A large international study has found that the severity of multiple sclerosis (MS) can vary depending on latitude, with those living furthest from the equator worse affected by the disease.

Professor Tomas Kalincik, MS study
Professor Tomas Kalincik stands next to a whiteboard sketch of a world map, with two dots representing the rough locations of Copenhagen and Madrid and '+16%' indicating the difference between them.

The observational study led by the MSBase Study Group included data from more than 46,000 patients with MS, assessing how their symptoms varied based on their location.

While the severity of MS varies widely among individuals, the findings suggest that levels of ultraviolet B (UVB) radiation exposure could play an important role – with disparities in sunlight helping to potentially explain the link between MS symptoms and latitude.

Head of the MS Centre at the Royal Melbourne Hospital and head of the Clinical Outcomes Research unit at the University of Melbourne, Professor Tomas Kalincik played a leading role in the study.

“What we observed both in Northern and Southern Hemispheres, is that increasing latitudes seems to be associated with more severe causes of MS,” Prof Kalincik said.

“To quantify, if we compare exactly the same patients with the same characteristics living in Madrid versus living in Copenhagen, the one in Copenhagen on average will have more severe disability related to MS.

“It could possibly be related to the amount of UVB radiation, which is one of the associations that we explored in this study.

“That association seems to be determined in early life, as early as the age of six, indicating that those with a lower UVB exposure in their childhood could be more likely to experience severe symptoms of MS.

“But this relationship is not limited to childhood. There are also many other facets that we haven’t accounted for, which could all potentially play a role.

“This includes exposure to external pathogens - bacteria and viruses, dietary habits, use of sunscreen, time spent outdoors and vitamin D supplementation,” Prof Kalincik added.

Multiple sclerosis is one of the most common diseases of the central nervous system with over 25,000 people living with the disease in Australia and more than two million diagnosed worldwide.

There is currently no cure for MS, however there are treatment options available to help manage symptoms.

The RMH runs the largest MS service in Australia, with patients travelling from far and wide to receive specialist care from our MS & Neuroimmunology clinic.

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