# Brain Cells Thought Protective May Fuel Cognitive Decline, New Study Finds

> A study published in Nature Medicine reveals that oligodendrocytes, brain cells previously considered beneficial, can become dysfunctional with age and actively contribute to cognitive decline.

By PrimaryBrief newsroom · Published 2026-10-17T20:51:29.557951Z
Canonical: https://primarybrief.com/article/brain-cells-thought-protective-may-fuel-cognitive-decline-new-study-finds-7427e5e3

Scientists from the University of Edinburgh and the UK Dementia Research Institute published new research on August 25, 2026, revealing that oligodendrocytes, brain cells previously believed to be solely protective, can actively contribute to cognitive decline by producing unhealthy myelin [1][2][5][7]. This discovery fundamentally alters the understanding of how these cells function in brain aging.

This research identifies a new pathway for age-related cognitive decline, a condition for which there are currently no treatments [2][5]. The findings offer a promising target for developing new therapies to preserve cognitive function in older adults [2][3][5].

## What the records show

The investigation centered on oligodendrocytes, specialized brain cells responsible for producing myelin, the fatty sheath that insulates nerve fibers for efficient brain communication [1][3]. Historically, these cells were considered always beneficial, playing a supportive role in brain health [1][5]. However, the study posits that as these cells become dysfunctional with age, they can disrupt nerve fibers and potentially worsen memory and thinking skills [1][3]. Researchers analyzed human brain tissue from the Lothian Birth Cohort 1936, a group whose cognitive abilities were tracked from childhood into older age [3][6]. Cognitive performance of cohort members was assessed between ages 70 and 82, using standardized tests for memory, processing speed, and spatial skills [3]. More severe cognitive decline was associated with fewer large nerve fibers and an excess of unhealthy, thicker myelin [3][5][6]. These changes correlated with the *rate* of cognitive decline over time, indicating an active process contributing to cognitive worsening [3]. A key discovery involved the protein NRF2 within oligodendrocytes [3][6]. The study found that individuals experiencing more severe cognitive decline had reduced NRF2 levels in these cells [3][6]. NRF2 regulates genes involved in protecting cells from damage [3]. Experiments in mice showed that reducing NRF2 specifically in oligodendrocytes led to excess myelin, reduced large nerve fibers, and impaired cognitive performance as the mice aged, establishing a causal relationship [3][6].

## The study's publication

The findings were published under the title "Oligodendrocyte dysfunction in human age-related cognitive decline" in *Nature Medicine* on August 25, 2026 [5][7]. Georgina Craig was identified as the first author and a Postdoctoral Fellow at St. Michael's Hospital in Toronto and the UK Dementia Research Institute [5]. Dr. Veronique Miron, an MRC Senior Non-Clinical Fellow and UK Dementia Research Institute Group Leader at the University of Edinburgh and St. Michael's Hospital, was a corresponding author [5].

## What the researchers said

Georgina Craig stated, "This study has fundamentally shifted how we think about these brain cells in aging. We have always considered oligodendrocytes as purely beneficial, yet here we surprisingly find that they can become dysfunctional and contribute to cognitive impairment in aging" [5]. Dr. Miron highlighted the broader implications for public health, noting, "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" [5].

## Potential for new treatments

The discovery also opens avenues for potential new therapeutic strategies [2]. The NRF2 pathway is already targeted by existing drugs, including some used to treat multiple sclerosis (MS) [3][5]. Previous research indicated that activating NRF2 can improve cognitive function in individuals with MS [3]. This raises the possibility that existing treatments could be repurposed to target oligodendrocyte dysfunction and combat age-related cognitive decline [2][3][5]. Further studies would be needed to translate this approach into new therapies [2][3].

## What we could not confirm

We could not confirm specific timelines for when these research findings might translate into human clinical trials or new approved therapies for age-related cognitive decline.

## Evidence cited
1. Brain cells meant to protect us may be fueling cognitive decline (www.sciencedaily.com) — https://www.sciencedaily.com/releases/2026/10/261015073222.htm
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3. Brain cells that produce the protective coating around nerve fibres can become dysfunctional with age and may actively contribute to cognitive decline, according to new research. A study found that people with more severe cognitive decline had changes to nerve fibres and myelin – the protective coating around nerve fibres that helps messages travel efficiently through the brain. Experiments in mice showed that disrupting oligodendrocytes – the cells that produce myelin – also altered the coating (eurekalert.org) — https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGADHKcxNzuNRbMC21kZSxXg9pmiyxohORLOSPmtYR-nyAq3ReI0EI2bxC-U1NFBlBR6yVGX_2LASjDrELWZVivYcYjCtT-zrJOlxzNfE-0uUIK0wTlOX-cCsfELvF_jaQuIPe5OMuTchZYtw==
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