How does the epidemiology of Multiple Sclerosis provide clues to its cause?
Some unusual features characterize the epidemiology of Multiple Sclerosis.
Multiple Sclerosis is more common the farther one moves away from the equator.
It is more common in women than men.
It primarily strikes people of northern European ancestry and is almost unknown in other racial groups such as Eskimos and Gypsies, a finding that may be related to specific human leukocyte antigen type (i.e., immune functions) and genetic predisposition.
The chance of developing Multiple Sclerosis seems to be set by approximately age 15 years.
A person born in a high-risk area (such as Scandinavia) who leaves for a low-risk area (in the tropics) after age 15 years will carry the high risk for developing MS.
A person who emigrates before age 15 years acquires the low risk of the new home. In short, the risk of Multiple Sclerosis is determined before age 15 years, even though the disease itself does not appear, on average, until age 30 years.
Unfortunately, none of these tantalizing epidemiologic findings has yet led to a coherent hypothesis for the etiology of Multiple Sclerosis .
The cause of Multiple Sclerosis is still unknown.