Browsing by Author "Tate, David F."

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    Age‐dependent white matter disruptions after military traumatic brain injury: Multivariate analysis results from ENIGMA brain injury
    (Wiley, 2022) Bouchard, Heather C.; Sun, Delin; Dennis, Emily L.; Newsome, Mary R.; Disner, Seth G.; Elman, Jeremy; Silva, Annelise; Velez, Carmen; Irimia, Andrei; Davenport, Nicholas D.; Sponheim, Scott R.; Franz, Carol E.; Kremen, William S.; Coleman, Michael J.; Williams, M. Wright; Geuze, Elbert; Koerte, Inga K.; Shenton, Martha E.; Adamson, Maheen M.; Coimbra, Raul; Grant, Gerald; Shutter, Lori; George, Mark S.; Zafonte, Ross D.; McAllister, Thomas W.; Stein, Murray B.; Thompson, Paul M.; Wilde, Elisabeth A.; Tate, David F.; Sotiras, Aristeidis; Morey, Rajendra A.; Psychiatry, School of Medicine
    Mild Traumatic brain injury (mTBI) is a signature wound in military personnel, and repetitive mTBI has been linked to age‐related neurogenerative disorders that affect white matter (WM) in the brain. However, findings of injury to specific WM tracts have been variable and inconsistent. This may be due to the heterogeneity of mechanisms, etiology, and comorbid disorders related to mTBI. Non‐negative matrix factorization (NMF) is a data‐driven approach that detects covarying patterns (components) within high‐dimensional data. We applied NMF to diffusion imaging data from military Veterans with and without a self‐reported TBI history. NMF identified 12 independent components derived from fractional anisotropy (FA) in a large dataset (n = 1,475) gathered through the ENIGMA (Enhancing Neuroimaging Genetics through Meta‐Analysis) Military Brain Injury working group. Regressions were used to examine TBI‐ and mTBI‐related associations in NMF‐derived components while adjusting for age, sex, post‐traumatic stress disorder, depression, and data acquisition site/scanner. We found significantly stronger age‐dependent effects of lower FA in Veterans with TBI than Veterans without in four components (q < 0.05), which are spatially unconstrained by traditionally defined WM tracts. One component, occupying the most peripheral location, exhibited significantly stronger age‐dependent differences in Veterans with mTBI. We found NMF to be powerful and effective in detecting covarying patterns of FA associated with mTBI by applying standard parametric regression modeling. Our results highlight patterns of WM alteration that are differentially affected by TBI and mTBI in younger compared to older military Veterans.
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    Regional areas and widths of the midsagittal corpus callosum among HIV-infected patients on stable antiretroviral therapies
    (Springer US, 2011-08) Tate, David F.; Sampat, Mehul; Harezlak, Jaroslaw; Fiecas, Mark; Hogan, Joseph; Dewey, Jeffrey; McCaffrey, Daniel; Branson, Daniel; Russell, Troy; Conley, Jared; Taylor, Michael; Schifitto, Giavoni; Zhong, J.; Daar, Eric S.; Alger, Jeffrey; Brown, Mark; Singer, Elyse; Campbell, T.; McMahon, D.; Tso, Y.; Matesan, Janetta; Letendre, Scott; Paulose, S.; Gaugh, Michelle; Tripoli, C.; Yiannoutsos, Constantine; Bigler, Erin D.; Cohen, Ronald A.; Guttmann, Charles R. G.; Navia, Bradford; HIV Neuroimaging Consortium; Department of Biostatistics, Richard M. Fairbanks School of Public Health
    Recent reports suggest that a growing number of human immunodeficiency virus (HIV)-infected persons show signs of persistent cognitive impairment even in the context of combination antiretroviral therapies (cART). The basis for this finding remains poorly understood as there are only a limited number of studies examining the relationship between CNS injury, measures of disease severity, and cognitive function in the setting of stable disease. This study examined the effects of HIV infection on cerebral white matter using quantitative morphometry of the midsagittal corpus callosum (CC) in 216 chronically infected participants from the multisite HIV Neuroimaging Consortium study currently receiving cART and 139 controls. All participants underwent MRI assessment, and HIV-infected subjects also underwent measures of cognitive function and disease severity. The midsagittal slice of the CC was quantified using two semi-automated procedures. Group comparisons were accomplished using ANOVA, and the relationship between CC morphometry and clinical covariates (current CD4, nadir CD4, plasma and CSF HIV RNA, duration of HIV infection, age, and ADC stage) was assessed using linear regression models. HIV-infected patients showed significant reductions in both the area and linear widths for several regions of the CC. Significant relationships were found with ADC stage and nadir CD4 cell count, but no other clinical variables. Despite effective treatment, significant and possibly irreversible structural loss of the white matter persists in the setting of chronic HIV disease. A history of advanced immune suppression is a strong predictor of this complication and suggests that antiretroviral intervention at earlier stages of infection may be warranted.
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    Relative sensitivity of magnetic resonance spectroscopy and quantitative magnetic resonance imaging to cognitive function among nondemented individuals infected with HIV
    (Cambridge University Press, 2008-09) Paul, Robert H.; Ernst, Thomas; Brickman, Adam M.; Yiannoutsos, Constantin T.; Tate, David F.; Cohen, Ronald A.; Navia, Bradford A.; Biostatistics, School of Public Health
    In the present study, we examined the relationships among cognitive function, magnetic resonance spectroscopy (MRS) brain metabolite indices measured in the basal ganglia, and quantitative magnetic resonance imaging (MRI) of the caudate nucleus and the putamen in the earliest stages of HIV-related cognitive involvement. Participants included 22 HIV-positive individuals and 20 HIV-negative individuals. HIV-positive individuals performed significantly more poorly than the HIV-negative individuals on several cognitive measures. In addition, the choline/creatine ratio was significantly higher and the N-acetyl aspartate/choline ratio was significantly lower among HIV patients. The caudate and putamen sizes were smaller among HIV-positive patients compared with controls; however, the differences did not reach statistical significance. Correlation analyses revealed associations between cognitive function and select MRS indices. In addition, caudate size was significantly correlated with performances on higher-order thinking tests whereas putamen size was significantly correlated with performances on motor tests. The results suggest that MRS differences are more pronounced than area size differences between seropositive and seronegative individuals in mild stages of HIV-related cognitive impairment. However, basal ganglia size remains an important contributor to cognitive status in this population. Longitudinal studies are needed to determine the evolution of these imaging correlates of HIV-cognitive impairment in HIV.