Introduction: Sleep-dependent memory consolidation differs by sex and maybe disrupted by Alzheimer disease (AD) risk. Whether sex moderates associations between apolipoprotein E varepsilon4(APOE varepsilon4) status, non-rapid eye movement (NREM) sleep, and memory remains unclear. Methods: Eighty cognitively unimpaired older adults completed a word-pair memory task with encoding and immediate testing occurring prior to overnight polysomnography with high-density electroencephalography (hdEEG) and delayed recall occurring after sleep. Sleep-memory associations were examined as a function of sex and APOE varepsilon4 status. Results: In this sample, a sex by APOE varepsilon4 interaction was associated with overnight memory retention, with female carriers exhibiting less overnight forgetting than female non-carriers and male varepsilon4 carriers. NREM sleep differed by sex and APOE varepsilon4 status and was associated with memory retention in varepsilon4 carriers. Discussion: These findings indicate sex-specific, sleep-dependent memory mechanisms associated with genetic AD risk, highlighting sleep as a potential early target for intervention, pending replication in larger samples. This study was not a clinical trial.
Adaptation to free-living drives loss of beneficial endosymbiosis through metabolic trade-offs
Symbioses are widespread (1) and underpin the function of diverse ecosystems (2-6), but their evolutionary stability is challenging to explain (7,8). Fitness trade-offs between con-trasting