Multiple sclerosis rates are rising in what are generally considered low-risk areas because of population and ethnicity changes, according to researchers.
Countries that traditionally have low rates of multiple sclerosis (MS) are seeing cases rise, according to research published Aug. 26 in BMC Neurology.
Researchers from the Department of Medicine at the University of Kuwait assessed MS risk in second-generation and migrants who were born in or lived in Kuwait between January 1, 1950 and April 30, 2013 from the Kuwait National MS Registry.
In general, the Arabian Gulf region is a low-risk zone for MS, the researchers noted, while the United States is considered a high-risk zone. However, they suggest, recent studies show MS prevalence has increased in recent years, which the researchers attribute to population and ethnicity changes.
During the study period, the overall risk for MS in migrants per 100,000 births was 23.8. Non-Kuwaiti females demonstrated a statistically significant higher risk of MS over their non-Kuwaiti male counterparts; 28.6 versus 18.7 per 100,000 births, respectively.
The researchers also examined the MS risk in participants for the specific month-to-month distribution. In non-Kuwaiti patients, the risk did not differ significantly. However, births in September through February showed an increased tendency for MS in non-Kuwaiti births based on the Hewitt’s non-parametric test.
“The MS risk among migrants seems to be dependent not only on a sufficiency of people who change their residence from one risk area to another but also on ages at immigration and their length of stay (exposure period) in the new land,” the researchers wrote. “Additionally, this relationship of geography and MS risk is further confounded by predilection for MS regardless of region. There is evidence from mortality data that moving from low-risk to high-risk MS regions does increase the risk of dying from MS.”
In their report, the researchers mentioned the risk of MS in southern-born US veterans who moved north in unpublished and unconfirmed studies. Similar results were found in unconfirmed studies examining Vietnamese participants who moved to France, children born in the United Kingdom born to West Indian immigrants, and the Irish population in Northern Ireland. Though unconfirmed, the researchers think the cause of MS is mainly environmental, which they believe means it is preventable.
“In line with earlier studies investigating the genetic and spatial epidemiology of this complex disease, more recent studies have highlighted how MS arises from a combination of genetic susceptibility and environmental exposures acting from gestation to early adulthood,” the researchers conclude. “For example, in a recent meta-analysis it has been argued that latitude-dependent month of birth effect on MS risk is likely due to ultraviolet light exposure and maternal vitamin D level.”
The researchers hope their findings will help design MS prevention strategies in those particularly vulnerable, from gestation to early adulthood.