Background Despite the high prevalence of cognitive issues in Veterans and active military personnel, there is relatively little understanding regarding the cognitive effects following intense, military training regimens designed to reflect a combat environment and blast exposure. Anecdotal evidence has shown that soldiers complain of cognitive issues post-training similar to those who have sustained brain trauma. Accordingly, this study looks to investigate the cognitive effects associated with intense, military combat training regimens or so-called repetitive sub-concussive forces. Specifically, study participants will undergo cognitive testing in tandem with EEG recordings pre- and post-military training to assess cognition.
Research Objective To assess the effects of repetitive, sub-concussive exposure (RSCE) on cognitive functioning and brain electrophysiology in Special Operation Forces (SOF) personnel. Furthermore, the relation between repetitive sub-concussive exposure and symptoms will be clarified.
Participants and Procedure 20 SOF members will complete a symptom profile, a vestibular ocular motor screening (VOMS), ImPACTTM Cognitive Testing and VoxNeuroTM Electroencephalogram (EEG) assessment pre-and post-training to assess cognitive functioning in the following domains: attention and concentration, working memory, and information processing. Investigators will look for correlations pre and post training
The cognitive assessment(s) to be taken are:
1. ImPact Cognitive Testing
2. VoxNeuro Assessment (EEG)
1. Attention \& Concentration Test - 10min
2. Continuous Visual Memory Test - 5min
3. Flanker Test (Optional) - 10min
4. Hayling Test (TBD - Currently only an English version available) - 10min
Test Descriptions
* Participants will keep logbooks looking at trauma exposure to help identify occupational vs non occupational causes, however given the intensity and length of the course significant non Paroccupational exposure is unlikely.
* Blast Measurement will be monitored using a validated system of three worn blast gauges (Black-box Biometrics Inc.). These gauges - placed on the back of the helmet, non-firing shoulder, and chest - will be used to collect blast overpressure exposure levels above 0.5 psi at the location of the participant during the breaching events. Blast gauges will be issued to all participants prior to blast overpressure exposure and monitored throughout the duration of the study.
* Vestibular Ocular Motor Screening (VOMS) consists of symptom reporting (eg headache, dizziness, nausea, and fogginess) ranging from 0 (none) to 10 (severe) after testing smooth pursuits, saccades (horizontal and vertical), convergence, Neer Point of Convergence (NPC) distance, horizontal VOR, vertical VOR, and visual motor sensitivity (VMS). For the purpose of this study, we will use the VOMS cutoff scores of ≥2 total symptom score on any VOMS subscale and/or ≥5 cm on NPC average distance
* ImPACT is an FDA cleared online tool for baseline and post-injury testing. It measures patient reported symptoms, visual and verbal memory, reaction time, and processing speed to help determine if a patient can safely return to activity.
* VoxNeuro Assessment:
* Attention \& Concentration: An auditory oddball task where the participant is asked to identify the difference between one (1) or more auditory stimuli while EEG is recorded simultaneously to assess Attention and Concentration function at the neurophysiological level.
* Continuous Visual Memory Test (CVMT): A visual task whereby participants are asked to differentiate between visual stimuli that have been previously presented to them and newly presented visual stimuli while EEG is recorded simultaneously to assess Memory function at the neurophysiological level.
* Flanker Task: This test consists of participants identifying target stimulus while a target is flanked by non-target stimuli which correspond either to the same directional response as the target (congruent flankers), to the opposite response (incongruent flankers), or to neither (neutral flankers). The test is administered while EEG is recorded simultaneously to assess Executive Function and Response Inhibition at the neurophysiological level.
* Hayling Test: This test consists of participants being aurally presented congruent and incongruent sentences; whereby, the congruent sentences are "normal" sentences with the final word being correct (e.g., "The pizza was too hot to eat"). In contrast, the incongruent sentences have the final word of a sentence being incorrect (e.g., The pizza was too hot to sing"). The test is administered while EEG is recorded simultaneously to assess Language Comprehension at the neurophysiological level.
Biological Markers Measured (up to 7) ● N100/P200 - Auditory and Visual Processing
* N100 ERP is a temporal and frontal component elicited by auditory stimuli. The response is associated with perception.
* P200 ERP is mainly exhibited at the frontal and occipital lobes and represents higher order perceptual processes such as visual search, language, context information, memory and repetition effects. I.e. all processes modulated by attention.
* N200 - Information Processing and Executive Function
* N200 is a centro-cortical component associated with conscious stimuli detection (i.e. information processing and response inhibition) ● P300 - Attention and Memory
* The P3a is a fronto-central component associated with attention orienting and is followed by the P3b, a centro-parietal component often linked to processes related to memory and attention allocation
● N400 - Language Comprehension (TBD)
* N400 is a central component and acts as the normal brain response to semantic stimuli. For example, words, sign language, pictures, faces, smells.
Benefits and Military Significance Understanding the relationship between exposure to repetitive, sub-concussive impacts to behavioural symptomatology, vestibular ocular dysfunction, brain electrophysiology, and cognition to aid in early detection/prevention, treatment and prognostication of SOF members. Moreover, this study will lay the foundation for future research for years to come.
