Cardiovascular stress responses and their relation to symptoms in Gulf Warveterans with fatiguing illness

Objective: The objective of this study was to examine whether inappropriate cardiovascular responses to stressors may underlie symptoms in Gulf War ve terans with chronic fatigue. Methods: Psychophysiological stress testing wa s performed on 51 Gulf War veterans with chronic fatigue (using the 1994 ca se definition of the Centers for Disease Control and Prevention) and 42 hea lthy veterans. Hemodynamic responses to cold presser, speech, and arithmeti c stressors were evaluated using impedance cardiography. Results: Veterans with chronic fatigue had diminished blood pressure responses during cogniti ve (speech and arithmetic) stress tests due to unusually small increases in total peripheral resistance. The cold presser test, however, evoked simila r blood pressure responses in the chronic fatigue and control groups. Low r eactivity to cognitive stressors was associated with greater fatigue rating s among ill veterans, whereas an opposite relation was observed among healt hy veterans. Self-reported neurocognitive decline was associated with low r eactivity to the arithmetic task. Conclusions: These results suggest a phys iological basis for some Gulf War veterans' reports of severe chronic fatig ue. A greater deficit with responses processed through cerebral centers, as compared with a sensory stimulus (cold presser), suggests a defect in cort ical control of cardiovascular function. More research is needed to determi ne the specific mechanisms through which the dissociation between behaviora l and cardiovascular activities identified in this study may be contributin g to symptoms in Gulf War veterans.