0080 Daytime Sleepiness Correlates with Increased Gray Matter Volume in the Right Middle Temporal Gyrus in Healthy Young Individuals

Abstract

Abstract Introduction Daytime sleepiness has been associated with some neuroimaging metrics, including altered functional connectivity within the default mode network and decreased gray matter volume (GMV) of the medial prefrontal cortex. Most prior studies, however, have focused on patients with sleep disorders or other pathologies. Here we examined the association between GMV and self-reported daytime sleepiness among a healthy group of young adults who reported no sleep-related problems. Methods Forty-five healthy adults (22 female; Mean Age=25.4, SD=5.6), who self-reported no history of sleep-related disorders or major medical conditions, completed the Epworth Sleepiness Scale (ESS), the Repeatable Battery for Neuropsychological Status (RBANS) and underwent high-resolution structural neuroimaging at 3T. Gray matter volumes were processed using standard procedures in SPM12. After controlling for age, sex, and intracranial volume, GMV was regressed against ESS scores. Results Greater ESS was associated with larger GMV within a cluster of voxels in the right middle temporal gyrus (MNI coordinates: 57, -9, -22; k=1344 voxels, p=.003, FWE cluster corrected). After controlling for ESS scores, larger GMV in this region was associated with poorer delayed memory performance (r=-.345, p=.022) and total neurocognitive performance on the RBANS (r=-.303, p=.046). Conclusion Greater daytime sleepiness in healthy normal sleepers was associated with greater GMV within a region of the right middle temporal gyrus. Greater volume of this region was also associated with poorer neuropsychological performance. Decreased GMV of this same region has previously been reported in patients with obstructive sleep apnea and insomnia, suggesting that it may be particularly sensitive to sleep disruption or may play a role in the etiology of sleep disorders, even among young individuals who deny any history of sleep-related dysfunction. Longitudinal work should focus on the potential of this region as a biomarker of vulnerability to sleep problems. Support