Hormones and MS - the differences between men and women


12 January 2016

The study in brief

MS is more common in women than men, so this research paper is a review of the evidence for how gender and hormones can affect MS.

The review identifies several differences in MS between men and women. For example men are more likely to develop primary progressive MS and have worse cognitive symptoms. There is an increasing proportion of women developing MS, and vitamin D has been shown to have a greater effect on the immune system in women with MS than in men.

Pregnancy also has a large effect on a woman’s MS, with less MS activity during pregnancy and an increase risk of having a relapse in the months after giving birth.

All of this evidence points to an important role of the sex hormones in MS. It will be important to work out what is going on and understand the effects that hormones have on the immune system particularly during pregnancy. This could help develop new strategies for the treatment of MS, such as treating men and women is different ways as they might respond to therapies differently.

The study in detail

Background

MS is thought to be an autoimmune condition as the immune system attacks the myelin covering of nerves in the central nervous system. In common with many other autoimmune conditions, MS occurs more often in women than in men and the proportion of women is going up. Due to this gender difference, the effect of sex hormones on MS has been an area of interest for researchers.

How this study was carried out

This research paper is a review of the evidence for how gender and hormones can affect MS.

What was found

The review found:

Gender differences

  • MS is more common in women than men, and research suggests the proportion of women with MS is increasing.
  • Women with MS appear to have more inflammatory lesions (seen on MRI brain scans) than men.
  • Men have a higher risk of developing primary progressive MS.
  • Men appear to have more neurodegeneration and women less. This may be due to higher levels of oestrogen in women as some studies have shown it to be neuroprotective.
  • Men also appear to have worse cognitive symptoms than women.
  • Men and women with late onset MS (that is diagnosis after 50 years of age) have a very similar MS course. This may be due to hormone changes that occur during the menopause, which make the hormone differences between men and women less extreme.
  • Vitamin D has been shown to have a greater effect on the immune system in women with MS than in men.

Effect of pregnancy

  • Being pregnant is associated with a lower risk of experiencing a relapse especially in the second half of the pregnancy. During pregnancy the immune system changes, so the mother’s body does not reject the baby it is carrying. These changes mean less the immune cells associated with autoimmune conditions like MS and a move towards the other types of immune cells. Many of these changes are probably related to the hormone changes that happen during pregnancy, including from hormones produced by the placenta.
  • There is a higher risk of relapse after giving birth, particularly in the first three months. The reasons for this are not entirely clear but may be due to the abrupt changes in hormones, such as a large drop off in oestrogen, and also the immune system returns to its usual state.
  • There is no evidence that childbirth affects the longer term course of a woman's MS.

Other factors

  • Being overweight or obese appears to increase the risk of developing MS. This may be due to hormones such as leptin, which is present at higher levels in people who are overweight. It is similar in structure to an immune system chemical and has been shown to have effects on inflammation. Higher levels of leptin have been found in people with MS when compared to people who do not have MS.

What does it mean?

The review concludes that it will be important to work out what is going on and understand the effects that hormones have on the immune system and autoimmune conditions. Of particular interest is what is happening during pregnancy when MS activity decreases. This could help when choosing treatments as men and women might respond to therapies differently and it might even provide a way of using hormones as a treatment, as some researchers have already tried in some small studies.

Airas L.
Hormonal and gender-related immune changes in multiple sclerosis.
Acta Neurol Scand. 2015;132(199):62-70. doi: 10.1111/ane.12433.
Abstract
Read the full text of this paper

More about hormones, gender and MS

Who gets MS and why is a complex subject but, at the moment, it occurs in about three times more women than men and research suggests the proportion of women with MS is increasing.

The reasons why it is generally more common in women than men are not really known. To try and work out why, there is an active area of research around hormones, as the ratio of men and women being diagnosed with MS is equal before puberty and after the menopause, when hormonal differences are not as extreme. Additionally many women with MS find that their MS changes around their period, during pregnancy and at the menopause when their hormone levels change. Some researchers have started to look at the role of sex hormones as potential treatments for MS with some studies suggesting they could have both an anti-inflammatory and neuroprotective effect.

As this review shows although we can see the differences in MS between men and women but more work is needed to work out if hormones are the reason for the gender differences and if so what specific effects do hormones have on the immune system.

To read more about pregnancy in MS, our A-Z on pregnancy and parenthood contains helpful information about the health aspects of MS and becoming a parent.

On this page