Study: Changes in the retina may be linked to parts of the brain of healthy individuals at risk of Alzheimer’s

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The brain structures with most changes coincide with those which are altered most in Alzheimer’s, according to a study by researchers at the Universidad Complutense de Madrid in Spain.

In subjects who are cognitively healthy but have a high genetic risk of developing Alzheimer’s, correlations have been demonstrated between the retina and various brain structures which suffer changes as a result of the disease, such as the entorhinal cortex, the lingual gyrus and the hippocampus.

This is the main conclusion of a study1 led by the Ramón Castroviejo Institute for Ophthalmological Research (IIORC) of the Complutense University of Madrid (UCM).

According to a UCM news release, the novelty of the study, published in Alzheimer’s Research & Therapy, lies in the fact that for the first time it has examined the correlations between the retinal areas and the cerebral structures most affected in Alzheimer’s, a disease in which up to two decades can pass before the first appearance of symptoms.

“This means that the retina, which is an easily accessible tissue, may provide information on the state of the brain and the changes taking place in it”, Inés López-Cuenca, IIORC researcher and lead author of the work, said in the UCM news release.

Participating in the research with UCM were the San Carlos Clinical Hospital and the Technical University of Madrid, as part of a COGDEM study.

Next step: studying vision

To carry out the research, a group of patients was included whose fathers or mothers suffered from Alzheimer’s and who had a mutation in their gene ApoE ɛ4, which predisposes them to suffer from the disease.

According to the UCM news release, the IIORC gave them ophthalmological examinations, including Optical Coherence Tomography (OCT). These tests were then compared with those of the magnetic resonance imaging (MRI) carried out by the Neurological Service of the San Carlos University Clinical Hospital of Madrid, and resulting in measurements of more than 20 different brain structures from both hemispheres.

“We have seen that these participants already show changes in some areas of the retina measured with OCT, while the brain MRI is still normal”, López-Cuenca noted in the UCM news release.

As well as the structure of the retina, the UCM group is collecting data on patients’ eyesight, to discover how the visual network operates in these phases of the disease which are still asymptomatic.

Reference

1 Inéz López-Cuenca, Alberto Marcos-Dolado, Miguel Yus-Fuertes, Elena Salobrar-García, et.al. The relationship between retinal layers and brain areas in asymptomatic first-degree relatives of sporadic forms of Alzheimer’s disease: an exploratory analysis; Alzheimer’s Research and Therapy, published June 4, 2022. DOI 10.1186/s13195-022-01008-5