Summary: In a new study, researchers discovered that damage to the brainโs white matter, the “information highway” of the brain, is a primary driver of changes typically associated with neurodegenerative diseases like Alzheimerโs and Parkinsonโs.
By creating localized damage to myelin (the protective coating of white matter), the team found that the brain triggers a coordinated, remote response in connected grey matter. While this response is initially a part of the brain’s repair toolkit, the failure of myelin to regenerate turns this helpful process into the chronic inflammation that defines neurodegeneration.
Key Facts
- The Connected Response: Localized white matter damage causes remote grey matter regions to lose neuronal connections and activate microglia (immune cells). This proves that white matter lesions are not isolated events but affect the entire brain circuit.
- Inflammation as Repair: The study found that grey matter inflammation is actually necessary for healing. When researchers blocked this inflammatory response, the white matter failed to regenerate its myelin coating.
- The Chronic Cycle: If myelin fails to regenerate, the grey matter response doesn’t go away; it becomes chronic. This suggests that failed repair, rather than the initial damage itself, drives persistent low-grade inflammation in brain disorders.
- Therapeutic Shift: The findings suggest that future treatments for Alzheimerโs and Parkinsonโs should prioritize myelin regeneration to halt the progression of cognitive decline and inflammatory damage.
Source: Cambridge Stem Cell Institute
Damage to white matter in the brain can trigger features associated with neurodegenerative disease, Cambridge researchers have discovered in a new study published today in the journalย Nature.
Until now, it was thought that neurodegenerative diseases such as Alzheimerโs and Parkinsonโs disease were primarily associated with changes to the brainโs grey matter.
This new finding suggests that treatments for neurodegenerative disease should target damage to the brainโs white matter, in addition to grey matter which has been the focus until now.
The brain is equally divided into grey and white matter. Grey matter contains the brainโs processing hubs, linked by an information highway โ the white matter. Although white matter damage is a defining feature of multiple sclerosis and is also seen in neurodegeneration including Alzheimerโs and Parkinsonโs disease, the consequences of white matter damage are not well understood.
The team, led by Professor Ragnhildur Thรณra Kรกradรณttir at the University of Cambridgeโs Stem Cell Institute, created localised damage to myelin โ the main component of white matter โ in a well-defined brain circuit and followed what happened over time.
They found that small, localised myelin damage triggered a striking response in a connected, remote grey matter region. Neuronal activity fell, microglia โ the brainโs immune cells โ became activated, and connections between neurons were lost.
Crucially, these changes were not permanent. After myelin was regenerated, neuronal activity recovered, connections between neurons returned, and the inflammatory response subsided.
The study also challenges a common assumption about brain inflammation. Grey matter inflammation is traditionally viewed as harmful. But here, the team found that this transient response was part of the repair process itself. When they prevented grey matter inflammation, myelin regeneration was impaired.
Conversely, when the team blocked myelin regeneration, the grey matter response did not resolve and instead became chronic. This suggests that failed myelin regeneration may help drive the persistent low-grade inflammation seen in neurodegenerative disease.
Kรกradรณttir, who also holds a position at the University of Cambridgeโs Department of Veterinary Medicine, said: โWe found that a focal lesion in white matter is not just a local event. It can trigger a coordinated response in connected grey matter, and that response is not simply damage. It is part of the brainโs attempt to repair itself.โ
The finding is particularly relevant to multiple sclerosis, where white matter lesions, chronic inflammation and incomplete myelin regeneration are closely linked to disease progression.
The work offers a new framework for understanding how local white matter damage may contribute to wider dysfunction across the brain and, when regeneration fails, to sustained inflammation.
Professor Alasdair Coles, Professor of Clinical Neuroimmunology and Head of Clinical Neurosciences at the University of Cambridge, added: โThese findings suggest that therapies enhancing myelin regeneration could help slow the progression of a potentially wide range of brain disorders.โ
Key Questions Answered:
A: If grey matter is the “processing center” where thoughts happen, white matter is the cabling that connects those centers. Without healthy white matter, the different parts of your brain cannot communicate, leading to the “disconnection” symptoms seen in many neurological diseases.
A: In the short term, yes. This research shows that “transient” inflammation is a signal the brain uses to start the repair process. The problem starts when the repair (remyelination) fails, causing the inflammation to get “stuck” in the on position, which eventually kills neurons.
A: MS is already known as a white matter disease, but this research provides a new framework. It shows that by focusing on regenerating myelin, we aren’t just fixing the “cable”, we are actually protecting the “processing hubs” (grey matter) from turning chronically inflamed and degenerate.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neuroscience research news
Author:ย Laura Puhl
Source:ย Cambridge Stem Cell Institute
Contact:ย Laura Puhl โ Cambridge Stem Cell Institute
Image:ย The image is credited to Neuroscience News
Original Research:ย Open access.
โFocal white matter lesions drive grey matter inflammation and synapse lossโ by Omar de Faria Jr,ย Stavros Vagionitisย (ฮฃฯฮฑฯฯฮฟฯ ฮฮฑฮณฮนฯฮฝฮฏฯฮทฯ),ย Andrea Lopez-Lopez,ย Michael Perry,ย Joseph Jo Yin Wongย (้ป็ฅๅฝฅ),ย Leslie Rodrรญguez-Kirby,ย Bastien Hervรฉ,ย Balazs Viktor Varga,ย Eneritz Agirre,ย Sabrina Ghosh,ย Sebastian Timmler,ย Mert Yucel,ย Andrew T. Setley,ย Kimberley Anne Evans,ย Tanja Mist Birgisdรณttir,ย Sindri Gรญslason,ย Yan Ting Ngย (ๅณ่ค้),ย Courtney Kremler,ย Helene O. B. Gautier,ย Yasmine Kamen,ย Helena Pivonkova,ย Katrin Volbracht,ย Felix Hildebrand,ย Christian A. Cepeda,ย Javier Rueda-Carrasco,ย Soyon Hong,ย George Malliaras,ย Sabine Dietmann,ย Gonรงalo Castelo-Brancoย &ย Ragnhildur Thรณra Kรกradรณttir.ย Nature
DOI:10.1038/s41586-026-10414-w
Abstract
Focal white matter lesions drive grey matter inflammation and synapse loss
Focal white matter lesions occur in most neurodegenerative disorders. Despite occurring early in disease, white matter lesions are considered to be independent of, or secondary to, grey matter neuroinflammation, synapse loss and altered neuronal activity.
Notably, their functional effect on neuronal circuits remains understudied. To address this, we generated a focal white matter lesion inย the rat brain withinย a clinically relevant, anatomically well-defined circuit, in which these lesions occur in many neurodegenerative disorders.
Hereย we show that focal white matter lesions evoke transient neuronal activity changes and microgliosis, with subsequent synapse loss and increased microglial engulfment in the grey matter, which is reversed if myelin regeneration completes.
Grey matter microgliosis is often considered to be detrimental; however, we show that it is an integral part of regenerationย and is conserved across three distinctย mouse circuits and lesioning methods.
Preventing these transient changes in the grey matter blocks myelin regeneration in the white matter. Conversely, inducing myelin regeneration failure leads to chronic grey matter neuroinflammation. This recapitulates the low-grade inflammation considered to be a dominant mechanism underlying neurodegeneration.
Our findings reveal a form of regenerative plasticity coupling white matter integrity to grey matter function, which may underlie multiple neurodegenerative conditions, and highlight the potential of targeting myelin regeneration to prevent chronic neuroinflammation.
