The overall objective is to evaluate objective dual-task turning measures for use as rehabilitative outcomes and as tools for return-to-duty assessments in individuals with mild traumatic brain injury (mTBI).This project consists of three goals examining the I) Diagnostic Accuracy, II) Predictive Capacity, and III) Responsiveness to Intervention of dual task turning measures in individuals with mTBI.

The investigators hypothesize that objective measures of dual-task turning will have high diagnostic accuracy, predictive capacity, and responsiveness to intervention in people with mTBI.

The purpose of this project is to expand the investigators' prior preliminary work on wearable sensors to evaluate objective dual-task turning measures for use as rehabilitative outcomes and as tools for objective return-to-duty assessments following mild traumatic brain injury (mTBI). The investigators will assess the diagnostic accuracy, predictive capacity, and responsiveness to intervention of measures obtained from clinically feasible, dual-task turning tasks in an effort to evaluate the utility of turning measures for clinical return-to-duty decisions.

This study is divided into two phases. For phase one, participants will be recruited from the general populations surrounding four sites (Oregon Health & Science University, the University of Utah, Courage Kenny Research Center, and Fort Sam Houston), including active duty service members at Fort Sam Houston. For phase two, participants will be recruited from active duty service members referred to military medical treatment facilities (Warrior Recovery Center, Madigan Army Medical Center) for vestibular rehabilitation following mTBI.

Phase One: Fifty civilian individuals with mTBI, 50 healthy control individuals, and 40 healthy control active duty service members will be recruited for phase one. Participants will complete a battery of clinical, neuropsychological, and balance tests, including three clinically feasible turning tasks while wearing inertial sensors. The investigators will evaluate the capability of objective, dual-task turning measures to discriminate between healthy controls and people with chronic mTBI, determine clinically relevant measures of dual-task turning based on clinometric properties (e.g., minimum detectable change), and determine whether active-duty SMs perform dual-task turning tasks differently than civilians, assess the capacity of dual-task turning measures to predict performance in a civilian-relevant task, and assess the capacity of dual-task turning measures to predict performance in a military-relevant task.

Phase Two: Forty active-duty service members with mTBI referred to vestibular rehabilitation at the Warrior Recovery Center or Madigan Army Medical Center will be recruited for phase two. Participants will complete a selected turning task from phase one at the beginning and end of the treatment. The investigators will determine the clinically important difference of turning outcomes and compare the effect of rehabilitation to the minimum detectable change for each outcome.

Inclusion criteria.

Participants may be active duty (at FSH), Veterans or non-Veterans or a civilian and must:

1. have a diagnosis of mTBI based upon VA/DoD criteria
2. be between 18-50 years-old,
3. be outside of the acute stage (> 3 weeks post-concussion) according to the VA/DoD clinical practice guidelines but within 3 years of their most recent mTBI and still reporting symptoms.

Exclusion criteria.

Participants must not:

1. have had or currently have any other injury, medical, or neurological illness that could potentially explain balance deficits (e.g., central or peripheral nervous system disease, stroke, greater than mild TBI, lower extremity amputation, recent lower extremity or spine orthopedic injury requiring a profile)
2. meet criteria for moderate to severe substance-use disorder within the past month, as defined by DSM-V,
3. display behavior that would significantly interfere with validity of data collection or safety during study,
4. be in significant pain during the evaluation (7/10 by patient subjective report),
5. be a pregnant female (balance considerations), or
6. unable to communicate in English.

Across all sites, Phase One will include 50 civilians with persistent symptoms from mTBI, 50 civilian healthy controls, and 40 active duty SM healthy controls in total. Three non-military sites will test civilians. A fourth military site (FSH) will enroll and test 40 healthy active duty SMs across a range of military experience and ability levels.

Subjects for Phase Two will include 40 active duty SMs with persistent symptoms from mTBI who are referred for physical therapy due to their symptoms. Participants will be recruited from two military medical centers specializing in the rehabilitation of active duty personnel after mTBI, WRC at Fort Carson and MAMC at Joint Base Lewis-McChord. Each site will recruit 20 participants for Aim III.