Who gets MS?
Frequency and geographical distribution
MS affects more than 400,000 people in North America, approximately 500,000 individuals in Europe and 2.5 million people worldwide. The frequency of MS differs in various regions over the globe, tending to be more common in areas that are economically developed. There is strong evidence for geographical differences of susceptibility. MS has the highest frequency (i.e. the number of people in a population who get MS) in temperate zones and is less common among people residing in hot climates. Many studies support the existence of a gradient of MS frequency increasing with distance from the equator, both in the northern as well as the southern hemispheres.
In Europe, for example, it steadily increases from the South to the North.
Age of onset
MS is typically seen in people between the ages 20 and 40, although it may also start at an earlier or later age. The average onset of the condition is 30 years of age. Regardless of differences in MS frequency, the age specific incidence appears to be the same all over the world.
Sex ratio
Many autoimmune diseases, such as MS, have an unbalanced sex distribution and affect women more often than men. This also holds true for MS, with women twice as likely as men to get the condition.
Hereditary risk
The question whether MS is inherited or not is an important issue, since the condition often affects young women at an age when they are planning a family. The risk for children (of a parent with MS) to also get MS, however, is only slightly increased compared to the general population. If only one parent has MS, the risk is quite low.
Pregnancy and MS
Pregnancy does not seem to increase the overall risk of relapses. It is reported that the relapse rate goes down during pregnancy, but increases again within the first couple of months after giving birth. During pregnancy it may become necessary to stop taking certain MS drugs and therefore it is highly advisable to seek professional help from a physician to discuss further therapy even before trying to get pregnant.
