Alzheimer’s: some brains protect themselves less well than others

We have just discovered that people with memory problems have brains that are less impermeable to harmful elements than others. In a healthy brain, the cells that make up blood vessels fit together so tightly that they form a barrier that prevents pathogens from reaching brain tissue. Scientists call this the “blood-brain barrier”.

Breakdown of the blood-brain barrier

However, in the context of Alzheimer’s disease, “our data show that individuals with early cognitive dysfunction develop brain damage and breakdown of the blood-brain barrier in the hippocampus”, say researchers in a new study. , published in NatureMedicine.

The study involved 161 elderly people. They assessed their memory and reasoning ability through a series of tasks and tests, and obtained a “clinical dementia score”. Result: whether or not tau* proteins were present in the brain, the blood-brain barrier was less solid in participants who had memory problems.

tau protein

The fact that blood vessels change “independent of tau and independent of amyloid” when people with mild cognitive impairment are affected suggests that this could be an entirely separate process or very early,” says lead author Berislav Zlokovic, director of the Zilkha Neurogenetic Institute at USC’s Keck School of Medicine. “It was surprising that this breakdown of the blood-brain barrier occurred independently,” he adds.

Such a discovery therefore opens the way to new avenues of treatment. In France, 900,000 people are affected by Alzheimer’s disease, and no less than 50 million people suffer from dementia worldwide. Rare before the age of 65, Alzheimer’s disease is first manifested by memory loss, followed over the years by more general and disabling cognitive disorders.

*Tau abnormalities are associated with Alzheimer’s disease.

*Alzheimer’s disease is characterized in particular by an aggregate of beta-amyloid proteins forming senile plaques in the neurons.