Pilot Study of Neurofeedback for Photosensitivity in Mild Traumatic Brain Injury

Photosensitivity (PS) is one of the more common sequelae of TBI, with over 50% of TBI patients reporting some level of PS in the acute and/or chronic stages. PS can range from mild to severe and can significantly impair social, physical, and cognitive functioning, as well as rehabilitation outcomes. While spectacle chromatic filters are conventionally used to alleviate symptoms, they are not designed to resolve issues with PS and have been associated with lower symptom recovery over time, underscoring the need to develop more effective, non-invasive treatment options that can reduce or eliminate PS. Recent work has shown that neurofeedback interventions, such as Low Intensity Pulse-Based Transcranial Electrical Stimulation (LIP-tES) may be effective in treating post-concussive symptoms and a preliminary case study from the investigators' research group suggests that LIP-tES may also be able to reduce PS symptoms in Veterans with a history of mild TBI. However, both the mechanism by which LIP-tES alters brain activity and alleviates symptoms across a range of disorders remains unclear as does the neurobiological basis of PS associated with mTBI and psychiatric comorbidities commonly seen in today's Veteran population. These knowledge gaps represent important limitations both for the clinical characterization of PS in Veterans and development/optimization of novel treatment options. This proposal will take an important first step in addressing these two important knowledge gaps. Aim 1: Complete a preliminary study testing the feasibility and acceptability of a novel LIP-tES intervention designed to reduce severity of PS in patients with a history of mTBI. Extending a recent case study completed by the investigators' research group, the investigators will complete a pilot study of LIP-tES for the treatment of PS in Veterans with a history of mTBI. The investigators will track recruitment capability (participants screened vs. enrolled, attrition rates and reasons for attrition), acceptability and suitability of the intervention, evaluate suitability of the sham procedure the investigators developed, and gain preliminary evaluation of participant responses to the intervention. Aim 2: Assess neurophysiological markers of PS and changes associated with LIP-tES intervention using resting-state fMRI. A subset of the participants will complete two MRI scans during the initial visit after the last LIP-tES or sham session. Preliminary work from the investigators' laboratory has identified a sparse connectome of regions that are predictive of moderate/severe PS ratings in a polymorbid sample of Veterans from the Translational Research Center for TBI and Stress Disorders (TRACTS) longitudinal cohort study. Extending this work, the investigators will test whether classification models using this previously identified connectome will correctly identify individuals who report a reduction in PS after treatment and whether connections are predictive of PS severity. By examining resting-state functional connectivity prior to and after completion of LIP-tES, the proposed study aims to increase the understanding of the underlying pathophysiological mechanisms of PS in mTBI and the mechanism by which LIP-tES may alleviate these symptoms.

Inclusion criteria

• Ages 18-65
• Documented history of mTBI at least 6 months prior to initial study visit
• Documented symptoms of photosensitivity
• Eye exam within the last 12 months documenting best-corrected acuity of 20/20 or better, normal pupillary function, color vision, no abnormalities on OCT scan, and normal Humphrey Visual Field test

Exclusion criteria

• History of strabismus or amblyopia
• Significant ocular media opacity that could reduce the amount of light entering the pupil in one or both eyes
• Previous or current history of retinal or optic nerve pathology in one or both eyes
• History of stroke and/or visual neglect
• History of neurodegenerative disease (e.g., Parkinson's, multiple sclerosis)
• History of epilepsy or seizures
• History of motor tics
• Current use of medications or substances that may severely affect pupillary response and/or increase photosensitivity
• Individuals with impaired decision-making capacity
• Illiterate or no English language proficiency