Stress as a diagnostic challenge for postconcussive symptoms: Sequelae of mild traumatic brain injury or physiological stress response

There is considerable controversy regarding whether persistent postconcussi ve symptoms (PCS) are injury-specific, in a subgroup of individuals after m ild traumatic brain injury (TBI). The following findings have contributed t o this controversy: (1) The base rate of PCS in mild TBI is comparable to u ninjured controls; and (2) The severity of PCS covary with daily stress lev els (Gouvier, Cubic, Jones, Brantley, & Cutlip, 1992). We examined this rel ationship further by evaluating the effects of experimental conditions of s tress or relaxation on individuals with TBI and uninjured control subjects, with low and high PCS endorsement. We evaluated psychophysiological parame ters, neuropsychological performance, and changes in PCS and stress percept ion. In our study, subjects with TBI increased PCS after engaging in cognit ively challenging tasks, and demonstrated significant autonomic changes in the stress condition. Symptomatic TBI subjects exposed to high stress had i ncreases in PCS complaints, decreased speed of information processing, and subtle memory deficits. Our results suggest that PCS are injury-specific an d that individuals with a history of TBI are susceptible to the effects of stress. Relaxation training including breathing retraining may be an effect ive means of decreasing PCS and cognitive complaints in subjects with mild TBI.