White matter differences predict cognitive vulnerability to sleep deprivation.

OBJECTIVES: In other disciplines, white matter (WM) differences have been linked to cognitive impairments. This study sets out to clarify whether similar microstructural differences in WM tracts predict a person's cognitive vulnerability to the effects of total sleep deprivation (TSD).

DESIGN: Participants completed a simple visual-motor task both before and after 24 h of TSD. Using a median split on the percent change in accuracy from pre-TSD to post-TSD, participants were separated into susceptibility groups. A diffusion tensor MR imaging (DTI) scan was acquired from each participant, and fractional anisotropy (FA) was calculated, examined across the brain, and compared between susceptibility groups.

SETTING: University of Texas at Austin.

PARTICIPANTS: Thirty-two West Point cadets (9 females, 23 males) between 19 and 25 years of age.

RESULTS: Participant susceptibility to TSD was correlated with lower FA values in multiple regions of white matter, including the genu of corpus callosum and ascending and longitudinal white matter pathways. Significantly higher FA values in those less vulnerable to TSD, indicating increased neural connectivity and WM organization, may moderate the cognitive effects of sleep deprivation.

CONCLUSIONS: Differences in distributed WM pathways reflect, and may contribute to, a person's ability to function effectively when sleep deprived. The widespread nature of this effect supports previous views that TSD has a global effect on brain functioning.