Breakthrough study reveals dual role of brain immune cells in Alzheimer’s disease

Belgian researchers have shed light on the role of brain immune cells, known as microglia, in Alzheimer’s disease, revealing that these cells can be both harmful and protective against the disease, the Stop Alzheimer Foundation stated on Wednesday.

In their study, published in the journal Nature Communications , the researchers from the Center for Brain Research at the Catholic University of Leuven (KU Leuven) demonstrated this dual function of microglia, which the Foundation described as a “major breakthrough in understanding Alzheimer’s disease.”

In Alzheimer’s disease, amyloid plaques—clusters of toxic proteins—accumulate in the brain. Microglia, responsible for clearing cellular waste, interact with these plaques, but their exact role had remained unclear until now, the study authors explained.

The team at the Center for Brain Research discovered that, in the early stages of the disease, microglia promote the formation of amyloid plaques, thus playing a detrimental role. However, at a later stage, these same cells reactivate to compact the plaques, thereby limiting their toxic effects and protecting neurons.

To better understand this dual function, the researchers studied the activation of microglia throughout the course of the disease. They found that the cells are initially in a “homeostatic” state, meaning they are minimally active, which allows plaque formation. As the disease progresses, the microglia become activated and adopt a protective role.

“Our work shows that homeostatic microglia, present at the onset of the disease, have a harmful role, whereas activated microglia, which appear later, have a protective effect,” said the study’s lead researcher Bart de Strooper.

“These findings clarify previously contradictory data and open up new avenues for therapeutic approaches,” he further noted. However, the researcher questions whether microglia should be activated or inhibited, and at what stage.