Alzheimer's Eye Test

[caption id="attachment_5807" align="alignnone" width="400"] Fang Ko, MD[/caption]   Monitoring retinal nerve fibre layer (RNFL) thickness may have a role in helping screen, and possibly diagnose, conditions such as Alzheimer’s disease (AD). This is according to research which found an association between thinner RNFL and poorer cognition. Details were presented at the 2016 Alzheimer’s Association International Conference in Toronto, Canada, by Fang Ko MD. She was at Moorfields Eye Hospital in London, UK, when conducting the research. This work was sponsored by the National Institute of Health Biomedical Research Centre of Moorfields Eye Hospital. Retinal thickness, detection of amyloid plaques (characteristic of AD) on the retina, and retinal vessel behaviour are all being investigated as ways to help screen for neurodegenerative diseases, which may put ophthalmologists at the forefront of screening efforts. The study used data from the UK Biobank, a project that includes medical and health details of 500,000 volunteers aged between 40 to 69 years from across England. Of these, 67,000 underwent eye exams, which included spectral-domain optical coherence tomography (SD-OCT) imaging. For the study, a large number were excluded, including those with poor image quality, any known ocular disease, elevated intraocular pressure, extreme refractive error, poor vision, neurologic disease or diabetes. This left a total of 33,000 participants. Some 32,000 also completed four different tests relating to cognition, including prospective memory, episodic memory, reasoning and reaction time. After three years, 1,251 participants repeated the cognitive tests. Researchers found that people with thinner RNFL tended to perform worse on each of the cognitive tests than people with thicker RNFL. The differences in cognition between thick and thin RNFL were statistically significant. Generally, it was found that the thinner the layers, the more poorly individuals performed. For instance, in the prospective memory test, the mean RNFL thickness was 53.3um for those who were able to recall details in the test correctly on the first attempt. For those who recalled details on a second attempt, the mean thickness was 52.5um, while those who did not succeed in recalling details had a mean thickness of 51.9um. “It may be that the nerve fibre layer could be a biomarker,” Dr Ko said. When it came to the 1,251 people who did follow-up cognitive tests, it was found that those who had thinner RNFL at baseline performed worse after three years. In other words, it may be possible to use thin RNFL as a predictor of cognitive decline, she said. However, various things “can influence someone’s nerve fibre layer or their cognitive function”, she said. Glaucoma and other retinal diseases can affect RNFL thickness, and other factors can cause cognitive decline. “Because of its availability and presence of OCT in most ophthalmology offices, its potential for clinical use (as a screening tool) is quite high,” Dr Ko added. Fang Ko: fangkomail@gmail.com

Tags: Alzheimer's Disease