Older people who eat a diet high in carbohydrates are four times more likely to develop mild cognitive impairment - a precursor to Alzheimer’s disease.
New research from the prestigious Mayo Clinic in America has found the risk is also higher with a diet high in sugar. On the other hand, proteins and fats appear to offer some protection – people who consumed plenty of them are less likely to suffer cognitive decline. Not everyone with mild cognitive impairment (MCI) develops Alzheimer's disease, but many do, said lead author Rosebud Roberts, a professor in the department of epidemiology at the Mayo Clinic.
MCI is defined as memory loss apparent to the individual and those around them, but with an absence of other dementia symptoms such as changes in personality and mood.
It’s estimated around 6% of us will develop MCI. Previous research suggested that 10-15% of people with MCI went on to develop dementia every year.
That's why it's so important to identify people with MCI, as they may be in the very early stages of the disease and more likely to benefit from early treatment in the future. The Mayo Clinic research tracked 1,230 people ages 70 to 89 and asked them to provide information on what they ate the previous year.
‘If we can stop people from developing MCI, we hope we can stop people from developing dementia. Once you hit the dementia stage, it's irreversible,’ Professor Roberts says. ‘A high-carbohydrate intake could be bad for you because carbohydrates impact your glucose and insulin metabolism.
'Sugar fuels the brain, so moderate intake is good. However, high levels of sugar may actually prevent the brain from using the sugar - similar to what we see with type 2 diabetes.’
She added that high glucose levels might affect the brain's blood vessels and play a role in the development of beta amyloid plaques, proteins toxic to brain health that are found in the brains of people with Alzheimer's. It’s thought these plaques are a leading cause of the disease.
People whose diets were highest in 'good' fats, such as those found in nuts and healthy oils were 42% less likely to get cognitive impairment. Those with a high intake of protein (such as meat and fish) had a reduced risk of 21%.