Incidence Of Multiple Sclerosis In Japan

Multiple Sclerosis is predominately a disease of the temperate latitudes and also of the western hemisphere. Principally, it is a disease prevailing in Europe, North America, Australia and New Zealand. Although Multiple Sclerosis is found in Japan, China and some other temperate, eastern countries, it is very much rare in these places than it is in the West.

Regions north of 40 degrees latitude have a markedly higher incidence than those who are south of this divide. Within Europe, Scandinavia, The British Isles, the Low Countries and Germany have extremely high rates. Canada, northern USA and New Zealand have an equivalently high prevalence as well. Within these areas, certain localities such as the border areas of Scotland, Crowsnest Pass in Alberta, Canada, the northern-most province of Sweden and others have been found to have a really high incidence of the disease.

Why is Multiple Sclerosis distributed around the world the way it is, is not something that is well understood. There are two known features of the prevalence data for Multiple Sclerosis that need to be explained: the unequal temperate/tropical distribution of the disease and the other being the much higher rates in Western Hemisphere.

Understanding why Multiple Sclerosis is so rare in tropical climes and so common in temperate ones is a critical piece of the jigsaw puzzle of understanding why people get this disease. Population genetics, which shall be discussed later, would provide some of the answers but not the whole picture at all. There are clearly one or more environmental factors that are involved in the development of multiple sclerosis and one or more of these may have a geographic element.

One theory explains the uneven distribution of Multiple Sclerosis by focusing on the differences in the pathogens that would affect the people in the tropics versus those that affect the people in the temperate lands. A currently popular theory for autoimmune diseases is called the molecular or epitopic mimicy. This suggests that people with Multiple Sclerosis have been infected prior with a very common pathogen.

The immune responses that have been developed against that are also reactive against some parts of the myelin-oligodendrocyte complex and, as a result, they must mount an immune attack against themselves in the form of Multiple Sclerosis.

Some researchers suggest that multiple sclerosis is common in most temperate regions due to the seasonal fluctuations in daylight affecting the body chemistry. Research has shown that both disease onset and relapses are more common during the springtime and are least common in the winter. Levels of vitamin D3, melatonin and other biochemical's have all been shown to vary with the different seasons and some of these have been shown to be immunologically or neurologically quite active.

If these biochemicals are related to the development of Multiple Sclerosis in any way then do they also affect its course after onset? If they do, should therapies involving them concentrate on increasing their absolute levels inside the body throughout the year or should we attempt to load our levels only during those times of the year when they are at their lowest? Studies in other diseases suggest that this may even be a fruitful therapeutic line.

• Felicia Byrnes
• 08/06/2009, 6:59 PM
• 0 Comments