Assessment of mild head injury with ERPs and neuropsychological tasks

Mild head injury can result in the development of persistent symptoms including impairments of memory and: attention in a small but significant minority. The problem in assessing these difficulties in such cases is the likely interaction of psychogenic and organic causes. The aim of the present research:is to more,accurately characterize the nature of these cognitive deficits. Twelve asymptomatic volunteers, who;had experienced a mild head injury in the last 3.5 years, were compared to a matched control group. ERPs were recorded during the performance of the paced auditory serial addition task (PASAT) and a 3-stimulus auditory "oddball" task. Verbal paired associate, Trails A and B, Digit Symbol, Rey Figure Recall, NART, and Digit Span were also administered. The mild head injured group showed evidence of a mild impairment of episodic memory, slowing of attention shifting, but no changes in reaction time or error rates in either the "oddball" task or the PASAT. Although there was no-evidence of impairment of brain orienting responses in the 3-stimulus auditory oddball task there was evidence of reduced frontal negativity associated with changes in task demand in the PASAT This particular ERP feature appears similar to those associated with activation of selective attention mechanisms, thus suggesting that these asymptomatic individuals may be showing signs of a mild. impairment of allocation of attention resources.