ORKNEY continues to top the table for rates of multiple sclerosis in Scotland, a study has revealed.

Tayside has the highest incidence of the disease in mainland Scotland, while the central belt and Borders have the lowest rates of MS.

The findings provide the first detailed snapshot of people affected by the disease across the country.

They are from the Scottish Multiple Sclerosis Register – a national database with records of people diagnosed since 2010.

The only previous analysis was based on a survey of MS-related hospital admissions across Scotland. 

The study confirms that Scotland has one of the highest rates of MS diagnosis in the world.

Read more: Researchers in bid to explain Scotland's high rates of MS

It also exposes huge regional variations in the disease.

The widest gulf is between females in Orkney - where 19.9 per 1000 women will develop MS in their lifetime - and men in the Borders, whose lifetime risk of the disease is just 1.6 per 1000.   

That equates to a woman in Orkney having a one in 50 chance of developing MS during her lifetime, compared with around one in 600 for a man living in the Borders.

Research has previously suggested that lower exposure to vitamin D, naturally generated by the human body in response to sunlight, could be a risk factor for the disease.

It is more common among populations further from the equator and Scotland has a higher incidence than England and mainland Europe.

However, the map reveals that the prevalence of MS varies substantially between regions, even on the mainland.

The researchers, from Edinburgh University, also said that they believe previous estimates for MS prevalence in Scotland "are likely underestimates". 

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Women are particularly susceptible, with rates of the disease double that of men.

The study adds weight to previous findings that disease rates are greater in northern regions but suggests that other factors may also be important.

Figures showed incidence of the disease in Shetland is more than one-third lower than in Orkney, despite Shetland being located farther north.

Rates of MS in Tayside are almost double those in Lothian, however.

Further studies are needed to probe the underlying causes of regional and gender differences, the team says.

The research was led by the Anne Rowling Regenerative Neurology Clinic at the University of Edinburgh.

It is published today in the Journal of Neurology.

Read more: Struggle of one of Scotland's youngest MS patients - aged 13

Dr Patrick Kearns, Rowling Scholars Training Fellow at the University of Edinburgh’s Centre for Clinical Brain Sciences, said: “The Scottish MS Register is a powerful new resource – the result of substantial far-sighted investment – which builds on the strength of the NHS in Scotland. It allows us to study, in detail, the geographic risk of developing MS.

“There is much more work to be done, not least to further ensure the accuracy and precision of the register.

"However, our hope is that by understanding more precisely where the areas of higher and lower risk are found in Scotland, we can start to work out why.”