Abstract
Background:
Reaction time is a common clinical measure for assessing patients with concussion, but common approaches have limited functional applicability (i.e., sport-related with cognitive-motor integration). Previous studies have recently developed a reliable and valid functional reaction time battery called the Standardized Assessment of Reaction Time (StART) to assess functional reaction time. It is unknown, however, how StART performance changes over time post-concussion. Thus, our purpose was to longitudinally examine StART performance in adolescent athletes following a concussion.
Hypothesis:
We hypothesized adolescent athletes would demonstrate slower (i.e., impaired) StART performance acutely (1-month) relative to 6-months and 12-months post-concussion.
Methods:
We assessed 22 adolescent athletes (age: 15.2±2.5 years, 54.5% female, 30 median days post-concussion) at 3 timepoints: 1-month, 6-months, and 12-months post-concussion. Participants completed the standardized StART evaluation, which consisted of 3 movements (standing, single-leg balance, athletic cutting) under 2 cognitive conditions (single-task, dual-task [subtracting by 6’s or 7’s]) with three trials for each cognitive-movement condition (6 conditions total). All StART trials had participants moved from a standardized starting position immediately after a video-synchronized penlight illuminated randomly (2-10 second interval), with StART outcomes being time (s) between penlight and initial movement. The StART outcomes consisted of a single-task and dual-task composite score. We used repeated-measures ANOVAs to evaluate change in StART performance across the 3 timepoints for each StART outcome, with post-hoc Tukey t-tests, mean differences (MD), and 95% confidence intervals (95%CI).
Results:
Overall significant changes over time were observed for StART single- and dual-task composite scores (p<0.001). Single-task post-hoc t-tests demonstrated slower reaction times at 1-month relative to 6-months (MD:0.026s, 95%CI: 0.006-0.046, p=0.047) and 12-months post-concussion (MD:0.041s, 95%CI: 0.023-0.058, p<0.001). Dual-task assessments demonstrated slower reaction times with larger effect sizes than single-task assessments at 1-month relative to 6-months (MD:0.060s, 95%CI: 0.036-0.085, p<0.001) and 12-months post-concussion (MD:0.084s, 95%CI: 0.065-0.102, p<0.001). StART performance was significantly slower at 6-months relative to 12-months post-concussion for both single-task (MD:0.015s, 95%CI: 0.003-0.027, p<0.001) and dual-task (MD:0.023s, 95%CI: 0.006-0.040, p=0.033).
Conclusion:
Both single- and dual-task StART were slower at 1-month relative to 6-months and 12-months post-concussion, with dual-task StART demonstrating greater mean differences than single-task. Slower reaction time at 6-months relative to 12-months for single- and dual-task may indicate either prolonged impairments post-concussion or learning effects. Future work should evaluate a longitudinal control group to further evaluate the potential utility of StART before clinical diagnostic or prognostic use.