There are some clear racial and gender differences in the behavior of multiple sclerosis which are important in management and in prognosis.
At the American Academy of Neurology meeting in April of 2016, Dr. Annette Langer-Gould presented evidence that vitamin D levels which are very important in both the risk of developing MS and in its severity in Caucasians, did not apply to Americans of African origin. The effect of ultra violet light is important in converting vitamin D precursors into the active form of the vitamin. Despite this lack of correlation with vitamin D, the risk did correlate with ultraviolet (sun) exposure. The reason for this is not known. I hypothesize that it relates to two other risk factors for MS. First, obesity which is a known risk factor for MS. People who work outdoors are rarely obese. Think construction workers, farm workers and those who work on landscape. These people are generally well built but rarely obese. The second factor is sodium. People who work outside sweat a lot and lose sodium in the process. Serum sodium level is another known risk factor for MS. At least in the South Eastern U.S., the diet is generally high in sodium. This was necessary 60 years ago when a large part of the black population worked in the fields but diet has changed relatively little with the urbanization that has occurred with the introduction of machines to do what used to be done by hand. Thus, sodium levels are higher in those who work inside in more sedentary occupations than they are in those who work outside. This may explain much of the increase in MS that has occurred in the Southern U.S. over the past 50 years.
Multiple sclerosis, on average is much more severe in people of African origin than in Caucasians. This is particularly true in the black male population where disability appears to progress much more rapidly. Part of the problem has been the lack of response to interferons which was the mainstay of MS treatment until quite recently. We have suspected now for several years that the interferons don’t work well in the black population and this was confirmed by the work reported by Dr. Langer-Gould. Fortunately we now have multiple treatment options.
Asians with MS are more likely to have what is known as optico-spinal MS. Some of these cases turned out to be neuromyelitis optica (NMO) but many are MS and the optico-spinal form is more aggressive than the usual relapsing remitting MS. I am not aware of any reported differences in response to MS drugs in this population.
It has been difficult to get clinical trial data broken down by race. Bayer did a very large trial comparing Betaseron®, double dose Betaseron® and Copaxone® but we have not been able to get a breakdown by race. With the newer medications we are not aware of racial differences in their effectiveness. It seems clear that natalizumab (Tysabri®) is effective regardless of race. Experience with the other newer medications is too limited to know if there are significant differences in the response.
There is a large international consortium doing extensive genetic work on MS looking at risk factors and factors that affect severity. I expect that they will find a number of genetic factors that relate to disease severity as well as basic disease risk and, eventually, i expect we will be able to tailor treatment based on genetic factors.