We already know that MS affects more women than men, but is that the whole story?
The MS and Gender session held late last week at ECTRIMS was an informative overview of how and why MS affects males and females differently. French researcher Dr. Vukusik, who started the session off with a lecture on the epidemiology – the study of population patterns – of MS noted that the link between MS and gender is somewhat of a paradox.
While MS is more frequent in women, it appears that MS is more severe and progresses more rapidly in men. She added that the female to male ratio in MS is dependant on the status of disease at onset. For example, for relapsing-remitting MS, the ratio is 2 women to 1 man. For progressive MS, the ratio is 1:1. This was observed in both Europe and in Canada. Interestingly, the sex ratio in MS has increased by 30% since the 1940’s, which prompts the question of what may have led to the increased cases of MS in women or decreased cases of MS in men.
Researchers have looked at factors such as age, life-expectancy, diagnosis, genetics, smoking, environmental factors, oral contraceptives, age at pregnancy, etc. to come up with an explanation.
As research technology advances, more answers begin to surface. Dr. Rhonda Voshkul from the UCLA Department of Neurology has done extensive research into the role of hormones in the observed gender differences in MS. In her ECTRIMS presentation, she noted that several studies show a decrease in MS activity during pregnancy, conferring a possible protective effect governed by changes in hormone levels.
Scientists continue to conduct both human and animal research that will fully unravel the role of hormones in MS. According to Dr. Voshkul, progesterone and estradiol – key hormones in the female reproductive cycle – display anti-inflammatory and remylination abilities in a number of MS studies. In addition, removal of testosterone in mice with MS-like disease has led to worsening of symptoms. This finding suggests that testosterone may have a protective capacity in MS. New research evaluating the therapeutic potential of testosterone shows that treatment with the hormone increases brain plasticiy and remyelination in mice with MS-like disease.
I am confident that with all the great research on hormones, and other gender-specific or gender-related factors such as menopause, lifestyle habits, and genetics, we will have a clearer picture of the impact of gender on susceptibility and severity of MS, as well as a better explanation for the differences observed between men and women.