Sympathetic contributions to habituation and recovery of the cardiac defense response

Low defensive cardiac reactivity as a physiological correlate of psychopathic fearlessness: Gender differences

Affective/interpersonal features of psychopathy have been consistently associated with diverse psychophysiological indicators of low threat sensitivity, suggesting an underlying deficit in the reactivity of the brain's defensive motivational system. This study examined the Cardiac Defense Response (CDR) -a complex pattern of heart rate changes in response to an aversive, intense, and unexpected stimulus- and its second accelerative component (A2), as a new physiological indicator of the fearlessness trait component of psychopathy. The differential contribution of dispositional fearlessness, externalizing proneness, and coldheartedness to the CDR pattern elicited during a defense psychophysiological test was examined in a mixed-gender sample of 156 undergraduates (62% women) assessed by the Psychopathic Personality Inventory-Revised (PPI-R). Higher PPI-R Fearless Dominance scores were related to lower heart rate changes throughout the CDR in women, but not in men. Further analyses on scales conforming the fearless dominance factor revealed that the hypothesized reduced A2 was specifically related to higher PPI-R Fearlessness scores only in women. Our findings provide initial evidence for the utility of the A2 to better understand the physiological aspects of fearlessness tendencies and its potential distinct manifestations across genders.

Cardiovascular reactivity during sadness induction predicts inhibitory control performance

Higher negative affectivity has an association with decreased executive function and cognitive control. Heart rate variability (HRV) serves as an index of cardiac vagal regulation differences in the autonomic nervous system for both cognition and emotion. The current study investigates this association using a classic as well as emotional antisaccade paradigm to study inhibitory control performance. Ninety participants completed affective questionnaires (Beck Depression Inventory-II, and Mood Scale), a 6-minute baseline electrocardiogram, and two different antisaccade tasks. After the baseline, subjects were presented with a video sequence with either neutral, sad, or emotionally arousing content. By subtracting the baseline from the video sequence, we computed HRV reactivity and tested whether the reactivity score could predict inhibitory control performance. We hypothesized that this would be the case in both the sadness and arousal group, but not in the neutral one. Furthermore, we awaited significant performance differences between experimental groups. Contrary to our assumption, inhibitory control performance did not differ between experimental groups. Moreover, there was no significant relation between affective measures and task performance. Nevertheless, cardiovascular reactivity in terms of HRV was predictive of error rates in both antisaccade tasks in the sadness group. We could find this effect neither in the neutral nor in the arousal group. In addition, BDI scores moderated the effect in the emotional task. Results indicate that emotional reactivity to a sad video stimulus as indexed by HRV as well as the interaction with current emotional state predict inhibitory control performance.

Complex sympathetic regulation in adolescent mitral valve prolapse

Mitral valve prolapse (MVP) belongs to cardiac disorders characterized by impaired closure of mitral leaflets. We studied adolescent group of patients with MVP suffering from symptomatology that cannot be explained by mitral regurgitation alone. Several studies suggested that symptoms can be explained by autonomic, in particular sympathetic-linked dysfunction. Thus, we assessed non-invasive sympathetic indices of blood pressure and heart rate variability and electrodermal activity (EDA). Fifty-three adolescents with MVP (age: 15.1+/-0.4 years) and 43 healthy age- and gender-matched adolescents (age: 14.9+/-0.4 years) were examined. Blood pressure, heart rate and EDA were continuously recorded during 6-min rest. Evaluated parameters were: low frequency band of systolic blood pressure variability, systolic, diastolic and mean blood pressure, mean RR interval, cardiac sympathetic indices: symbolic dynamics (0V%), left ventricular ejection time (LVET), pre-ejection period (PEP), and EDA. Our findings revealed significantly higher systolic, diastolic, and mean blood pressure values, shortened mean RR interval, increased 0V%, and shortened LVET in MVP patients vs. controls (p=0.028, p<0.001, p=0.002, p<0.001, p=0.050, p<0.001; respectively). Our study revealed enhanced cardiovascular sympathetic regulation in adolescent MVP patients. We suggest that evaluation of non-invasive sympathetic parameters could represent potential biomarkers for early diagnosis of cardiovascular complications associated with MVP already at adolescent age.

Cardiovascular Variability and Reactivity in Major Depressive Disorder

Abstract. This study investigated cardiovascular variability and stress reactivity in major depressive disorder (MDD). While previous research has documented reduced heart rate variability, knowledge about blood pressure variability in MDD remains scarce. Regarding reactivity, a particular focus was placed on the time courses of the cardiovascular responses, which may provide insight into the autonomic mechanisms underlying the hypo-reactivity expected in MDD. In 76 MDD patients and 71 healthy controls, blood pressure was continuously recorded at rest and during mental stress induced by a 3-min serial subtraction task. Compared to controls, patients exhibited lower systolic and diastolic blood pressure, heart rate variability, and systolic and diastolic blood pressure variability. Moreover, smaller stress-related changes in heart rate, systolic and diastolic blood pressure, and sensitivity of the cardiac baroreflex arose in patients. Cardiovascular parameters did not differ between patients using antidepressants and unmedicated patients. According to time-course analysis, reduced hemodynamic modulations in MDD mainly occurred after 50 s of the stress period. Low heart rate variability in MDD reflects deficient top-down integration of the brain mechanisms allowing flexible autonomic and behavioral control; diminished blood pressure variability is indicative of poor homeostatic capacity with respect to the regulation of blood pressure and organ perfusion. Moreover, blunted cardiovascular reactivity implies poor adjustment of energetic resources to internal and environmental demands and may be a correlate of deficient motivational dynamics characterizing MDD. While cardiovascular hypo-reactivity in MDD may be mediated by baroreflex and adrenergic mechanisms, the fast-acting parasympathetic system may play a subordinate role.

Cardiac defense reactivity and cognitive flexibility in high- and low-resilience women

Resilience is a protective health variable that contributes to successful adaptation to stressful experiences. However, in spite of its relevance, few studies have examined the psychophysiological and neuropsychological mechanisms involved in resilience. The present study analyzes, in a sample of 54 young women, the relationships between high- and low-resilience, measured with the Spanish versions of Connor-Davidson Resilience Scale questionnaire and the Resilience Scale, and two indices of psychophysiological and neuropsychological adaptability, the cardiac defense response (CDR) and cognitive flexibility. The CDR is a specific reaction to an unexpected intense noise characterized by two acceleration-deceleration heart rate components. Cognitive flexibility, defined as the ability to adapt our behavior to changing environmental demands, is measured in this study with the CAMBIOS neuropsychological test. The results showed that the more resilient people, in addition to having better scores on mental health questionnaires, had a larger initial acceleration-deceleration of the CDR-indicative of greater vagal control, obtained better scores in cognitive flexibility, and evaluated the intense noise as less unpleasant than the less resilient people. No group differences were found in the second acceleration-deceleration of the CDR-indicative of sympathetic cardiac control, in the skin conductance response, or in subjective intensity of the noise. The present findings broaden the understanding of how resilient people change their adaptable responses to address environmental demands.

Features of autonomic cardiovascular control during cognition in major depressive disorder

Previous research has suggested reduced parasympathetic cardiac regulation during cognitive activity in major depressive disorder (MDD). However, little is known about possible abnormalities in sympathetic control and cardiovascular reactivity. This study aimed to provide a comprehensive analysis of autonomic cardiovascular control in the context of executive functions in MDD. Thirty six MDD patients and 39 healthy controls participated. Parameters of sympathetic (pre-ejection period, PEP) and parasympathetic control (high and low frequency heart rate variability, HF HRV, LF HRV; and baroreflex sensitivity, BRS) as well as RR interval were obtained at rest and during performance of executive function tasks (number-letter task, n-back task, continuous performance test, and Stroop task). Patients, as compared to controls, exhibited lower HF HRV and LF HRV during task execution and smaller shortenings in PEP and RR interval between baseline and tasks. They displayed longer reaction times during all conditions of the tasks and more omission errors and false alarms on the continuous performance test. In the total sample, on-task HF HRV, LF HRV and BRS, and reactivity in HF HRV, LF HRV, and PEP, were positively associated with task performance. As performance reduction arose independent of executive function load of the tasks, the behavioral results reflect impairments in attention and processing speed rather than executive dysfunctions in MDD. Abnormalities in cardiovascular control during cognition in MDD appear to involve both divisions of the autonomic nervous system. Low tonic parasympathetic control and blunted sympathetic reactivity imply reduced physiological adjustment resources and, by extension, provide suboptimal conditions for cognitive performance.