Simple vision tests can predict which people with Parkinson’s disease will develop brain weakness and depression 18 months later, according to a new study by UCL researchers.
The study, published in Movement Disorders, adds to evidence that vision changes precede the mental decline that occurs in many, but not all, Parkinson’s Disease.
In another new study published today in Communication Biology, the same research team found that structural and functional connections of brain segments differ throughout the entire brain in people with Parkinson’s disease, especially among people with vision problems.
The two studies together show how loss and changes in brain wiring underlie the brain impairment that many people with Parkinson’s disease suffer from.
Lead author Dr Angeliki Zarkali (Dementia Research Center, UCL Queen ‘s Square Neurology Institute) said: “We have found that people with Parkinson’ s disease with visual impairments are more likely to develop dementia, and that is explained by fundamental changes in their brain wiring.
“Vision tests can allow us to predict Parkinson’s dementia before it starts, which can help us find ways to stop the mental decline before it’s too late. ”
For the Movement Disorder Paper, published earlier this month, the researchers studied 77 people with Parkinson’s disease and found that simple vision tests predicted who would go on to get depressed after a year and a half.
Depression is a common, debilitating component of Parkinson’s disease, which is estimated to affect about 50% of people within 10 years of being diagnosed with Parkinson’s.
These long-term findings draw on previous studies conducted at one time, which had suggested performance in vision tests, including commonly used eyepieces and winged images of cats and dogs, linked to risk of mental retardation.
The new study also found that those who went on to develop Parkinson’s depression had a loss in brain wiring, including areas related to vision and memory. The researchers used recently developed methods to analyze detailed MRI scans, allowing them to pick up the damage to the white matter of the brain.
The researchers identified white matter damage to some of the long-distance wiring connecting the front and back of the brain, which helps the brain function as a coherent whole network.
The Communication Biology a study included 88 people with Parkinson’s disease (33 of whom were visually impaired and therefore considered at high risk of depression) and 30 healthy adults as a control group, who were brainwashed designed using MRI scans.
In the healthy brain, there is a correlation between the strength of the structural (physical) connections between two regions, and the extent to which those two regions are actively linked. That connection is not uniform throughout the brain, as there is a degree of disconnection in the healthy brain, especially in areas involved in high-grade processing, which can lead to pass flexibility to enable abstract reasoning. Too much separation seems to be linked to bad outcomes.
The researchers found that people with Parkinson’s disease exhibited a higher level of disconnection across the entire brain. In areas at the back of the brain, and less specific areas, patients with Parkinson’s Disease had the highest rate of segregation.
Parkinson’s patients with visual impairment were more isolated in some, but not all brain regions, especially in memory-related regions in the temporal lobe.
The research team also found changes in the levels of some neurotransmitters (chemical messengers) in people at risk of mental decline, suggesting that receptors for these transmitters may be potential targets. for new drug treatments for Parkinson’s dementia. In particular, although dopamine is known to be involved in Parkinson’s Disease, the researchers found that other neurotransmitters – acetylcholine, serotonin and noradrenaline – had a specific effect in people at risk of mental decline.
Dr Angeliki said: “The two papers together help us to understand what is going on in the brains of people with Parkinson ‘s Disease who are suffering from mental retardation, as it seems to be driven by breakdown in the wiring that connects different brain regions. ”
Dr Rimona Weil (Queen’s Square Neurology Institute of UCL), lead author of both papers, said: “Our findings can be valuable for clinical trials, showing that vision tests can help us to ‘identify who we should be targeting trials of new drugs that may be able to slow down Parkinson’ s Disease. And ultimately, if effective treatments are found, these simple tests may help us identify who will benefit from these treatments. ”
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The researchers were supported by Alzheimer’s Research UK, Wellcome, and the UCLH Center for Biomedical Research of the National Institute for Health Research.
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