Abstract

Objective: Intra-individual variability (IIV) is an emerging concept as a marker of neuropathology. This study examined the clinical utility and gender effects of IIV in concussed and non-concussed athletes. Method: Concussed and non-concussed individuals were matched according to gender, age, and education (N = 58: 62.1% male, 61.1% H.S. athlete, mean age = 17.4 (SD = 2.2), mean education = 11.6 years (SD = 2.0). Overall test battery mean (OTBM) was derived from the normed standard scores of the 8 clinical domains from the Concussion Vital Signs (CVS) battery. IIV was operationalized as the OTBM standard deviation (OTBM SD). To examine gender, data from 225 athletes (60%) and college controls (40%) who were tested at two times were utilized. Mean demographics: 18.1 years (SD = 3.1), education 11.7 (SD = 1.8), and 60% male. Results: Paired samples t-test comparing OTBM SD in concussed (mean = 11.3, SD = 5.3) to non-concussed (mean = 11.2, SD = 4.4) was not significant, t(58) = .045, p = .965. A repeated measures ANOVA found a main effect for gender (F = 7.248, p < .01) with females performing lower than males at each time but there was no interaction (F = 0.01, p = .988). Conclusion(s): There was no significant difference in variability between the concussed and non-concussed groups. IIV does not appear to be a potentially useful diagnostic tool for concussion. However, we did find a gender effect for IIV.