The study published in Movement Disorders adds to previously collected evidence showing that vision changes precede the cognitive decline that occurs in many people with Parkinson’s. It involved 77 people whose data was analyzed to find that simple vision tests could predict who would get dementia after a year and a half.
The study also found that those who developed Parkinson’s dementia had losses in the wiring of the brain, including in areas relating to memory and vision. These findings were possibly due to a new method the researchers recently developed that analyzes finely detailed MRI scans, enabling them to pick up the damage to the brain’s white matter.
Brain Regions Decoupled
In another study published in Communications Biology, the same research team found that functional and structural connection of the brain regions become decoupled throughout the entire brain in people with Parkinson’s disease, particularly among those with vision problems. This study involved 88 people with Parkinson’s disease and 30 healthy adults as a control group. All participants had a brain image using MRI scans.
There is a connection between how strong the structural connections between two regions are and how much the two regions are connected functionally in the healthy brain. Too much decoupling appears to be linked to poor outcomes. The people with Parkinson’s disease exhibited a higher degree of decoupling across the whole brain.
These two studies’ collective data show how changes and losses to the brain’s wiring underlie the cognitive impairment experienced by many people with Parkinson’s disease.
Dementia is a common, debilitating aspect of Parkinson’s disease. It is estimated to affect roughly 50% of people within ten years of a Parkinson’s diagnosis and could progress to become Alzheimer’s disease.
Lead author Dr. Angeliki Zarkali 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.”
Researchers believe these findings can be valuable for clinical trials by showing that eye tests can help identify which patients should be targeted for trials of new drugs that might slow Parkinson’s. Ultimately, this research will help find effective treatments and enable simple tests to help identify those who will benefit from which treatments.