Effects of beta-hydroxybutyrate on cognition in memory-impaired adults.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 15123336 · doi:10.1016/S0197-4580(03)00087-3
What was done
Twenty adults with Alzheimer's disease (AD) or mild cognitive impairment (MCI) received a single oral drink containing emulsified medium-chain triglycerides (MCTs) or a placebo on separate testing days in a crossover design. Plasma beta-hydroxybutyrate (beta-OHB) levels were measured at baseline, 90 minutes, and 120 minutes post-dose. Cognitive testing, including the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) and paragraph recall, was administered at 90 minutes post-dose. Outcomes were analyzed overall and stratified by apolipoprotein E (APOE) epsilon 4 allele status (APOE4+ vs APOE4-).
What was found
Oral MCTs significantly elevated plasma beta-OHB levels at 90 minutes post-treatment compared to placebo (P=0.007). The pharmacokinetic profile differed by genotype (P=0.036): beta-OHB levels remained constant between 90 and 120 minutes in APOE4- subjects, whereas levels continued to rise in APOE4+ subjects (P<0.009). Cognitive improvement on the ADAS-cog was observed following MCT treatment specifically in APOE4- participants, but not in APOE4+ participants (P=0.04). Across all 20 subjects, higher plasma ketone concentrations correlated with greater improvement in paragraph recall relative to placebo (P=0.02). Absolute scores and baseline values were not reported in the abstract.
Why it matters
This study provides early human proof-of-concept that oral MCTs can induce acute ketosis and transiently support cognitive performance in memory-impaired individuals lacking the APOE4 allele, potentially bypassing impaired brain glucose utilization.
Limits
The sample size was very small (n=20), limiting statistical power. The study examined only acute, single-dose effects at 90–120 minutes; long-term cognitive efficacy, tolerance, and clinical relevance remain unmeasured. AD and MCI participants were combined, and cognitive benefits were restricted to the APOE4- subgroup.
Cited by
- supports Clinical studies administering ketone bodies or MCTs to patients with mild cognitive impairment or early Alzheimer's showed memory improvements in APOE3 carriers but not in APOE4 carriers.