Stress affects the selection of relevant from irrelevant stimuli

NrCAM-deficient mice exposed to chronic stress exhibit disrupted latent inhibition, a hallmark of schizophrenia

The neuronal cell adhesion molecule (NrCAM) is widely expressed and has important physiological functions in the nervous system across the lifespan, from axonal growth and guidance to spine and synaptic pruning, to organization of proteins at the nodes of Ranvier. NrCAM lies at the core of a functional protein network where multiple targets (including NrCAM itself) have been associated with schizophrenia. Here we investigated the effects of chronic unpredictable stress on latent inhibition, a measure of selective attention and learning which shows alterations in schizophrenia, in NrCAM knockout (KO) mice and their wild-type littermate controls (WT). Under baseline experimental conditions both NrCAM KO and WT mice expressed robust latent inhibition (p = 0.001). However, following chronic unpredictable stress, WT mice (p = 0.002), but not NrCAM KO mice (F < 1), expressed latent inhibition. Analyses of neuronal activation (c-Fos positive counts) in key brain regions relevant to latent inhibition indicated four types of effects: a single hit by genotype in IL cortex (p = 0.0001), a single hit by stress in Acb-shell (p = 0.031), a dual hit stress x genotype in mOFC (p = 0.008), vOFC (p = 0.020), and Acb-core (p = 0.032), and no effect in PrL cortex (p > 0.141). These results indicating a pattern of differential effects of genotype and stress support a complex stress × genotype interaction model and a role for NrCAM in stress-induced pathological behaviors relevant to schizophrenia and other psychiatric disorders.

Behavioral and neural mechanisms of latent inhibition

Fear is an adaptive emotion that serves to protect an organism against potential dangers. It is often studied using classical conditioning paradigms where a conditioned stimulus is paired with an aversive unconditioned stimulus to induce a threat response. Less commonly studied is a phenomenon that is related to this form of conditioning, known as latent inhibition. Latent inhibition (LI) is a paradigm in which a neutral cue is repeatedly presented in the absence of any aversive associations. Subsequent pairing of this pre-exposed cue with an aversive stimulus typically leads to reduced expression of a conditioned fear/threat response. In this article, we review some of the theoretical basis for LI and its behavioral and neural mechanisms. We compare and contrast LI and fear/threat extinction-a process in which a previously conditioned cue is repeatedly presented in the absence of aversive outcomes. We end with highlighting the potential clinical utility of LI. Particularly, we focus on how LI application could be useful for enhancing resilience, especially for individuals who are more prone to continuous exposure to trauma and stressful environments, such as healthcare workers and first responders. The knowledge to be gained from advancing our understanding of neural mechanisms in latent inhibition could be applicable across psychiatric disorders characterized by exaggerated fear responses and impaired emotion regulation.

The C Factor: Cognitive dysfunction as a transdiagnostic dimension in psychopathology

Research into cognitive functions across psychological disorders suggests that cognitive deficiencies may be present across multiple disorders, potentially pointing to a transdiagnostic phenomenon. More recently, a single dimension model of psychopathology, the p factor, has been proposed, in which cognitive deficits are thought to be an intrinsic construct, assumed to be transdiagnostic. However, no systematic investigation to date tested this hypothesis. The aim of the present study was to systematically review meta-analyses to assess the hypothesis that the C factor (cognitive dysfunction) is transdiagnostic in psychopathology and review potential moderators that may account for such a phenomenon. We conducted a systematic review of meta-analyses examining cognitive function across all disorders for which data were available. Included meta-analyses (n = 82), comprising 97 clinical samples, yielded 1,055 effect sizes. Twelve major disorders/categories (e.g., bipolar disorder, substance use disorders) were included, comprising 29 distinct clinical entities (e.g., euthymic bipolar disorder; alcohol use disorder). Results show that all disorders reviewed are associated with underperformance across cognitive domains, supporting the hypothesis that the C factor (or cognitive dysfunction) is a transdiagnostic factor related to p. To examine moderators that may explain or contribute to c, we first consider important interpretative limitations of neuropsychological data in psychopathology. More crucially, we review oft-neglected motivational and emotional transdiagnostic constructs of p, as prominent contributing constructs to the C factor. These constructs are offered as a roadmap for future research examining these constructs related to p, that contribute, and may account for cognitive dysfunctions in psychopathology.

Neuropsychological Research in Obsessive-Compulsive Disorder: Current Status and Future Directions

Neuropsychological functions in obsessive-compulsive disorder (OCD) have been extensively investigated. Despite some common findings across studies indicating deficient test performance across cognitive domains with small to medium effect sizes, results remain inconsistent and heterogeneous. However, multiple past attempts to identify moderators that may account for such variability have been unrewarding. Typical moderators including symptom severity, age at onset, medication status, and comorbid conditions failed to provide sufficient explanatory power. It has then been posited that these inconsistencies may be attributed to the inherent heterogeneous nature of the disorder (i.e., symptom dimensions), or to the natural fluctuation in symptom severity. However, recent meta-analyses suggest that these factors may not account for the persistent unexplained variability. Other potential factors-some of which are unique to neuropsychological testing-received scarce research attention, including definition of cognitive impairments, specificity and selection of test and outcome measures, and their limited ecological validity. Other moderators, particularly motivational aspects, and metacognitive factors (e.g., self-efficacy) were not previously addressed despite their potential association to OCD, and their documented impact on cognitive function. The aim of the present mini-review is to provide an updated succinct overview of the current status of the neuropsychological literature in OCD and expanding upon oft-neglected potential moderators and their putative impact on neuropsychological findings in OCD. Our goal is to highlight important avenues for further research and provide a road map for investigators in order to advance our understanding of cognitive functions in OCD that has been stagnant in the past decade.

Personality, creativity and latent inhibition

The current study set out to investigate the relationship between creativity, multi‐dimensional schizotypy and personality more generally. This was achieved by analysing scores on a range of personality scales and measures of creativity, where it was found that the creativity measures were more closely related to asocial‐schizotypy than positive‐schizotypy. The study also sought to test Eysenck's prediction (1993, 1995) that, given the putative relationship between creativity and psychosis‐proneness, high psychosis‐prone scoring individuals and high creativity scoring individuals would demonstrate the same cognitive style of ‘overinclusiveness’ on latent inhibition. However, the results failed to demonstrate any evidence of a shared ‘widening of the associative horizon’ between high creativity and high psychosis‐prone scorers. The findings are discussed in relation to multi‐dimensional schizotypy. Copyright © 2006 John Wiley & Sons, Ltd.

Does stress influence the performance of cardiopulmonary resuscitation? A narrative review of the literature

Cardiopulmonary resuscitation represents a major physical and psychological challenge for all involved health care workers because survival of the patients is closely related to the timely and accurate actions of rescuers. Consequently, rescuers may experience high levels of acute mental stress. Stress, in turn, may influence attentional resources and distractibility, which may affect the quality of resuscitation. This narrative review summarizes the current state of research concerning the influence of stress on resuscitation performance. Peer-reviewed studies retrieved in scientific databases were eligible. We found that rescuers experience high levels of stress and some associations of higher levels of stress with lower resuscitation performance. Finally, few interventional studies assessed whether interventions aiming at reducing levels of stress may have a beneficial effect on resuscitation performance, but results are variable. Although the mechanisms linking stress to performance of emergency teams are still not fully understood, factors such as individual experience and self-confidence of rescuers, gender composition and hierarchy within resuscitation teams may play an important role. This review provides a targeted overview of how stress can be defined and measured, how it may influence emergency situations such as a cardiopulmonary resuscitation, and which interventions have the potential to reduce overwhelming stress.

Modeling the cardiac indices of stress and performance of nuclear power plant operators during simulated fault scenarios

Acute stress can affect cognitive processing and decrease performance in demanding, stressful situations. Here, we recorded the cardiac indices of stress, that is, the heart rate and heart rate variability together with the physical activity of nuclear power plant operators, and examined their association with crew performance, while the operator crews were managing simulated incident and accident situations. Crew performance was evaluated both by the operator instructor and as the time taken to resolve the situation. In total, 64% of the variance in the information-seeking performance (adj-R²  = .64, p < .01), and 41% of variation in the performance time (adj-R²  = .41, p < .01) were explained by the psychophysiology. The cardiac measures indicated that increased stress was associated with poorer information-seeking performance and longer performance time. Increased physical activity was associated with poorer information seeking only. Otherwise, crew performance was robust, as the diagnosis and corrective actions, use of emergency operations procedures, and collaboration, were only weakly associated with the stress physiology. The association between information-seeking performance and stress might be explained by the larger requirement for cognitive processing at the information-gathering phase of the task. The results of the study show that psychophysiological measurements of stress and activity can provide valuable information on stress and its association with cognitive performance at work.

Inhibited Personality Temperaments Translated Through Enhanced Avoidance and Associative Learning Increase Vulnerability for PTSD

Although many individuals who experience a trauma go on to develop post-traumatic stress disorder (PTSD), the rate of PTSD following trauma is only about 15-24%. There must be some pre-existing conditions that impart increased vulnerability to some individuals and not others. Diathesis models of PTSD theorize that pre-existing vulnerabilities interact with traumatic experiences to produce psychopathology. Recent work has indicated that personality factors such as behavioral inhibition (BI), harm avoidance (HA), and distressed (Type D) personality are vulnerability factors for the development of PTSD and anxiety disorders. These personality temperaments produce enhanced acquisition or maintenance of associations, especially avoidance, which is a criterion symptom of PTSD. In this review, we highlight the evidence for a relationship between these personality types and enhanced avoidance and associative learning, which may increase risk for the development of PTSD. First, we provide the evidence confirming a relationship among BI, HA, distressed (Type D) personality, and PTSD. Second, we present recent findings that BI is associated with enhanced avoidance learning in both humans and animal models. Third, we will review evidence that BI is also associated with enhanced eyeblink conditioning in both humans and animal models. Overall, data from both humans and animals suggest that these personality traits promote enhanced avoidance and associative learning, as well as slowing of extinction in some training protocols, which all support the learning diathesis model. These findings of enhanced learning in vulnerable individuals can be used to develop objective behavioral measures to pre-identify individuals who are more at risk for development of PTSD following traumatic events, allowing for early (possibly preventative) intervention, as well as suggesting possible therapies for PTSD targeted on remediating avoidance or associative learning. Future work should explore the neural substrates of enhanced avoidance and associative learning for behaviorally inhibited individuals in both the animal model and human participants.

Human latent inhibition: Problems with the stimulus exposure effect

Latent inhibition (LI) is a startlingly simple effect in which preexposure of a stimulus without consequence retards subsequent responding to a stimulus-consequence relation. The effect was first demonstrated with Pavlovian conditioning in animals and was later suggested to be a marker of human psychopathology such as schizophrenia. Individual differences in LI has supported the continued use of animal models to understand human mental health. In this review, we ask whether there is sufficient evidence to support the continued application of LI from animal models to human psychopathology because of the weak evidence for LI in humans. There is considerable variability in the methods used to assess LI, sustaining different theoretical accounts of the effects observed, which differ from the accepted accounts of LI as demonstrated in animals. The review shows that although there have been many experiments testing human LI, none provide the necessary experimental controls to support the conclusion that retarded responding is caused simply by preexposure to a stimulus, as has been demonstrated with animal models. Establishing this conflict, we set out a framework for future research.

Virtually Being Einstein Results in an Improvement in Cognitive Task Performance and a Decrease in Age Bias

The brain's body representation is amenable to rapid change, even though we tend to think of our bodies as relatively fixed and stable. For example, it has been shown that a life-sized body perceived in virtual reality as substituting the participant's real body, can be felt as if it were their own, and that the body type can induce perceptual, attitudinal and behavioral changes. Here we show that changes can also occur in cognitive processing and specifically, executive functioning. Fifteen male participants were embodied in a virtual body that signifies super-intelligence (Einstein) and 15 in a (Normal) virtual body of similar age to their own. The Einstein body participants performed better on a cognitive task than the Normal body, considering prior cognitive ability (IQ), with the improvement greatest for those with low self-esteem. Einstein embodiment also reduced implicit bias against older people. Hence virtual body ownership may additionally be used to enhance executive functioning.

Cardiac measures of nuclear power plant operator stress during simulated incident and accident scenarios

Maintaining optimal performance in demanding situations is challenged by stress-induced alterations in performance. Here, we quantified the stress of nuclear power plant (NPP) operators (N = 20) during a full-scale simulator training for incident and accident scenarios. We compared the ambulatory electrocardiography measurements of heart rate (HR) and heart rate variability (HRV), and self-reported stress during baselines and simulated scenarios. Perceived (scale 0-10) and physiologically measured stress were low during baseline after the scenarios and normal NPP operation (means 1.8-2.2, mean HR 75-80 bpm). During a cognitively challenging scenario simulating a sensor malfunction, the operators' stress was mild to moderate (mean 3.4; HR + 12% from baseline). During simulations of severe accidents of fire and radioactive steam leakage, the experienced stress and cardiac activity were on a moderate to high level (means 4.2 and 4.6; HR + 23% and + 14% from baseline, respectively). Cardiac activity paralleled the self-reported stress: correlation of self-reported stress to HR was 0.61 (p < .001) and to HRV features RMSSD, HF, LF/HF, SD1, and SD1/SD2 were -0.26, -0.28, 0.35, -0.40, and -0.39 (p < .01), respectively. The low shared variance (22%) between HR and physical activity further support the interpretation that the cardiac activity was strongly linked to the experience of stress and not accountable by operators' movement within the simulator. Cardiac measurements in naturalistic settings can thus reveal relevant information on acute stress with the benefit of not interrupting the primary task.

Impaired Latent Inhibition in GDNF-Deficient Mice Exposed to Chronic Stress

Increased reactivity to stress is maladaptive and linked to abnormal behaviors and psychopathology. Chronic unpredictable stress (CUS) alters catecholaminergic neurotransmission and remodels neuronal circuits involved in learning, attention and decision making. Glial-derived neurotrophic factor (GDNF) is essential for the physiology and survival of dopaminergic neurons in substantia nigra and of noradrenergic neurons in the locus coeruleus. Up-regulation of GDNF expression during stress is linked to resilience; on the other hand, the inability to up-regulate GDNF in response to stress, as a result of either genetic or epigenetic modifications, induces behavioral alterations. For example, GDNF-deficient mice exposed to chronic stress exhibit alterations of executive function, such as increased temporal discounting. Here we investigated the effects of CUS on latent inhibition (LI), a measure of selective attention and learning, in GDNF-heterozygous (HET) mice and their wild-type (WT) littermate controls. No differences in LI were found between GDNF HET and WT mice under baseline experimental conditions. However, following CUS, GDNF-deficient mice failed to express LI. Moreover, stressed GDNF-HET mice, but not their WT controls, showed decreased neuronal activation (number of c-Fos positive neurons) in the nucleus accumbens shell and increased activation in the nucleus accumbens core, both key regions in the expression of LI. Our results add LI to the list of behaviors affected by chronic stress and support a role for GDNF deficits in stress-induced pathological behaviors relevant to schizophrenia and other psychiatric disorders.

Reward devaluation disrupts latent inhibition in fear conditioning

Three experiments explored the link between reward shifts and latent inhibition (LI). Using consummatory procedures, rewards were either downshifted from 32% to 4% sucrose (Experiments 1-2), or upshifted from 4% to 32% sucrose (Experiment 3). In both cases, appropriate unshifted controls were also included. LI was implemented in terms of fear conditioning involving a single tone-shock pairing after extensive tone-only preexposure. Nonpreexposed controls were also included. Experiment 1 demonstrated a typical LI effect (i.e., disruption of fear conditioning after preexposure to the tone) in animals previously exposed only to 4% sucrose. However, the LI effect was eliminated by preexposure to a 32%-to-4% sucrose devaluation. Experiment 2 replicated this effect when the LI protocol was administered immediately after the reward devaluation event. However, LI was restored when preexposure was administered after a 60-min retention interval. Finally, Experiment 3 showed that a reward upshift did not affect LI. These results point to a significant role of negative emotion related to reward devaluation in the enhancement of stimulus processing despite extensive nonreinforced preexposure experience.

Chronic mild stress impairs latent inhibition and induces region-specific neural activation in CHL1-deficient mice, a mouse model of schizophrenia

Schizophrenia is a neurodevelopmental disorder characterized by abnormal processing of information and attentional deficits. Schizophrenia has a high genetic component but is precipitated by environmental factors, as proposed by the 'two-hit' theory of schizophrenia. Here we compared latent inhibition as a measure of learning and attention, in CHL1-deficient mice, an animal model of schizophrenia, and their wild-type littermates, under no-stress and chronic mild stress conditions. All unstressed mice as well as the stressed wild-type mice showed latent inhibition. In contrast, CHL1-deficient mice did not show latent inhibition after exposure to chronic stress. Differences in neuronal activation (c-Fos-positive cell counts) were noted in brain regions associated with latent inhibition: Neuronal activation in the prelimbic/infralimbic cortices and the nucleus accumbens shell was affected solely by stress. Neuronal activation in basolateral amygdala and ventral hippocampus was affected independently by stress and genotype. Most importantly, neural activation in nucleus accumbens core was affected by the interaction between stress and genotype. These results provide strong support for a 'two-hit' (genes x environment) effect on latent inhibition in CHL1-deficient mice, and identify CHL1-deficient mice as a model of schizophrenia-like learning and attention impairments.

Effect of stress and attention on startle response and prepulse inhibition

The startle reflex magnitude can be modulated when a weak stimulus is presented before the onset of the startle stimulus, a phenomenon termed prepulse inhibition (PPI). Previous research has demonstrated that emotional processes can modulate PPI and startle intensity, but the available evidence is inconclusive. In order to obtain additional evidence in this domain, we conducted two experiments intended to analyze the effect of induced stress and attentional load on PPI and startle magnitude. Specifically, in Experiment 1 we used a between subject strategy to evaluate the effect on startle response and PPI magnitude of performing a difficult task intended to induce stress in the participants, as compared to a group exposed to a control task. In Experiment 2 we evaluated the effect of diverting attention from the acoustic stimulus on startle and PPI intensity. The results seem to indicate that induced stress can reduce PPI, and that startle reflex intensity is reduced when attention is directed away from the auditory stimulus that induces the reflex.

Effects of hearing loss on heart rate variability and skin conductance measured during sentence recognition in noise

OBJECTIVE

The purpose of the study was to determine the effects of hearing loss and noise on (1) two autonomic nervous system measures associated with stress (skin conductance and heart rate variability) and on (2) subjective ratings of workload/stress. The authors hypothesized that hearing loss would increase psychophysiological and subjective reactivity to noise during speech recognition tasks. Both psychophysiological and subjective indicators of workload/stress were expected to increase with a reduction in signal-to-noise ratio.

DESIGN

Sentence recognition in the presence of babble noise was assessed in 15 adults with clinically normal hearing and 18 adults with sensorineural hearing loss. Mean sentence recognition was equalized for the two groups using an adaptive procedure to estimate 80% recognition of words in sentences. Sentences were then presented in quiet and at four fixed signal-to-noise ratios: -6, -3, 0, and +3 dB relative to the individually determined signal-to-noise thresholds. Electrocardiography and skin conductance recordings were obtained during each listening condition. The high-frequency spectral component of heart rate variability was extracted from the electrocardiographic recordings as a measure of parasympathetic nervous system activity. Subjective ratings of effort, mental demand, stress, and perceived performance were obtained after each listening condition using the National Aeronautics and Space Administration Task Load Index.

RESULTS

Recognition scores referenced to the adaptive threshold were similar for the two groups. Participants with hearing loss showed a decrease in high-frequency heart rate variability at lower signal-to-noise ratios, whereas those with normal hearing did not. Skin conductance levels were not sensitive to changes in signal-to-noise ratio. However, overall skin conductance reactivity to noise (relative to quiet) was higher for those with hearing loss than for those with normal hearing. In contrast to the psychophysiological findings, there were no significant differences between subjective ratings for the two groups.

CONCLUSIONS

Listeners with hearing loss show greater autonomic nervous system reactivity to babble noise during speech recognition than do listeners with normal hearing, when recognition performance is equal. The findings are consistent with the conclusion that listeners with hearing loss experience increased effort and/or stress during speech recognition in noise.

Impact of alprazolam in allostatic load and neurocognition of patients with anxiety disorders and chronic stress (GEMA): observational study protocol

INTRODUCTION

The allostatic load model explains the additive effects of multiple biological processes that accelerate pathophysiology related to stress, particularly in the central nervous system. Stress-related mental conditions such as anxiety disorders and neuroticism (a well-known stress vulnerability factor), have been linked to disturbances of hypothalamo-pituitary-adrenal with cognitive implications. Nevertheless, there are controversial results in the literature and there is a need to determine the impact of the psychopharmacological treatment on allostatic load parameters and in cognitive functions. Gador study of Estres Modulation by Alprazolam, aims to determine the impact of medication on neurobiochemical variables related to chronic stress, metabolic syndrome, neurocognition and quality of life in patients with anxiety, allostatic load and neuroticism.

METHODS/ANALYSIS

In this observational prospective phase IV study, highly sympthomatic patients with anxiety disorders (six or more points in the Hamilton-A scale), neuroticism (more than 18 points in the Neo five personality factor inventory (NEO-FFI) scale), an allostatic load (three positive clinical or biochemical items at Crimmins and Seeman criteria) will be included. Clinical variables of anxiety, neuroticism, allostatic load, neurobiochemical studies, neurocognition and quality of life will be determined prior and periodically (1, 2, 4, 8, and 12 weeks) after treatment (on demand of alprazolam from 0.75 mg/day to 3.0 mg/day). A sample of n=55/182 patients will be considered enough to detect variables higher than 25% (pretreatment vs post-treatment or significant correlations) with a 1-ß power of 0-80. t Test and/or non-parametric test, and Pearson's test for correlation analysis will be determined.

ETHICS AND DISSEMINATION

This study protocol was approved by an Independent Ethics Committee of FEFyM (Foundation for Pharmacological Studies and Drugs, Buenos Aires) and by regulatory authorities of Argentina (ANMAT, Dossier # 61 409-8 of 20 April 2009), following the law of Habeas Data and psychotherapeutic drug control.

TRIAL REGISTRATION NUMBER

GEMA 20811.

Chronic stress induces a hyporeactivity of the autonomic nervous system in response to acute mental stressor and impairs cognitive performance in business executives

The present study examined the incidence of chronic stress in business executives (109 subjects: 75 male and 34 female) and its relationship with cortisol levels, cognitive performance, and autonomic nervous system (ANS) reactivity after an acute mental stressor. Blood samples were collected from the subjects to measure cortisol concentration. After the sample collection, the subjects completed the Lipp Inventory of Stress Symptoms for Adults and the Stroop Color-Word Test to evaluate stress and cognitive performance levels, respectively. Saliva samples were collected prior to, immediately after, and five minutes after the test. The results revealed that 90.1% of the stressed subjects experienced stress phases that are considered chronic stress. At rest, the subjects with chronic stress showed higher cortisol levels, and no gender differences were observed. No differences were found between the stressed and non-stressed subjects regarding salivary amylase activity prior to test. Chronic stress also impaired performance on the Stroop test, which revealed higher rates of error and longer reaction times in the incongruent stimulus task independently of gender. For the congruent stimulus task of the Stroop test, the stressed males presented a higher rate of errors than the non-stressed males and a longer reaction time than the stressed females. After the acute mental stressor, the non-stressed male group showed an increase in salivary alpha-amylase activity, which returned to the initial values five minutes after the test; this ANS reactivity was not observed in the chronically stressed male subjects. The ANS responses of the non-stressed vs stressed female groups were not different prior to or after the Stroop test. This study is the first to demonstrate a blunted reactivity of the ANS when male subjects with chronic psychological stress were subjected to an acute mental stressor, and this change could contribute to impairments in cognitive performance.

Stress, schizophrenia and bipolar disorder

The role of stress in precipitating psychotic episodes in schizophrenia and bipolar disorder has long been acknowledged. However, the neurobiological mechanism/s of this association have remained elusive. Current neurodevelopmental models of psychosis implicate early dysfunction in biological systems regulating hypothalamic-pituitary-adrenal axis and immune function, with long-term effects on the development of the brain networks responsible for higher order cognitive processes and stress reactivity in later life. There is also increasing evidence of childhood trauma in psychosis, and its impact on the development of brain systems regulating stress. These findings are emerging in the context of a new era of epigenetic methods facilitating the study of environmental effects on gene expression. The evidence is thus converging: exposure to stress at critical periods in life may be an important factor in the development of the brain dysfunction that represents psychosis vulnerability, rather than merely interacting with an independent 'biological vulnerability' to manifest in psychosis.

Does HPA-Axis Dysregulation Account for the Effects of Income on Effortful Control and Adjustment in Preschool Children?

The effects of low income on children's adjustment might be accounted for by disruptions to hypothalamic-pituitary-adrenal (HPA)-axis activity and to the development of effortful control. Using longitudinal data and a community sample of preschool-age children (N = 306, 36-39 months) and their mothers, recruited to over-represent low-income families, we explored the associations among diurnal cortisol levels and effortful control, and we tested a model in which diurnal cortisol and effortful control account for the effects of family income on child adjustment. Continuous indicators of morning cortisol level and diurnal slope, as well as dichotomous indicators reflecting low morning levels and flat diurnal slope, were examined as predictors of rank-order changes in two dimensions of effortful control, executive control and delay ability. Low income was related to a flat diurnal cortisol slope, and above the effects of family income, a flat diurnal cortisol slope predicted lower social competence. Low morning cortisol level predicted smaller gains in executive control and higher total adjustment problems. Further, delay ability predicted lower adjustment problems above the effects of income and diurnal cortisol levels. The results suggest that HPA-axis dysregulation and effortful control contribute additively to children's adjustment.

Impact of a stress coping strategy on perceived stress levels and performance during a simulated cardiopulmonary resuscitation: a randomized controlled trial

BACKGROUND

Cardiopulmonary resuscitation (CPR) causes significant stress for the rescuers which may cause deficiencies in attention and increase distractibility. This may lead to misjudgements of priorities and delays in CPR performance, which may further increase mental stress (vicious cycle). This study assessed the impact of a task-focusing strategy on perceived stress levels and performance during a simulated CPR scenario.

METHODS

This prospective, randomized-controlled trial was conducted at the simulator-center of the University Hospital Basel, Switzerland. A total of 124 volunteer medical students were randomized to receive a 10 minute instruction to cope with stress by loudly posing two task-focusing questions ("what is the patient's condition?", "what immediate action is needed?") when feeling overwhelmed by stress (intervention group) or a control group. The primary outcome was the perceived levels of stress and feeling overwhelmed (stress/overload); secondary outcomes were hands-on time, time to start CPR and number of leadership statements.

RESULTS

Participants in the intervention group reported significantly less stress/overload levels compared to the control group (mean difference: -0.6 (95% CI -1.3, -0.1), p=0.04). Higher stress/overload was associated with less hands-on time. Leadership statements did not differ between groups, but the number of leadership statements did relate to performance. Hands-on time was longer in the intervention- group, but the difference was not statistically significant (difference 5.5 (95% CI -3.1, 14.2), p=0.2); there were no differences in time to start CPR (difference -1.4 (95% CI -8.4, 5.7), p=0.71).

CONCLUSIONS

A brief stress-coping strategy moderately decreased perceived stress without significantly affecting performance in a simulated CPR. Further studies should investigate more intense interventions for reducing stress.

TRIAL REGISTRATION

NCT01645566.

Enhanced conditioned eyeblink response acquisition and proactive interference in anxiety vulnerable individuals

In classical conditioning, proactive interference may arise from experience with the conditioned stimulus (CS), the unconditional stimulus (US), or both, prior to their paired presentations. Interest in the application of proactive interference has extended to clinical populations as either a risk factor for disorders or as a secondary sign. Although the current literature is dense with comparisons of stimulus pre-exposure effects in animals, such comparisons are lacking in human subjects. As such, interpretation of proactive interference over studies as well as its generalization and utility in clinical research is limited. The present study was designed to assess eyeblink response acquisition after equal numbers of CS, US, and explicitly unpaired CS and US pre-exposures, as well as to evaluate how anxiety vulnerability might modulate proactive interference. In the current study, anxiety vulnerability was assessed using the State/Trait Anxiety Inventories as well as the adult and retrospective measures of behavioral inhibition (AMBI and RMBI, respectively). Participants were exposed to 1 of 4 possible pre-exposure contingencies: 30 CS, 30 US, 30 CS, and 30 US explicitly unpaired pre-exposures, or Context pre-exposure, immediately prior to standard delay training. Robust proactive interference was evident in all pre-exposure groups relative to Context pre-exposure, independent of anxiety classification, with CR acquisition attenuated at similar rates. In addition, trait anxious individuals were found to have enhanced overall acquisition as well as greater proactive interference relative to non-vulnerable individuals. The findings suggest that anxiety vulnerable individuals learn implicit associations faster, an effect which persists after the introduction of new stimulus contingencies. This effect is not due to enhanced sensitivity to the US. Such differences would have implications for the development of anxiety psychopathology within a learning framework.

The Effect of Stress on Cognitive Structuring

In this article, we outline a model of the factors involved in the relationship between stress and cognitive structuring. More specifically, we propose that the desire for certainty, the need for cognitive structure, and perceived efficacy at satisfying one’s epistemic needs intervene in the effect exerted by stress on cognitive structuring. We further suggest expanding the model to account for aspects of general information processing and to encompass the effect of various trait-like characteristics on the cognitive response to stress. We also offer an account of the possible effects of extreme stress on the model’s components.

Time-dependent effects of cortisol on selective attention and emotional interference: a functional MRI study

Acute stress is known to induce a state of hypervigilance, allowing optimal detection of threats. Although one may benefit from sensitive sensory processing, it comes at the cost of unselective attention and increased distraction by irrelevant information. Corticosteroids, released in response to stress, have been shown to profoundly influence brain function in a time-dependent manner, causing rapid non-genomic and slow genomic effects. Here, we investigated how these time-dependent effects influence the neural mechanisms underlying selective attention and the inhibition of emotional distracters in humans. Implementing a randomized, double-blind, placebo-controlled design, 65 young healthy men received 10 mg hydrocortisone either 60 min (rapid effects) or 270 min (slow effects), or placebo prior to an emotional distraction task, consisting of color-naming of either neutral or aversive words. Overall, participants responded slower to aversive compared to neutral words, indicating emotional interference with selective attention. Importantly, the rapid effects of corticosteroids increased emotional interference, which was associated with reduced amygdala inhibition to aversive words. Moreover, they induced enhanced amygdala connectivity with frontoparietal brain regions, which may reflect increased influence of the amygdala on an executive network. The slow effects of corticosteroids acted on the neural correlates of sustained attention. They decreased overall activity in the cuneus, possibly indicating reduced bottom-up attentional processing, and disrupted amygdala connectivity to the insula, potentially reducing emotional interference. Altogether, these data suggest a time-specific corticosteroid modulation of attentive processing. Whereas high circulating corticosteroid levels acutely increase emotional interference, possibly facilitating the detection of threats, a history of elevation might promote sustained attention and thereby contribute to stress-recovery of cognitive function.

Acute stress alters auditory selective attention in humans independent of HPA: a study of evoked potentials

BACKGROUND

Acute stress is a stereotypical, but multimodal response to a present or imminent challenge overcharging an organism. Among the different branches of this multimodal response, the consequences of glucocorticoid secretion have been extensively investigated, mostly in connection with long-term memory (LTM). However, stress responses comprise other endocrine signaling and altered neuronal activity wholly independent of pituitary regulation. To date, knowledge of the impact of such "paracorticoidal" stress responses on higher cognitive functions is scarce. We investigated the impact of an ecological stressor on the ability to direct selective attention using event-related potentials in humans. Based on research in rodents, we assumed that a stress-induced imbalance of catecholaminergic transmission would impair this ability.

METHODOLOGY/PRINCIPAL FINDINGS

The stressor consisted of a single cold pressor test. Auditory negative difference (Nd) and mismatch negativity (MMN) were recorded in a tonal dichotic listening task. A time series of such tasks confirmed an increased distractibility occurring 4-7 minutes after onset of the stressor as reflected by an attenuated Nd. Salivary cortisol began to rise 8-11 minutes after onset when no further modulations in the event-related potentials (ERP) occurred, thus precluding a causal relationship. This effect may be attributed to a stress-induced activation of mesofrontal dopaminergic projections. It may also be attributed to an activation of noradrenergic projections. Known characteristics of the modulation of ERP by different stress-related ligands were used for further disambiguation of causality. The conjuncture of an attenuated Nd and an increased MMN might be interpreted as indicating a dopaminergic influence. The selective effect on the late portion of the Nd provides another tentative clue for this.

CONCLUSIONS/SIGNIFICANCE

Prior studies have deliberately tracked the adrenocortical influence on cognition, as it has proven most influential with respect to LTM. However, current cortisol-optimized study designs would have failed to detect the present findings regarding attention.

Avoidance perseveration during extinction training in Wistar-Kyoto rats: an interaction of innate vulnerability and stressor intensity

Given that avoidance is a core feature of anxiety disorders, Wistar-Kyoto (WKY) rats may be a good model of anxiety vulnerability for their hypersensitivity to stress and trait behavioral inhibition. Here, we examined the influence of strain and shock intensity on avoidance acquisition and extinction. Accordingly, we trained WKY and Sprague-Dawley (SD) rats in lever-press avoidance using either 1.0-mA or 2.0-mA foot-shock. After extinction, neuronal activation was visualized by c-Fos for overall activity and parvalbumin immunoreactivity for gamma-aminobutyric acid (GABA) neuron in brain areas linked to anxiety (medial prefrontal cortex and amygdala). Consistent with earlier work, WKY rats acquired lever-press avoidance faster and to a greater extent than SD rats. However, the intensity of foot shock did not differentially affect acquisition. Although there were no differences during extinction in SD rats, avoidance responses of WKY rats trained with the higher foot shock perseverated during extinction compared to those WKY rats trained with lower foot shock intensity or SD rats. WKY rats trained with 2.0-mA shock exhibited less GABAergic activation in the basolateral amygdala after extinction. These findings suggest that inhibitory modulation in amygdala is important to ensure successful extinction learning. Deficits in avoidance extinction secondary to lower GABAergic activation in baslolateral amygdala may contribute to anxiety vulnerability in this animal model of inhibited temperament.

Deficient proactive interference of eyeblink conditioning in Wistar-Kyoto rats

Wistar-Kyoto (WKY) rats exhibit behavioral inhibition and model anxiety vulnerability. Although WKY rats exhibit faster active avoidance acquisition, simple associative learning or the influence of proactive interference (PI) has not been adequately assessed in this strain. Therefore, we assessed eyeblink conditioning and PI in WKY and outbred Sprague-Dawley (SD) rats. Rats were pre-exposed to either the experimental context, the conditioned stimulus (CS), the unconditional stimulus (US), or the CS & US in an explicitly unpaired (EUP) manner, to examine latent inhibition (LI), US pre-exposure effect, or learned irrelevance (LIRR), respectively. Immediately following pre-exposures, rats were trained in a delay-type paradigm (500 ms CS coterminating with a 10-ms US) for one session. During training SD rats exhibited LI and inhibition from US pre-exposures without evidence of LIRR. PI was less evident in WKY rats; LI was absent in WKY rats. Even in the context of reduced PI to CS-alone and US-alone pre-exposures, LIRR was not apparent in WKY rats. The more normal acquisition rates exhibited by WKY rats, under conditions which degrade performance in SD rats, increases the overall likelihood for WKY rats to acquire defensive responses. Enhanced acquisition of defensive responses is a means by which anxiety vulnerability (e.g., behavioral inhibition) is translated to anxiety psychopathology.

Are providers more likely to contribute to healthcare disparities under high levels of cognitive load? How features of the healthcare setting may lead to biases in medical decision making

Systematic reviews of healthcare disparities suggest that clinicians' diagnostic and therapeutic decision making varies by clinically irrelevant characteristics, such as patient race, and that this variation may contribute to healthcare disparities. However, there is little understanding of the particular features of the healthcare setting under which clinicians are most likely to be inappropriately influenced by these characteristics. This study delineates several hypotheses to stimulate future research in this area. It is posited that healthcare settings in which providers experience high levels of cognitive load will increase the likelihood of racial disparities via 2 pathways. First, providers who experience higher levels of cognitive load are hypothesized to make poorer medical decisions and provide poorer care for all patients, due to lower levels of controlled processing (H1). Second, under greater levels of cognitive load, it is hypothesized that healthcare providers' medical decisions and interpersonal behaviors will be more likely to be influenced by racial stereotypes, leading to poorer processes and outcomes of care for racial minority patients (H2). It is further hypothesized that certain characteristics of healthcare settings will result in higher levels of cognitive load experienced by providers (H3). Finally, it is hypothesized that minority patients will be disproportionately likely to be treated in healthcare settings in which providers experience greater levels of cognitive load (H4a), which will result in racial disparities due to lower levels of controlled processing by providers (H4b) and the influence of racial stereotypes (H4c).The study concludes with implications for research and practice that flow from this framework.

Cognitive functioning under stress: evidence from informal caregivers of palliative patients

BACKGROUND

Caring for a terminally ill family member can be extremely stressful, and stress is known to have a negative influence on aspects of cognition. In contrast to the well-known physical and mental health risks associated with caregiving, little is known about its impact on cognitive functioning.

OBJECTIVE

The primary objective of this study was to explore cognition among caregivers of palliative family members with a battery of neuropsychological tests. A secondary objective was to examine changes in cognition following caregiving by retesting a subset of participants at least 6 months after the death of their care recipient.

METHOD

While caregiving, 27 participants completed an assessment battery measuring attention, learning, and memory, as well as intelligence, mood, and general health; 22 participants completed this battery again post-caregiving. We compared caregivers' cognitive performance to healthy normative samples.

RESULTS

Participants who were caring for palliative relatives exhibited significant impairments in attention, including difficulty monitoring their performance and regulating their attentional resources. In contrast, participants' episodic and working memory performance was not impaired while caregiving. A mixed pattern of improvement and worsening of cognitive functioning was evident among caregivers retested after their family member's death.

CONCLUSIONS

In addition to the well-documented physical and mental health risks associated with caregiving, this study adds to a small body of literature demonstrating impaired cognitive functioning among family members providing end-of-life care. Secondary findings of both improvement and deterioration of cognition post caregiving provide tentative support for the possibility of reversing certain cognitive deficits by reducing caregiver stress.

Abnormal latent inhibition and impulsivity in coloboma mice, a model of ADHD

Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. The coloboma mouse model of ADHD exhibits profound hyperactivity. To determine whether coloboma mice exhibit other signs of ADHD, we assessed latent inhibition as a test of attention, and impulsivity in a delayed reinforcement paradigm. Latent inhibition was present in control mice but was disrupted in coloboma mice. Coloboma mice also exhibited impaired performance on the delayed reinforcement task and were not able to wait as long as control mice to obtain the greater reinforcer. Because norepinephrine mediates hyperactivity in coloboma mice, we examined the role of norepinephrine in disrupted latent inhibition and impulsivity. Reduction of norepinephrine with DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride) restored latent inhibition but did not ameliorate impulsivity. In summary, coloboma mice exhibit hyperactivity, inattention as determined by latent inhibition, and impulsivity, and norepinephrine mediates hyperactivity and inattention but not impulsivity in these mice.

The visual search analogue of latent inhibition: implications for theories of irrelevant stimulus processing in normal and schizophrenic groups

Latent inhibition (LI) is a robust phenomenon that is demonstrated when a previously inconsequential stimulus is less effective in a new learning situation than a novel stimulus. Despite LI's simplicity, there is considerable disagreement as to its theoretical basis. Attentional theories claim that unattended stimulus preexposures reduce stimulus associability. Alternatively, it has been asserted that associability is unaffected and that LI is a result of competition/retrieval processes. The present article reviews a series of visual search studies, some with normal subjects, both undifferentiated and divided into low and high schizotypals, and others with pathologies that entail dysfunctional attention, such as schizophrenia, Parkinson's disease, and anxiety. The visual search conditions were designed to model those of traditional LI experiments, while tapping attentional processes independently of the learning scores that index LI. A variety of evidence from these and other studies is used to support the involvement of attentional and retrieval processes in LI. A model of the mechanism of action of these processes in LI is presented, together with its application to schizophrenia.

Regulation of emotion and psychological symptoms in people with spinal cord injury

This cross-sectional study examined the contribution of regulation of emotion on depression, symptoms of traumatic and general distress, perceived disability, and somatic symptoms following spinal cord injury. Depressed and non-depressed participants (N = 264, mean age = 46 years) differed in their use of adaptive and maladaptive ways of regulating emotions. In addition to somatic symptoms and symptoms of traumatic stress, maladaptive emotional regulation (avoidance and distortion of awareness) accounted for 8% of the total variance of depression. It is concluded that adaptive and maladaptive ways of regulating emotions are important factors in dealing with negative feelings. Regulation of emotion appears to influence perceived disability mainly via depression. Limitations of the study and implications for rehabilitation are discussed.

Latent inhibition deficits in high-schizotypal normals: symptom-specific or anxiety-related?

Latent inhibition (LI) is the phenomenon in which subjects who have repeatedly experienced an irrelevant stimulus perform more poorly on a new learning task with that stimulus than with a novel stimulus, presumably because of a decline in stimulus-specific attention. The present article reviews the literature on LI deficits in high-schizotypal normal subjects and schizophrenic patients. Although LI-deficits have been thought to be specific to these groups, evidence is presented that the effects may be related to the anxiety components of high-schizotypality and related pathologies.