A ketogenic diet improves memory in females in the APOE4 mouse model of Alzheimer's disease.

The ??4 allele of Apolipoprotein E (APOE4) is the strongest genetic risk factor for Alzheimer's disease (AD), affecting approximately 68 million Americans. APOE4 carriers exhibit cerebral metabolic deficits decades before clinical onset. We previously demonstrated that ketogenic diet (KD), a low-carbohydrate, high-fat diet promoting ketone metabolism, confers cognitive benefits in aged and PS1/APP mice. Here, we evaluated the effects of KD in a humanized APOE4 AD mouse model. KD significantly improved composite cognitive performance and spatial working memory, with pronounced effects in females. Synaptic plasticity, measured via long-term potentiation (LTP), was likewise enhanced exclusively in females. Transcriptomic and protein analyses revealed KD-induced activation of CREB pathway, marked by increased phosphorylation of ERK and CREB in female brains. Moreover, KD selectively reduced pro-inflammatory cytokine levels in females. These findings demonstrate sex-specific neuroprotective effects of KD in APOE4 mice and suggest its potential therapeutic role in mitigating AD risk in APOE4-positive women. Overall design: RNA was isolated from 10 mg of frozen murine brain cortex (N = 4–6 per group; 22-month-old ApoE4 males/females on control or ketogenic diet), using the RNeasy Mini Kit (QIAGEN) according to the manufacturer's instructions. Extracted RNA was used for NGS library preparation following Illumina's instruction (TruSeq Stranded Total RNA Library Prep Gold), while sequencing was performed on NovaSeq 6000 (Illumina) running in a 50-bp paired-end mode.