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Altered Frontoparietal Structural Correspondence Relates to Slower Processing Speed in Combat Blast

Poster No:

2104 

Submission Type:

Abstract Submission 

Authors:

Chang-Le Chen1, Minjie Wu1, Matthew Reid2,3,4, Jan Kennedy2,3,5, Aaron Betts3,6, John Ritter3, Cynthia Muncy2,3,4, Maya Troyanskaya7,8, Randall Schiebel7,8, Emily Dennis9,10, Elisabeth Wilde10, Howard Aizenstein1, David Tate10,9, Lisa Lu2,3,5

Institutions:

1University of Pittsburgh, Pittsburgh, PA, 2Defense Health Agency Traumatic Brain Injury Center of Excellence, Arlington, VA, 3Brooke Army Medical Center, Houston, TX, 4Ciconix LLC, Annapolis, MD, 5General Dynamics Information Technology, Falls Church, VA, 6Uniformed Services University, Bethesda, MD, 7Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, 8Baylor College of Medicine, Houston, TX, 9University of Utah School of Medicine, Salt Lake City, UT, 10George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT

First Author:

Chang-Le Chen  
University of Pittsburgh
Pittsburgh, PA

Co-Author(s):

Minjie Wu, PhD  
University of Pittsburgh
Pittsburgh, PA
Matthew Reid  
Defense Health Agency Traumatic Brain Injury Center of Excellence|Brooke Army Medical Center|Ciconix LLC
Arlington, VA|Houston, TX|Annapolis, MD
Jan Kennedy  
Defense Health Agency Traumatic Brain Injury Center of Excellence|Brooke Army Medical Center|General Dynamics Information Technology
Arlington, VA|Houston, TX|Falls Church, VA
Aaron Betts  
Brooke Army Medical Center|Uniformed Services University
Houston, TX|Bethesda, MD
John Ritter  
Brooke Army Medical Center
Houston, TX
Cynthia Muncy  
Defense Health Agency Traumatic Brain Injury Center of Excellence|Brooke Army Medical Center|Ciconix LLC
Arlington, VA|Houston, TX|Annapolis, MD
Maya Troyanskaya  
Michael E. DeBakey Veterans Affairs Medical Center|Baylor College of Medicine
Houston, TX|Houston, TX
Randall Schiebel  
Michael E. DeBakey Veterans Affairs Medical Center|Baylor College of Medicine
Houston, TX|Houston, TX
Emily Dennis  
University of Utah School of Medicine|George E. Wahlen Veterans Affairs Medical Center
Salt Lake City, UT|Salt Lake City, UT
Elisabeth Wilde  
George E. Wahlen Veterans Affairs Medical Center
Salt Lake City, UT
Howard Aizenstein, M.D., PhD.  
University of Pittsburgh
Pittsburgh, PA
David Tate  
George E. Wahlen Veterans Affairs Medical Center|University of Utah School of Medicine
Salt Lake City, UT|Salt Lake City, UT
Lisa Lu  
Defense Health Agency Traumatic Brain Injury Center of Excellence|Brooke Army Medical Center|General Dynamics Information Technology
Arlington, VA|Houston, TX|Falls Church, VA

Introduction:

Blast exposure within a military context has garnered increasing attention due to its potential long-term cognitive implications [1]. Low-level blast exposure (overpressure from outgoing munitions [2]) has been associated with slower reaction time amongst breachers [3]. We investigated the macroscopic structural correspondence associated with combat blast exposure and explored the potential cognitive relevance of altered frontoparietal structural correspondence [4-6].

Methods:

Eighty-two service members/veterans were included in this study, comprising 43 with blast exposure (age at time of evaluation: 37.4 [7.6] years, 40 males, years since last deployment: 6.4 [3.3] years]) and 39 without blast exposure (age: 38.9 [8.4] years, 29 males, years of deployment: 7.8 [3.9] years]). Structural brain scans were acquired using T1-weighted 3D MPRAGE sequence from Siemens Skyra 3T MRI scanner with the imaging parameters: TR = 2530 ms, TE = 2.6 ms, image size 176 x 256 x 256, and voxel size 1 x 1 x 1 mm^3. All images were first checked for quality assurance [7] then were analyzed by voxel-based morphometry to estimate gray matter volume [7]. Regional frontal and parietal gray matter volumetric measures were sampled according to the LPBA-40 atlas [8]. Cognitive measures of processing speed (Trailmaking Test A completion time in seconds [Trails A]) and working memory (number of correct responses for Paced Auditory Serial Addition Test Trial 1 and Auditory Consonant Trigram 36-second delay) were also collected. To estimate structural correspondence between frontal and parietal lobes, we performed partial correlation analysis within each blast exposure group with age and sex as covariates. Fisher z test was used to test if correlation coefficients were significantly different between groups. To explore cognitive associates of altered structural correspondence, we used the bootstrapping approach to resample brain features, cognitive measures, and covariates (i.e. age and sex) from all subjects and re-estimated partial correlations between frontal and parietal lobes 1,000 times to create an empirical spectrum of structural correlations, on which we tested the relationship between frontoparietal structural correspondence and cognitive measures using a linear regression model that adjusted for age and sex. Multiple comparisons for cognitive measures were addressed using Bonferroni correction.

Results:

We found that there was no significant frontoparietal correlation in the non-blast group (rho = -0.155, p-value = 0.368); however, significant negative frontoparietal correlation was found in the blast group (rho = -0.579, p-value < 0.001). Correlations significantly differed between blast and non-blast groups (Z = 2.18, p = 0.029) (Figure 1A). Out of three cognitive measures, frontoparietal correspondence was negatively associated with TrailsA Time (p = 0.003, Figure 1B); slower Trails A completion time was associated with higher magnitude of negative structural correlations (discrepant frontal and parietal gray matter volumes).
Supporting Image: Figure1_blast_gm_conn.png
 

Conclusions:

Among military personnel with blast exposure, discrepant frontal and parietal gray matter volumes was associated with slower response time, but this was not the case for those not exposed to blast. This suggested that although processing speed was similar across groups, frontal-parietal correspondence may influence processing speed in those exposed to blast. This is consistent with neuroimaging findings suggesting subtle altered connectivity in blast-related mild traumatic brain injury [5] despite lack of long-term cognitive impairment [9]. Microstructural features related to this macrostructural finding need to be explored to elucidate this preliminary finding.

Higher Cognitive Functions:

Higher Cognitive Functions Other 2

Neuroanatomy, Physiology, Metabolism and Neurotransmission:

Anatomy and Functional Systems 1

Keywords:

Cognition
MRI
Structures
Trauma
Other - Combat Blast

1|2Indicates the priority used for review

Provide references using author date format

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