Behind the headlines: can the different rates of MS in men and women be explained by testosterone?

Fri 02 February 2018

Caitlin Astbury

Recent media reports suggest testosterone plays a role in protecting men against MS. We look behind the headlines to see what the study actually showed.

Almost three times as many women as men have MS, and understanding why could be important for prevention and treatment. We know changing hormone levels during pregnancy have a big impact on MS, but the exact ways hormones are involved in MS are still largely unclear.

New research suggests that the hormone testosterone may have role to play.

Is IL-33 the ‘guardian’ molecule?

Researchers at Northwestern University in Chicago looked at the role hormones play in the immune response in MS.

They studied a mouse model of MS called EAE (or experimental autoimmune encephalomyelitis). These mice lose the protective myelin around their nerves and experience inflammation in the brain in a similar way to the human condition. 

The researchers showed that the high levels of testosterone seen in male mice triggered an immune response that protected them from EAE. In contrast, the low levels of testosterone in female mice failed to trigger this response, causing them to develop EAE. The immune response was mediated by a protein molecule called IL-33.

What does this mean for people with MS?

Understanding the role of hormones in the immune response is important in MS, but more research is needed to confirm if the results apply to people.

“This paper sheds important new light on the role of hormones in the immune response, but these results have so far only been shown in a mouse model of MS.” said Dr David Schley, our Research Communications Manager, “The researchers concluded this process alone would not be enough to protect against MS, and we need to see studies in humans to know whether it has potential.”

Although men have a significantly higher level of testosterone than women, it may be they react differently to it too - in the same way that a strong cup of coffee will have less effect on someone who regularly has caffeine.

Treating and preventing MS

This early study found a response only in one specific strain of mice, and so it is not clear if the processes identified could be a potential target for new treatments. David said “ There is, however, an undeniable need for new treatment targets, which is why we’re investing in research across the whole of the UK. Naturally we welcome any studies that are a stepping stone to that goal.”

We know that hormones alone don’t explain the cause of MS. Lots of different factors influence whether someone develops the condition - it’s likely to be a mix of genes, things in your environment and lifestyle factors.