"We are now investigating if we can detect similar changes in blood.

"Normally MIF would be part of the immune response to the build-up of abnormal proteins in the brain, and we think that because sugar damage reduces some MIF functions and completely inhibits others that this could be a tipping point that allows Alzheimer's to develop."

In the study, scientists from the university worked with colleagues at the Wolfson Centre for Age Related Diseases, King's College London.

Dr Rob Williams, also from the department of biology and biochemistry, added: "Knowing this will be vital to developing a chronology of how Alzheimer's progresses and we hope will help us identify those at risk of Alzheimer's and lead to new treatments or ways to prevent the disease."

Globally, there are around 50 million people with Alzheimer's disease and the figure is predicted to rise to more than 125 million by 2050.

Dr Omar Kassaar, from the University of Bath, added: "Excess sugar is well known to be bad for us when it comes to diabetes and obesity, but this potential link with Alzheimer's disease is yet another reason that we should be controlling our sugar intake in our diets."

The study, funded by the Dunhill Medical Trust, used brain tissue provided through Brains for Dementia, a joint initiative between Alzheimer's Society and Alzheimer's Research UK in association with the Medical Research Council.