A link between memory loss and a high calorie diet has been suggested by researchers in the US.
They were investigating mild cognitive impairment (MCI), which can be an early sign of dementia.
Research, presented at a conference, claimed a high calorie diet was linked to having twice the risk of MCI, compared with a low calorie diet.
Alzheimer's Research UK said a healthy lifestyle was known to help protect against dementia.
Mild cognitive impairment has become increasingly interesting to researchers as it may help predict who will go on to develop dementia, such as Alzheimer's.
A team at the Mayo Clinic in the US has investigated the effect of diet in 1,233 people aged between 70 and 89. None had dementia, but 163 were diagnosed with mild cognitive impairment.Doubling
The patients were divided into low calorie intake (600 to 1,526 calories a day), middle (1,526 to 2,142.5) and high (2,142.5 to 6,000) and the incidence of mild cognitive impairment was compared.
The results were presented at the annual meeting of the American Academy of Neurology. They showed no difference in the low and middle groups, however, the high intake group had more than double the incidence of MCI.
Researcher Dr Yonas Geda said: "We observed a dose-response pattern which simply means; the higher the amount of calories consumed each day, the higher the risk of MCI."
The study cannot say that a high calorie diet causes MCI, people who are cognitively impaired could end up eating more food or there could be another factor involved which increases the risk of both.
It has also not yet been published in a peer-reviewed academic journal.
But Dr Geda did suggest there was potential for therapy: "Cutting calories and eating foods that make up a healthy diet may be a simpler way to prevent memory loss as we age."
Dr Marie Janson, from Alzheimer's Research UK, said the findings were interesting, and fitted in with "the bigger picture of a healthy lifestyle preventing Alzheimer's in later life".
She said it was "difficult" to work out what a mechanism linking calories and cognitive impairment would be.
But she added: "We know that age is one of the greatest risk factors for dementia, but adopting a healthy lifestyle including a balanced diet and regular exercise, is beneficial in protecting against dementia along with a number of other chronic diseases."