Monday, 12 November 2012

Research: Sex-MS is increasing in women

Trojano M et al. Geographical Variations in Sex Ratio Trends over Time in Multiple Sclerosis. PLoS One. 2012;7(10):e48078. doi: 10.1371/journal.pone.0048078. Epub 2012 Oct 25

BACKGROUND: A female/male (F/M) ratio increase over time in multiple sclerosis (MS) patients was demonstrated in many countries around the world. So far, a direct comparison of sex ratio time-trends among MS populations from different geographical areas was not carried out.


OBJECTIVE: In this paper we assessed and compared sex ratio trends, over a 60-year span, in MS populations belonging to different latitudinal areas.


METHODS: Data of a cohort of 15,996 (F = 11,290; M = 4,706) definite MS with birth years ranging from 1930 to 1989 were extracted from the international MSBase registry and the New Zealand MS database. Gender ratios were calculated by six decades based on year of birth and were adjusted for the F/M born-alive ratio derived from the respective national registries of births.


RESULTS: Adjusted sex ratios showed a significant increase from the first to the last decade in the whole MS sample (from 2.35 to 2.73; p = 0.03) and in the subgroups belonging to the areas between 83° N and 45° N (from 1.93 to 4.55; p<0.0001) and between 45° N to 35° N (from 1.46 to 2.30; p<0.05) latitude, while a sex ratio stability over time was found in the subgroup from areas between 12° S and 55° S latitude. The sex ratio increase mainly affected relapsing-remitting (RR) MS.


CONCLUSIONS: Our results confirm a general sex ratio increase over time in RRMS and also demonstrate a latitudinal gradient of this increase. These findings add useful information for planning case-control studies aimed to explore sex-related factors responsible for MS development.




This study was based in New Zealand and shows what has been happening elsewhere that MS is increasing in women. This aspect is impart influenced by distance from the equator..

6 comments:

  1. Has there been any research into eating disorders and MS? Given the rising number of women who at various stages of life (but especially in teenage years) abuse their bodies by witholding nutrition, taking slimming pills and potions and consuming "diet" meals and drinks (with all their dodgy additives) I wondered if there was any correlation.

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  2. Macmillan cancer support released analysis this week that forecast a big rise in lung cancer in women over the next thirty years. It's linked to a historic rise in women smoking, with a peak in the 1960's.

    Given the link between smoking (is this both direct and passive ?) and increased risk of MS, could this not be one of the drivers of the rise in F:M ratio ?

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    1. Prof G posted this about passive smoking when I queried it the other day: I've never smoked, but spent nearly 13 years living with parents who both smoked in the house and in the car. When we moved house, they both began smoking outdoors, but 13 years is a long time!

      http://multiple-sclerosis-research.blogspot.co.uk/2012/11/passive-smoking-and-ms.html

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    2. Yes, about 40-60% of the increased incidence may be ascribed to smoking. But as the ratio was increasing before woman started smoking there must be something else in the environment to explain this. In addition, in countries such as Iran were very few woman smoke there is an epidemic of MS amongst woman; the F:M ration is 5:1. Smoking can't explain increase incidence of MS in Iranian woman.

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  3. I imagine women in Iran are severely deficient of sunlight and therefor probably vitamin D, it is their custom to have women keep themselves almost 100% covered with veils while men don't follow any such customs, just a thought. Also, if the increase in women with MS is a more recent situation, maybe this has to do with more women's rights (admittedly still not nearly enough) that have resulted in women going to doctors instead of being forced to stay at home.

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    1. Prior to the revolution Iran was secular; woman had more rights then than they have now. They only started covering-up after the revolution. Yes you are correct they are more vD deficient, but the increase in MS cannot be explained by smoking in Iran.

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