How does geographical migration affect the risk of developing multiple sclerosis?

The impact of geographical migration on the risk of developing multiple sclerosis (MS) is well documented in epidemiological studies. Individuals who migrate from regions with low incidence of MS to areas with high incidence show an increased risk of developing the disease, particularly if the migration occurs during childhood or adolescence.

The reason behind this trend lies in the critical period of neurodevelopment and potential environmental factors that can influence susceptibility to MS. When individuals migrate to a different geographical area, they may adopt the environmental exposures of the new location, which might include factors such as diet, climate, or viral exposures that are associated with MS risk.

The statement that migrants retain original risk if moving after age 15 reflects the understanding that after this age, individuals are less likely to be influenced by the environmental factors linked to the new area, thereby maintaining the risk associated with their original location. This points to the idea that pre-adolescent years are crucial in terms of the development of MS, making the timing of migration a significant factor.

This information highlights the importance of age at migration in determining MS risk, as opposed to suggesting that everyone consistently retains their original risk regardless of age, or asserting that individuals moving from low to high risk areas see no change in susceptibility. Additionally, stating that