A modified Atkins diet (very low carbohydrates and extra fat) may improve brain function and episodic memory, according to a small study of 14 older adults with mild cognitive problems suggestive of early Alzheimer’s disease.
Diet that restricts glucose may help brain function. Image credit: Cattalin.
“Typically, the brain uses the sugar glucose — a product of carbohydrate breakdown — as a primary fuel,” said Professor Jason Brandt, from the Johns Hopkins University School of Medicine.
“However, in the early stage of Alzheimer’s disease the brain isn’t able to efficiently use glucose as an energy source. Some experts even refer to Alzheimer’s as ‘type 3 diabetes’.”
“Ketones — chemicals formed during the breakdown of dietary fat — can be used as an alternative energy source in the brains of healthy people and those with mild cognitive impairment. For example, when a person is on a ketogenic diet, consisting of lots of fat and very few sugars and starches, the brain and body use ketones as an energy source instead of carbs.”
Professor Brandt’s team wanted to see if people with mild cognitive impairment, often an indicator of developing Alzheimer’s disease, would benefit from a diet that forced the brain to use ketones instead of carbohydrates for fuel.
They were able to enroll 27 people in the 12-week diet study. There were a few dropouts, and so far, 14 participants completed the study. The participants were an average age of 71. Half were women, and all but one were white.
To enroll, each participant required a study partner (typically a spouse) who was responsible for ensuring that the participant followed one of two diets for the full 12 weeks. The participants and their partners were also asked to keep food diaries.
Nine participants followed a modified Atkins diet meant to restrict carbs to 20 grams per day or less, with no restriction on calories.
The other five participants followed a National Institute of Aging diet, similar to the Mediterranean diet, that doesn’t restrict carbohydrates, but favors fruits, vegetables, low- or fat-free dairy, whole grains and lean proteins such as seafood or chicken.
Prior to starting the diets, those assigned to the modified Atkins diet were consuming about 158 grams of carbs per day. By week six of the diet, they had cut back to an average of 38.5 grams of carbs per day and continued dropping at nine weeks, but still short of the 20-gram target, before rising to an average of 53 grams of carbs by week 12.
Participants on the National Institute of Aging diet continued to eat well over 100 grams of carbs per day.
Each participant also gave urine samples at the start of the dietary regimens and every three weeks up to the end of the study, which were used to track ketone levels.
More than half of the participants on the modified Atkins diet had at least some ketones in their urine by six weeks into the diet until the end; as expected, none of the participants on the National Institute of Aging control diet had any detectable ketones.
Participants completed the Montreal Cognitive Assessment, the Mini-Mental State Examination and the Clinical Dementia Rating Scale at the start of the study.
They were tested with a brief collection of neuropsychological memory tests before starting their diets and at six weeks and 12 weeks on the diet. At the six-week mark, the study authors found a significant improvement on memory tests, which coincided with the highest levels of ketones and lowest carb intakes.
When comparing the results of tests of delayed recall — the ability to recollect something they were told or shown a few minutes earlier — those who stuck to the modified Atkins diet improved by a couple of points on average (about 15% of the total score), whereas those who didn’t follow the diet on average dropped a couple of points.
“Many people would rather take a pill that causes them all kinds of nasty side effects than change their diet,” Professor Brandt said.
“Older people often say that eating the foods they love is one of the few pleasures they still enjoy in life, and they aren’t willing to give that up.”
The study was published in the Journal of Alzheimer’s Disease.
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Jason Brandt et al. 2019. Preliminary Report on the Feasibility and Efficacy of the Modified Atkins Diet for Treatment of Mild Cognitive Impairment and Early Alzheimer’s Disease. Journal of Alzheimer’s Disease 68 (3): 969-981; doi: 10.3233/JAD-180995
