P300 and stress in mild head injury patients

Objective: The P300 component of event-related potentials is affected by personal meaningfulness of the stimulus to the subject. Thus, the P300 component could provide an objective parameter in the emotional assessment of road accident mild head injury patients, when exposed to relevant stimuli.

Methods: Thirteen patients with post-traumatic symptoms and 14 healthy controls were evaluated in this study. Two word types, distinguished by color, were presented on a computer screen in active `oddball' paradigm conditions. In the first subtest, the targets were accident-related (stressful) words; in the second subtest, the targets were non-accident-related (neutral) words. Target (20%) and non-target (80%) were defined by word color. Data recorded from Pz were analyzed for P300 parameters.

Results: Patients and controls differed in their reaction to word types (group×word main effect P=0.0089), regardless of the oddball presentation. Overall, accident-related words produced a significantly larger P300 wave than neutral words in patients (P=0.0001), but not in controls (P=0.5741). Significant correlation was found between combined P300 amplitude difference (all stressful words vs. all neutral words) and the patient's Zung state anxiety score (r=0.68, P=0.01).

Conclusion: We suggest the P300 component can provide a useful, objective tool in the assessment of mild head injury patients.