A large portion of veterans returning from of Operations Enduring Freedom, Iraqi Freedom and New Dawn (OEF/OIF/OND) have sustained a traumatic brain injury (TBI), with over 80 percent categorized as mild (i.e., mTBI; U.S. Department of Defense, 2017). Although many military mTBIs result from blunt trauma, a unique mechanism of injury among service members is blast exposure. Many veterans experience repetitive blast-related mTBIs over the course of their service—this form of injury has begun to receive increased research attention in regard to its neurological and cognitive sequelae, assessing whether the consequences of mTBI due to blast exposure are distinct from mTBI due to blunt trauma (Karr, Areshenkoff, Duggan, & Garcia-Barrera, 2014a). Notably, the cognitive sequelae of mTBI tend to be transient, quickly resolving within the weeks to months post injury (Karr, Areshenkoff, & Garcia-Barrera, 2014b). Persistent reductions in cognitive functioning following mTBI are often mild at most, and potentially undetectable on most traditional neuropsychological tests. However, despite good prognosis, about a third of veterans with a history of mTBI report post-concussive symptoms, inclusive of cognitive complaints (Brenner et al., 2010; Donnell, Kim, Silva, & Vanderploeg, 2012; Schneiderman, Braver, & Kang, 2008). This discrepancy led to the research question: if post-mTBI reductions in cognitive functioning are expected to resolve within weeks to months, why do veterans present with cognitive concerns for years following injury?
The current study was presented as a paper at the 2018 APA Annual Convention in San Francisco, California, and received a Certificate of Merit for Outstanding Student Presentation Focused on Assessment and Emerging Leaders in Assessment Award, sponsored by APA Divs. 5, 12 (Section IX) and 40. The study examined variables associated with perceived decline in executive function among a sample of 59 veterans with a history of blast-related mTBI occurring about six years prior to their enrollment in the study. The study was cross-sectional, and veterans retrospectively rated their pre-injury executive function along with their current executive function. Whereas about 1 in 10 veterans rated their pre-mTBI executive function problems as clinically significant, over 80 percent rated their post-mTBI executive function problems as clinically significant. However, norm-referenced scores across neuropsychological tests were predominantly within the average range among the sample of participants. Multiple variable sets served as predictors of self-reported decline in executive function in a series of regression models. Pre-injury characteristics (e.g., estimated premorbid intelligence), injury-related characteristics (e.g., loss of consciousness), and postinjury neuropsychological executive function test performances did not emerge as significant predictors. Only current PTSD symptoms were independently associated with self-reported decline in executive function.
These findings are consistent with previous studies on veterans and active duty service members showing both minimal correspondence between objective and subjective measurements of cognitive functioning (French, Lange, & Brickell, 2014) and a stronger relationship between subjective cognitive complaints and mental health (e.g., depression) than neuropsychological test performances (Schiehser et al., 2011). They indicate that, despite perceptions of reduced cognitive functioning, performances on neuropsychological tests do not show evidence of significant cognitive impairment years post mTBI. PTSD has been associated with greater cognitive impairment than a remote history of blast-related mTBI (Scott et al., 2015; Karr et al., 2014b). In the current analysis, current PTSD symptoms explained a significant amount of variance in perceived cognitive decline. Fortunately, current PTSD symptoms are potentially modifiable through evidence-based trauma-focused treatments, and previous studies have shown improvements in objective executive function test performances and reductions in cognitive complaints with intervention (Storzbach et al., 2017; Walter, Palmieri, & Gunstad, 2010; Wolf et al., 2018). Treatments that focus on both trauma and cognitive rehabilitation needs may be the most effective, and attractive to veterans interested in a comprehensive treatment program addressing cognitive and mental health needs.
References
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