Response Time and Gaze Behaviour in Individuals with Post Concussion Syndrome

Abstract

Upon sustaining a concussion, a minority of cases may experience symptoms beyond the expected average recovery timeline of 3-15 days and are classified as having Post-Concussion Syndrome (PCS). Possible predictors of PCS include attention and memory tasks, serum protein levels, headaches and dizziness. However, these predictors are only able to identify those at risk of experiencing PCS and require further examination. More recent research has suggested the assessment of eye movement in this population. Longer fixations indicate that more information is being gathered, specifically the final fixation on a target/object, referred to as Quiet Eye (QE), prior to making a response. PURPOSE: To assess whether gaze behaviour is related to performance on a choice reaction time (CRT) task in non-concussed (NC) individuals and individuals with PCS (PCS). HYPOTHESES: Individuals with PCS will display greater Response Time (RT), decreased accuracy, and different gaze behaviour compared to NC. METHODS: Twenty-one non-concussed individuals (24 ± 2 years) and 9 individuals with PCS (23 ± 2 years) were tested. All participants were asked to complete a CRT task in the form of an iPad application, which measured each individual’s response time (RT) to a decision-making task during two blocks of trials while wearing a head-mounted Eye Tracker system. RESULTS: Mean RT was significantly greater (slower) (p < .01) in the PCS group compared to the non-concussed group at both blocks (Block 1: PCS µ = 0.96s, s = 0.13s, NC: µ = 0.75s, s = 0.18s; Block 2: PCS µ = 0.90s, s = 0.16s, NC: µ = 0.72s, s = 0.17s). Overall task accuracy, measured as percent correct, was also significantly lower in PCS (µ = 0.53, s = 0.03) compared to NC (µ = 0.58, sE = 0.03). Final QE duration was significantly longer (p < .05) in NC compared to PCS at block 1 (NC: µ = 0.234, s = 0.140; PCS: µ = 0.068, s = 0.139) and 2 (NC: µ = 0.221, s = 0.136; PCS: µ = 0.069, s = 0.136), indicating that fundamental levels of cognitive processing may be hindering decision-making abilities in the PCS population. CONCLUSION: Individuals with PCS are unable to demonstrate similar RT scores compared to non-concussed individuals at rest. Higher levels of cognitive processing, assessed through gaze behaviour, may explain this difference in response time and should be further considered a predictor of the onset of PCS.