We know that MS can differ in men and women. We’re now working to understand the role hormones like oestrogen and testosterone play in MS.

About hormones and MS

Hormones are a type of chemical messenger in the body. They travel through the blood and instruct our bodies to do lots of important jobs – from controlling our temperature to telling us when we’re hungry.

Our sex hormones are a special type of hormone responsible for the development of our reproductive system. They drive the physical differences between men and women. Oestrogen, testosterone and progesterone are all sex hormones.

Men and women have different levels of these sex hormones. Women generally have high levels of progesterone and oestrogen and low levels of testosterone, while men generally have high levels of testosterone and low levels of progesterone and oestrogen.

As well as giving men and women different physical features, we think these sex hormones play a role in MS.

Women are two and a half times more likely to be diagnosed with MS than men. Although men are less likely to be diagnosed with MS, the course of the condition is often more severe in men and it can take less time for their MS to become progressive.

Researchers are trying to understand what role different hormones play in MS. Studying the differences between men and women is one way to do this.

Hormones are likely to affect activity in our immune systems or how our nerve cells stay safe and healthy.

Oestrogen and MS

Oestrogen levels vary a lot throughout our lives. Sometimes there are more dramatic changes, like during pregnancy or menopause.

We know that pregnant women generally have fewer symptoms of MS. There have been lots of studies looking at the impact of pregnancy on MS. They all show that pregnancy appears to have a positive influence. The number of relapses tends to go down, especially during the third trimester when oestrogen levels are especially high. We don’t yet know exactly why this happens. Although oestrogen probably plays a very important role, lots of other things also change during pregnancy, like levels of progesterone and vitamin D.

In the first three months after the baby is born, the risk of relapse rises. We think this happens because hormones return to pre-pregnancy levels.

Read more about pregnancy and MS

Some studies have shown symptoms of MS can get worse for some women after the menopause, when the body stops producing oestrogen. In two small surveys, 40-54% of women said they felt their MS symptoms got worse after menopause. In a larger online survey, women who went through the menopause earlier, reported worse symptoms. Researchers in the US followed 124 women with MS over 10 years and found that menopause might have a small effect on MS disability getting worse. This worsening of symptoms could not be explained by vitamin D levels, treatment changes or smoking status.

The menopause makes hormonal differences between men and women less extreme - whichcould also explain why men and women with late onset MS have a more similar experience of symptoms. But some studies have not found a link between menopause and MS symptoms getting worse. A small study published in 2018 showed that after the menopause, women with MS actually experienced fewer relapses, but there was no change in how much their disability progressed.

More research is needed to fully understand the impact menopause can have on MS, but it highlights the potential effect of hormones like oestrogen.

Testosterone and MS

Some studies have suggested that men with MS may have low levels of testosterone. A study in the US of 96 men with relapsing remitting MS, found that over a third had a condition called hypogonadism, where the body doesn’t produce enough testosterone. Lower levels of testosterone were also linked to more severe disability. But this study didn’t compare their results with a group of men without MS. Another study looked at data from hospital records of 5000 men with hypogonadism. They found that these men were more likely to be diagnosed with MS than men who did not have the condition.

One of the few studies of that investigated testosterone in women with MS found that women with lower levels of testosterone showed more lesions on an MRI scan.

But not all studies have found a link between MS and lower levels of testosterone. And unfortunately some didn’t look properly at other factors that could have explained the differences.

Importantly, it is hard to tell whether low levels of testosterone could be a cause or a symptom of MS.

What other hormones play a role in MS?

Our thyroid hormones are produced by the thyroid gland in the neck. They move around our bloods and affect our heart rate, body temperature and how we convert food into energy.

Researchers believe thyroid hormones also play a role in the creation of myelin. As well as studying this in mice and rats, they have also begun a small phase 1 clinical trial to test the safety and dosage of thyroid hormones for remyelination in MS.

Understanding the differences between men and women with MS, and the role of hormones, could be important for prevention and treatment.

We hope understanding the role of hormones in MS could lead to new targets for treatments. However, more research is needed.

And hormones alone don’t explain the differences in MS between men and women. Researchers think genetic and environmental differences are also a key part of the puzzle.

Scientists have studied how changing hormone levels can affect an MS-like condition in mice called EAE. Lots of studies have shown that giving both female and male mice different types of oestrogen treatment can reduce the effects of EAE.

One study shed some new light on the potential role of testosterone in MS. They showed that the high levels of testosterone seen in male mice triggered an immune response that protected them from EAE. In contrast, low levels of testosterone in female mice increased their risk of EAE. But the researchers concluded that this process alone wouldn’t be enough to protect against MS. And more research is needed to confirm if these results apply to people.

Several small trials have also tested the benefits of oestrogen for women with relapsing MS. One phase 2 study found that taking oestriol with a disease modifying therapy (DMT) reduced relapses by 47% after one year. This was when compared to just taking a DMT alone. The effect was less obvious in the second year of the trial. We need larger trials to fully test the benefits of oestrogen for women with MS.

A study in California did look at the potential of testosterone as a treatment for MS. The researchers found an improvement in cognitive performance and slower loss of brain tissue from using testosterone skin gel. But this was a very small pilot trial, with only ten men with relapsing remitting MS, so we need much more research before we can begin to properly understand the potential of testosterone in MS treatment.

Our hormones research

 We recently funded a study at the University of Oxford aimed at trying to understand how women’s bodies are able to suppress MS symptoms during pregnancy. Researchers will look at changes in immune cells before, during and after pregnancy.

Read about current projects investigating hormones and MS