Sleep complaints and cerebral white matter: A prospective bidirectional study

Sleep complaints and brain changes co-occur in older adulthood, but the temporal relation between these processes is poorly understood. Poor sleep may destabilize axonal integrity and deteriorate white matter, but white matter pathology can also precede sleep complaints. Our objective was to explore a prospective, possibly bi-directional association between subjective sleep complaints and micro- and macro-structural properties of cerebral white matter. We assessed sleep complaints and brain magnetic resonance imaging at two time-points (2006-2008 and 2011-2014) in a population-based cohort including 2529 participants (56 ± 6 years old, 55% women). Sleep complaints were assessed with the Pittsburgh Sleep Quality Index. White matter lesion (WML) volume was assessed from fluid-attenuated inversion recovery images and global and tract-specific white matter microstructural integrity with diffusion tensor imaging. Sleep complaints at baseline were not associated with changes in WML volume or global white matter microstructure. In tract-specific analyses, however, sleep complaints were associated with reduced microstructural integrity in two white matter tracts projecting to the brainstem, but only when uncorrected for multiple testing. Likewise, we found no evidence for the reverse association; micro- or macro-structural properties of white matter were not related to changes in sleep complaints over time. This study provides evidence against the hypothesis that sleep complaints lead to white matter changes in the aging brain, and shows that white matter properties do not underlie sleep complaints in older persons. As subjective sleep complaints increase in later life, it is important to demonstrate that these are not etiologically related to cerebral white matter pathology.