Serial 7’S Do Not Discriminate Between Sports-related Concussion And Controls: Alternative Dual-task Paradigms

Abstract

Dual-task (DT) tandem gait has been used as a viable, functional task of postural stability and cognitive changes following a sports-related concussion (SRC). Additionally, completing tasks that test cognitive abilities during DT, such as serial 7’s, is thought to capture cognitive changes. However, current methods of collecting DT information may not have sensitive psychometric properties. PURPOSE: The purpose of this study was to examine differences in time and errors in DT tandem gait testing between NCAA Division I athletes with and without SRC. METHODS: 13 Division I athletes with sports-related concussion (SRC: 6 males and 7 females, age=20±1) and 13 nearly-matched controls (CON: age=19±1) completed three trials of DT tandem gait using the Tekscan Strideway (100Hz, Boston, MA). All SRC participants had a medically-verified SRC and were assessed within 24-48 hours post-injury. All CON assessments were collected during pre-season. In the DT condition, all participants completed serial 7’s subtraction with random numbers between 50-100. Data collected for tandem gait trials included time to complete the walking task and number of errors emitted. RESULTS: Paired t-tests were used to assess the differences across the average time and errors across trials. Results indicate that the SRC group (M time=23.7±7.5s) took significantly longer to complete DT compared to the CON group (M time=17.2±5.1s, p=0.03, d=1.0). Total amount of errors emitted during the DT were not significantly different (SRC: M errors=1.3±1.6, CON: M errors =0.7±0.6, p=0.18, d=0.49). CONCLUSIONS: Only time in DT trials appears to be a viable method of discriminating between participants who experienced an SRC compared to those without SRC. This indicates that errors emitted during a serial 7’s task may not provide meaningful information regarding cognitive changes following SRC. Extant literature indicates that serial 7’s may be a favored task among researchers, however, alternative tasks may provide a more sensitive measure of cognitive changes. Future research should examine the use of alternative tasks, such as an auditory Stroop task, which may provide more clinically meaningful data.