The Interrelationship and Diagnostic Utility of Memory and Reaction Time in Concussed Students

Abstract

More than 40 million American youth participate in interscholastic, community-based, and collegiate sports. A risk of participation is traumatic brain injury (TBI). In up to 40% of TBI cases, athletes experience persistent functional and cognitive deficits. It is important to understand the variables that lead to these deficits to improve diagnosis and prognostic management. PURPOSE: To evaluate memory and reaction time as markers of TBI severity among patients experiencing prolonged recovery. METHODS: We retrospectively analyzed student-athletes admitted to a Midwestern outpatient clinic for neuropsychological evaluation; 78 patients had relatively comprehensive profiles and were included in the analysis. We conducted a health history, a 22-item post-concussion symptom inventory, and the ImPACT computerized test, which evaluated memory and reaction time. Pearson’s and point-biserial correlation coefficients tested the direction and strength of association between memory, reaction time, and markers of injury severity. Logistic, negative binomial, and linear regressions tested memory and reaction time as predictors of whether symptoms were reported, the number of reported symptoms, and the severity of symptoms. RESULTS: Patients were 16.0 ± 2.6 years of age, 56.3% were male, and they had experienced 1.2 ± 1.5 previous concussions. Reaction time was 0.64 ± 0.13 seconds; visual motor speed score was 44.7 ± 34.6; visual memory score was 92.0 ± 69.3; verbal memory score was 98.0 ± 80.9; cognitive efficiency score was 0.34 ± 0.12. Reaction time was a significant predictor (p<0.05) of balance problems, dizziness, mental fogginess, and sensitivity to light and noise; it was a trending predictor (p=0.061) of the summed severity of symptoms. Verbal memory was a significant predictor (p<0.05) of balance problems, sleeping problems, and fatigue. Visual memory, visual motor speed, and cognitive efficiency index were poor predictors of injury severity. CONCLUSIONS: Reaction time and memory are common components of testing batteries for concussed athletes. In our sample, reaction time and verbal memory emerged as useful predictors of severity among patients suffering long-term symptoms of TBI. It may be of value for coaches and athletic trainers to establish baseline values at the onset of a competitive season.