Female Sex Hormones & Multiple Sclerosis

It has been known for a while that women are more likely to develop multiple sclerosis than men.  There have been many studies that have indicated that this may be related to female sex hormones.  For example, it has been shown that during pregnancy, the relapse rate drops significantly (up to a 70% decrease during the last trimester).  However, women are also highly susceptible to severe relapses in the 6 months after giving birth.  In paediatric MS, relapse rates increase as a girl begins to enter puberty, further highlighting the role that sex hormones may be playing in the disease process.

If we isolate the pregnancy example, we can analyse the changes in hormone levels across this period.  Looking at the above image, we see that during the last trimester, oestrogen and progesterone are at high levels, whereas the gonadotrophins are at low levels.  After birth, we can see that the oestrogen and progesterone levels drop rapidly.  It is also known that the gonadotrophin levels increase again after birth.  Does this mean that oestrogen and/or progesterone have a protective or beneficial effect in MS?  Or do the gonadotrophins have a negative impact?  Is it a combination of the two?

Considering the information above, it is plausible that the contraceptive pill (which regulates these hormone levels) would have an impact on MS.  In the first in a series of articles on this topic, we are going to look at whether the contraceptive pill decreases the likelihood of getting MS.  Unfortunately, the answer to this question isn’t simple.  Two separate studies have asked this question and received very opposite results.  In one study (published in the Archives of Neurology), it was found that the risk of developing MS was 40% lower in women who took the pill.  However, in a more recent study (presented at the 2014 American Academy of Neurology meeting), it was suggested that women who took the pill were between 35-50% more likely to develop MS.

It is thought that the difference in the results may be due to the types of contraceptive pill taken (mostly in terms of the types of progesterone used).  Although there is no clear answer, the studies do provide further evidence of a role for female sex hormones in the development of MS and suggest that determining a clear answer will be useful in helping our understanding of MS.  As well as potentially having a protective effect before MS occurs, these hormones have also been tested as possible therapeutics.