Vision linked to cognitive decline, white matter degeneration in Parkinson’s disease

Patients with Parkinson’s disease and visual dysfunction had a higher risk for cognitive impairment and greater white matter degeneration compared with those without visual dysfunction, according to results published in Movement Disorders.

“The objectives of this study were to identify longitudinal white matter changes in patients with [PD] and low visual function and also in those who developed mild cognitive impairment,” Angeliki Zarkali, MBBS, a research fellow at the University College London, and colleagues wrote.

In a longitudinal cohort study, Zarkali and colleagues conducted a fixel-based analysis of 76 patients with PD — 13 of whom had mild cognitive impairment at baseline — and 25 controls. Among the 76 patients with PD, 54 (men, 48.1%; mean age, 63.7 years) scored high on visual performance tests and 22 (men, 68.2%; mean age, 69.3 years) scored low on computer-based visual performance tests. Participants underwent diffusion MRI and clinical assessments at baseline and again after 18 months. The study’s outcomes of interest included cognitive function and micro- and macrostructural changes across white matter.

Patients with low visual performance at baseline were more likely to develop mild cognitive impairment at follow-up (P = .008). The researchers wrote that among these patients, “overall cognitive performance was lower.”

Additionally, fiber cross-sections showed longitudinal reductions in white matter macrostructure of patients who scored low on visual performance tests, compared with those who scored high (P < .05).

“These findings provide evidence that visual changes in PD are a marker for incipient white matter degeneration and cognitive decline,” researchers wrote.