Diet Linked To Build-Up Of Alzheimer’s Protein And Cognitive Decline

A US study has suggested that diets high in certain compounds may be linked to Alzheimer’s disease, the most common cause of dementia. The research, which investigated the effect of foods containing molecules called AGEs, is published on Monday 24 February in the journal PNAS online.

Led by researchers from the Icahn School of Medicine at Mount Sinai, in New York, the study investigated the possible role of compounds called advanced glycation endproducts (AGEs) in diseases that cause dementia, such as Alzheimer’s. AGEs, which have already been linked to diabetes, can occur inside the body, but they are also found in certain foods. Earlier research has suggested foods such as meat, cheese, oils and nuts are high in AGEs compared to vegetables, fruits and whole grains, while cooking methods such as frying, roasting and grilling are thought to cause higher AGEs than boiling, poaching or steaming.

The researchers began by comparing mice that were given different amounts of AGEs as part of their diet. They found that mice on a high-AGE diet were more likely to have memory problems and difficulty with motor skills than those that were fed a regular diet, or a diet that was low in AGEs. These mice were also more likely to show signs of insulin resistance, as well as a build-up of a protein called amyloid, which is known to be involved in Alzheimer’s, in their brains. The researchers also looked at levels of a protein called SIRT1 – which previous research has linked to healthy ageing – and found that mice on high-AGE diets had less of this protein in their blood and in their brains.

In addition, the researchers recruited 93 people over the age of 60 who did not have dementia, and measured their blood for levels of AGEs and SIRT1. The participants were asked for information on their diet and calorie intake, and each was given a Mini Mental State Exam (MMSE) – a memory test commonly used by doctors to diagnose dementia – at the start of the study and again after nine months. The results showed that people with high levels of AGEs in their blood tended to have less SIRT1, and were also more likely to see a decline in their memory scores.

The authors suggest that AGEs may contribute to dementia, and speculate that a diet with reduced AGEs might be able to help fight the condition.

Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, said:

“Diabetes has previously been linked to an increased risk of dementia, and this small study provides some new insight into some of the possible molecular processes that may link the two conditions. Although these findings add to some earlier evidence linking a decrease in the SIRT1 protein to Alzheimer’s, the most common cause of dementia, it’s important to note that the people in this study did not have dementia. This subject has so far not been well-studied in people, and we don’t yet know whether the amount of AGEs in our diet might affect our risk of dementia.

“This research is at an early stage, and continued investment in research is crucial to understand the significance of results like this. The diseases that cause dementia are complex, and our risk of the condition is likely to be affected by a number of genetic and environmental factors that are not yet fully understood. In the meantime, the best evidence suggests that a balanced diet can help lower the risk of Alzheimer’s, as part of a healthy lifestyle that includes regular exercise, not smoking, and keeping blood pressure and weight in check.”