Diffusion tensor imaging findings and neuropsychological performance in adults with TBI across the spectrum of severity in the chronic-phase.

Primary Objective: To examine associations between neuroimaging indicators of cerebral tract integrity and neurocognitive functioning in traumatic brain injury (TBI).
Research Design: Between-Groups design with two TBI groups and controls.
Method and Procedures: Forty-four participants with TBI and 27 matched controls completed diffusion tensor imaging and neuropsychological measures of processing speed, attention, memory, and executive function. Multivariate analyses were conducted to examine group differences in white matter integrity (fractional anisotropy) for 11 regions of interest and cognitive performance among adult males with chronic phase, mild, moderate, or severe TBI. Correlational analyses investigated associations between white matter integrity, brain injury severity, and cognitive status.
Main Outcomes and Results: Participants with moderate or severe TBI exhibited reduced white matter integrity in 8 of 11 ROIs and worse performance on most cognitive measures, relative to control participants. Persons with mild TBI did not differ from controls on white matter integrity values and differed on one measure of processing speed. Significant correlations were found between injury severity ratings and 10 ROIs, most notably between ROIs and measures of processing speed or memory.
Conclusions: These findings provide nuanced information regarding white matter connectivity as it relates to neurocognitive abilities across the TBI severity spectrum.