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Retinal imaging may predict Alzheimer’s in those at genetic risk

JAMA Ophthalmology
Reuters Health - 20/11/2020 - Retinal alterations visible via optical coherence tomography (OCT) in carriers of familial Alzheimer's disease (AD) may well forerun disease onset, according to a cross-sectional study.

As Dr. John Miller told Reuters Health by email, "This study has important clinical implications because we identified OCT changes before the onset of cognitive decline in patients with a genetic predisposition to develop Alzheimer's with virtual certainty."

"This is important because it minimizes the typical confounders of age and more advanced disease seen in many of the other prior studies from other groups in OCT and Alzheimer's," he added.

Dr. Miller of Harvard Medical School, in Boston, and colleagues studied 10 carriers of the PSEN1 E280A mutation who were cognitively unimpaired and 10 healthy family members without the mutation. All were members of the world's largest known autosomal dominant AD kindred, which is centered in Antioquia, Colombia. Their mean age overall was about 36 years.

"These individuals carry a genetic mutation for Alzheimer's disease and are destined to develop dementia by their 50s," co-author Dr. Yakeel T. Quiroz, also of Harvard Medical School, explained in an email to Reuters Health.

"There is an urgent need for inexpensive and non-invasive ways of identifying individuals at risk for Alzheimer's disease, years before they develop memory loss," he said. "While there is no cure for the disease, unfortunately, detecting it earlier on may help with early diagnosis and early initiation of symptomatic treatments."

OCT imaging showed that the mutation carriers had a generalized decrease in thickness of the whole retina as well as individual layers, the researchers report in JAMA Ophthalmology. This was most prominent in the inner nuclear layer, outer plexiform layer and outer nuclear layer.

Moreover, although age was a significant effect modifier for the association between PSEN1 mutation and amyloid alpha levels in cortical regions, say the researchers, this was "not significant for the association between PSEN1 mutation and retinal thickness."

Thus, they conclude that "OCT findings and retinal vascular parameters may be biomarkers prior to the onset of cognitive decline."

Dr. Miller added, "OCT is a non-invasive, readily available, reproducible, and more affordable tool than traditional neuroimaging metrics for Alzheimer's disease. This work may help support additional advancements to make OCT an effective biomarker for screening as well as measuring treatment effects of new therapeutics."

The study did not have commercial funding.

By David Douglas

SOURCE: https://bit.ly/3kDOBTS JAMA Ophthalmology, online November 12, 2020.

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