Is poorer sleep linked to faster hippocampal volume loss in adulthood?

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Poor sleep is associated with multiple age-related neurodegenerative and neuropsychiatric conditions. The hippocampus plays a special role in sleep and sleep-dependent cognition, and its atrophy typically accelerates with age. The researchers aimed to establish how the relationship between sleep and hippocampal volume loss unfolds across the adult lifespan.

They obtained self-reported sleep measures and MRI-derived hippocampal volumes from 3,105 cognitively normal participants aged 18–90 in major European brain studies in the Lifebrain consortium. They estimated hippocampal volume change using 5,116 MRIs from 1,299 participants who had longitudinal scans, with follow-up of up to 11 years and a mean interval of 3.3 years. Cross-sectional analyses were repeated in 21,390 UK Biobank participants.

No cross-sectional relationships between sleep and hippocampal volume were found. Over time, however, worse sleep quality and efficiency, more sleep problems, and daytime tiredness were related to greater hippocampal volume loss; high scorers showed 0.22% greater annual loss than low scorers. The relationship between sleep and hippocampal atrophy did not vary across age. Simulations showed that the observed longitudinal effects were too small to be detected as age interactions in the cross-sectional analyses.

Worse self-reported sleep was associated with higher rates of hippocampal volume decline across the adult lifespan. The findings suggest that sleep is relevant to understanding individual differences in hippocampal atrophy, but the limited effect sizes call for cautious interpretation.