Scientists have found that the brain removes waste products through the nose

Scientists from the Gladstone Institutes in the United States have discovered that a significant portion of the brain's protein waste is cleared through nasal passages, brain membranes, and skull tissues, rather than through cervical lymph nodes, as was previously believed. According to the researchers, disruption of this clearance system may be linked to the development of Alzheimer's disease. The results of the study have been published in the journal Cell.

The brain constantly produces proteins that must be removed from tissues after they have fulfilled their functions. Until now, scientists believed that the primary pathway for removing such waste was through the lymph nodes of the neck. However, the new study has shown that the actual clearance system works differently.

To trace the pathway of proteins, the researchers genetically modified mouse neurons, causing them to produce a glowing green protein. This allowed them to observe, for the first time, the movement of waste from the moment of its formation to its removal from the body.

It turned out that only a small portion of proteins reaches the cervical lymph nodes. Instead, the majority of them leave the brain through its membranes, skull tissues, and nasal passages.

Additionally, the scientists discovered that different brain regions use their own clearance routes. Proteins from the upper regions were removed through nearby pathways, while waste from deep structures exited through channels at the base of the brain. The researchers called this principle the "nearest exit model."

In an Alzheimer's disease model, this system's function was found to be impaired: protein waste was less efficiently cleared from the brain and began to accumulate in tissues. The authors believe that such disruptions may contribute to the accumulation of toxic proteins characteristic of neurodegenerative diseases.

According to the researchers, the discovery will help to better understand the mechanisms behind the development of Alzheimer's disease and may in the future lead to new treatment methods aimed at restoring the brain's natural clearance system.