United States Military Service Members Demonstrate Substantial and Heterogeneous Long-Term Neuropsychological Dysfunction after Moderate, Severe, and Penetrating Traumatic Brain Injury

The objective of the study was to examine long-term neuropsychological outcome after moderate, severe, and penetrating traumatic brain injury (TBI) in U.S. military service members and veterans (SMVs). Eighty-five SMVs with a history of moderate (n = 18), severe (n = 17), or penetrating (n = 26) TBI, or an injury without TBI (i.e., trauma control [TC], n = 24) were assessed five or more years (mean = 69.4 months; standard deviation = 35.6) post-injury. All passed performance validity tests. Participants completed a battery of neurocognitive tests and a personality inventory. Five cognitive domain composites, each composed of four test scores, and an overall test battery mean (OTBM) were computed. The penetrating TBI group performed worse than the TC group and/or the moderate TBI group on most cognitive domains and the OTBM. The severe TBI group also performed worse than the TC group and moderate TBI group on processing speed and the OTBM, and worse than the TC group on attention/working memory. Just more than half of participants with severe (56%) or penetrating (64%) TBI met criteria for mild neurocognitive disorder, with processing speed the most commonly impaired domain. In addition, 80% of TBI participants had one or more clinically elevated scales on the Minnesota Multiphasic Personality Inventory-2-Restructured Form^® (MMPI-2-RF), with somatic complaints the most common elevation. In conclusion, there was significantly reduced cognitive and psychological functioning many years after severe and penetrating TBI in SMVs. Cognitive and psychological dysfunction, however, were highly variable, with a substantial minority of SMVs having good outcome. Long-term individualized support is necessary for individuals after moderate, severe, and penetrating TBI.