Information processing difficulty long after self-reported concussion.

Recovery of cognitive function after mild head injury (MHI) is thought to be relatively swift and complete. The present study replicates and extends previous work in which university students with self-reported concussion demonstrated reduced P300 amplitude on a set of easy and difficult attention tasks, in addition to performing more poorly than controls on demanding cognitive tasks many years after injury. In the present study, 13 students with self-reported concussion (MHI group: M time since injury = 8 years) and 10 controls were matched for age, sex, education, and a variety of cognitive, physical and emotional complaints. Controls outperformed the MHI group on the Digit Symbol substitution task and on a difficult dual task involving tone discrimination and visual working memory. Additionally, controls exhibited larger P300 amplitudes on both an easy and a difficult auditory discrimination task. A combination of electrophysiological, neuropsychological and self-report indices predicted group membership (MHI vs. control) with 88% accuracy. The present results, coupled with previous work, offer preliminary evidence that the combination of event-related potentials and demanding behavioral measures might reveal long-lasting, subtle cognitive problems associated with MHI. These findings may challenge existing notions of complete recovery after MHI.