Evaluating Reductions in Hippocampal Volume Related to Blast Exposure and Their Effect on Memory Function
Abstract
FY21 TBIPHRP IIRA Focus Area to be Addressed: Understanding injury (blast) and biological factors (hippocampal size) contributing to long-term outcomes (memory) following brain injury or traumatic events. Objectives and Rationale: The overarching purpose of this proposal is to determine whether, when, and under what circumstances exposure to blast affects brain health long term, beyond what is expected for normal aging. The specific focus of this proposal will determine if reductions in hippocampal size as a result of blast exposure continue to change over time and how these changes relate to memory function. This focus builds upon our novel finding that increasing severity of blast exposure is related to lower hippocampal size in combat Veterans. The relationship between blast exposure and hippocampal size was strong, even after accounting for other conditions, including post-traumatic stress disorder and traumatic brain injury. This project will advance our research by identifying how size differences and/or size changes related to blast exposure affect memory performance, which relies on the hippocampus. Previous research has shown a strong relationship between blast exposure and smaller hippocampal size in both animals and humans. The relationship between hippocampal size and memory performance is also well established. Previous research has demonstrated that exposure to a blast at close range is associated with poorer memory. However, we do not know whether blast exposure leads to a process of hippocampal degeneration that continues over time, which may also explain memory complaints among service members when a clear cause cannot be identified. Importantly, our preliminary finding demonstrates that changes in hippocampal size seen shortly after blast exposure may endure for many years. It also leads to the troubling possibility that the size of the hippocampus may continue to decline more than expected over time due to blast exposure. The objective of this study is responsive to the Understand focus area in two ways. First, the proposed study will determine whether reduction in hippocampal size related to blast exposure is an ongoing process of neurodegeneration. We will identify potential characteristics of blast exposure that may be responsible for ongoing changes in hippocampal size. Identifying a specific characteristic of blast exposure, such as the severity of blast pressure experienced, would be highly informative to the development of in-theater protocols (e.g., rest following specific exposure) and treatment or intervention guidelines. Second, the proposed study will determine if hippocampal size explains the relationship between blast exposure and difficulties with learning and memory (i.e., neurocognitive disorders, commonly referred to as dementia). In addition to the hippocampus, we will also evaluate other brain regions of interest to determine whether blast accelerates change beyond normal aging. If this is indicated, blast may be a contributing risk factor for negative outcomes, such as dementia. This is responsive to the DoD Warfighter Brain Health Initiative that has identified blast as an exposure of interest that might affect brain health. Overall, this study will increase what we know about the nature of problems following blast exposure and the blast event characteristics associated with those outcomes. Knowledge gained from this research will support future studies in evaluation of potential strategies to mitigate or alleviate these negative outcomes in an informed and effective manner. Outcomes: This research represents a necessary step along the translational science continuum towards clinical applications. Too little is currently known about the relationship between blast exposure, brain structure, and associated functional outcomes for effective interventions to be developed. Further, we know very little about the relationship between blast exposure and clin
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310789
Entities
People
- Sarah Martindale
Organizations
- United States Army