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Researchers found that lower levels of the protective protein NRF2 in oligodendrocytes were associated with greater cognitive decline in older adults. Experiments in mice suggest that reducing NRF2 in these myelin-producing cells can damage nerve fibers and alter myelin, but whether NRF2-targeting drugs can slow age-related decline in people remains unknown.
Researchers report that oligodendrocytes, brain cells that maintain the insulating coating around nerve fibers, may contribute to age-related cognitive decline when they become dysfunctional. In a study published in Nature Medicine, lower levels of the protective protein NRF2 in these cells were linked to greater decline in older adults, while experiments in mice connected reduced NRF2 to abnormal myelin and loss of large nerve fibers.
The team, led by researchers from the University of Edinburgh and the UK Dementia Research Institute, studied participants in the Lothian Birth Cohort 1936. This group has had cognitive abilities tracked from childhood into old age. From 1,091 people enrolled, 866 completed additional cognitive testing after age 70. Tests between ages 70 and 82 assessed memory, processing speed and spatial reasoning. Almost all participants experienced some decline, but its rate varied.
Researchers examined brain tissue collected after death from a subset of participants. People who had declined more quickly tended to have fewer large nerve fibers and abnormal accumulations of myelin, the coating that helps electrical signals travel along fibers. These tissue changes were associated with the pace of decline, rather than a person’s cognitive test performance at one particular age.
The researchers also found that people with more severe decline had lower NRF2 levels in oligodendrocytes. In mice, specifically reducing NRF2 in those cells led to excessive myelin, loss of large nerve fibers and smaller improvements in cognitive performance as the animals aged. The mouse experiments support a possible causal role for NRF2 loss in the observed changes, but do not establish that the same mechanism causes cognitive decline in humans.
A New Target in Brain Aging
The findings add to evidence that cognitive aging may involve not only damage to neurons, but also changes in the cells that support them. Oligodendrocytes are generally understood to maintain myelin; this study suggests that changes in their function may undermine that support and affect nerve fibers. If follow-up research confirms the pathway’s role in people, it could give researchers a target for investigating ways to preserve brain function.
The study also points to a possible route for future treatment research. NRF2 is already targeted by drugs used for other neurological conditions, including multiple sclerosis. That makes the pathway a candidate for further study, but does not show that existing medicines prevent or reverse age-related cognitive decline. The results do not establish a treatment for older adults, and testing would be needed to determine safety and benefit in that population.
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From Long-Term Testing to Brain Tissue
The Lothian cohort gives researchers a way to compare biological findings with changes in cognition over many years, rather than relying only on test results from a single point in time. In this study, participants’ cognitive assessments in later life were considered alongside brain tissue examined after death. That allowed the team to look for features associated with different rates of decline.
Myelin is essential to normal communication along nerve fibers, but the report describes an association between faster decline and abnormal myelin buildup, particularly around remaining large fibers. The study’s findings complicate the simple view that more myelin is always beneficial. They instead point to the importance of how myelin is produced and maintained, and to the condition of the oligodendrocytes responsible for that work.
“As the prevalence of cognitive decline is rising with an aging population and no current treatments exist, we are excited about this work as it points to a potential strategy for new therapeutic strategies to preserve cognitive ability in aging.”
— Veronique Miron, MRC Senior Non-Clinical Fellow and UK Dementia Research Institute group leader at the University of Edinburgh and St. Michael’s Hospital
Human Cause and Treatment Remain Unproven
The human findings show associations between faster cognitive decline, abnormal myelin and lower NRF2 in oligodendrocytes. They do not establish that reduced NRF2 caused participants’ decline. The mouse experiments offer evidence that manipulating NRF2 can produce similar tissue changes in animals, but results in mice cannot establish what would happen in older people.
The report does not show that an NRF2-targeting drug can prevent or slow age-related cognitive decline. It also does not identify a tested dose, treatment duration or the people who might benefit. Whether the pathway explains decline across different populations, or applies to particular causes of cognitive impairment, remains unclear.
Testing the NRF2 Pathway in People
The next steps are to establish how reduced NRF2 affects oligodendrocytes and nerve fibers over time, and to test whether restoring pathway activity can protect brain function. Researchers would need to determine whether a drug that affects NRF2 reaches the relevant cells and has an acceptable safety profile for older adults.
Clinical studies would then be needed to assess whether such treatment changes cognitive outcomes, rather than only altering biological markers. Until those questions are answered, the study identifies a potential research target, not a proven therapy or a recommendation for patients.
Key Questions
What are oligodendrocytes?
Oligodendrocytes are brain cells that produce and maintain myelin, the insulating coating around nerve fibers that helps electrical signals travel efficiently.
What did the study find in older adults?
Among participants whose brain tissue was examined after death, greater cognitive decline was associated with fewer large nerve fibers, abnormal myelin buildup and lower NRF2 levels in oligodendrocytes. These are associations and do not prove cause and effect in humans.
Did the researchers show that NRF2 drugs prevent cognitive decline?
No. The study identifies NRF2 as a possible treatment-research target. It did not show that an NRF2-targeting drug prevents or slows age-related cognitive decline in people.
Why were mice used in the research?
The researchers reduced NRF2 specifically in mouse oligodendrocytes to examine whether this could produce changes resembling those seen in human brain tissue. The animals developed excessive myelin and lost large nerve fibers, but mouse findings do not confirm the same effects in humans.
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