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. 2012 Feb;33(2):425.e19-27.
doi: 10.1016/j.neurobiolaging.2010.10.006. Epub 2010 Dec 3.

Dietary Ketosis Enhances Memory in Mild Cognitive Impairment

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Free PMC article

Dietary Ketosis Enhances Memory in Mild Cognitive Impairment

Robert Krikorian et al. Neurobiol Aging. .
Free PMC article

Abstract

We randomly assigned 23 older adults with mild cognitive impairment to either a high carbohydrate or very low carbohydrate diet. Following the 6-week intervention period, we observed improved verbal memory performance for the low carbohydrate subjects (p = 0.01) as well as reductions in weight (p < 0.0001), waist circumference (p < 0.0001), fasting glucose (p = 0.009), and fasting insulin (p = 0.005). Level of depressive symptoms was not affected. Change in calorie intake, insulin level, and weight were not correlated with memory performance for the entire sample, although a trend toward a moderate relationship between insulin and memory was observed within the low carbohydrate group. Ketone levels were positively correlated with memory performance (p = 0.04). These findings indicate that very low carbohydrate consumption, even in the short term, can improve memory function in older adults with increased risk for Alzheimer's disease. While this effect may be attributable in part to correction of hyperinsulinemia, other mechanisms associated with ketosis such as reduced inflammation and enhanced energy metabolism also may have contributed to improved neurocognitive function. Further investigation of this intervention is warranted to evaluate its preventive potential and mechanisms of action in the context of early neurodegeneration.

Conflict of interest statement

Disclosure Statement

None of the authors has a conflict of interest influencing this work.

Figures

Figure 1
Figure 1
Pre- and post-intervention memory performances for the low and high carbohydrate groups as measured by the Verbal Paired Associate Learning Test (Krikorian, 1996). Values are unadjusted means of the cumulative number of correct immediate recall responses summed across four learning trials. Vertical bars represent standard error. The ANCOVA analysis indicated improved learning for the low carbohydrate subjects, F(1,20) = 6.45, p = 0.01, Cohen’s f = 0.26.
Figure 2
Figure 2
Individual values for fasting insulin (μU/mL) and long-term memory performance (paired associate learning score) plotted from left to right to show change from pre-intervention baseline visit to final visit, respectively. Upper panel shows values for the high carbohydrate subjects and the lower panel for low carbohydrate subjects. Variability across the intervention is apparent for insulin and memory for subjects in both groups, although the trends toward lower insulin and higher memory performance are more consistently demonstrated among the low carbohydrate subjects.

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