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Studies have found a new link between changes to visual abilities and the development of Alzheimer’s disease.
The two studies, funded by the National Institute on Aging (NIA), found that changes in a person’s eyesight could be biomarkers for Alzheimer’s. The disease is usually diagnosed through cognitive changes, such as increased memory loss and difficulty processing information or making decisions.
Results of the new studies may help in the early diagnosis of Alzheimer’s disease.
In the first study, the researchers assessed the participants’ visual contrast sensitivity, the ability to distinguish an object from its background. The results showed that poorer visual contrast sensitivity was associated with protein deposits in the brain that are indicative of the early onset of Alzheimer’s.
The second study investigated how people’s pupils dilated while they were taking a cognitive exam. The researchers found that the pupils of the participants who were mildly impaired cognitively grew bigger than those of normal individuals. This is because the pupils dilate more when a person exerts greater effort during demanding cognitive tasks. These people were found to have a higher risk of Alzheimer’s, so the researchers connected the greater degree of pupil dilation to a higher genetic risk for the disease.
The two studies show that eye tests can be used as effective, affordable, and non-invasive ways to detect Alzheimer’s early. The new non-invasive methods proposed in the studies can replace invasive techniques such as blood tests and expensive procedures like magnetic resonance imaging (MRI) and computed tomography (CT) scans that are usually used to diagnose Alzheimer’s.
Although using biomarkers like pupil dilation and visual contrast sensitivity does not provide a way to stop Alzheimer’s from developing, it helps in detecting the disease during the initial stages, which is essential for slowing down its progression.