Chronic white matter changes detected using diffusion tensor imaging following adult traumatic brain injury and their relationship to cognition

Abstract

Objective: White matter (WM) changes detected using diffusion tensor imaging (DTI) are reportedly related to cognitive outcomes following traumatic brain injury (TBI), but much existing research is underpowered or has only examined general outcomes, rather than cognitive functioning. Method: A large sample of adults who had sustained mild, moderate or severe TBIs seven months prior (N = 165) and a control group (N = 106) underwent DTI and cognitive testing. Fractional anisotropy and mean diffusivity were calculated for 5 regions (corpus callosum: genu, body, splenium; fornix; superior longitudinal fasciculus) that recent meta-analyses identified as being affected by TBI and related to cognition following TBI. Memory, attention and executive functioning, which are often affected by TBI, were assessed. Results: Overall, mild TBI did not show significant WM or cognitive changes, relative to controls, but moderate to severe TBI was associated with large WM alterations (all regions) and poorer cognitive performance. No significant correlations were found between DTI findings and cognition in the moderate to severe group. Conclusions: The findings have shown that moderate to severe TBI leads to considerable WM and cognitive changes. Early and ongoing examination of mild TBI is needed to determine whether WM and cognitive changes are initially present and, if so, when they resolve.