Alzheimer’s disease begins to alter and damage the brain years—even decades—before symptoms appear, making early identification of the risk paramount to slowing its progression.
In recent years, researchers investigating the pathology of Alzheimer’s have primarily directed their attention at two causative or contributory factors: the accumulation of protein plaques in the brain called amyloid-beta and tangles of a protein called tau.
Both have been linked to damaging and killing neurons, resulting in progressive cognitive dysfunction.
In a recent study from the University of California San Diego, researchers say with further developments, measuring how quickly one’s pupil dilates can help show a person’s risk of Alzheimer’s disease.
Combined with cognitive tests, eye tests may be a low-cost, low-invasive method to aid in screening people at increased genetic risk for Alzheimer’s before cognitive decline begins.
The study is published in the Neurobiology of Aging. The lead author is William S. Kremen, Ph.D.
The new study focuses on pupillary responses which are driven by the locus coeruleus (LC), a cluster of neurons in the brainstem involved in regulating arousal and also modulating cognitive function.
Tau is the earliest occurring known biomarker for Alzheimer’s. It first appears in the LC and it is more strongly associated with cognition than amyloid-beta.
The LC drives the changing diameter of the eyes’ pupils during cognitive tasks. (Pupils get bigger the more difficult the brain task.)
In their previous work, the researchers had reported that adults with mild cognitive impairment, often a precursor to Alzheimer’s, displayed greater pupil dilation and cognitive effort than cognitively normal individuals.
The scientists link pupillary dilation responses with identified Alzheimer’s risk genes.
The team says that measuring pupillary response during cognitive tasks could be another screening tool to detect Alzheimer’s before symptoms appear.
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