For decades, oligodendrocytes had a simple job description. They wrap nerve fibers in myelin, the fatty sheath that lets electrical signals travel quickly, and they were considered unambiguously helpful. A study in Nature Medicine argues they can also turn against the brain they support.
Researchers at the University of Edinburgh and the UK Dementia Research Institute found that people whose thinking declined fastest in old age had a shift toward smaller nerve fibers, abnormally thick myelin on the largest ones, more oligodendrocytes, and reduced levels of a protective protein inside those cells. When the team removed that protein from oligodendrocytes in mice, the animals developed the same white matter changes and learned less well over time.
