People living on a group of Scottish islands could have the highest rate of multiple sclerosis in the world thanks to the Vikings, researchers claim. Scientists at Edinburgh University found that one in every 170 women in the Orkney Islands suffers from the disease. Dr Jim Wilson, who led the study, said their Norse ancestry may be at least partly to blame. The Vikings used the islands as a base for their raids and they remained under the rule of Norwegian “jarls” until 1231.
Dr Wilson, a genetics expert at Edinburgh University, said: ‘Something people have thought for a long time is that the prevalence of MS could be linked to the island’s Scandinavian history, and this could be an explanation for it, though not the entire story.
‘Studies that I have done, as well as others, show that half of the general population of the isles originates from Scandinavia, through the Vikings.
‘There are places in Scandanavia with a higher prevalence [of MS], but there is also a real Scottish element to this disease.
‘We studied in Canada as well and area’s where there is a large Scottish heritage seems to have more people that suffer from the disease, compared to a place like Quebec where the descendents are mainly French.
‘I think there is a combination of genetic and environmental factors- a lack of vitamin D from the limited sun exposure is also considered to be linked.’
Dr Wilson said that the 20,000 population on the Orkneys could be more exposed due to an inherited genetic weakness yet to be discovered by scientists.
He said: ‘With this clustering, some people would try to say it is due to the soil or something in the water. But, at least in the past, people married in their own community very often.
‘At some level with their genetic background people in a parish are part of the same extended family. Even if we have not been able to find a genetic factor [to explain the dense levels of MS] it does not mean that it is not out there.’
MS causes myelin – a layer that insulates nerve cells in the brain – to break down. This weakens and slows the messages sent through nerves cells from the brain to other parts of the body. The symptoms include numbness, loss of eyesight, fatigue, dizziness and muscle weakness that can accumulate, leading to disability.
It has long been known that Scotland, and the Orkney islands in particular, have among the world’s highest rates of MS along with parts of Canada and Scandinavia.
The last comprehensive study was in 1974, which found the number of people in Orkney diagnosed with probable or definite MS was 309 per 100,000.
The new research, published in the Journal of Neurology, Neurosurgery & Psychiatry, found this has now increased to 402 per 100,000, which would equate to roughly 80 people on the islands.
This compares to 295 per 100,000 in Shetland and 229 per 100,000 in Aberdeen. The most recently reported rates for Alberta and Nova Scotia in Canada were about 350 per 100,000.
Dr Wilson, of Edinburgh University’s Centre for Population Health Sciences, said better diagnostic tests, along with better survival chances, may help explain why the number of sufferers had increased.
He said: ‘It could also be a real underlying trend – that there is a rise in the number of people developing the disease.’
There were ‘in-comers’ with MS as well as lifelong residents, but no evidence that lots of people chose to live in Orkney because they had MS.
MS has long been linked to the so-called sunshine-drug Vitamin D, but Dr Wilson said that as the Shetland Islands, further north, appeared to have less of a problem than Orkney this was unlikely to fully explain the Orkney situation.
A study measuring vitamin D levels in thousands of Orcadians is currently taking place.
Mr Wilson said: ‘We saw within Orkney and Shetland there were hotspots and cold spots. Some isles and parishes and villages had a much increased rate and in other parts there were hardly any residents who had it.’