Pupillary dilation may aid in identifying risk for Alzheimer’s

In a previous study, researchers demonstrated how examining retinal health might be beneficial in identifying early symptoms of Alzheimer’s disease. New findings released in Neurobiology of Aging found that pupillary responses during cognitive tests may aid in screening older adults at risk of developing the neurodegenerative disease.

In the study, a team of researchers at the University of California San Diego School of Medicine looked into pupillary responses and how its association with locus coeruleus (LC) modulates cognitive function. During cognitive tests, the LC initiates a pupillary response, such as the enlargement of pupil dilation.

As determined in prior findings of adults with mild cognitive impairment (MCI), greater pupil dilation was associated with a decline in cognitive health. In the new findings, researchers established a similar link; pupillary dilation responses may help identify Alzheimer’s disease (AD) risk genes.

“Pupillary responses during cognitive tasks are driven by the LC and index cognitive effort. Despite equivalent task performance, adults with mild cognitive impairment have greater pupil dilation/effort during digit span than cognitively normal (CN) individuals,” according to the findings. “We hypothesized that AD polygenic risk scores would be associated with pupillary responses in middle-aged CN adults.”

“These results are proof-of-concept that measuring pupillary response during cognitive tasks could be another screening tool to detect Alzheimer’s before symptom appear,” the study’s senior author stated.

“Results support pupillary response—and by inference, LC dysfunction—as a genetically-mediated biomarker of early MCI/AD risk,” the findings say. “In combination with other biomarkers, task-evoked pupillary responses may provide additional information for early screening of genetically at-risk individuals even before cognitive declines.”