Changes in MS Incidence During a Half-Century

That the frequency of multiple sclerosis (MS) declines with geographic latitude has long been appreciated. To examine temporal trends in incidence, these researchers conducted a systematic review of the literature from 1966 through February 1, 2007.

In their analysis, incidence of MS was greater at higher latitudes only before 1980. After 1980, incidence increased in general but particularly in lower latitudes. There was also an apparent increase in the female-to-male ratio over time, from 1.4 in 1955 to 2.3 in 2000.