Women with multiple sclerosis are being diagnosed at younger ages and in greater numbers than men, except for those with primary progressive disease (PPMS), where men 50 or older tend to predominate, a European review study that looked at trends over several decades reports.
The study “Age‐dependent variation of female preponderance across different phenotypes of multiple sclerosis: A retrospective cross‐sectional study” was published in the journal CNS Neuroscience & Therapeutics.
MS particularly affects women, with the last decades showing a greater disease prevalence among women and an increase in the female-to-male ratio. This is true for the relapsing‐remitting (RRMS) form of the disease, while in primary progressive MS (PPMS) the opposite occurs, with a slightly higher male preponderance, approximately 60 percent.
Still, “studies investigating the sex distribution in MS are sparse,” the researchers wrote.
A team led by researchers at the University of Bern, in Switzerland, collected data from people being treated for MS across four European centers — one each in Greece and Switzerland, and two in Germany — along with data from previously published retrospective MS studies.
They analyzed data looking specifically at the female‐to‐male ratio at MS diagnosis, and how findings associate with age at diagnosis and year of birth.
Their analysis included 945 patients — 52 diagnosed with radiologically isolated syndrome, 170 with clinically isolated syndrome (CIS), 625 with RRMS, and 98 with PPMS.
Results showed that age at diagnosis varied among the different MS subtypes, with PPMS first being detected in people of an older age (median of 50 years).
But data looking at all MS patients showed women to be younger (mean age, 34) at diagnosis than men (mean age, 38.9 ).
The overall ratio of women diagnosed with MS was 1.9 times higher than that of men, except for those with PPMS — in this subtype, men were twice as affected as women.
Interestingly, the higher prevalence of women with MS declined with increasing age at diagnosis; among RRMS patients, those first diagnosed at age 58 or older were more often men — a gender switch “not found in other disease courses,” the study notes.
Overall, “our data demonstrate an age dependency of female preponderance in MS except for PPMS,” the researchers wrote.
“Differences between MS phenotypes may provide further insights into pathophysiology with female sex hormones being associated with stronger autoimmune responses, while male sex hormones may predispose to neurodegeneration during the progressive phase of the disease,” the researchers suggested.