Mild cognitive impairment (MCI), a state between normal aging and dementia, affects 19 per cent of people aged 65 and over.
Around 46 per cent of people with MCI go on to develop dementia within three years, compared with 3 per cent of the general population.
The study, led by researchers at UCL and published in the American Journal of Psychiatry, reviewed data from 62 separate studies following a total of 15,950 people diagnosed with MCI.
It found those with diabetes were 65 per cent more likely and those with psychiatric symptoms, such as depression, were twice as likely to develop dementia.
“Lifestyle changes to improve diet and mood might help people with MCI to avoid dementia, and bring many other health benefits,” said lead author Dr Claudia Cooper.
“This doesn’t necessarily mean that addressing diabetes, psychiatric symptoms and diet will reduce an individual’s risk, but our review provides the best evidence to date about what might help.”
It is well established that a Mediterranean diet rich in fruit, vegetables, oily fish, poultry and olive oil can help protect against Type 2 diabetes.
It is recommended by the Alzheimer’s Society charity to help prevent dementia, along with staying socially and physically active.
With a higher proportion of unsaturated to saturated fats and largely unprocessed foods it can help people with diabetes control their blood sugar levels.