The retina may reveal risk of Alzheimer disease in middle age

A simple eye test may one day could make the diagnosis of the earliest stages of “diseases of old age” possible at a much younger age, according to researchers from the University of Otago in New Zealand.

According to researchers, parts of the retina have been considered as biomarkers for Alzheimer disease, but the team from Otago’s Dunedin Multidisciplinary Health and Development Research Unit have been investigating the retina’s potential to indicate cognitive change earlier in life.

Ashleigh Barrett-Young, PhD, who is heading up the study, noted in a university news release that diseases of old age, such as Alzheimer disease, are usually diagnosed when people start forgetting things or acting out of character.

“This is often when the disease is quite far along,” she explained.

Early detection is possible through MRI or other brain imaging, but this is expensive and impractical for most, Barrett-Young noted in the university news release.

“In the near future, it's hoped that artificial intelligence will be able to take an image of a person's retina and determine whether that person is at risk for Alzheimer disease long before they begin showing symptoms, and when there is a possibility of treatment to mitigate the symptoms,” she said in the release.

The study, published in JAMA Ophthalmology, analysed data from 865 Dunedin Study participants looking specifically at the retinal nerve fibre layer (RNFL) and ganglion cell layer (GCL) at age 45.

Barrett-Young says they found thicker RNFL and GCL in middle age was associated with better cognitive performance in childhood and adulthood. Thinner RNFL was also linked to a greater decline in processing speed (the speed in which a person can understand and react to the information they receive) from childhood to adulthood.

Moreover, Barrett-Young pointed out in the news release that the findings suggest that RNFL could be an indicator of overall brain health, highlighting the potential for optical scans to aid in the diagnosis of cognitive decline.

“Given we haven’t been able to treat advanced Alzheimer’s, and that the global prevalence of the disease is increasing, being able to identify people in the preclinical stage, when we may still have the chance to intervene, is really important,” she explained in the release.

The university noted in the release that further studies are required to determine if retinal thinning predicts Alzheimer disease, or just the normal cognitive decline of old age, but the researchers have hope.

According to Barrett-Young, the findings could result in AI being used to take a typical optical coherence tomography scan, done by an ophthalmologist or optometrist, and combine it with other health data to determine a patient’s likely risk for developing Alzheimer disease.