Abstract
The cholinergic nuclei in the basal forebrain innervate frontal cortical structures regulating attention. Our aim was to investigate if cognitive test results measuring attention relate to the longitudinal volume change of cholinergically innervated structures following traumatic brain injury (TBI). During the prospective, observational TBIcare project patients with all severities of TBI (n = 114) and controls with acute orthopedic injuries (n = 17) were recruited. Head MRI was obtained in both acute (mean 2 weeks post-injury) and late (mean 8 months) time points. T1-weighted 3D MR images were analyzed with an automatic segmentation method to evaluate longitudinal, structural brain volume change. The cognitive outcome was assessed with the Cambridge Neuropsychological Test Automated Battery (CANTAB). Analyses included 16 frontal cortical structures, of which four showed a significant correlation between post-traumatic volume change and the CANTAB test results. The strongest correlation was found between the volume loss of the supplementary motor cortex and motor screening task results (R-sq 0.16, p < 0.0001), where poorer test results correlated with greater atrophy. Of the measured sum structures, greater cortical gray matter atrophy rate showed a significant correlation with the poorer CANTAB test results. TBI caused volume loss of frontal cortical structures that are heavily innervated by cholinergic neurons is associated with neuropsychological test results measuring attention.
Highlights
Traumatic brain injury (TBI) is a significant cause of death and long-term physical and cognitive impairment [1]
We aimed to investigate if the volume changes after TBI in regions with cholinergic innervation would associate with cognitive test results, especially those measuring attention
Functional magnetic resonance imaging (MRI) studies in humans have shown that the cholinergic system is involved in the attentional activity in frontal structures [6, 50, 51]
Summary
Traumatic brain injury (TBI) is a significant cause of death and long-term physical and cognitive impairment [1]. Contusions causing focal damage are usually situated in ventral and polar frontal and anterior temporal regions, where the bony ridges of the skull base bruise the brain [5, 6]. These regions are important for emotional self-regulation, and social intelligence, which are often defective in patients with TBI. Diffuse axonal injury (DAI) interferes with the inter-neural connections, resulting in slowing and deficits in memory and attention, which are frequently observed in patients with chronic sequelae of TBI [7]. It has been suggested that DAI accounts for a greater part of post-traumatic disability compared to focal contusions, and is associated with poorer outcome [7, 8]
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