A new study suggests that a key difference in the brains of male and female patients with multiple sclerosis (MS) may explain why more women than men get the disease.

Scientists at Washington University School of Medicine found higher levels of protein S1PR2 in tests on the brains of female mice and dead women with MS than in male equivalents.

Four times more women than men are currently diagnosed with MS.

Experts said the finding was “really interesting”.

MS affects the nerves in the brain and spinal cord, which causes problems with muscle movement, balance and vision.

Four times more women than men are currently diagnosed with MS

Abnormal immune cells attack nerve cells in the central nervous system in MS patients.

There is currently no cure, although there are treatments that can help in the early stages of the disease.

Researchers in Missouri looked at relapsing remitting MS, where people have distinct attacks of symptoms that then fade away either partially or completely. About 85% of people with MS are diagnosed with this type.

Scientists studied the blood vessels and brains of healthy mice, mice with MS, and mice without the gene for S1PR2, a blood vessel receptor protein, to see how it affected MS severity.

They also looked at the brain tissue samples of 20 people after they had died.

They found high levels of S1PR2 in the areas of the brain typically damaged by MS in both mice and people.

The activity of the gene coding for S1PR2 was positively correlated with the severity of the disease in mice, the study said.

Scientists said S1PR2 could work by helping to make the blood-brain barrier, in charge of stopping potentially harmful substances from entering the brain and spinal fluid, more permeable.

A more permeable barrier could let attacking cells, which cause MS, into the central nervous system, the study said.

Prof. Robyn Klein, of the Washington University School of Medicine, said: “We were very excited to find the molecule, as we wanted to find a target for treatment that didn’t involve targeting the immune cells.

“This link [between MS and S1PR2] is completely new – it has never been found before.”

She said she did not know why the levels of S1PR2 were higher in women with MS, adding she had found oestrogen had “no acute role”.

Prof. Robyn Klein would be looking at taking her findings to clinical trials in the “next few years”.

The research was published in the Journal of Clinical Investigation.