THE RISK of developing dementia depends on how far north a person lives, new research has found.
New statistics have revealed that middle-aged Scots living in the Grampian area are more likely to develop the disease compared to those who live in the Borders.
Researchers say that environmental factors – such as lack of sunlight – are to blame, and that rates of the disease could be halved if these triggers can be identified.
The study, carried out by researchers at the University of Edinburgh, focused on mapping the incidence of the disease in twins in Sweden.
It revealed that those living in the north were two to three times more likely to develop dementia compared with those in the south, when factors such as age, gender and genes were taken into account.
Another study used data gathered from a nationwide survey of children born in 1921 to examine the risk of developing dementia.
This research found that while there was no change linked to where people lived as children, by the time men and women reached middle-age there was once again a higher risk for those who lived in areas further north.
Tom Russ, clinical lecturer in old age psychiatry at Edinburgh University’s Alzheimer Scotland Dementia Research Centre, said lack of vitamin D could be one possible reason for the link.
He said: “The north-south divide does make you think about latitude and it may be it is something to do with sunlight exposure and vitamin D – that is a possibility and it has certainly been linked to healthy brain function and dementia.
“The next step is to pin down what these factors could be.
“Given that two to threefold variation, it is not going to be one factor – but if you could identify what these factors are and optimise them in the whole population, you could potentially lave dementia rates.”
Mr Russ added that the Swedish study of twins allowed any genetic factors which might explain the north-south divide to be “taken out of the picture”.
He said: “In the Scottish study, everybody was born in 1921, so they will have experienced different things all at the same time – for example, they will all have been the same age when the NHS was introduced. By middle age, there was a big variation across Scotland and it was a similar pattern: higher in the north and lower in the south.”
Lindsay Kinnaird, research manager at Alzheimer Scotland, said: “We’re delighted that Scotland is leading the way in helping us to understand what causes this illness.
“If we are able to identify environmental risk factors, then we have the opportunity to make adaptations to lifestyle that can minimise their impact.”
In 2014, approximately 88,000 people in Scotland were living with dementia, symptoms of which can include memory loss and difficulties with thinking, problem-solving and languages. Around 32,000 of these people were under the age of 65.