THE ARISING · Longevity & Healthspan
Faulty Myelin-Making Brain Cells Linked to Faster Cognitive Decline After 70
Nearly everyone loses some thinking skill in later life, but the pace varies widely from person to person. A new study suggests that one reason may lie in brain cells long seen as purely helpful: the ones that build the insulation around nerve fibers.
The work, published in Nature Medicine in 2026 by Craig and colleagues, combines two kinds of evidence. First, it is an observational study of human brain white matter, which links the tissue's features to each person's own rate of cognitive decline. Second, it includes experiments in mice. An observational link in people cannot prove cause. The mouse work was designed to test cause.
The cells are called oligodendrocytes. They make myelin, the fatty coating that helps nerve signals travel efficiently. The researchers examined changes in human white matter, the brain's wiring tracts, and compared them with how quickly each person's cognition had changed with age.
Worse cognitive trajectories were "unexpectedly" associated with smaller myelinated axons (the nerve fibers themselves), thicker myelin, and more oligodendrocytes. Those cells also showed lower activity of a gene pathway called NRF2.
To test whether that pathway matters, the team studied aged mice in which NRF2 was knocked out only in oligodendrocytes. These mice showed attenuated cognitive improvement over time. Their white matter changes mirrored those seen in the human brains with greater decline. The authors conclude that oligodendrocytes contribute to cognitive decline and that NRF2 is a possible therapeutic target.
It says the human data came from the Lothian Birth Cohort 1936, in which 1,091 people were enrolled and 866 completed cognitive testing after age 70. It says brain tissue was examined after death in a subset of participants. It also says the pattern tracked how fast people declined, not how well they scored at one age.
The coverage also says drugs that act on NRF2, including one prescribed for multiple sclerosis, might one day be repurposed. That goes further than the study shows. The study calls NRF2 a target but reports no drug test in older adults with cognitive decline. The coverage says further research is needed to learn whether such treatments would help. Veronique Miron, a senior author, said in the coverage that no current treatments exist for this decline.
Why does this matter for ordinary ageing? If the finding holds, part of normal memory and thinking decline may come from faulty upkeep of the brain's wiring, not only from the plaques and protein clumps that dominate Alzheimer's research. The weakest point is that the human evidence is observational and the mouse model is only one test of cause, so whether these white matter changes drive decline in people remains unproven.
This is a different line of research from the Arising's October 6 report on a gut bacterial molecule, ImP, linked to Alzheimer's-related brain changes. The two studies are unrelated, but both look at factors in cognitive decline beyond a single cause.
What to watch next
Whether other groups find the same white matter pattern in different populations, and whether any NRF2-targeting drug is tested for effects on thinking in older adults.
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