Résumé
Background
Numerous studies report that sleep disturbances are associated with brain alterations; yet, results still remain controversial. Our aim was thus to examine the associations between self‐reported and objective sleep parameters, and volumes of hippocampus and white matter hyperintensities (WMH).
Method
This cross‐sectional analysis used data from the French ESPRIT study. At baseline, 718 participants aged 65‐80 underwent a brain magnetic resonance imaging examination. Among them, 675 had hippocampus volume data and 712 had WMH volume data. They also completed a sleep questionnaire at baseline and 167 participants underwent an ambulatory polysomnography to assess their objective sleep. Logistic regression models were performed and minimally adjusted for age, sex, educational level, and APOE ε4 status to assess the associations between sleep parameters and volumes of hippocampus and WMH.
Result
The participants’ mean age at baseline was 71.4 years (±4.0) and 51.3% were women. We found that a short (≤6 hours) but also a long (≥9 hours) 24‐hour sleep duration, a late (>8 am) get‐up time and a low score at the Epworth Severity Scale were associated with a low hippocampal volume. However, these associations did not remain significant after false discovery rate (FDR) correction. We also observed, even after FDR correction, that an early get‐up time (≤6 am) and having difficulty in initiating sleep were associated with a high WMH volume whereas a late bedtime (≥11 pm) was associated with a low WMH volume. Regarding objective data, longer rapid eye movement sleep and slow wave sleep durations were associated with a low WMH volume, and a higher number of periodic leg movements during sleep was associated with a high WMH volume; but these associations were not significant after FDR correction. All the results remained similar after taking into account intracranial volume.
Conclusion
In this population‐based study in older adults, the most robust findings concerned higher WMH volume for participants with early get‐up time, difficulties in initiating sleep or late bedtime. Overall, these results are consistent with the general view that there may be specific types of sleep parameters that can play a role in brain alterations.