This observational study will examine the association of chronic traumatic cerebrovascular injury and cardiovascular risk factors with TBI-related cognitive impairment and vascular dementia. Cerebrovascular, inflammatory, and neurodegenerative blood biomarkers as well as clinical and neuroimaging data
The investigators will enroll 300 Service Members (SMs) and Veterans who participated in the National Intrepid Center of Excellence (NICoE) intensive outpatient program or Defense and Veterans Brain Injury Center/Traumatic Brain Injury Center of Excellence (DVBIC/TBICoE) 15-Year TBI Natural History of TBI Study (NatHx) at least three years prior to the present evaluation and provided prior blood specimens stored for analysis. Following informed consent, participants will undergo semi-structured interviews assessing posttraumatic stress disorder (PTSD) and updated lifetime TBI history, neurological examination, neuropsychological testing, structural Magnetic Resonance Imaging (MRI) T1, T2, fluid attenuated inversion recovery (FLAIR), diffuse tensor imaging (DTI), as well as novel imaging techniques to assess imaging biomarkers of traumatic cerebrovascular injury (TCVI): 1) functional MRI (fMRI)-Blood Oxygen Level Dependent (BOLD) with hypercapnia challenge to measure cerebrovascular reactivity (CVR); and 2) Dynamic Contrast Enhanced-MRI to assess blood brain barrier integrity, and an additional research blood draw \[apolipoprotein E (APOE) genotype; plasma biomarkers including vascular (e.g., vascular endothelial growth factor, von Willebrand Factor, cholesterol, homocysteine), inflammatory (e.g., high sensitivity c-reactive protein, interleukin-6 (IL-6), chitinase-3-like protein 1 (YKL-40)), and neuronal degeneration (e.g., neurofilament light, phosphorylated tau, brain-derived neurotrophic factor, beta amyloid proteins)\]. A medical record review will be conducted specifically for current and past history of cerebrovascular risk factors (e.g., hypertension, diabetes, tobacco use) and psychological conditions (e.g., PTSD, depression). The project will also leverage previously collected data, comparing participants' symptoms, cognitive performance, imaging, and, blood biomarkers to those previously collected through the NICoE, 15-Year study and/or the DOD serum repository, with data from at least two time points on all individuals.
Study Type
OBSERVATIONAL
Enrollment
300
There are no interventions being tested in the Cognitive and Vascular Functioning Following TBI study.
Walter Reed National Military Medical Center
Bethesda, Maryland, United States
RECRUITINGPanel of blood biomarkers
A panel of blood biomarkers including vascular (e.g., vascular endothelial growth factor, von Willebrand Factor, cholesterol, lipoproteins, homocysteine, fibrinogen, hemoglobin A1C), inflammatory (e.g., high sensitivity c-reactive protein, Tumor Necrosis Factor-alpha, IL-6, IL-12p70, YKL-40), and neuronal degeneration (e.g., neurofilament light, Glial Fibrillary Acidic Protein, phosphorylated tau, Clusterin, brain-derived neurotrophic factor, beta amyloid proteins) will be compared between TBI groups. One-way ANOVAs will be run with TBI severity as the independent variable and each individual blood biomarker (measured in pg/mL) as the dependent variable. Spearman's rank order correlations will evaluate the relationship between blood biomarkers, number of TBIs, and TBI severity.
Time frame: 3 years
Cognitive Performance- Overall Test Battery Mean
Neurocognitive data will be corrected for age, gender, education, and race, as available. An overall test battery mean (OTBM) T-score will be calculated as the average of seven cognitive domain T-scores (attention/processing speed, working memory, executive functioning, learning/immediate memory, delayed memory, language, perceptual reasoning). Each biomarker will be correlated with the OTBM using Spearman's rank order correlations. Cognitive domain T-scores will also be evaluated to understand which are driving changes in the OTBM. All scores will be evaluated as T-scores (mean=50, SD=10, min=0, max=100), for which higher scores indicate higher cognitive performance. Multivariable logistic regression will be used to evaluate the relationship between TBI number, TBI severity, blood biomarkers and normal cognition vs. mild cognitive impairment (MCI).
Time frame: 3 years
Change in panel of blood biomarkers over time
Linear mixed effect (LME) models will be fit to the analysis dataset which use the panel of blood biomarkers as the response variables and investigate TBI severity, number of TBI events, and time. The panel of blood biomarkers will include vascular (e.g., vascular endothelial growth factor, von Willebrand Factor, cholesterol, lipoproteins, homocysteine, fibrinogen, hemoglobin A1C), inflammatory (e.g., high sensitivity c-reactive protein, Tumor Necrosis Factor-alpha, IL-6, IL-12p70, YKL-40), and neuronal degeneration (e.g., neurofilament light, Glial Fibrillary Acidic Protein, phosphorylated tau, Clusterin, brain-derived neurotrophic factor, beta amyloid proteins) biomarkers, all measured in pg/mL.
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Time frame: 3 years
Change in overall test battery mean over time
The investigators will fit a cross-sectional multivariable regression model to the data with the response variable being the change (Time 3 - Time 2) in the OTBM T-score (mean=50, SD=10, min=0, max=100). Individual cognitive domain composite T-scores will also be evaluated to understand the main components driving change in the OTBM.
Time frame: 3 years
Change in brain volume over time
The investigators will fit a cross-sectional multivariable regression model to the data with the response variable being the change (Time 3 - Time 2) in total brain volume \[milliliters (mL)\].
Time frame: 3 years
Change in white matter lesions over time
The investigators will fit a cross-sectional multivariable regression model to the data with the response variable being the change (Time 3 - Time 2) in total and total number of white matter lesions.
Time frame: 3 years
Cerebrovascular Reactivity
Linear regression models will be run with the difference score in each vascular blood biomarker from the initial visit to the current study visit as the independent variable and global CVR (%S/mmHG) - (assessed during the current visit only) as the dependent variable.
Time frame: 3 years
DCE-MRI
Linear regression models will be run with the difference score in each vascular blood biomarker from the initial visit to the current study visit as the independent variable and overall blood brain barrier function (assessed during the current visit only as the percentage of brain volume with suprathreshold voxels) as the dependent variable.
Time frame: 3 years