It is a disease of the central nervous system.The symptoms of this disease is myelin (fatty insulating sheathes protecting nerve fibres) becomes damaged and scarred. It affects a person's motor, sensory and even cognitive functions. The causes of Multiple sclerosis are genetic and environmental factors.
The incidence and prevalence of multiple sclerosis in several Norwegian counties have been assessed in a number of epidemiological studies since the first nationwide study covering the period from 1935 to 1948. Although the observations are not continuous, a large increase in incidence and prevalence is reported in these studies.