Thinking about a close relationship differentially impacts cardiovascular stress responses among depressed and nondepressed women.

OBJECTIVE: Individuals with depression and low social support are at elevated risk for developing cardiovascular disease--presumptively through mechanisms involving dysregulated stress physiology. While depressed individuals often report diminished social support and elevated levels of social distress, few studies have examined how social factors impact stress-related cardiovascular activity in depressed samples. Accordingly, we evaluated the social modulation of stress-related cardiovascular activity in a sample of 38 medically healthy, unmedicated depressed and nondepressed individuals. METHODS: Cardiovascular and psychological measures were obtained before and after depressed and nondepressed women engaged in a speech stress task. To evaluate the impact of social factors on stress responses, half of the women completed the speech stress task first, while the other half completed the speech stress after engaging in a relationship-focused imagery task. RESULTS: Nondepressed women who first thought about a close relationship displayed global attenuations in blood pressure throughout the subsequent stress task, consistent with a stress-buffering effect of perceived social support. Conversely, depressed women who first thought about a close relationship displayed global elevations in blood pressure throughout the subsequent stress task, consistent with a stress-enhancing effect of perceived social distress in depressed women. CONCLUSION: Thinking about a close relationship differentially impacted subsequent cardiovascular activity during an evocative stressor in depressed and nondepressed women. Understanding the social context in which stress is experienced may aid in identifying, and ultimately attenuating, cardiovascular risks observed among patients with major depressive disorder.

Cardiac vagal control in nonmedicated depressed women and nondepressed controls: impact of depression status, lifetime trauma history, and respiratory factors.

OBJECTIVE: To evaluate the impact of acute stress and relationship-focused imagery on cardiac vagal control, as indicated by levels of respiratory sinus arrhythmia (RSA), in depressed and nondepressed women. Impairment in cardiac parasympathetic (vagal) control may confer risk for cardiac mortality in depressed populations. METHODS: Electrocardiogram and respiratory rate were evaluated in 15 nonmedicated depressed women and 15 matched controls during two laboratory conditions: 1) a relationship-focused imagery designed to elicit vagal activation; and 2) a speech stressor designed to evoke vagal withdrawal. RESULTS: As expected, the relationship-focused imagery increased RSA (F(3,66) = 3.79, p = .02) and the speech stressor decreased RSA (F(3,66) = 4.36, p = .02) across women. Depressed women exhibited lower RSA during the relationship-focused imagery, and this effect remained after control for respiratory rate and trauma history (F(1,21) = 5.65, p = .027). Depressed women with a trauma history exhibited the lowest RSA during the stress condition (F(1,22) = 9.61, p = .05). However, after controlling for respiratory rate, Trauma History × Task Order (p = .02) but not Trauma History × Depression Group (p = .12) accounted for RSA variation during the stress condition. CONCLUSION: Depression in women is associated with lower RSA, particularly when women reflect on a close love relationship, a context expected to elicit vagal activation and hence increase RSA. In contrast, depression-related variation in stressor-evoked vagal activity seems to covary with women's trauma history. Associations between vagal activity and depression are complex and should be considered in view of the experimental conditions under which vagal control is assessed, as well as physiological and behavioral factors that may affect vagal function.

Evidence of dysregulated peripheral oxytocin release among depressed women.

OBJECTIVE: Oxytocin is a hypothalamic neuropeptide that plays a key role in mammalian female reproductive function. Animal research indicates that central oxytocin facilitates adaptive social attachments and modulates stress and anxiety responses. Major depression is prevalent among postpubertal females, and is associated with perturbations in social attachments, dysregulation of the hypothalamic-pituitary-adrenal stress axis, and elevated levels of anxiety. Thus, depressed women may be at risk to display oxytocin dysregulation. The current study was developed to compare patterns of peripheral oxytocin release exhibited by depressed and nondepressed women. METHODS: Currently depressed (N = 17) and never-depressed (N = 17) women participated in a laboratory protocol designed to stimulate, measure, and compare peripheral oxytocin release in response to two tasks: an affiliation-focused Guided Imagery task and a Speech Stress task. Intermittent blood samples were drawn over the course of two, 1-hour sessions including 20-minute baseline, 10-minute task, and 30-minute recovery periods. RESULTS: The 10-minute laboratory tasks did not induce identifiable, acute changes in peripheral oxytocin. However, as compared with nondepressed controls, depressed women displayed greater variability in pulsatile oxytocin release over the course of both 1-hour sessions, and greater oxytocin concentrations during the 1-hour affiliation-focused imagery session. Oxytocin concentrations obtained during the imagery session were also associated with greater symptoms of depression, anxiety, and interpersonal dysfunction. CONCLUSIONS: Depressed women are more likely than controls to display a dysregulated pattern of peripheral oxytocin release. Further research is warranted to elucidate the clinical significance of peripheral oxytocin release in both depressed and nondepressed women.