Health effects of the stressors of extreme environments on military women.

This article examines the health effects of generic and unique stressors on military women's health. It is an outgrowth of work performed under the Defense Women's Health Research Program and participation in the Forum on the Health of Women in the Military held at the Uniformed Services University of the Health Sciences on June 17 to 19, 1996. We review gender differences in the effects of stress on health. We comment on some of the methodological challenges in researching gender effects. We hypothesize about some of the ways in which military women may be more vulnerable to specific stressors and/or use different coping strategies than their male counterparts. Finally, we make recommendations about military training and future research.

D2 dopamine receptor gene TaqI A1 and B1 restriction fragment length polymorphisms: enhanced frequencies in psychostimulant-preferring polysubstance abusers.

Several lines of evidence suggest that presence of a D2 dopamine receptor (DRD2) gene variant marked by TaqI restriction fragment length polymorphisms (RFLPs) might contribute to vulnerability to substance abuse. Psychostimulants display the most robust enhancement of dopamine activity in mesolimbic/mesocortical circuits important for behavioral reward. The present study tests the hypothesis that a DRD2 gene variant might be more prominent in polysubstance users who preferentially use psychostimulants than in addicts with preferential opiate use or in those with no drug preference. Polysubstance users with histories of heavy daily preferential psychostimulant use more often displayed one or two copies of the TaqI A1 (27/62 = 43.5% vs 33/119 = 27.7% for controls), and B1 (20/62 = 32.3% vs 23/119 = 19.8% for controls) markers at the DRD2 locus. DRD2 gene marker distributions in abusers with more prominent opiate use, or those with no history of drug preference, were similar to control genotypes. Psychostimulant-preferring drug users also reported earlier onset of psychostimulant use. Our data are consistent with the hypothesis that DRD2 gene variants marked by these polymorphisms may work, probably in concert with other genetic and environmental factors, to enhance vulnerability to psychostimulant abuse.

The circadian variation of cardiovascular stress levels and reactivity: relationship to individual differences in morningness/eveningness.

Two studies assessed the circadian variation of cardiovascular responses to stress in healthy and coronary artery disease (CAD) populations. In within-subjects designs, stressors were administered to healthy male subjects and male CAD patients both in the morning and afternoon, and subjects were classified as either morning or evening types using the Morningness-Eveningness Questionnaire (Horne & Ostberg, 1976, International Journal of Chronobiology, 4, 97-110). No consistent circadian variation in blood pressure or heart rate responses was observed in the aggregate sample of either healthy subjects or CAD patients. However, there were significant interactions between circadian type and time of day. In both populations, morning subjects exhibited higher cardiovascular levels during the morning session, and evening subjects exhibited higher levels during the afternoon session. Analyses of cardiovascular reactivity revealed less consistent evidence for this interaction. Self-reports of stress revealed interactions between time of day and morningness/eveningness only in the CAD sample. In CAD patients, preliminary analysis of myocardial wall function, an index of myocardial ischemia, did not reveal a significant interaction between morningness/eveningness and time of day, perhaps due to small sample size. The presence of differing circadian patterns in stress response based on individual differences in morningness/eveningness is discussed in terms of its methodological implications for psychophysiological research and in terms of the role of stress as an acute trigger of CAD.

Circadian variation of ambulatory myocardial ischemia. Triggering by daily activities and evidence for an endogenous circadian component.

BACKGROUND: The morning peak in myocardial ischemia has been related to diurnal variations in physical and mental activities and to postural changes upon awakening. This study assesses (1) the effects of exogenous activity triggers at different times of the day and (2) the contribution of an endogenous (ie, activity- and posture-independent) circadian vulnerability for ambulatory ischemia. METHODS AND RESULTS: Sixty-three stable coronary artery disease patients underwent ambulatory ECG monitoring and completed a structured diary assessing physical and mental activities. During 2519 hours of observation, a morning increase in ischemia coincided with increases in physical and mental activities, and an evening decrease in ischemia coincided with a decline in activities. During the morning, ischemic versus ischemia-free periods were more likely to occur with high levels of physical activity (P < .001). High physical activity triggered ischemia to a lesser but still significant extent (P < .05) in the afternoon but not in the evening (P = NS). High levels of mental activity triggered ischemia significantly during the morning (P < .04) and evening (P < .04) but not in the afternoon. When a residualized score procedure was used to correct ischemic time for each patient's simultaneously measured activities, for hourly heart rates, or for activity-related heart rate fluctuations, the circadian variation in ischemia was still observed (P < .001), with a peak at 6 AM. A significant increase in ischemia occurred immediately after awakening (P < .05), but activity-adjusted increases in morning ischemia persisted (P < .05) for 2 hours after awakening. CONCLUSIONS: Exogenous factors (physical and mental activities) are most potent as triggers of ischemia during the morning hours, and the postural change after awakening contributes to the morning increase in ischemia. There is also evidence for an endogenous, activity-independent circadian influence on ischemic susceptibility that is independent of exogenous factors and that sustains the increase in ischemia upon awakening.

Triggers of myocardial ischemia during daily life in patients with coronary artery disease: physical and mental activities, anger and smoking.

OBJECTIVES: This study assessed the potency of physical and mental activities and emotions (anger and anxiety) and smoking and other substance use as proximate triggers of ischemia in patients with coronary artery disease during daily life. BACKGROUND: Myocardial ischemia occurs during a wide variety of activities in patients with coronary artery disease, but frequency and relative potency of physical and mental activities, smoking and use of caffeine and alcohol as triggers of ischemia during daily life have not been established. METHODS: Patients (n = 63) with coronary artery disease and evidence of out-of-hospital ischemia kept a validated structured diary of physical and mental activities and psychologic states while undergoing ambulatory electrocardiographic monitoring for 24 to 48 h. RESULTS: Ischemia occurred most frequently during moderately intense physical and mental activities. Patients spent the largest proportion of time engaged in low intensity physical and mental activities (p < 0.05), but the likelihood of ischemia was greatest during intense physical (p < 0.0001) and stressful mental activities (p < 0.03). The percentage of time in ischemia was elevated and approximately equivalent for high intensity physical and high intensity mental activities (5%) compared with 0.2% when patients were engaged in low intensity activities. Strenuous physical activity (e.g., effortful walking, p < 0.05) and the experience of intense anger were potent ischemic triggers, and heart rates at onset of ischemia increased with the intensity of physical and mental activity and with anger. Among smokers, ischemia was more than five times as likely when patients smoked than when they did not (during 24% vs. 5% of diary entries, p < 0.0001). Coffee and alcohol consumption were also related to ischemia (p < 0.05), but this association disappeared after controlling for concurrent cigarette smoking. CONCLUSIONS: Triggers of ischemia in patients with coronary artery disease during daily life include not only strenuous exercise, but also activities involving low levels of exertion, such as anger and smoking. Mental activities appear to be as potent as physical activities in triggering daily life ischemia. Coffee and alcohol consumption are related to ischemia only by virtue of their associations with smoking.

Triggers of angina and ST-segment depression in ambulatory patients with coronary artery disease: evidence for an uncoupling of angina and ischemia.

This study evaluated daily-life physical and mental triggers of painful and painless myocardial ischemia and of anginal pain in patients with coronary artery disease (CAD) by using ambulatory electrocardiographic monitoring and a structured diary. Eighty-five percent of ambulant ischemic episodes occurred without chest pain; 66% of anginal pain reports were made in the absence of ischemic ST-segment depression. Chest pain reports in the absence of ischemia could not be attributed to "borderline" ST-segment changes. Compared with silent ischemia, painful ischemia was triggered at higher levels of physical activity (p < 0.05) and at higher levels of self-rated effort and negative emotion (p < 0.05). Painful episodes were associated with greater-magnitude ST depression (p < 0.02), but a substantial percentage of episodes with > or = 2 mm and > or = 3 mm ST depression were silent. These results reveal an uncoupling of anginal symptoms from ambulatory ischemic episodes in patients with CAD during daily life. In addition, specific activities and emotions correlate with the presence or absence of anginal symptoms as much as does the presence of ischemic ST depression. These results may have implications for antiischemic and antianginal treatment strategies.

Measuring the average evoked response to light flashes: the contribution of eye-blink artifact to augmenting-reducing.

There have been numerous reports relating individual differences in stimulus intensity control to psychopathology and personality. Most of these studies record the averaged evoked response (AER) to light flashes of different brightness and assess the relationship between response amplitude and stimulus intensity. The present investigation used procedures commonly employed in these studies to examine the effects of eye blinks on the AER. Twenty normal subjects were tested twice over a 1-week interval while the AER and electroocculographic (EOG) response generated by a blink were recorded. The averaged EOG was digitally subtracted from the AER to yield a blink-corrected AER. Various comparisons of amplitude measures derived from corrected and uncorrected AERs and the averaged EOG revealed that blinking contributed a pronounced artifact that tended to reduce the magnitude of AER amplitude, especially to the more intense stimuli. These findings raise questions about the validity of interpretations drawn from studies of AER augmenting-reducing, very few of which control for eye-blink artifact. The linearity of the amplitude-intensity relationship for each subject was also assessed. This analysis revealed that the data points were poorly described by a straight line and therefore that the use of linear slope to characterize the amplitude-intensity relationship is unwarranted.