Résumé
Background
The relationship between sleep and dementia risk is complex, with both longer and shorter sleep duration being associated with cognitive decline. The thalamus has an important role in regulating the sleep‐wake cycle and structural changes may be a good marker of sleep abnormalities. Our aim was to investigate the association between dementia risk, sleep and the volume of thalamic nuclei.
Method
We analysed baseline data from PREVENT‐dementia, a multicentre, prospective cohort study of cognitively intact participants aged 40 to 59 years, who were stratified according to presence of the ApoE4 allele and parental family history of dementia (FH+). Sleep data was collected using the Pittsburgh Sleep Quality Index (PSQI) which measures subjective sleep quality, latency, duration, efficiency, disturbances, medication use and daytime dysfunction. T1‐weighted 3T MRI images were analysed using Freesurfer (version 7.1.0) to determine the volume of the thalamus and its subnuclei, controlling for total intracranial volume. The score on the centre for epidemiologic studies depression scale and the number of analgesic medications, were also used as covariates in the analysis to control for mood and pain. The data was analysed in R Studio using robust logistic regression.
Result
Complete data was available for 594 participants. The total PSQI score was lower in FH+ subjects (p = 0.046) but was not associated with ApoE4 status. FH+ subjects had smaller volumes of mediodorsal medial (p = 0.03) and lateral (p = 0.03) nuclei, longer sleep duration (p = 0.02), and counterintuitively less sleep‐related daytime dysfunction (p = 0.01) compared to controls. In the FH+ group, larger pulvinar nucleus was associated with better sleep quality (r = ‐0.17, p = 0.002). In apoE4 non‐carriers, a larger thalamus (r = ‐0.12, p = 0.02) and larger centromedian nucleus (r = ‐0.13, p = 0.01) were both associated with a lower total PSQI score. They also had an association between larger pulvinar (r = ‐0.11, p = 0.04) and centromedian (r = ‐0.14, p = 0.007) nuclei and increased sleep efficiency.
Conclusion
Middle‐aged subjects with a FH+ had longer sleep duration and smaller thalamic volumes which may represent early neurodegenerative changes. Furthermore, we found an association between larger thalamic nuclei and better sleep variables, especially in ApoE4 non‐carriers, indicating that the thalamus may be an important imaging correlate of sleep quality.