Effects of β-hydroxybutyrate on cognition in memory-impaired adults

Glucose is the brain's principal energy substrate. In Alzheimer's disease (AD), there appears to be a pathological decrease in the brain's ability to use glucose. Neurobiological evidence suggests that ketone bodies are, an effective alternative energy substrate for the brain. Elevation of plasma ketone body levels. through an oral dose of medium chain triglycerides (MCTs) may improve cognitive functioning in older adults with memory disorders. On separate days, 20 subjects with AD or niild cognitive impairment consumed a drink containing emulsified MCTs or placebo: Significant increases in levels of the ketone body beta-hydroxybutyrate (beta-OHB) were observed 90 min after treatment (P = 0.007) when cognitive tests were administered. beta-OHB elevations were moderated by apolipoprotein E (APOE) genotype (P = 0.036). For epsilon4+ subjects, beta-OHB levels continued to rise between the 90 and 120 min blood draws in the treatment condition, while the p-OHB levels of epsilon4- subjects held constant (P < 0.009). On cognitive testing, MCT treatment facilitated performance on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) for epsilon4- subjects, but not for epsilon4+ subjects (P = 0.04). Higher ketone values were associated with greater improvement in paragraph recall with MCT treatment relative to placebo across all subjects (P = 0.02). Additional research is warranted to determine the therapeutic benefits of MCTs for patients with AD and how APOE-epsilon4 status may mediate p-OHB efficacy. (C) 2003 Elsevier Science Inc. All rights reserved.