Trait anxiety and salivary cortisol during free living and military stress.

INTRODUCTION: Accumulating evidence suggests that negative affect is associated with elevated cortisol. Limited research has investigated this association in young, highly functioning, and stress-resilient populations. METHODS: We examined the relation of trait anxiety with total and diurnal salivary cortisol during free-living conditions and during a stressful military exercise in 26 military men ages 19-30 yr (M = 21.6, SD = 2.3). Salivary cortisol was assessed at five time points over 2 consecutive days of free-living measurement, and three time points during a stressful military experience. Trait anxiety was measured with the trait portion of the Spielberger State-Trait Anxiety Inventory 1-3 wk prior to the military exercise. RESULTS: Total cortisol concentrations were similar between men reporting high or low anxiety during free-living conditions (8.6 +/- 3.2 vs. 7.4 +/- 2.8 nmol x L(-1), respectively, P > 0.05), and military stress (21.3 +/- 7.3 vs. 19.0 +/- 7.0 nmol x L(-1), respectively, P > 0.05). The diurnal cortisol profile differed significantly (P = 0.04) between these men during the free-living condition, but not the stressful military experience (P > 0.05). Specifically, during free living, men with low anxiety exhibited a diurnal cortisol pattern that peaked in the early morning, decreased precipitously during the midmorning, and continued to decrease throughout the day, reaching a nadir in the evening. By contrast, the cortisol pattern of high-anxiety men remained elevated and significantly higher than their low-anxiety counterparts during the midmorning, decreased more slowly throughout the day, and reached its lowest level in the evening. Results were not substantially altered following adjustment for sleep duration or wake time. CONCLUSION: These findings suggest that trait anxiety influences the diurnal cortisol pattern in young, apparently healthy men during free-living conditions, but does not predict the cortisol response to uncontrollable military stress.

Stressful military training: endocrine reactivity, performance, and psychological impact.

INTRODUCTION: We examined the responsiveness of both cortisol and dehydroepiandrosterone sulfate (DHEAS) to the stress of survival training in military men and evaluated relationships to performance, peritraumatic dissociation, and the subsequent impact of stressful events. METHODS: Baseline salivary cortisol samples were self-collected by 19 men at 0900 and 1930 in a free-living (FL) environment. DHEAS samples were also collected in a subset of this sample (N = 12). Samples were subsequently taken at similar time points during a stressful captivity (SC) phase of training. Repeated-measures analyses of variance with follow-up paired t-tests examined differences across time and conditions. RESULTS: Significant increases were observed at both time points (0900 and 1930) from FL to SC in both cortisol (0900: 9.2 +/- 3.4 nmol x L(-1) vs. 18.4 +/- 10.5 nmol x L(-1); 1930: 3.5 +/- 3.0 nmol x L(-1) vs. 27.7 +/- 10.9 nmol x L(-1)) and DHEAS (0900: 1.7 +/- 1.3 ng x ml(-1) vs.6.7 +/- 3.5 ngx ml(-1); 1930: 1.5 0.84 ng x ml(-1) vs. 4.5 +/- 3.0 ng x ml(-1)). Also, overall performance during a high-intensity captivity-related challenge was inversely related to the DHEAS-cortisol ratio; conversely, overall performance during a low-intensity captivity-related challenge was positively related to DHEAS at the 0900 time point during SC. Dissociation was unrelated to endocrine indices measured during SC, while total impact of events was inversely related to percent change in DHEAS from FL to SC. CONCLUSIONS: Cortisol and DHEAS increase in response to allostatic load, and may relate to human performance during SC as well as PTSD symptoms.

Neurophysiologic methods to measure stress during survival, evasion, resistance, and escape training.

Training in Survival, Evasion, Resistance, and Escape (SERE) is required for U.S. military members at high risk of capture. This physically and psychologically demanding course is considered an analog to the stress imposed by war, captivity, and related events, thus offering a unique and unprecedented medium in which to systematically examine human stress and performance during a realistically intense operational context. Operational stress is multifaceted, manifesting cerebral, neuroendocrine, cardiac, and cognitive characteristics, and necessitating an integration of multiple methods of measurement to appropriately characterize its complexity. Herein we describe some of our present research methods and discuss their applicability to real-time monitoring and predicting of key aspects of human performance. A systems approach is taken, whereby some of the "key players" implicated in the stress response (e.g., cerebral, neuroendocrine, cardiac) are briefly discussed, to which we link corresponding investigative techniques (fMRI, acoustic startle eye-blink reflex, heart rate variability, and neuroendocrine sampling). Background and previous research with each investigative technique and its relationship to the SERE context is briefly reviewed. Ultimately, we discuss the operational applicability of each measure, that is, how each may be integrated with technologies that allow computational systems to adapt to the performer during operational stress.

Management of allergic rhinitis.

Allergic rhinitis is the most common chronic childhood disease. Reduced quality of life is frequently caused by this IgE-mediated disease, including sleep disturbance with subsequent decreased school performance. Asthma and exercise-induced bronchospasm are commonly seen concurrently with allergic rhinitis, and poorly controlled allergic rhinitis negatively affects asthma outcomes. Nonsedating antihistamines or intranasal azelastine are effective agents to manage allergic rhinitis, often in combination with oral decongestants. For moderate to severe persistent disease, intranasal corticosteroids are the most effiective agents. Some patients require concomitant intranasal corticosteroids and nonsedating antihistamines for optimal management. Other available agents include leukotriene receptor antagonists, intranasal cromolyn, intranasal ipratropium, specific immunotherapy, and anti-IgE therapy.

A closed-loop reduced oxygen breathing device for inducing hypoxia in humans.

BACKGROUND: Hypoxia poses a documented threat to aerospace and diving operations in healthy people and is a component of many clinical conditions. Practical training for aircrew, and research on clinically relevant hypoxic conditions frequently rely exclusively on large, expensive hypobaric chambers. PURPOSE: Here we describe and report the efficacy of a compact, economical, closed-loop rebreather-type reduced-oxygen breathing device (ROBD) for hypoxia induction in humans. METHODS: Subjects were four healthy student Naval flight surgeons. During baseline, subjects breathed normoxic air (21% O2, equivalent to sea-level). Baseline was followed by an altitude period, during which participants were exposed to hypoxic air (about 10% O2, approximating 5,486 m [18,000 ft mean sea-level]) for 30 min followed by a normoxic recovery period. Subjects' peripheral arterial oxygen saturation (SpO2), BP, impedance cardiography, cardiac output, and systemic vascular resistance served as dependent measures along with the fraction of inspired oxygen (FiO2). RESULTS: Circuit FiO2 and subjects' SpO2 were significantly lower during the altitude period than the baseline and recovery periods. HR and cardiac output were significantly higher, and systemic vascular resistance was significantly lower, during hypoxic air exposure than during baseline or recovery. CONCLUSIONS: These data support the closed-loop ROBD as a potentially useful device for training and research involving acute hypoxia in healthy and clinical populations.