Effects of hydrocortisone and yohimbine on decision-making under risk

Decision-making under stress: A psychological and neurobiological integrative model

Understanding the impact of stress on cognitive processes, particularly decision-making, is crucial as it underpins behaviors essential for survival. However, research in this domain has yielded disparate results, with inconsistencies evident across stress-induction paradigms and drug administration protocols designed to investigate specific stress pathways or neuromodulators. Building upon empirical studies, this research identifies a multifaceted matrix of variables contributing to the divergent findings. This matrix encompasses factors such as the temporal proximity between stressors and decision tasks, the nature of stressors and decision contexts, individual characteristics including psychobiological profiles and affective states at the time of decision-making and even cultural influences. In response to these complexities, we propose a comprehensive model that integrates these relevant factors and their intricate interplay to elucidate the mechanisms governing decision-making during stressful events. By synthesizing these insights, our model not only refines existing paradigms but also provides a framework for future study designs, offering avenues for theoretical advancements and translational developments in the field of stress's impact on cognitive functions. This research contributes to a deeper understanding of the nuanced relationship between stress and decision-making, ultimately advancing our knowledge of cognitive processes under challenging conditions.

The effects of yohimbine and hydrocortisone on selective attention to fearful faces: An fMRI study

INTRODUCTION

Selective attention to salient emotional information can enable an advantage in the face of danger. The present study aims to investigate the influence of the stress neuromodulators, norepinephrine and cortisol, on selective attention processes to fearful faces and its neuronal activation.

METHODS AND MATERIALS

We used a randomized, double-blind, placebo-controlled design. 167 healthy men between 18 and 35 years (mean [SD] age: 25.23 [4.24] years) participated in the study. Participants received either: (A) yohimbine (n= 41), (B) hydrocortisone (n = 41), (C) yohimbine and hydrocortisone (n = 42) or (D) placebo only (n= 43) and participated in a dot-probe task with fearful and neutral faces in an fMRI scanner.

RESULTS

We found an attentional bias toward fearful faces across all groups and related neuronal activation in the left cuneus. We did not find any differences between experimental treatment groups in selective attention and its neuronal activation.

DISCUSSION

Our results provide evidence that fearful faces lead to an attentional bias with related neuronal activation in the left cuneus. We did not replicate formerly reported activation in the amygdala, intraparietal sulcus, dorsal anterior cingulate cortex, and thalamus. Suitability of the dot-probe task for fMRI studies and insignificant treatment effects are discussed.

Noradrenergic modulation of stress induced catecholamine release: Opposing influence of FG7142 and yohimbine

Background

Life stress modulates decision making, particularly in the face of risk, in some cases prompting vulnerable populations to make suboptimal, life-altering choices. In the brain, stress is known to alter the extracellular release of catecholamines in structures such as basolateral amygdala (BLA) and nucleus accumbens (NAc), but the relationship between catecholamines and decision-making behavior under stress has not been systemically explored.

Methods

We developed an operant touchscreen decision-making task for rats comprising elements of loss aversion and risk seeking behavior. Rats were first injected systemically with an adrenergicα 2 A -receptor agonist (guanfacine) and antagonist (yohimbine), as well as a partial inverse GABAA agonist, FG 7142, known to induce anxiety and stress related physiological responses in a variety of species, including humans. We then used fiber photometry to monitor NE in the basolateral amygdala (BLA), and DA activity in the nucleus accumbens (NAc) while animals engaged in decision-making and following systemic injections of FG 7142 and yohimbine.

Results

Neither yohimbine nor guanfacine had any impact on decision making strategy but altered motivational state with yohimbine making the animal almost insensitive to the reward outcome. The pharmacological induction of stress with FG 7142 biased the rats' decisions towards safety, but this bias shifted toward risk when co-treated with yohimbine. In the BLA and NAc, the FG 7142 altered catecholamine release, with systemic yohimbine producing opposing effects on NE and DA release.

Conclusions

Stress induced changes in catecholamine release in the BLA and NAc can directly influence loss sensitivity, decisions and motivation, which can be modulated by theα 2 A adrenoreceptor antagonist, yohimbine.

COVID-19 stressor reduces risk taking: the role of trait interoception

The Framing Effect (FE) demonstrated that the way two alternatives are displayed affects people's inclination to make a specific choice, showing a risk aversion when alternatives are displayed on positive frames and risk seeking in negative frames. Risk seeking in negative frames is closely linked to loss aversion. Moreover, classical research and the salience-of-losses hypothesis argues that stress may enhance the FE and loss aversion. Recent studies also suggest that the trait interoception and alexithymia could interact and moderate the framing susceptibility. However, experimental paradigms on stress could ignore variables such as threat perception. In this sense, COVID-19 pandemic has become a powerful real-life stressor in many countries. We aimed to study how real-life stressors influence decision-making under risk. A total of 97 participants were divided into a control (n = 48) and an experimental group (n = 49). The experimental group were exposed to a stressor manipulation, a 5 min COVID-19 lockdown documentary. Our results show that COVID-19-related stressors significantly decreased bet acceptance regardless of the frame, also reducing loss aversion. Moreover, interoception was a significant predictor of loss aversion under stress conditions. Our results do not support classical research on stress and FE.

The effects of hydrocortisone and yohimbine on human behavior in approach-avoidance conflicts

RATIONALE

Balancing approach of positive and avoidance of negative stimuli is essential when faced with approach-avoidance conflicts, e.g., situations with both positive and negative outcomes. This balance is disturbed in several mental disorders, e.g., excessive avoidance in anxiety disorders, and heightened approach in substance use disorders. Since stress is assumed to impact these disorders' etiology and maintenance, it seems crucial to understand how stress influences behavior in approach-avoidance conflicts. Indeed, some studies suggested altered approach-avoidance behavior under acute stress, but the mechanism underlying these effects is unknown.

OBJECTIVES

Investigate how the pharmacological manipulation of major stress mediators (cortisol and noradrenaline) influences task-based approach-avoidance conflict behavior in healthy individuals.

METHODS

Ninety-six participants (48 women, 48 men) received either 20mg hydrocortisone, 20mg yohimbine, both, or placebo before performing a task targeting foraging under predation in a fully crossed double-blind between-subject design. Moreover, we investigated effects of gender and endogenous testosterone and estradiol levels on approach-avoidance behavior.

RESULTS

While biological stress markers (cortisol concentration, alpha amylase activity) indicated successful pharmacological manipulation, behavior in approach-avoidance conflicts was not affected as expected. Although yohimbine administration affected risky foraging latency under predation, we found no main effect of hydrocortisone or their interaction on behavior. In contrast, we found gender differences for almost all behavioral outcome measures, which might be explained by differences in endogenous testosterone levels.

CONCLUSIONS

The investigated major stress mediators were not sufficient to imitate previously shown stress effects on approach-avoidance conflict behavior. We discuss potential reasons for our findings and implications for future research.

Implicit Negativity Bias Leads to Greater Loss Aversion and Learning during Decision-Making

It is widely accepted there is the existence of negativity bias, a greater sensitivity to negative emotional stimuli compared with positive ones, but its effect on decision-making would depend on the context. In risky decisions, negativity bias could lead to non-rational choices by increasing loss aversion; yet in ambiguous decisions, it could favor reinforcement-learning and better decisions by increasing sensitivity to punishments. Nevertheless, these hypotheses have not been tested to date. Our aim was to fill this gap. Sixty-nine participants rated ambiguous emotional faces (from the NimStim set) as positive or negative to assess negativity bias. The implicit level of the bias was also obtained by tracking the mouse's trajectories when rating faces. Then, they performed both a risky and an ambiguous decision-making task. Participants displayed negativity bias, but only at the implicit level. In addition, this bias was associated with loss aversion in risky decisions, and with greater performance through the ambiguous decisional task. These results highlight the need to contextualize biases, rather than draw general conclusions about whether they are inherently good or bad.

The Effects of Citalopram and Thalamic Dopamine D2/3 Receptor Availability on Decision-Making and Loss Aversion in Alcohol Dependence

Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for patients who misuse alcohol, especially in the context of comorbid depressive symptoms. Deficits in impulse control and decision-making are linked to routine alcohol consumption and alcohol dependence. The goal of this study was to determine the effects of a single dose of citalopram on measures of impulsivity, decision-making, and/or brain dopamine receptor availability in alcohol-dependent individuals. A double-blind, placebo-controlled, within-subject, outpatient study was conducted with active alcohol-dependent (DSM-IV-TR criteria) participants (n = 12) and matched healthy controls (n = 13). Serial doses of both citalopram (40 mg) and saline were administered intravenously before laboratory tests of decision-making (Balloon Analogue Risk Task, delay discounting task, and Loss Aversion Gambling Task) and positron emission tomography with [¹⁸F]-fallypride to measure dopamine D_2/3 receptor availability, separated by at least one week. Alcohol-dependent participants demonstrated greater loss aversion than healthy controls, but there were no group differences in risk taking on the Balloon Analogue Risk Task. Citalopram increased delay discounting across groups, with no group difference in the effect. There were no effects of citalopram on risk taking on the Balloon Analogue Risk Task. PET showed a negative correlation between thalamic dopamine D_2/3 receptor availability and loss aversion across groups. The effect of citalopram to decrease the valuation of monetary reward as a function of delay raises the possibility that SSRIs can influence risky decision-making in clinical populations. In addition, these results suggest that altered thalamic dopamine signaling may play an important role in disproportionately valuing losses in patients with Alcohol Use Disorder. This trial is registered under ClinicalTrials.gov registration NCT01657760.

Altruism under Stress: Cortisol Negatively Predicts Charitable Giving and Neural Value Representations Depending on Mentalizing Capacity

Altruism, defined as costly other-regarding behavior, varies considerably across people and contexts. One prominent context in which people frequently must decide on how to socially act is under stress. How does stress affect altruistic decision-making and through which neurocognitive mechanisms? To address these questions, we assessed neural activity associated with charitable giving under stress. Human participants (males and females) completed a charitable donation task before and after they underwent either a psychosocial stressor or a control manipulation, while their brain activity was measured using functional magnetic resonance imaging. As the ability to infer other people's mental states (i.e., mentalizing) predicts prosocial giving and may be susceptible to stress, we examined whether stress effects on altruism depend on participants' general capacity to mentalize, as assessed in an independent task. Although our stress manipulation per se had no influence on charitable giving, increases in the stress hormone cortisol were associated with reductions in donations in participants with high mentalizing capacity, but not in low mentalizers. Multivariate neural response patterns in the right dorsolateral prefrontal cortex (DLPFC) were less predictive of postmanipulation donations in high mentalizers with increased cortisol, indicating decreased value coding, and this effect mediated the (moderated) association between cortisol increases and reduced donations. Our findings provide novel insights into the modulation of altruistic decision-making by suggesting an impact of the stress hormone cortisol on mentalizing-related neurocognitive processes, which in turn results in decreased altruism. The DLPFC appears to play a key role in mediating this cortisol-related shift in altruism.SIGNIFICANCE STATEMENT Altruism is a fundamental building block of our society. Emerging evidence indicates a major role of acute stress and stress-related neuromodulators in social behavior and decision-making. How and through which mechanisms stress may impact altruism remains elusive. We observed that the stress hormone cortisol was linked to diminished altruistic behavior. This effect was mediated by reduced value representations in the right dorsolateral prefrontal cortex and critically depended on the individual capacity to infer mental states of others. Our findings provide novel insights into the modulation of human altruism linked to stress-hormone dynamics and into the involved sociocognitive and neural mechanisms, with important implications for future developments of more targeted interventions for stress-related decrements in social behavior and social cognition.

Sunk costs under stress: Acute stress reduces the impact of past expenses on risky decisions

Rational choice should be guided solely by the prospects of available options. However, our decisions are often influenced by irrecoverable past costs, even when the current course of action turns out to be unfavorable, reflecting a cognitive bias known as the "sunk-cost effect". In everyday life, many decisions are made under stress or elicit stress themselves. Whether and how stress impacts the sunk-cost effect, however, is not known. Based on evidence suggesting that the sunk-cost effect critically depends on the dorsolateral prefrontal cortex, which in turn is highly sensitive to stress, we hypothesized that stress may reduce the influence of past expenses on current decisions. Participants underwent a psychosocial stress manipulation or control procedure, before we assessed their sunk-cost tendency in a monetary investment task. Overall, participants showed a pronounced sunk-cost effect, particularly for options with low expected value. Acute stress reduced this tendency to invest in risky options with low probability of success following high prior investments. Moreover, the strength of this reduction of the sunk-cost effect was predicted by individual cortisol reactivity. These findings show that acute stress may reduce the impact of past expenses on current choice and that this effect may be mediated by glucocorticoid action.

Emotional stress & decision-making: an emotional stressor significantly reduces loss aversion

Stress influences loss aversion, the principle that losses loom larger than gains, although the nature of this relationship is unclear. Studies show that stress reduces loss aversion; however, stress response has been only studied by means of physiological measures, but the stressor emotional impact remained unclear. Since emotions can modify stress response and increase the activity of the loss aversion neural substrates, it could be expected that an emotional stressor may produce the opposite effect, i.e. loss aversion increase. 69 participants were divided into experimental and control group. The first one was exposed to emotional stress through a 5-minutes video, and control group viewed a match-length distractor video. Physiological stress response was assessed by means of electrodermal activity (EDA), and both perceived stress, and negative affect (i.e. psychological stress response) were registered through questionnaires. Both groups performed a mixed gamble task, which allowed the extraction of loss aversion through a Bayesian-computational model. During and after video, experimental group had higher electrodermal activity, perceived stress, and negative affect than controls, suggesting that emotional stress induction was effective. However, rather than increasing, loss aversion of stressed participants was lower. These results constitute a new evidence of emotional stress influencing loss aversion and highlight that stress, regardless of its emotional impact, can reduce this phenomenon. These results should be considered when predicting risky decisions.

Effects of glucocorticoid and noradrenergic activity on implicit and explicit facial emotion recognition in healthy young men

The ability to recognize emotions from facial expressions is crucial for social interaction. Only few studies have examined the effect of stress hormones on facial emotion recognition, although stressful events affect social interactions on a daily basis. Those studies that examined facial emotion recognition mostly used explicit prompts to trigger consciously controlled processing. However, facial emotions are processed mainly implicitly in real life. Therefore, we investigated separate and combined effects of noradrenergic and glucocorticoid stimulation on implicit and explicit facial emotion recognition. One hundred and four healthy men (mean age = 24.1 years ±SD 3.5) underwent the Face Puzzle task to test implicit and explicit facial emotion recognition after receiving either 10 mg hydrocortisone or 10 mg yohimbine (an alpha 2-adrenergic receptor antagonist that increases noradrenergic activity) or 10 mg hydrocortisone/10 mg yohimbine combined or placebo. Salivary cortisol and salivary alpha amylase (sAA) were measured during the experiment. Compared to the placebo condition hydrocortisone significantly increased salivary cortisol and yohimbine significantly increased sAA. Participants were better and faster in explicit than in implicit facial emotion recognition. However, there was no effect of separate and combined noradrenergic and glucocorticoid stimulation on implicit and explicit facial emotion recognition performance compared to placebo. Our results do not support an essential role of the glucocorticoid and noradrenergic system in FER in young healthy men.

Effects of hydrocortisone and yohimbine on selective attention to emotional cues

INTRODUCTION

Facial expressions contain important affective information, and selective attention to facial expression provides an advantage in the face of loss, stress and danger. In addition, the sympathetic nervous system and hypothalamus-pituitary-adrenal axis mediate the organism's response to loss and danger. Here, we aimed at investigating the influence of sympathetic nervous system and hypothalamus-pituitary-adrenal axis activation on selective attention to affective facial stimuli.

METHODS AND MATERIALS

One hundred-and-four healthy men between 18-35 years old (mean (standard deviation) age: 24.1 (3.5) years) participated in the study. We used a randomised, double-blind, placebo-controlled design. Participants received either: (a) yohimbine, (b) hydrocortisone, (c) yohimbine and hydrocortisone or (d) placebo only and participated in a dot-probe task with sad, happy and neutral faces. We collected salivary samples to measure cortisol and alpha amylase activity in addition to measurements of blood pressure and heart rate. Salivary cortisol served as correlate of hypothalamus-pituitary-adrenal axis activation and salivary alpha amylase activity, blood pressure and heart rate as correlates of sympathetic nervous system activation. Measurements were carried out before and after drug administration.

RESULTS

We did not find a main effect or interaction effect of hydrocortisone or yohimbine administration on selective attention to happy faces. However, we found an interaction of yohimbine and hydrocortisone on selective attention to sad faces. Post-hoc t-test revealed an attentional bias away from sad stimuli and towards neutral faces in the hydrocortisone-only group.

DISCUSSION

Only hydrocortisone administration led to an attentional bias away from sad faces. Future studies should investigate these effects in major depression disorder, as this disorder is characterised by glucocorticoid resistance and increased processing of sad stimuli.

Causal Role of the Dorsolateral Prefrontal Cortex in Belief Updating under Uncertainty

Adaptive performance in uncertain environments depends on the ability to continuously update internal beliefs about environmental states. Recent correlative evidence suggests that a frontoparietal network including the dorsolateral prefrontal cortex (dlPFC) supports belief updating under uncertainty, but whether the dlPFC serves a "causal" role in this process is currently not clear. To elucidate its contribution, we leveraged transcranial direct current stimulation (tDCS) over the right dlPFC, while 91 participants performed an incentivized belief-updating task. Participants also underwent a psychosocial stress or control manipulation to investigate the role of stress, which is known to modulate dlPFC functioning. We observed enhanced monetary value updating after anodal tDCS when it was normatively expected from a Bayesian perspective. A model-based analysis indicates that this effect was driven by belief updating. However, we also observed enhanced non-normative value updating, which might have been driven instead by expectancy violation. Enhanced normative and non-normative value updating reflected increased vs. decreased Bayesian rationality, respectively. Furthermore, cortisol increases were associated with enhanced positive, but not with negative, value updating. The present study thereby sheds light on the causal role of the right dlPFC in the remarkable human ability to navigate uncertain environments by continuously updating prior knowledge following new evidence.

Heart rate variability after vigorous physical exercise is positively related to loss aversion

BACKGROUND AND OBJECTIVES OF THE ARTICLE

Loss aversion bias, whereby losses loom larger than gains, can be reduced by stress. At the same time, vigorous physical exercise is a powerful neuroendocrine stressor and heart rate variability (HRV) provides an objective measure of the actual exercise impact, relative to each individual physical condition. Our aim was to study whether vigorous exercise can influence loss aversion, considering HRV in this relation. We hypothesized that the lower HRV derived from vigorous exercise (i.e., when stressor produced the most impact) would predict a lower loss aversion.

METHODS

Two groups (Experimental, N = 37; Control, N = 39) completed a loss aversion task, but the experimental group was exposed to an acute physical stressor before.

RESULTS

Results revealed a significant group x HRV interaction. In the control group, HRV was not associated with loss aversion. Conversely, as hypothesized, the lower HRV levels derived from exercise were associated with a lesser loss aversion in the experimental group.

CONCLUSIONS

Results suggest that physiological changes from physical exercise could affect decision-making by reducing loss aversion.