How does one know that they will suffer from a degenerative disease like Alzheimer's? A new study published by Neurobiology of Aging journal, researchers from the School of Medicine of the University of California say that the dilation of the pupils during a cognitive test may be a simple, yet effective trick to measure the risk. The researchers believe that this may be the more cost-effective, low invasive method to screen individuals of the increased risk for Alzheimer's Disease (AD) even before any form of cognitive decline even sets in.
In recent years, researchers have been focused on investigating the pathology of this degenerative disease directing their attention more on the contributing factors that causes the disease to develop and its symptoms to set in. The accumulation of the amyloid-beta and the protein called tau in the brain causes damage to the neurons, which then leads to cognitive dysfunction that's progressive in nature.
This new study, however, focuses more on pupillary functions. The responses of this part of the eye is driven by the locus coeruleus (LC). It is a cluster of neurons at the tip of the brainstem that helps modulate the cognitive function and regulate feelings of arousal. Tau is considered as the earliest market of AD, particularly because it appears first in the LC. Compared to the amyloid-beta, Tau is more strongly associated with cognitive decline.
William S. Kremen, primary author of the study, alongside Carol E. Franz, senior author, both work as co-directors at the Center for Behavior Genetics of Aging. They both teach as professors of psychiatry in the School of Medicine at the UC San Diego.
The LC is primarily known for the control it has on pupillary responses. The diameter of the pupil changes as a person is submitted to various cognitive tasks. As the exam becomes more difficult, the pupil gets bigger. Critically, the latest paper on pupillary response links the dilation with the identified risks of developing AD.
"Given the evidence, the Tau and LC are strongly associated between pupillary response and the polygenic risks of a person to develop AD. The results are proof the role of pupillary response as a screening tool to detect the risk for developing AD even before the early symptoms appear," Kremen said.
