Eye tests predict Parkinson’s-linked cognitive decline
Eyesight tests can predict which people with Parkinson's disease will develop cognitive impairment and possible dementia 18 months later, new research suggests.
Scientists say the study, published in Movement Disorders, adds to evidence that vision changes precede the cognitive decline that occurs in many, but not all, people with Parkinson's.
In another study published in Communications Biology, the same research team found that structural and functional connections of brain regions become decoupled throughout the entire brain in people with the disease.
According to the paper this was particularly the case among people with vision problems.
The two studies indicate how losses and changes to the brain's wiring underlie the cognitive impairment experienced by many people with Parkinson's disease.
Lead author Dr Angeliki Zarkali of the Dementia Research Centre, UCL Queen Square Institute of Neurology, said: "We have found that people with Parkinson's disease who have visual problems are more likely to get dementia, and that appears to be explained by underlying changes to their brain wiring.
"Vision tests might provide us with a window of opportunity to predict Parkinson's dementia before it begins, which may help us find ways to stop the cognitive decline before it's too late."
For the Movement Disorders paper, published earlier this month, researchers studied 77 people with Parkinson's disease and found that simple vision tests predicted who would go on to get dementia after a year and a half.
The study also found that those who went on to develop Parkinson's dementia had losses in the wiring of the brain, including in areas relating to vision and memory.
The Communications Biology study involved 88 people with Parkinson's disease, 33 of whom had visual dysfunction and were thus judged to have a high risk of dementia, and 30 healthy adults as a control group, whose brains were imaged using MRI scans.
In the healthy brain there is a correlation between how strong the structural (physical) connections between two regions are, and how much those two regions are connected functionally.