A new study in rats reveals the potential of MRI to detect deficiencies in brain connectivity before the first symptoms of Alzheimer's disease appear. The images were processed to obtain a map of the structural and functional connectivity of the brain. The results showed that in sick animals there was a delay in learning ability.
Researchers from the August Pi i Sunyer Biomedical Research Institute (IDIBAPS) have published a study in the Alzheimer's Research & Therapy journal in which they demonstrate the potential of magnetic resonance imaging to detect deficiencies in brain connectivity before the first symptoms of Alzheimer's appear .
They have achieved this through studies in animal models – transgenic rats that develop the disease – carried out with a 7 Tesla resonance apparatus, much more powerful than those used for patients, which are 1.5 T or 3 T. The study has coordinated Guadalupe Soria, researcher in charge of the IDIBAPS 7T Experimental Magnetic Resonance Imaging Unit, with Emma Muñoz-Moreno as first author.
Animal models in Alzheimer's are key to understanding its progression and developing markers that allow its early detection. As this pathology has also been defined as a disconnection syndrome, the measurement of brain connectivity by magnetic resonance imaging (connectomics) can allow the characterization of alterations in the associated brain connection networks.
In animals with Alzheimer's there was a less efficient organization of the structural networks of the brain, but the functionality was not affected
In this article, both behavior and brain connectivity were analyzed at 5 months of age, when there is still no neurodegeneration and the characteristic β-amyloid plaques have not yet appeared.
The cognitive and functional capacities were studied by means of a behavioral test preceded by a training stage in which the animal learned to perform a certain task. After the test, magnetic resonance imaging was performed with 7-tesla equipment and the acquired images were processed to obtain a map of the structural and functional connectivity of the brain.
Neurocognitive deficits in early stagespranas
The results show that in the transgenic animals there was a delay in the learning capacity. The researchers observed that, globally, there was a less efficient organization of the structural networks of the brain but that the functionality was not affected, that is, it was still preserved.
"We observed that there were certain brain regions with structural and functional differences, such as the areas related to memory and reward processes, which are known to also be altered in patients with the disease," explains Guadalupe Soria.
"This study shows that there are neurocognitive and brain connectivity deficiencies in rats that develop Alzheimer's in very early stages, when the characteristic symptoms of the disease have not yet appeared," says Soria. "The work shows the potential of MRI-based connectomics as an early biomarker," she concludes.
