Alpha synuclein in the retina as a window into the brain
The takeawayAlpha-synuclein, which causes major damage to neurons in the brain in Parkinson’s and is also found in other parts of the body such as the gut, has been found in the retina, the innermost layer at the back of the eye. The results of this study indicate a close relationship between alpha-synuclein in the retina and the progression of Parkinson’s both in terms of symptoms and its effect on the brain.
Why is it important?Clinical examination of the eye could prove to be a useful new way of diagnosing Parkinson’s early, and reducing uncertainty around diagnosis in people at the earliest stages.
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The detailsPeople with Parkinson’s often have difficulties in reading, and report that their vision deteriorates: colours may appear less intense, vision is less sharp and the perception of moving objects can be impaired. Little is known about how Parkinson’s affects vision, and its exact effects on the eyes.
Since alpha-synuclein, and especially its harmful form which is phosphorylated (that is, a phosphate group has been chemically added to it), is known to move from cell to cell, these researchers investigated whether it could also be found in the nerve cells in the back of the eye.
The detailsSamples of donated tissue from 9 people with Parkinson’s, 6 healthy individuals and 4 people with Lewy Body disease were analysed using a staining technique specific for phosphorylated alpha-synuclein. Based on the location and amounts of alpha-synuclein within retinal nerve cells, it was possible to confirm the diagnosis of Parkinson’s in all 9 cases. There were significant correlations between the amount of retinal alpha-synuclein and the stage of the disease in the brain, as well as the severity of movement symptoms. Phosphorylated alpha-synuclein was undetectable in the case of the healthy individuals.
These findings indicate that retinal examination using existing routine methods could be a useful way of confirming early diagnosis and tracking the course of Parkinson’s.
Next stepsFuture work will need to focus on replicating these findings in a larger sample of people with Parkinson’s using some of the proposed routine methods of examining the retina.
See our summary on alpha-synuclein on tears