Effects of a Single-Task Versus a Dual-Task Paradigm on Cognition and Balance in Healthy Subjects.

Ross LM, Register-Mihalik JK, Mihalik JP, McCulloch KL, Prentice WE, Shields EW, & Guskiewicz KM. (2011). Journal of Sport Rehabilitation. 2011 August; 20(3), 296-310.

A proper evaluation of a concussion is imperative in assessing an athlete’s status. Neurocognitive testing is a great tool to assess a concussion; however, it does not identify all deficits that may accompany a brain injury. Likewise, assessing an athlete’s cognitive status and balance separately may not be challenging enough for proper identification. This article examines the reliability and validity of a dual-task paradigm, assessing the interaction between cognitive and vestibular systems, to assess a concussion. The effects of a single vs. a dual task on cognition and balance were examined in 30 healthy active college students (14 men, 16 women). A repeated-measures study design was used and the athletes were tested twice, fourteen days apart in a laboratory. Cognition was assessed through the procedural reaction-time test (PRT) and an adapted procedural auditory task (PAT). The PRT is a computer test, very similar to many popular neurocognitive tests, that requires the athlete to perform several cognitive function tests. The PRT also assesses cognitive function but involves the athlete closing their eyes while responding to auditory stimuli. Balance was examined through both the NeuroCom Sensory Organization Test (SOT) and the Balance Error Scoring System (BESS). The BESS test measures balance through a progression of tasks on both a firm and foam surface. Through similar progressions as the BESS, the SOT manipulates both the surface and the visual surroundings. Testing sessions consisted of the subjects first performing a single cognitive task using the PAT and PRT. Next single balance was tested using either the single SOT or BESS. Finally the first two tasks were combined to serve as the dual task. Two weeks later, subjects were follow-up tested. The sequential order of tests was alternated to minimize learning effects. They found that performance significantly improved between test sessions, and from the single to dual task on both the SOT and PRT. However, for the BESS and the PAT there were no differences in performance between test sessions. Reliability data demonstrated that the BESS is more reliable than the SOT when testing balance.

This article is important because the author’s findings support the use of a dual task involving the BESS test in a comprehensive concussion evaluation. Combining the BESS test with a cognitive task that can be performed with the eyes closed proved to be more reliable than when performed separately. In addition, due to performance not significantly improving for the BESS and PAT between testing sessions (unlike the PRT and SOT), these two tests may be incorporated together as an effective dual-task evaluation tool. Incorporating a dual task proves to be fairly easy for clinicians considering the BESS test is readily available, cost effective, and takes little time to perform. This tool could provide clinicians with another objective test to assess a concussion, as opposed to the subjective self-reported symptoms, which can be very unreliable. But before a dual-task paradigm is incorporated into a routine concussion evaluation, more studies need to be performed to assess the reliability and sensitivity in a concussed population. All in all, a dual task test may be a very useful tool in evaluating concussions. Do you already use a dual-task activity when evaluating concussions? What evaluation tools do you prefer?

Written by: Jacqueline Phillips
Reviewed by: Stephen Thomas