An investigation of white matter integrity and attention deficits following traumatic brain injury.

OBJECTIVE: This study aimed to investigate the association between white matter tracts and multiple aspects of attention and working memory deficits in a relatively acute traumatic brain injury (TBI) sample. METHOD: Neuropsychological measures of attention and working memory were administered to 20 participants with complicated mild-to-very severe TBI and 20 control participants. Tract-based spatial statistics was used to assess fractional anisotropy (FA) and mean diffusivity (MD) of white matter tracts for 15 TBI participants and 20 controls. RESULTS: When compared to controls, participants with TBI were found to have lower FA (p < 0.001) and higher MD (p < 0.001) values in the majority of white matter tracts. TBI participants were also slower to complete tasks including Trail Making Test, Hayling, computerized Selective Attention Task, n-back and Symbol Digit Modalities Test (p < 0.001), when compared to controls. When controlling for age and estimated premorbid intelligence, slowed information processing speed following TBI was found to be associated with FA values in the corpus callosum, superior longitudinal fasciculus, cingulum, inferior fronto-occipital fasciculi, corona radiata and cerebral white matter. CONCLUSION: The results highlight the widespread damage associated with TBI, as well as the impact of these alterations on information processing speed.

Cognitive training approaches to remediate attention and executive dysfunction after traumatic brain injury: A single-case series.

Attentional deficits are common following traumatic brain injury (TBI) and interfere with daily functioning. This study employed a single-case design to examine the effects of individualised strategy training on attention beyond the effects of computerised training using Attention Process Training 3 (APT-3), and to examine the participants' subjective experience of these approaches. An ABCA (baseline, APT-3, strategy training, follow-up) design was repeated across three participants with severe TBI. Outcomes were measured on alternate versions of the oral Symbol Digit Modalities Test (SDMT) and cancellation tasks; generalisation with the Test of Everyday Attention (TEA) and self and significant other (SO) ratings on the Rating Scale of Attentional Behaviour (RSAB); and participant experiences with semi-structured interviews. Planned Tau-U analyses revealed improvements in speed of processing on the SDMT and the automatic condition of the cancellation task after APT-3 and at follow-up, but with most improvement after strategy training. Limited generalisation was evident on TEA subtests and self-RSAB ratings. SO-RSAB ratings were mixed after APT-3, but demonstrated improvement after strategy training. Variability in attentional deficits and everyday attentional requirements between patients required individualised goals and approaches to rehabilitation. This study highlights the need for individualised rehabilitation of attention to improve everyday functioning after TBI.

Speed of processing and strategic control of attention after traumatic brain injury.

INTRODUCTION: Slowed information processing speed has consistently been documented after traumatic brain injury (TBI). Debate continues as to whether deficits in strategic control are proportionate to, or remain after controlling for, reduced speed of processing. The study aim was to investigate the association of speed of processing and strategic control of attention with working memory, selective attention, response inhibition, and mental flexibility task performance after TBI using traditional and novel clinical measures. METHOD: Twenty-five individuals with complicated mild to severe TBI (post-traumatic amnesia duration, M = 39.52 days, SD = 38.34; worst Glasgow Coma Scale score, M = 7.33, SD = 4.35; time post-injury, M = 392.64 days, SD = 537.19) and 25 matched healthy controls completed assessment of attentional and executive functioning. Measures included the Symbol Digit Modalities Test (SDMT), the computerized Selective Attention Task (SAT), the Ruff 2&7 Selective Attention Test (2&7), the visual n-back, Digit Span, Hayling Test, and Trail Making Test (TMT). RESULTS: t tests revealed that individuals with TBI demonstrated reduced processing speed on the SDMT, n-back, SAT, 2&7, Hayling Test, and TMT-A (p ≤ .002 for all). Digit Span performance did not differ between groups. Mixed-model ANOVAs revealed that individuals with TBI demonstrated a disproportionate increase in reaction time with complexity, which was accounted for by speed on the SAT but remained on the Hayling Inhibition Test after controlling for speed in ANCOVAs. Mann-Whitney U tests revealed that individuals with TBI also made more errors on the Hayling Test, missed responses on the n-back and were unable to benefit from the automatic condition of the 2&7. CONCLUSIONS: While slowed speed of information processing was pervasive across tasks after TBI, residual difficulties in response inhibition remained after controlling for slowness, which suggests impaired strategic control. These findings support targeted intervention for slowed speed of thinking and inhibition following TBI.