The association between a history of concussion and variability in behavioral and neuroelectric indices of cognition.

Associations between a history of concussion and variability in behavioral and neuroelectric indices of cognition were assessed in college-aged adults with a history of concussion and a healthy control group, in response to a stimulus discrimination task and a more attentionally demanding flanker task. Greater intra-individual variability was observed only for behavioral indices of reaction time in response to the flanker task for those with a history of concussion. An association was also observed between the number of concussions resulting in a loss of consciousness and greater variability of reaction time regardless of the type of task. Relative to neuroelectric measures, a concussive history was associated with smaller P3 amplitude only in response to the flanker task; with no differences between groups observed in response to the oddball task or for intra-individual variability measures. Thus, increased variability associated with a history of concussion appears to be behavior and process specific. The behavioral metrics and functions assessed are important considerations for identifying subtle, yet persistent influences of concussion on cognitive performance. Further, factors such as loss of consciousness associated with a concussive injury may moderate the extent to which these increases in behavioral variability manifest. Thus, the identification of persistent cognitive impairment following concussive injuries necessitates the utilization of appropriate tasks and may be facilitated by going beyond behavioral measures of central tendency.