A study shows an association between early tau brainstem accumulation and cortical hyperexcitability

A study by researchers from ULiège’s GIGA CRC In vivo Imaging laboratory shows, for the first time in humans, how the first deposits of tau proteins in the brain system are linked to processes neurophysiologic specific to the early stages of Alzheimer’s disease development.

During the preclinical stages of Alzheimer’s disease, i.e. when small changes occur in the brain but no mental symptoms are seen, the cortex enters a state of transient hyperexcitability. To date, several studies conducted in animals have shown that tau and beta-amyloid proteins – at the heart of the development of Alzheimer’s disease – were associated with increased cortical excitability and dysfunction of brain networks. However, the relationship between protein accumulation associated with Alzheimer’s disease and cortical hyperexcitability in the early stages of the disease remains poorly understood in humans, especially due to technological limitations in the precise amount of early protein deposition. .

A study, conducted by researchers from the Cyclotron Research Center (CRC In vivo Imaging / GIGA) of ULiège examined whether the first deposits of tau and beta-amyloid proteins in the brains of individuals aged 50 to 70 years could be linked to a higher degree of cortical excitability. To do this, we combined various neuroimaging methods (magnetic resonance imaging, positron emission tomography) to identify the size-sized character of tau and beta-amyloid proteins in their first agglomerations, ”explained Gilles Vandewalle, head of the laboratory. . That is to say, individually, in the brain system and in a series of high cortical areas. “In addition, the researchers also measured the excitability of the participants’ cortex in a non-invasive manner. , using transcranial magnetic stimulation techniques in conjunction with obtaining electroencephalographic recordings.

The findings of this study show that an increased amount of tau protein in the brain system – its main agglomeration site – is associated in particular with a higher level of cortical excitability, while the researchers did not observe important relationship for the level of beta-amyloid protein in the upper cortical areas. These results are the first in vivo observation in humans of the early link between proteins linked to Alzheimer’s disease and their effect on brain activity, “says Maxime Van Egroo, scientific collaborator at CRC In Vivo Imaging and first author the scientific article.

In addition, they suggest that the measurement of hyperexcitability of the cortex may be a useful indicator to inform the progression of some cerebral pathology processes associated with Alzheimer’s disease, thus contributing to the early identification of people. most at risk of developing the disease, well before the first mental symptoms appear.