To assess how traumatic brain injury (TBI) and repetitive head impacts (RHI) may relate to behavioral measures of recognition memory in Veterans.

TBI and RHI are prevalent among military Veterans and increase the risk of chronic traumatic encephalopathy (CTE). Behavioral correlates of recognition memory (identifying previously encountered information) may reflect medial temporal lobe pathology in CTE. There are two components of recognition: recollection (detailed remembering) and familiarity (general sense of remembering). We hypothesized that while both would be impaired in Veterans with head injury compared to controls, recollection would show greater impairments due to its sensitivity to hippocampal damage. 

In pilot data, 13 older Veterans with exposure to both TBI and RHI, aged 52-89 years, were compared with 7 age-matched healthy Veterans without head injury. Participants underwent a word recognition memory task, providing confidence judgments to quantitatively measure recollection and familiarity. The Ohio State University TBI Identification Method was used to classify head trauma exposure. Questionnaires measuring aspects of mood, including the Neurobehavioral Symptom Inventory (NSI), Post-Traumatic Stress Disorder checklist (PCL), and Pittsburgh Sleep Quality Index (PSQI), were administered.

A two-sample t-test revealed a trend towards lower recollection in Veterans with RHI and TBI (mean 0.32 ± 0.22) compared to controls (mean 0.50 ± 0.16) (p=0.07). However, there were no differences in familiarity (means 0.81 ± 0.43 and 0.66 ± 0.61, respectively). Participants with RHI and TBI had significantly higher measures of NSI (p=0.049) and PCL (p=0.014), and a trend towards higher PSQI measures (p=0.058).  

These pilot data suggest that head injury exposure may be associated with impaired recollection and relatively intact familiarity. Future analyses will compare more Veterans with age-matched participants. Comparisons of mood found that head trauma may contribute to neurobehavioral dysregulation, post-traumatic stress, and sleep disturbances in older Veterans, consistent with prior literature.