A small group of Scottish islands has been identified as having the highest rate of multiple sclerosis in the world.
The Orkney Isles have more people with the degenerative neurological condition than any other place, according to a study that charts the prevalence of the disease worldwide.
It is the first study of its kind in nearly 40 years.
The research also found that the number of people with MS in Orkney has increased significantly and that one in 170 Orcadian women suffer from the condition.
Previous studies have shown high rates of MS in Orkney along with other parts of Scotland, Canada and Scandinavia.
The new study has found that the rate for probable or definite MS in Orkney is now 402 per 100,000 up from the previous high of 309 per 100,000, which was recorded in 1974.
The current figure for Orkney compares to 295 per 100,000 in Shetland and 229 per 100,000 in the city of Aberdeen.
Previously reported rates for Alberta and Nova Scotia in Canada were around 350 per 100,000, but in Quebec, rates were recorded to be only 180 per 100,000.
Multiple Sclerosis 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.
This can cause symptoms such as numbness, visual loss, fatigue, dizziness and muscle weakness that can accumulate, leading to disability. As with other neurological disorders, once the nerve cells are damaged, they are not replaced causing the condition to progressively worsen. More than 100,000 people in the UK have multiple sclerosis.
Dr Jim Wilson, of the University of Edinburgh’s Centre for Population Health Sciences, says: “Our study shows that Orkney has the highest prevalence rate of MS recorded worldwide. These findings may reflect improved diagnostic methods, improved survival or rising incidence. We are trying to work out why it is so high, but it is at least partly to do with genes.”
The study, carried out with the University of Aberdeen, is published in the Journal of Neurology, Neurosurgery & Psychiatry.
The University of Edinburgh