We know that MS is more common among people in Europe, the United States, Canada, New Zealand, and sections of Australia and less common among people in Asia and the tropics. Within regions with temperate climates, cases of MS increase in incidence and prevalence farther from the equator (or in higher latitudes). The color-coded map below shows the number of people with MS throughout the world. Notice that greater numbers are found in higher northern and southern latitudes.
World distribution of multiple sclerosis: greater prevalence in higher northern and southern latitudes
In the US, the number of people with MS is estimated to be about 400,000, with approximately 10,000 new cases diagnosed every year (that’s 200 new cases per week).
Is MS more common in females than males?MS is much more common in females than males, about 2 to 3 times more common in relapsing-remitting MS. This is also true for other autoimmune diseases, like rheumatoid arthritis.
In which age groups is MS most common?MS can affect people of any age. However, it’s most commonly diagnosed in people between the ages of 20 and 50 years. The average age when MS symptoms first appear is between the ages of 30 and 35 years. Researchers have found that MS affects different age groups differently. For instance, people who are diagnosed when they are 50 years or older typically have a more progressive disease course.
Is MS more common in certain ethnic groups?MS is more common among Caucasians and among people of Northern or Central European descent. By contrast, MS is less common among Hispanics, Asians, and in people of African descent. MS rarely occurs among some ethnic groups, such as Inuits, Aborigines, and Maoris.
Is MS becoming more common?Compared with years ago, an increasing number of people are being diagnosed with MS. However, researchers are unsure if this means that the incidence of MS is increasing. Instead, it may be that there is increased awareness of MS and better diagnostic tools, such as magnetic resonance imaging (MRI), for diagnosing the disease. Additionally, the availability of better treatment options may make physicians more willing to make a firm diagnosis of MS.
The possibility does exist that MS is increasing which may be linked to exposure to environmental factors, such as viruses or bacteria or toxins, or changes in lifestyle, or some, as of yet, unknown factor.
Organizations such as the US Centers for Disease Control and Prevention (CDC), the National MS Society, and the Parkinson’s Action Network are exploring the possibility of establishing a shared national registry for chronic neurologic diseases. Such an effort could shed light on important research questions about MS, including whether it is on the rise.