduction of white matter concentration and a reduction of optic chiasm volume—the part of the brain where the left and right optic nerves intersect.

“The study in depth of visual symptoms may provide sensitive markers of Parkinson’s disease,” Arrigo said. “Visual processing metrics may prove helpful in differentiating Parkinsonism disorders, following disease progression, and monitoring patient response to drug treatment.”

The researchers will now continue further studies to better underst5and the timing of degeneration along visual pathways as well as the specific changes.

The study was published in Radiology.