Two observations led a team of British scientists to explore the link between sugar and Alzheimer's disease.
Firstly, the fact that prevalence of Alzheimer's disease is increased in individuals with diabetes. High blood sugar levels also increase prevalence of this disease in non-diabetic individuals.
Secondly, the fact that proteins chemicaly modified by sugar are present in the earliest stages of Alzheimer's disease pathology.
That said, the molecular link between Alzheimer's disease and sugar had to be clarified.
The British group now propose a model.
In their study published last February in Scientific Report, they suggest a mechanism explaining how too much blood sugar can contribute to Alzheimer's disease.
High blood sugar damages the cells by attacking proteins in a process called "glycation."
The British team behind the study discovered that the glycation of a particular protein, named MIF, impedes brain cells responsible for removing waste.
As a result, waste such as protein aggregates accumulates in the brain.
The researchers made their discovery by comparing brain samples from people with and without Alzheimer’s disease at an early stage.
According to them, the inactivation of the MIF protein by sugar could be the tipping point that causes uncontrolled accumulation of amyloid-beta plaques in the brain, and eventually Alzheimer’s disease.
The team is now searching for a similar biomarker in the blood.
Having such a biomarker would allow scientists to identify cases of Alzheimer's disease several years before the onset of symptoms.
Nonetheless, this study reveals one important finding to keep in mind: an excess of sugar can not only lead to diabetes, but Alzheimer's disease too.