The Association Between Sleep and Brain Morphology in Mild Cognitive Impairment

In patients with mild cognitive impairment (MCI), sleep habits are associated with gray matter atrophy and alterations in functional connectivity, according to study results published in Alzheimer’s & Dementia.

Previous studies have suggested that poor sleep quality may increase the risk for Alzheimer disease in patients with MCI. The objective of the current study was to determine the association between sleep habits and gray matter atrophy and functional connectivity in patients with MCI.

This case-control study included 38 patients with MCI and 38 age-matched controls. All study participants completed structural magnetic resonance imaging (MRI) to assess brain atrophy and resting-state functional MRI to determine functional connectivity.

Study researchers utilized the Sleep Continuity in Alzheimer’s Disease Scale, a self-reported questionnaire, to stratify patients with MCI as “good” sleepers (20 patients) and “poor” sleepers (18 patients). They then conducted independent component analyses to identify the default mode (DMN) and frontoparietal (FPN) networks, and computed z-score maps for each patient and modality. In addition, they computed a composite z-score map across modalities for each participant and network.

In both patients with MCI classified as good or poor sleepers, connectivity DMN values within the precuneus significantly exceeded atrophy. However, connectivity FPN values exceeding atrophy in frontal, temporal, and parietal regions were documented only in MCI good sleepers.

When study researchers compared composite z-score maps between poor and good sleepers with MCI, they documented significant FPN connectivity values exceeding atrophy in the right inferior frontal gyrus in good sleepers.

Ultimately, these findings may “suggest different sleep-induced slopes in brain atrophy and connectivity within the FPN network. These results might offer novel targets and surrogate outcomes for interventions aimed at restoring sleep disorders in MCI,” concluded the study researchers.

Reference

Wennberg AMV, Pini L, Mitolo M, et al. Sleep‐dependent association between atrophy and functional connectivity in mild cognitive impairment. Alzheimers Dement. Published online December 7, 2020. doi:10.1002/alz.040387