A group of researchers from the Center for Research on Neurological Diseases (CIEN) has shown in a new study that a conventional magnetic resonance imaging scan can be used to assess the condition of the brain connections involved in memory and attention.
The study, funded by the Reina Sofía Foundation and published in the American scientific journal 'Alzheimer's & Dementia', is based on magnetic resonance imaging scans performed after death on 55 donors from 'BT-CIEN', the center's neurological tissue bank. The sample included brains from people with Alzheimer's, Lewy body dementia, both pathologies combined, and other neurodegenerative diseases.
"We were able to verify that what the radiologist evaluates in the visual scale of damage to the acetylcholine pathways in a conventional magnetic resonance imaging scan serves as a very useful indicator of the real microstructural damage in those pathways," said the head of CIEN's neuroimaging platform and coauthor of the study, Michel J. Grothe. The expert also emphasized that "it is a tool that is already within reach of any Radiology Service, at a time when knowing precisely which brain systems are affected is more important than ever".
The images were obtained a few hours after death and before the autopsy, which has made it possible to directly compare what the scan reflects with the findings of the analysis of the brain tissue. The scientists focused on acetylcholine, an essential chemical messenger for memory and attention, which originates in a small area at the base of the brain and reaches the cortex through two large bundles of white matter fibers, the "wiring" that links different brain areas and which constitutes the target of the drugs used for decades to alleviate the symptoms of Alzheimer's.
So far, a precise assessment of the condition of these pathways required advanced magnetic resonance imaging techniques, reserved mainly for research. In contrast, the authors show that a visual scale centered on the regions through which those fibers run is related to their microstructural deterioration, with a stronger association with damage to cholinergic pathways than the usual scales for assessing lesions in the brain's white matter.
International collaboration and factors associated with damage
The work is part of a collaboration with the Karolinska Institute (Sweden) and has also involved the Technical University of Prague (Czech Republic), the University of Ljubljana (Slovenia), Amsterdam UMC (Netherlands), and the Universidad Fernando Pessoa Canarias. The results indicate that the damage is more pronounced in Alzheimer’s and in mixed conditions, although it is not determined solely by the main diagnosis. Among the neuropathological factors evaluated, vascular lesions and hippocampal sclerosis have been identified as the elements most closely linked to the deterioration of these pathways.
"Being able to directly compare what we observe in the magnetic resonance imaging with the lesions that we later find in the study of the same brain gives us a unique opportunity to better understand what lies behind the changes we see in the images," noted the CIEN researcher and first author of the article, Francisco J. López-González. In his view, magnetic resonance offers a representation of the brain, but it is neuropathological analysis that makes it possible to "confirm what lies behind that image".
In his opinion, "being able to combine both perspectives in the same brains is an exceptional opportunity to advance knowledge of neurodegenerative diseases". The scientific director of CIEN, Pascual Sánchez-Juan, highlighted that the project "demonstrates the value of the model that CIEN and the Fundación Reina Sofía have been building together for almost two decades: clinical care and follow-up, neuroimaging, and neuropathology in the same center".