Scientists have discovered that immune cells, known as microglia, help maintain the health of myelin – the insulating layer that forms around nerve cells – which is important for nerve cells in the brain and spinal cord to function optimally.
Changes in the structure of myelin and damage to myelin are considered to contribute to the early stages of dementia, but the mechanisms underlying these changes are, until now, poorly understood.
The findings can be used to better understand what goes wrong in the brain in dementia and pave the way for potential future treatments, experts say.
Key role
In mice without microglia, scientists from the UK Dementia Research Institute at the University of Edinburgh observed the same changes to myelin that are seen with ageing and in neurodegenerative disease, which are associated with cognitive decline.
The same changes are present in a rare genetic disorder called ALSP, which is characterised by early-onset dementia. In ALSP a decrease in microglia occurs specifically in areas of the brain that have a high level of myelin.
Myelin damage
The team discovered that a signalling molecule released by microglia called TGF-β is important to keep myelin in a healthy state.
They plan to build on this work by understanding how microglia and TGF-β are altered in neurodegenerative diseases where myelin damage and cognitive decline occur, like multiple sclerosis and Alzheimer’s disease.
The findings have been published in Nature and were funded by the Wellcome and Medical Research Council.