title: Blast-related mild traumatic brain injury: a Bayesian random-effects meta-analysis on the cognitive outcomes of concussion among military personnel.
abstract: Throughout their careers, many soldiers experience repeated blasts exposures from improvised explosive devices, which often involve head injury. Consequentially, blast-related mild Traumatic Brain Injury (mTBI) has become prevalent in modern conflicts, often occuring co-morbidly with psychiatric illness (e.g., post-traumatic stress disorder [PTSD]). In turn, a growing body of research has begun to explore the cognitive and psychiatric sequelae of blast-related mTBI. The current meta-analysis aimed to evaluate the chronic effects of blast-related mTBI on cognitive performance. A systematic review identified 9 studies reporting 12 samples meeting eligibility criteria. A Bayesian random-effects meta-analysis was conducted with cognitive construct and PTSD symptoms explored as moderators. The overall posterior mean effect size and Highest Density Interval (HDI) came to d = -0.12 [-0.21, -0.04], with executive function (-0.16 [-0.31, 0.00]), verbal delayed memory (-0.19 [-0.44, 0.06]) and processing speed (-0.11 [-0.26, 0.01]) presenting as the most sensitive cognitive domains to blast-related mTBI. When dividing executive function into diverse sub-constructs (i.e., working memory, inhibition, set-shifting), set-shifting presented the largest effect size (-0.33 [-0.55, -0.05]). PTSD symptoms did not predict cognitive effects sizes, β PTSD  = -0.02 [-0.23, 0.20]. The results indicate a subtle, but chronic cognitive impairment following mTBI, especially in set-shifting, a relevant aspect of executive attention. These findings are consistent with past meta-analyses on multiple mTBI and correspond with past neuroimaging research on the cognitive correlates of white matter damage common in mTBI. However, all studies had cross-sectional designs, which resulted in universally low quality ratings and limited the conclusions inferable from this meta-analysis.
authors.affiliation: Department of Psychology, University of Victoria, P.O. Box 1700, Victoria, BC, V8W 2Y2, Canada, jkarr@uvic.ca.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Karr
authors.forename: Corson N
authors.initials: CN
authors.lastname: Areshenkoff
authors.forename: Emily C
authors.initials: EC
authors.lastname: Duggan
authors.forename: Mauricio A
authors.initials: MA
authors.lastname: Garcia-Barrera
mesh_terms: D000328:Adult; D001499:Bayes Theorem; D001753:Blast Injuries / Q000150:complications*; D003072:Cognition Disorders / Q000209:etiology; D003130:Combat Disorders / Q000209:etiology / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008889:Military Personnel / Q000523:psychology*; D038223:Post-Concussion Syndrome / Q000209:etiology* / Q000523:psychology*