Their findings relate specifically to people aged 70 or more years.
They also found that seniors whose diets are high in protein and fat are less likely to develop cognitive impairment.
Most studies have mentioned low carb and high protein diets as the best to keep the weight off, but hardly any have focused on how it affects cognition.
Co-author, Rosebud Roberts, M.B., Ch.B., explained that a well-balanced or well-rounded diet is what really matters for overall physical and mental health.
Dr. Roberts said:
"We think it's important that you eat a healthy balance of protein, carbohydrates and fat, because each of these nutrients has an important role in the body."
Dr. Roberts and team followed 1,230 people aged between 70 and 89 years who reported on their eating habits during the previous twelve months. At the beginning of the study their cognitive function was assessed by an expert panel of doctors, nurses and neuropsychologists. Only approximately 940 of them showed no signs of cognitive impairment; they were asked to come back for further evaluations.
By year 4 of the study, 200 of the 940 started to show signs of mild cognitive impairment, with deficits in language, memory, thinking and judgment.
The researchers found that:
- The highest carbohydrate eaters had a 1.9 times higher risk of mild cognitive impairment than the participants who ate the fewest carbs.
- The highest sugar consumers had a 1.5 times higher risk of cognitive impairment compared to the lowest consumers.
- The participants with the highest fat intake had a 42% lower risk of developing cognitive impairment compared to the lowest fat eaters.
- The highest protein consumers had a 21% lower chance of developing dementia compared to the lowest consumers of protein.
- When taking into account fat and protein intake, the highest carb eaters had a 3.6 times higher chance of developing mild cognitive impairment.
"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."
What is mild cognitive impairment?Mild cognitive impairment, also known as MCI, is a brain disorder which affects a person's ability to think, concentrate, reason, remember and formulate ideas. It is not a learning disability, which occurs early in life - MCI is acquired later on.
A person with mild cognitive impairment is usually able to function independently in everyday activities, but may have trouble remembering things, such as the names of people they have recently met, following the flow of a conversation may be harder than before. People with MIT typically forget where they left things.
Those who become aware of this may try to adjust by keeping notes and ticking things off on a calendar. For a diagnosis of MCI to be reached, the patient must be able to perform all his/her daily activities successfully, without more help then they previously required.
MCI is not dementia. People with dementia have deficits that have progressed more, to such a point that they cannot function independently. A large proportion of people with MCI are eventually diagnosed with Alzheimer's disease some years later.
Written by Christian Nordqvist