The relationship between cognitive function, Alzheimer's disease and sleep duration: A Mendelian randomisation study

Structured abstractO_ST_ABSImportanceC_ST_ABSSleep duration is associated with cognitive function, with Mendelian randomisation evidence supporting a relationship in this direction. However, whether cognitive function may also precede problematic sleep duration remains unclear. ObjectiveTo assess whether reaction time and visual memory are causally associated with sleep duration. DesignSummary-level Mendelian randomisation design between visual memory (30 SNPs), reaction time (44 SNPs), and self-reported and objective sleep duration Setting: Population-based study. ParticipantsIndividuals from the UK Biobank, who were included in genome-wide association studies for our exposures and outcomes, aged 40-69y at baseline (mean 56y), 54% female and self-reported sleep was 7.2 hours. ExposuresVisual memory, reactiontime Main outcomesself-reported and objective sleep duration ResultsMendelian randomisation results showed that worse performance on the visual memory task was associated with longer ({beta}=0.09, 95% CI=0.02;0.17), while slower reaction time was associated with shorter ({beta}=-0.15, 95% CI=-0.29;-0.01), objective sleep duration. Sensitivity analyses revealed no issues with horizontal pleiotropy (MR-Egger intercept p-value <0.05). No association was observed between either cognitive measure and self-reported sleep duration. Conclusions and relevanceThese results suggest a potential causative relationship between reaction time and objective sleep duration, where worse visual memory is associated with longer, and worse reaction time with shorter objective sleep duration. This study furthers our understanding of the relationship between brain health and sleep duration and sheds light on the causal nature of these associations. Key pointsO_ST_ABSQuestionC_ST_ABSIs genetically predicted sleep duration (accelerometer-derived and self-reported) associated with cognitive function outcomes? FindingsIn this summary-level Mendelian randomisation study, worse visual memory was associated with longer, whereas worse reaction time was associated with shorter, objective sleep duration. No associations were observed between cognitive measures and self-reported sleep duration. MeaningThese findings suggest a causal association between cognition and objective sleep duration measures, expanding our understanding of the relationship between cognition and sleep.