Experts may have found a way of stopping multiple sclerosis (MS) in its tracks, promising new research suggests.
Scientists are still not exactly sure of what causes the disease that affects around 150,000 people in the UK and more than 900,000 Americans.
Research has previously suggested MS is triggered by damage to the myelin sheaths in the nervous system, the protective coverings around nerve fibers.
Special cells in the nervous system called oligodendrocytes are the only way to produce and protect myelin sheaths.
Now, US scientists say they have discovered a built-in 'brake' that prevents myelin from developing too early, helping to ensure oligodendrocytes can protect myelin sheaths.
The 'brake', is a protein known scientifically as SOX6.
Dr Kevin Allan, a researcher in genetics at Case Western Reserve University in Cleveland and study co-author, said: 'We were surprised to find that SOX6 can so tightly control when oligodendrocytes mature. 'This gives us a potential explanation for why these cells often cannot restore myelin damaged neurons in diseases like MS.'
Jesse Zhan, a neuroscience researcher at Case Western Reserve University and study co-author, added: 'Our findings suggest that oligodendrocytes in MS are not permanently broke, but may simply be stalled.
'More importantly, we show that it is possible to release the brakes on these cells to resume their vital functions in the brain.'
In the study, published in the journal Cell, researchers tracked thousands of molecular changes in the cells before pinpointing the protective effects of SOX6.
But the same effect was not seen on samples from Alzheimer's and Parkinson's disease patients, suggesting it may only help patients with MS.
The researchers, however, cautioned further research must first be done to prove this is the case.
MS is a debilitating condition that affects the brain and spinal cord and leaves people with mobility issues, memory loss and fatigue.
There are two main types of MS: relapsing remitting, in which symptoms flare and subside for periods, and primary progressive, in which there are no periods of remission and symptoms worsen steadily, leaving the suffering disabled.
Many patients with relapsing remitting MS develop the primary progressive form.
There is no cure but some treatment can slow progression and ease symptoms, so offering the right medication at the right time is key to keeping patients well for as long as possible.
Symptoms of the condition include fatigue, numbness and tingling, loss of balance and dizziness, and stiffness or spasms.
Memory and thinking problems, vision changes, bowel trouble, bladder problems, pain, and tremors are also key signs.
Many people discover they have MS in their thirties and forties, but the first signs can start years earlier.