Structural dissociation of attentional control and memory in adults with and without mild traumatic brain injury

Abstract

Memory and attentional control impairments are the two most common forms of dysfunction following mild traumatic brain injury (TBI) and lead to significant morbidity in patients, yet these functions are thought to be supported by different brain networks. This 3 T magnetic resonance diffusion tensor imaging (DTI) study investigates whether microstructural integrity of white matter, as measured by fractional anisotropy (FA) within a small set of individually localized regions of interest (ROIs), is associated with these cognitive domains in normal adults and adults with mild TBI. Results in a sample of 23 normal controls reveal a significant correlation between attentional control and FA within a ROI in the left hemisphere anterior corona radiata. Furthermore, the controls demonstrate a correlation between memory performance and FA in a ROI placed in the uncinate fasciculus. Next, to examine whether these relationships are found in the pathological ranges of attention, memory and microstructural white matter integrity associated with mild TBI, these analyses were applied to a group of 43 mild TBI patients. Results, which generally demonstrated a wider range of attention, memory and FA scores, replicated the correlation between attentional control and FA in left hemisphere anterior corona radiata, as well as the correlation between memory performance and FA in the uncinate fasciculus. These two sets of brain-behaviour relationships were highly specific, as shown by a lack of correlation between attention and uncinate fasciculus FA and the lack of correlation between memory performance and anterior corona radiata FA. Furthermore, a 'correlational double dissociation' was demonstrated to exist between two distinct frontal structures independently associated with attention and memory, respectively, via a series of multiple regression analyses in both normal controls and adults with mild TBI. The results of the multiple regression analyses provide direct evidence that tract-specific variation in microstructural white matter integrity among normal controls and among mild TBI patients can account for much of the variation in performance in specific cognitive domains. More generally, such findings suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for neurocognitive function and dysfunction.

Common data elements in radiologic imaging of traumatic brain injury

“…In their study, they found that the number of structures with reduced FA correlated with executive, attentional, and memory cognitive measures. A number of other studies show that WM tract damage may be able to account for some forms of cognitive dysfunction (30,36). In summary, DTI can detect microstructural WM injury early after TBI, and there is a correlation with reduced FA, the number of affected tracts, and cognitive deficits even in mTBI.…”

Voxel-Based Analysis of Diffusion Tensor Imaging in Mild Traumatic Brain Injury in Adolescents

“…Findings suggest that the effects of mTBI are indeed widespread, consistent with the distribution of DTI abnormalities observed during the chronic phase following mTBI. [4][5][6]34 Given that the participants were all scanned within 6 days of injury, it is plausible that some of these acute abnormalities may evolve into more chronic WM changes. Longitudinal DTI investigation of patients with mTBI is underway to evaluate this further.…”

A Longitudinal Diffusion Tensor Imaging Study Assessing White Matter Fiber Tracts after Sports-Related Concussion

“…Other research, involving patients with a GCS 13-15, using a broad range of analyses, including TBSS, have reported abnormal diffusion measures in a subset of regions covered by the significant RD cluster reported in the current study. Specifically, such regions were observed in the IC, 24,26,29,32,[53][54][55][56][57][58] in either the inferior frontooccipital and/or inferior long fasciculus 27,28,[59][60][61] and the anterior thalamic radiation. 60 The current study lends further support to an earlier hypothesis, 12 which suggested that the prevalence of crossing and merging WM fiber tracts in the anatomical region of the RD cluster might make this particular area more vulnerable to the type of forces acting on the brain during the course of a concussion.…”

“…Further, significant correlations between attentional control and FA were found within the left anterior corona radiata as well as memory performance and FA within the UF. 28 A DTI study on patients with mTBI 29 demonstrated increased FA and decreased RD in the subacute phase after injury and subsequent partial normalization of FA values in left corona radiata and splenium. These studies provide evidence that anisotropy measurements cannot only be used to assess alterations in the microstructure of the WM, but also provide a biomarker of cognitive function and dysfunction.…”