A build-up of too much sugar in parts of the brain has been linked to Alzheimer's.
For the first time, scientists have found a link between high levels of glucose in the brain and the symptoms of Alzheimer's disease.
Our brains break down glucose – sugar in its most basic form – to provide energy to make our brains work.
People whose brains were worse at breaking down glucose suffered more brain plaques and tangles, the hallmark of the disease.
In addition, people whose brains were less efficient at breaking down glucose suffered worse outward dementia symptoms - such as memory loss - associated with Alzheimer's disease.
While the research is only at an early stage, and it is not clear why being bad at breaking down glucose causes plaques and tangles.
Dr Madhav Thambisetty, at the National Institute of Aging in the US looked at brain tissue samples from autopsies collected by the Baltimore Longitudinal study on Aging, part of a research project which tracks the health conditions of people over several decades.
Dr Thambisetty and colleagues focused on brain areas that are vulnerable to plaques and tangles – the frontal and temporal cortex – highly involved in memory and language.
They also looked at areas which resist these features, such as the cerebellum which deals with movement, muscles and muscular activity.
They found that the people with more severe Alzheimer's had problems breaking down the glucose to produce energy – a process known as glycolysis.
A slower rate of glycolysis and higher brain glucose levels was associated with more severe plaques and tangles in the brains of people with the disease.
Worse brain glycolysis was also related to Alzheimer's symptoms such as memory problems.
