White matter and neurocognitive changes in adults with chronic traumatic brain injury.

Diffusion tensor imaging was used to investigate white matter (WM) integrity in adults with traumatic brain injury (TBI) and healthy adults as controls. Adults with TBI had sustained severe vehicular injuries on the average of 7 years earlier. A multivariate analysis of covariance with verbal IQ as the covariate revealed that adults with TBI had lower fractional anisotropy and higher mean diffusivity than controls, specifically in the three regions of interest (ROIs), the centrum semiovale (CS), the superior frontal (SPF), and the inferior frontal (INF). Adults with TBI averaged in the normal range in motor speed and two of three executive functions and were below average in delayed verbal recall and inhibition, whereas controls were above average. Time since injury, but not age, was associated with WM changes in the SPF ROI, whereas age, but not time since injury, was associated with WM changes in the INF ROI, suggesting that the effects of WM on time since injury may interact with age. To understand the utility of WM changes in chronic recovery, larger sample sizes are needed to investigate associations between cognition and WM integrity of severely injured individuals who have substantial cognitive impairment compared to severely injured individuals with little cognitive impairment. (JINS, 2009, 15, 130-136.).

Intervention for executive functions after traumatic brain injury: a systematic review, meta-analysis and clinical recommendations.

A systematic review of studies that focused on the executive functions of problem solving, planning, organising and multitasking by adults with traumatic brain injury (TBI) was performed through 2004. Qualitative and quantitative methods were used to evaluate the 15 studies that met inclusion criteria. Demographic variables, design and intervention features, and impairment and activity/participation outcomes (ICF) (World Health Organization, 2001) were documented. Five randomised control treatment (RCT) studies used step-by-step, metacognitive strategy instruction (MSI) and outcomes were evaluated in a meta-analysis. Effect sizes (ESs) from immediate impairment outcomes after MSI and "control" intervention were similar to each other, and both were significantly larger than chance. ESs from immediate activity/participation outcomes after MSI were significantly larger than the ESs from control intervention, and both were significantly larger than chance. These results, along with positive outcomes from the other group, single-subject design and single case studies, provided sufficient evidence to make the clinical recommendation that MSI should be used with young to middle-aged adults with TBI, when improvement in everyday, functional problems is the goal (Level A) (American Academy of Neurology, 2004). Although maintenance effects were generally positive, there was insufficient data quantitatively to evaluate this. Furthermore, there was insufficient evidence to make clinical recommendations for children or older adults. Intervention that trained verbal reasoning and multi-tasking was promising, although the evidence is insufficient to make clinical recommendations at this time. Additional research needs were highlighted.