Author : Ponsford, Jennie
2021, Volume 4, Issue 1, Pages 68-79
Objective: Since 2000, over 350,000 US military personnel have been diagnosed with a traumatic brain injury (TBI) (VA, 2010). Whilst epidemiological studies report up to a fourfold increased risk for dementia associated with brain injury amongst veterans there is limited controlled research into the long-term neuropsychological burden of injury.
Main aim: The study aimed to determine whether Australian Vietnam war veterans with service-related TBI were more likely to exhibit cognitive deficits, 30-50 years after injury when compared to healthy veteran controls.
Materials and methods: 69 male veterans 60-85 years old, underwent psychiatric and neuropsychological assessment; 40 with a TBI (mean age = 68.0 ± 2.5) and 29 without (mean age = 70.1 ± 5.3). The TBI cohort included 15 mild, 16 moderate and nine severe TBI.
Results: After adjustment for identified covariates, veterans with moderate-to-severe TBI performed significantly worse than controls on composite measures of memory and learning (M = -0.55 ± 0.69, t(67) = 2.86, p=0.006, d=0.70) and attention and processing speed (M = -0.71 ± 1.08, t(52) = 2.53, p=0.014, d=0.69). There were no differences in cognitive performance between veterans with mild TBI (mTBI) and controls.
Conclusion: Results from this study suggest that amongst ageing veterans, a moderate-to-severe TBI sustained during early adulthood is associated with later-life cognitive deficits in memory and learning, attention and processing speed.
2021, Volume 4, Issue 1, Pages 80-94
Objective: Traumatic Brain Injury (TBI) and Post-Traumatic Stress Disorder (PTSD) are common in military veterans and have been associated with an increased risk of dementia. The mechanisms contributing to this relationship are poorly understood.
Main aim: This study investigated the effect of TBI and PTSD on white matter (WM) integrity, hippocampal and cortical volume within a cohort of Vietnam veterans.
Materials and methods: 87 male veterans in total. There were 31 with TBI (aged 69.0 ± 2.5 years), 35 with PTSD (aged 69.5 ± 2.6 years) and 21 controls (aged 70.1 ± 4.9 years) underwent 3Tesla Magnetic Resonance Imaging (MRI). The TBI cohort included 12 mild, 13 moderate and six severe injuries. WM integrity was assessed using tract-based spatial statistics and region-specific analyses of fractional anisotropy (FA) images. Automated processing of T1-weighted magnetisation-prepared rapid gradient-echo (MPRAGE) images resulted in hippocampal volumes and whole-brain cortical thickness estimation. Analyses were adjusted for IQ, Body Mass Index (BMI) and psychiatric comorbidities.
Results: The moderate-to-severe TBI group had significantly lower FA than controls in the genu (F(3,36)=8.81, p<0.05, partial η2 = 0.17), and body (F(3,36)=4.39, p <0.05, partial η2=0.14) of the corpus callosum, as well as in global WM (F(3,36)=5.35, p <0.05, partial η2=0.13). The PTSD FA values did not differ from controls and neither the TBI nor PTSD group differed significantly from controls in hippocampal volume nor cortical thickness in Alzheimer’s disease vulnerable regions.
Conclusion: These findings suggest that the widely reported loss of WM integrity observed after moderate to severe TBI persists throughout life but is not associated with hippocampal or grey matter atrophy after four decades. No PTSD-related structural or FA change was observed.