Latitudinal variation in MS incidence in Scotland

Area of Science:

• Epidemiology
• Neurology
• Geographic Health Studies

Background:

• Multiple sclerosis (MS) exhibits geographical variations in incidence.
• Understanding the influence of latitude on MS distribution is crucial for etiological research.

Purpose of the Study:

• To investigate the relationship between latitude and the incidence of multiple sclerosis (MS) in Scotland.
• To determine if population density influences the observed latitude-MS incidence correlation.

Main Methods:

• Utilized MS case data from the Scottish Multiple Sclerosis Register (2010-2015).
• Linked patient postcodes to the Scottish Index of Multiple Deprivation (SIMD) for geographical data.
• Performed linear regression analysis correlating latitude bands with MS cumulative incidence and population density.

Main Results:

• Latitude was significantly associated with MS incidence rate (r² = 0.22, p = 0.03).
• A predicted increase of 1.31 cases/100,000 person-years per degree of latitude was observed.
• MS cumulative incidence rates increased with northern latitude up to 59° North.

Conclusions:

• A clear association exists between increasing latitude and higher MS incidence in Scotland.
• This latitude-MS relationship was independent of population density.
• The multifactorial nature of MS likely contributes to these observed geographical patterns.