Low anxiety males display higher degree of salt sensitivity, increased autonomic reactivity, and higher defensiveness

Salt: The paradoxical philosopher's stone of autonomic medicine

Sodium chloride, or common table salt, for millennia has played a prominent role in human affairs. Salt is also a key molecule for regulating intravascular fluid volume in patients with orthostatic disorders. In this first article of a special issue of the journal focusing on salt and the autonomic nervous system, the historical and physiologic significance of salt is reviewed, highlighting its importance to society and to medicine. The relevance of salt both for civilization and for autonomic physiology penetrates into nearly every aspect of life and health. Replacing salt that has been depleted or administering salt to expand intravascular volume is considered standard treatment for patients with orthostatic hypotension and syndromes of orthostatic intolerance. The potential longterm effects of added salt, including effects unrelated to intravascular volume, have been insufficiently studied in patients with autonomic disorders. A salient concern is the potential increased risk of developing hypertension. Underappreciated aspects of salt include its ability to increase anxiety and through nonosmotic mechanisms to contribute to local tissue inflammation. Salt may be either salubrious or detrimental, or possibly both at the same time, depending on the clinical conditions. Reconciling these opposite effects in clinical practice requires weighing benefits against potential risks, assessing what is known alongside what is uncertain, and titrating treatment decisions to the particular needs of each individual patient.

Short-term effects of espresso coffee on heart rate variability and blood pressure in habitual and non-habitual coffee consumers--a randomized crossover study

OBJECTIVE

Coffee is one of the most widely consumed beverages worldwide. Aim of this study was to investigate short-term effects of espresso coffee on heart rate variability (HRV), a marker of vagal activity, in healthy habitual and non-habitual coffee consumers.

METHODS

Seventy-seven healthy subjects (38 habitual and 39 non-habitual coffee consumers, 74% women, mean age 26.97 ± 6.88 years) took part in three laboratory sessions in a randomized order. In condition 1, subjects consumed espresso; in condition 2, subjects consumed decaffeinated espresso; and in condition 3, subjects consumed warm water. HRV and blood pressure were assessed at rest before and after ingestion of the respective beverage.

RESULTS

HRV was significantly increased after consumption of caffeinated espresso, decaffeinated espresso, or water, indicating increased vagal activity in the course of the experiments. In the habitual coffee consumers, the increase in vagally mediated HRV was significantly lower after consumption of decaffeinated espresso compared to caffeinated espresso. Increases of systolic blood pressure were only found in the non-habitual consumers.

CONCLUSION

We found no evidence for specific short-term effects of caffeinated espresso on vagal activity in healthy subjects. Instead, consumption of decaffeinated espresso inhibited vagal activity in habitual consumers. This may be explained by an attempt of the organism to establish a sympathovagal equilibrium comparable to that after caffeine consumption. In the absence of caffeine-induced sympathetic activation, this may have been achieved by relative vagal withdrawal.

Influence of a Suggestive Placebo Intervention on Psychobiological Responses to Social Stress: A Randomized Controlled Trial

We tested the hypothesis that a suggestive placebo intervention can reduce the subjective and neurobiological stress response to psychosocial stress. Fifty-four healthy male subjects with elevated levels of trait anxiety were randomly assigned in a 4:4:1 fashion to receive either no treatment (n = 24), a placebo pill (n = 24), or a herbal drug (n = 6) before undergoing a stress test. We repeatedly measured psychological variables as well as salivary cortisol, alpha-amylase, and heart rate variability prior to and following the stress test. The stressor increased subjective stress and anxiety, salivary cortisol, and alpha-amylase, and decreased heart rate variability (all P < .001). However, no significant differences between subjects receiving placebo or no treatment were found. Subjects receiving placebo showed increased wakefulness during the stress test compared with no-treatment controls (P < .001). Thus, the suggestive placebo intervention increased alertness, but modulated neither subjective stress and anxiety nor the physiological response to psychosocial stress.

Trait Anxiety Has Effect on Decision Making under Ambiguity but Not Decision Making under Risk

Previous studies have reported that trait anxiety (TA) affects decision making. However, results remain largely inconsistent across studies. The aim of the current study was to further address the interaction between TA and decision making. 304 subjects without depression from a sample consisting of 642 participants were grouped into high TA (HTA), medium TA (MTA) and low TA (LTA) groups based on their TA scores from State Trait Anxiety Inventory. All subjects were assessed with the Iowa Gambling Task (IGT) that measures decision making under ambiguity and the Game of Dice Task (GDT) that measures decision making under risk. While the HTA and LTA groups performed worse on the IGT compared to the MTA group, performances on the GDT between the three groups did not differ. Furthermore, the LTA and HTA groups showed different individual deck level preferences in the IGT: the former showed a preference for deck B indicating that these subjects focused more on the magnitude of rewards, and the latter showed a preference for deck A indicating significant decision making impairment. Our findings suggest that trait anxiety has effect on decision making under ambiguity but not decision making under risk and different levels of trait anxiety related differently to individual deck level preferences in the IGT.

Trait anxiety affects decision-making differently in healthy men and women: towards gender-specific endophenotypes of anxiety

Excessive levels of trait anxiety are a risk factor for psychiatric conditions, including anxiety disorders and substance abuse. High trait anxiety has been associated with altered cognitive functioning, in particular with an attentional bias towards aversive stimuli. Decision-making is a crucial aspect of cognitive functioning that relies on the correct processing and control of emotional stimuli. Interestingly, anxiety and decision-making share underlying neural substrates, involving cortico-limbic pathways, including the amygdala, striatum and medial and dorsolateral prefrontal cortices. In the present study, we investigated the relationship between trait anxiety, measured by the State-Trait Anxiety Inventory, and complex decision-making, measured by the Iowa Gambling Task, in healthy male and female volunteers. The main focus of this study was the inclusion of gender as a discriminative factor. Indeed, we found distinct gender-specific effects of trait anxiety: in men, both low and high anxiety groups showed impaired decision-making compared to medium anxiety individuals, whereas in women only high anxiety individuals performed poorly. Furthermore, anxiety affected decision-making in men early in the task, i.e. the exploration phase, as opposed to an effect on performance in women during the second part of the test, i.e. the exploitation phase. These findings were related to different profiles of trait anxiety in men and women, and were independent of performance in the Wisconsin Card Sorting Test and cortisol levels. Our data show gender-specific effects of trait anxiety on emotional decision-making. We suggest gender-specific endophenotypes of anxiety to exist, that differentially affect cognitive functioning.

Low vagal tone is associated with impaired post stress recovery of cardiovascular, endocrine, and immune markers

Reduced heart rate variability (HRV) and delayed blood pressure recovery are associated with increased cardiovascular risk. Besides this evident link, the vagus is thought to play an inhibitory role in the regulation of other allostatic systems, including inflammation and the hypothalamic-pituitary-adrenal (HPA) axis. However, human evidence is scarce. To further explore these associations and with special regard to the postulated mediating role of the vagus, we hypothesised that subjects with low vagal tone as indexed by reduced resting HRV would show impaired post-stress recovery of cardiovascular, endocrine and immune system markers involved in cardiovascular pathology. 44 healthy men underwent a standardised mental stress test. Besides continuous measurement of systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and HRV serum cortisol, tumour necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) were measured before, after, 20, and 60 min after stress. Low versus high HRV groups was defined by median split on resting HRV (RMSSD). The task elicited significant time effects for SBP, DBP, HR, HRV, cortisol, and TNF-alpha. Subjects with low baseline HRV showed almost no modulation of HRV coupled with overall reduced HRV levels, and impaired recovery of DBP, cortisol, and TNF-alpha. Confirming our hypothesis, low vagal tone was associated with impaired recovery of cardiovascular, endocrine, and immune markers in healthy males. The data support an inhibitory role of the vagus in the regulation of allostatic systems as described in the neurovisceral integration model. We posit reduced resting HRV as a risk marker for future cardiovascular and other stress-related disease.