Circulatory and central nervous system responses to different types of mental stress

The purpose of the present study was to compare the physiological responses to different types of mental stress encountered in the workplace. Circulatory and central nervous system responses were examined in 8 healthy males by exposing them to 20-min of white noise (80 dB(A)) and 20-min of computer-based mental arithmetic tasks as models of vascular and cardiac stress, respectively. The results indicated that both cardiac and vascular stresses increased blood pressure and showed a cumulative effect as exposure period was extended. Heart rate and prefrontal oxygenated hemoglobin levels (measured by NIRS) increased in the face of cardiac stress but were not clearly altered by vascular stress and indicated that cardiac stress higher cardiac response and requires more oxygen supply to the brain. As the central nervous system responded, an event-related potential P300 component was elicited by an auditory oddball task presented before and after each stress. The P300 amplitude increased for both stresses. However, P300 latency increased in response to cardiac stress but decreased with vascular stress in the left prefrontal. Thus, the circulatory and central nervous system responses to cardiac stress and to vascular stress may have different underlying mechanisms, and measuring physiological indices appears to be an effective method by which to evaluate the influence of mental stress.