A new US study has found that people who eat too much in their seventies or older are doubling their risk of memory impairment, or mild cognitive impairment (MCI), which can be an early sign of Alzheimer's disease.
The study Daily Caloric Intake, Aging and Mild Cognitive Impairment by Yonas E Geda, associate professor of neurology and psychiatry with Mayo Clinic in Arizona will be presented in April at the annual meeting of the American Academy of Neurology, in New Orleans. The study is yet to be peer reviewed, so findings are considered to be preliminary but insightful.
Geda and his team collected data on 1233 people between the ages of 70 and 89 free of dementia, living in Minnesota, USA. Among these people, 163 had been diagnosed with the memory deficits known as MCI.
Each participant reported the amount of calories they ate or drank and were divided into three equal groups based on their daily caloric consumption. One-third of the participants consumed between 600 and 1526 calories per day, one-third between 1526 and 2143 and one-third consumed between 2143 and 6000 calories per day.
Among those who ate more than 2143 calories per day, it was found that the odds of being diagnosed with the impaired-memory disorder was more than twice that of those who ate the least, the researchers found.
"We observed a dose-response pattern which simply means the higher the number of calories consumed each day, the higher the risk of mild cognitive impairment," said Geda.
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"We also looked at BMI and obesity," Geda said. "But there was no significant difference between the normal [participants] and mild cognitive impairment when it comes to these two variables."
The results were the same after taking into account a history of stroke, diabetes, education and other risk factors for memory loss and it is important to note that the researchers found there was no significant increase in risk for memory problems among those in the middle group.
"Why overeating affects the brain isn't clear, but excessive caloric intake may lead to oxidative damage leading to structural changes in the brain," Geda suggested.
This is helpful news for researchers looking at the onset of memory loss in old age. It backs up previous studies that have shown diet and physical exercise as well as brain-training exercises like puzzles has been found to decrease risk of dementia.
A previous study, published in the Journal of Neurology, found middle aged people with visceral fat (carry a spare tyre) secreted hormones and other chemicals such as leptin which may have a damaging effect on brain function.
Although dementia affects mostly people in their seventies and eighties, it can appear in people who are in their forties or younger. "Cutting calories and eating foods that make up a healthy diet may be a simpler way to prevent memory loss as we age," Geda says.
Australians over the age of 65 have a one in 15 chance of developing the disease and among people aged 80 to 84 the rate is one in nine. With more than 162,000 Australians diagnosed with dementia, with perhaps as many again in the early stages, there is now more reason than ever to watch what you eat and practice regular exercise.
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