Hippocampal activation during a cognitive task is associated with subsequent neuroendocrine and cognitive responses to psychological stress

Altered fronto-limbic-motor response to stress differs between functional and epileptic seizures in a TBI model

BACKGROUND AND OBJECTIVES

Psychogenic nonepileptic (functional) seizures (FS) clinically resemble epileptic seizures (ES) with both often preceded by traumatic brain injury (TBI). FS and ES emergence and occurrence after TBI may be linked to aberrant neurobehavioral stress responses. We hypothesized that neural activity signatures in response to a psychosocial stress task would differ between TBI + FS and TBI + ES after controlling for TBI status (TBI-only).

METHODS

In the current multicenter study, participants were recruited prospectively from Rhode Island Hospital, Providence Rhode Island Veterans Administration Medical Center, and the University of Alabama at Birmingham Medical Center. Previous diagnoses of TBI, ES, and FS were verified based on data collected from participants, medical chart and record review, and, where indicated, results of EEG and/or video-EEG confirmatory diagnosis. TBI + ES (N = 21) and TBI + FS (N = 21) were matched for age and sex and combined into an initial group (TBI + SZ; N = 42). A TBI-only group (N = 42) was age and sex matched to the TBI with seizures (TBI + SZ) group. All participants completed an fMRI control math task (CMT) and stress math task (SMT) based on the Montreal Imaging Stress Task (MIST).

RESULTS

The TBI + SZ group (n = 24 female) did not differ in mood or anxiety severity compared to TBI-only group (n = 24 female). However, TBI + FS group (n = 11 female) reported greater severity of these symptoms compared to TBI + ES (n = 13 female). The linear mixed effects analysis identified neural responses that differed between TBI-only and TBI + SZ during math performance within the left premotor cortex and during auditory feedback within bilateral prefrontal cortex and hippocampus/amygdala regions. Additionally, neural responses differed between TBI + ES and TBI + FS during math performance within the right dorsolateral prefrontal cortex and bilateral amygdala during auditory feedback within the supplementary motor area. All tests comparing neural stress responses to psychiatric symptom severity failed to reach significance.

DISCUSSION

Controlling for TBI and seizure status, these findings implicate specific nodes within frontal, limbic, and sensorimotor networks that may maintain functional neurological symptoms and possibly distinguish FS from ES. This study provides class II evidence of differences in neural responses to psychosocial stress between ES and FS after TBI.

Dynamic modulation of the processing of unpredicted technical errors by the posterior cingulate and the default mode network

The pervasive use of information technologies (IT) has tremendously benefited our daily lives. However, unpredicted technical breakdowns and errors can lead to the experience of stress, which has been termed technostress. It remains poorly understood how people dynamically respond to unpredicted system runtime errors occurring while interacting with the IT systems on a behavioral and neuronal level. To elucidate the mechanisms underlying such processes, we conducted a functional magnetic resonance imaging (fMRI) study in which 15 young adults solved arithmetic problems of three difficulty levels (easy, medium and hard) while two types of system runtime errors (problem errors and feedback errors) occurred in an unexpected manner. The problem error condition consisted of apparently defective displays of the arithmetic problem and the feedback error condition involved erroneous feedback. We found that the problem errors positively influenced participants' problem-solving performance at the high difficulty level (i.e., hard tasks) at the initial stage of the session, while feedback errors disturbed their performance. These dynamic behavioral changes are mainly associated with brain activation changes in the posterior cingulate and the default mode network, including the posterior cingulate cortex, the mPFC, the retrosplenial cortex and the parahippocampal gyrus. Our study illustrates the regulatory role of the posterior cingulate in coping with unpredicted errors as well as with dynamic changes in the environment.

Threat exposure moderates associations between neural and physiological indices of emotion reactivity in adolescent females

Early life adversity (ELA) characterized by threat (e.g., abuse, witnessing violence) impacts neural and physiologic systems involved in emotion reactivity; however, research on how threat exposure impacts the interplay between these systems is limited. This study investigates ELA characterized by threat as a potential moderator of the association between (a) neural activity during a negative image processing fMRI task and (b) cortisol production following a modified Trier Social Stress Test (TSST). The sample is comprised of 117 young adolescent females (Mage = 11.90 years, SD = 1.69) at elevated risk for internalizing problems. Whole-brain analyses revealed a positive association between cortisol production and increased right lateral orbitofrontal cortex activity during the emotion reactivity task. In moderation models, threat exposure interacted with bilateral amygdala activation (b = -3.34, p = 0.021) and bilateral hippocampal activation (b = -4.14, p = 0.047) to predict cortisol response to the TSST. Specifically, participants with low, but not high, levels of threat exposure demonstrated a positive association between cortisol production and neural activity in these regions, while no significant association emerged for participants with high threat exposure. Findings contribute to the growing field of research connecting physiological and neural emotion processing and response systems, suggesting that dimensions of ELA may uniquely disrupt associations between neural activation and cortisol production.

Neural habituation during acute stress signals a blunted endocrine response and poor resilience

BACKGROUND

A blunted hypothalamic-pituitary-adrenal (HPA) axis response to acute stress is associated with psychiatric symptoms. Although the prefrontal cortex and limbic areas are important regulators of the HPA axis, whether the neural habituation of these regions during stress signals both blunted HPA axis responses and psychiatric symptoms remains unclear. In this study, neural habituation during acute stress and its associations with the stress cortisol response, resilience, and depression were evaluated.

METHODS

Seventy-seven participants (17-22 years old, 37 women) were recruited for a ScanSTRESS brain imaging study, and the activation changes between the first and last stress blocks were used as the neural habituation index. Meanwhile, participants' salivary cortisol during test was collected. Individual-level resilience and depression were measured using questionnaires. Correlation and moderation analyses were conducted to investigate the association between neural habituation and endocrine data and mental symptoms. Validated analyses were conducted using a Montreal Image Stress Test dataset in another independent sample (48 participants; 17-22 years old, 24 women).

RESULTS

Neural habituation of the prefrontal cortex and limbic area was negatively correlated with cortisol responses in both datasets. In the ScanSTRESS paradigm, neural habituation was both positively correlated with depression and negatively correlated with resilience. Moreover, resilience moderated the relationship between neural habituation in the ventromedial prefrontal cortex and cortisol response.

CONCLUSIONS

This study suggested that neural habituation of the prefrontal cortex and limbic area could reflect motivation dysregulation during repeated failures and negative feedback, which might further lead to maladaptive mental states.

Neural responses to acute stress predict chronic stress perception in daily life over 13 months

The importance of amygdala, hippocampus, and medial prefrontal cortex (mPFC) for the integration of neural, endocrine, and affective stress processing was shown in healthy participants and patients with stress-related disorders. The present manuscript which reports on one study-arm of the LawSTRESS project, aimed at investigating the predictive value of acute stress responses in these regions for biopsychological consequences of chronic stress in daily life. The LawSTRESS project examined law students either in preparation for their first state examination (stress group [SG]) or in the mid-phase of their study program (control group [CG]) over 13 months. Ambulatory assessments comprising perceived stress measurements and the cortisol awakening response (CAR) were administered on six sampling points (t1 = - 1 year, t2 = - 3 months, t3 = - 1 week, t4 = exam, t5 =  + 1 week, t6 =  + 1 month). In a subsample of 124 participants (SG: 61; CG: 63), ScanSTRESS was applied at baseline. In the SG but not in the CG, amygdala, hippocampus, and (post-hoc analyzed) right mPFC activation changes during ScanSTRESS were significantly associated with the trajectory of perceived stress but not with the CAR. Consistent with our finding in the total LawSTRESS sample, a significant increase in perceived stress and a blunted CAR over time could be detected in the SG only. Our findings suggest that more pronounced activation decreases of amygdala, hippocampus, and mPFC in response to acute psychosocial stress at baseline were related to a more pronounced increase of stress in daily life over the following year.

Adolescents' neural reactivity to acute psychosocial stress: dysfunctional regulation habits are linked to temporal gyrus response

Mid-adolescence is a critical time for the development of stress-related disorders and it is associated with significant social vulnerability. However, little is known about normative neural processes accompanying psychosocial stress at this time. Previous research found that emotion regulation strategies critically influence the relationship between stress and the development of psychiatric symptoms during adolescence. Using functional magnetic resonance imaging (fMRI), we examined neural responses to acute stress and analyzed whether the tendency to use adaptive or maladaptive emotion regulation strategies is related to neural and autonomic stress responses. Results show large linear activation increases from low to medium to high stress levels mainly in medial prefrontal, insulae and temporal areas. Caudate and subgenual anterior cingulate cortex, neural areas related to reward and affective valuations, showed linearly decreasing activation. In line with our hypothesis, the current adolescent neural stress profile resembled social rejection and was characterized by pronounced activation in insula, angular and temporal cortices. Moreover, results point to an intriguing role of the anterior temporal gyrus. Stress-related activity in the anterior temporal gyrus was positively related to maladaptive regulation strategies and stress-induced autonomic activity. Maladaptive coping might increase the social threat and reappraisal load of a stressor, relating to higher stress sensitivity of anterior temporal cortices.

Sex-dependent multimodal response profiles to psychosocial stress

INTRODUCTION

Sex differences in stress reactions are often reported in the literature. However, the sex-dependent interplay of different facets of stress is still not fully understood. Particularly in neuroimaging research, studies on large samples combining different indicators of stress remain scarce.

MATERIALS AND METHODS

In a functional magnetic resonance imaging study, a sample of 140 healthy participants (67 females using oral contraceptives) underwent a standardized stress induction protocol, the ScanSTRESS. During the experiment, salivary cortisol and subjective ratings were obtained at multiple time points and heart rate was recorded.

RESULTS

Sex differences emerged in different facets of the stress response:Women reacted with enhanced subjective feelings of stress and increases in heart rate, while men showed more pronounced neural activation in stress-related brain regions such as the inferior frontal gyrus and insula. Subjective feelings of stress and (para) hippocampal activity were negatively related in women,whereas a slightly positive association was observed in men.

DISCUSSION

These results provide further insight in the sex-specific stress response patterns. Moreover, they emphasize the role of the hippocampus in the regulation of the stress response. This paves the way for the identification of sex-dependent vulnerability factors that can, in the future, be implemented in the prevention and treatment of stress-related disorders.

Triple Network Functional Connectivity During Acute Stress in Adolescents and the Influence of Polyvictimization

BACKGROUND

Exposure to both chronic and acute stressors can disrupt functional connectivity (FC) of the default mode network (DMN), salience network (SN), and central executive network (CEN), increasing risk for negative health outcomes. During adolescence, these stress-sensitive triple networks undergo critical neuromaturation that is altered by chronic exposure to general forms of trauma or victimization. However, no work has directly examined how acute stress affects triple network FC in adolescents or whether polyvictimization-exposure to multiple categories/subtypes of victimization-influences adolescent triple network neural acute stress response.

METHODS

This functional magnetic resonance imaging study examined seed-to-voxel FC of the DMN, SN, and CEN during the Montreal Imaging Stress Task. Complete data from 73 participants aged 9 to 16 years (31 female) are reported.

RESULTS

During acute stress, FC was increased between DMN and CEN regions and decreased between the SN and the DMN and CEN. Greater polyvictimization was associated with reduced FC during acute stress exposure between the DMN seed and a cluster containing the left insula of the SN.

CONCLUSIONS

These results indicate that acute stress exposure alters FC between the DMN, SN, and CEN in adolescents. In addition, FC changes during stress between the DMN and SN are further moderated by polyvictimization exposure.

Stress-related hippocampus activation mediates the association between polyvictimization and trait anxiety in adolescents

Early life stress exposures are associated with adverse health outcomes and heightened anxiety symptoms in adolescents. Stress-sensitive brain regions like the hippocampus and amygdala are particularly impacted by early life adversities and are also implicated in the development of anxiety disorders. However, to date, no studies have specifically examined the neural correlates of polyvictimization (exposure to multiple categories of victimization) or the contribution of stress-sensitive neural nodes to polyvictimization's impact on mental health. To elucidate these relationships, the current study analyzed associations between polyvictimization, hippocampal and amygdalar activation during an acute stress task and trait anxiety in a sample of 80 children and adolescents aged 9-16 years (33 female participants). Results showed that polyvictimization was associated with higher trait anxiety as well as greater stress-related right hippocampus activation, and this greater hippocampal activity predicted heightened trait anxiety. Robust mediation analyses revealed that stress-related right hippocampus activation partially mediated the relationship between polyvictimization and trait anxiety. Our results expand upon the existing polyvictimization literature by suggesting a possible neurobiological pathway through which polyvictimization is connected to the etiology of mental illness.

Inter-relationships between changes in stress, mindfulness, and dynamic functional connectivity in response to a social stressor

We conducted a study to understand how dynamic functional brain connectivity contributes to the moderating effect of trait mindfulness on the stress response. 40 male participants provided subjective reports of stress, cortisol assays, and functional MRI before and after undergoing a social stressor. Self-reported trait mindfulness was also collected. Experiencing stress led to significant decreases in the prevalence of a connectivity state previously associated with mindfulness, but no changes in two connectivity states with prior links to arousal. Connectivity did not return to baseline 30 min after stress. Higher trait mindfulness was associated with attenuated affective and neuroendocrine stress response, and smaller decreases in the mindfulness-related connectivity state. In contrast, we found no association between affective response and functional connectivity. Taken together, these data allow us to construct a preliminary brain-behaviour model of how mindfulness dampens stress reactivity and demonstrate the utility of time-varying functional connectivity in understanding psychological state changes.

Precentral gyrus and insula responses to stress vary with duration to diagnosis in functional seizures

OBJECTIVE

This study was undertaken to determine whether undiagnosed illness duration (time between functional seizures [FS] onset and diagnosis) is linked to differences in neural response and functional connectivity during processing of stressful experiences.

METHODS

Forty-nine participants with traumatic brain injury preceding the onset of FS confirmed by video-electroencephalography were recruited prospectively. Participants completed psychiatric symptom assessments before undergoing functional magnetic resonance imaging (fMRI) with an acute psychosocial stress task. Linear mixed effects (LME) analyses identified significant interactions between the factors of group (early vs. delayed diagnosis) and time lag to diagnosis on neural responses to stressful math performance and auditory feedback (corrected α = .05). Functional connectivity analysis utilized clusters from initial LME analyses as seed regions to determine significant interactions between these factors on network functional connectivity.

RESULTS

Demographic and psychiatric symptom measures were similar between early (n = 25) and delayed (n = 24) groups. Responses to stressful math performance within the left anterior insula and functional connectivity between the anterior insula seed region and a precentral gyrus cluster were significantly negatively correlated with time lag to diagnosis for the early but not the delayed FS diagnosis group. There was no correlation between fMRI findings and psychiatric symptoms.

SIGNIFICANCE

This study indicates that aberrant left anterior insula activation and its functional connectivity to the precentral gyrus underlie differences in processing of stressful experiences in patients with delayed FS diagnosis. Follow-up comparisons suggest changes are associated with undiagnosed illness duration rather than psychiatric comorbidities and indicate a potential mechanistic association between neuropathophysiology, response to stressful experiences, and functional neuroanatomy in FS.

Association of stress-related neural activity and baseline interleukin-6 plasma levels in healthy adults

Several studies suggest a link between acute changes in inflammatory parameters due to an endotoxin or (psychological) stressor and the brain's stress response. The extent to which basal circulating levels of inflammatory markers are associated with the brain's stress response has been hardly investigated so far. In the present study, baseline plasma levels of the cytokine interleukin (IL)-6 were obtained and linked to neural markers of psychosocial stress using a modified version of the Montreal Imaging Stress Task in a sample of N = 65 healthy subjects (N = 39 female). Of three a-priori defined regions of interest - the amygdala, anterior insula, and anterior cingulate cortex - baseline IL-6 was significantly and negatively associated with stress-related neural activation in the right amygdala and left anterior insula. Our results suggest that baseline cytokines might be related to differences in the neural stress response and that this relationship could be inverse to that previously reported for induced acute changes in inflammation markers.

Altered relationship between cortisol response to social stress and mediotemporal function during fear processing in people at clinical high risk for psychosis: a preliminary report

Evidence suggests that people at Clinical High Risk for Psychosis (CHR) have a blunted cortisol response to stress and altered mediotemporal activation during fear processing, which may be neuroendocrine-neuronal signatures of maladaptive threat responses. However, whether these facets are associated with each other and how this relationship is affected by cannabidiol treatment is unknown. We examined the relationship between cortisol response to social stress and mediotemporal function during fear processing in healthy people and in CHR patients. In exploratory analyses, we investigated whether treatment with cannabidiol in CHR individuals could normalise any putative alterations in cortisol-mediotemporal coupling. 33 CHR patients were randomised to 600 mg cannabidiol or placebo treatment. Healthy controls (n = 19) did not receive any drug. Mediotemporal function was assessed using a fearful face-processing functional magnetic resonance imaging paradigm. Serum cortisol and anxiety were measured immediately following the Trier Social Stress Test. The relationship between cortisol and mediotemporal blood-oxygen-level-dependent haemodynamic response was investigated using linear regression. In healthy controls, there was a significant negative relationship between cortisol and parahippocampal activation (p = 0.023), such that the higher the cortisol levels induced by social stress, the lower the parahippocampal activation (greater deactivation) during fear processing. This relationship differed significantly between the control and placebo groups (p = 0.033), but not between the placebo and cannabidiol groups (p = 0.67). Our preliminary findings suggest that the parahippocampal response to fear processing may be associated with the neuroendocrine (cortisol) response to experimentally induced social stress, and that this relationship may be altered in patients at clinical high risk for psychosis.

Psychosocial stress has weaker than expected effects on episodic memory and related cognitive abilities: A meta-analysis

The impact of stress on episodic memory and related cognitive abilities is well documented in both animal and human literature. However, it is unclear whether the same cognitive effects result from all forms of stress - in particular psychosocial stress. This review systematically explored the effects of psychosocial stress on episodic memory and associated cognitive abilities. PubMed, PsycInfo, and Web of Science databases were searched. Fifty-one studies were identified and compared based on the timing of stress induction. A small positive effect of post-learning psychosocial stress with a long retention interval was shown. No other effects of psychosocial stress were seen. Re-analysis of previous meta-analyses also showed no significant effect of psychosocial stress on episodic memory, highlighting potentially different effects between stressor types. Psychosocial stress also had a moderately different effect when emotional vs. neutral stimuli were compared. Finally, psychosocial stress also decreased performance on executive function, but not working memory tasks. Our findings demonstrate that psychosocial stress may not have the clear effects on episodic memory previously ascribed to it.

Feelings of shame and guilt are associated with distinct neural activation in youth

Shame and guilt are moral emotions that play an important role in social functioning. There is limited knowledge about the neural underpinnings of these emotions, particularly in young people. In the current study, 36 healthy females (mean age 18.8 ± 1.9 years) underwent functional Magnetic Resonance Imaging, during which they reflected on their decisions about social moral dilemmas, and subsequently received negative or positive peer feedback. Ratings of shame and guilt were used as parametric modulators of brain activity. Shame was associated with decreased activity in the superior temporal sulcus and precentral gyrus during reflection. Guilt was associated with decreased activity in the precuneus during positive feedback, and in the hippocampus and supramarginal gyrus during negative feedback. Results suggest that shame and guilt are associated with activity in brain regions involved in social cognition and emotion regulation; however, they have distinct underlying neural circuitry that may be differentiated based on social evaluation.

Neural mechanisms of acute stress and trait anxiety in adolescents

Adolescence is a critical period of heightened stress sensitivity and elevated vulnerability for developing mental illness, suggesting a possible association between stress exposure and the etiology of psychiatric disorders. In adults, aberrant neurobiological responses to acute stress relate to anxiety symptoms, yet less is known about the neural stress response in adolescents and how it relates to biological and psychological variables. Here we characterize the neurobiology of stress response in adolescents using multiple modalities, including neuroimaging, subjective stress ratings, heart rate, and cortisol data. We evaluated stress response in adolescents using the Montreal Imaging Stress Task (MIST), an acute psychosocial stressor commonly administered in adult functional magnetic resonance imaging (fMRI) studies but not previously utilized with this population. FMRI data were acquired from 101 adolescents (44 female; 9-16 years) exhibiting varied trait anxiety severity. The MIST elicited decreased high-frequency heart rate variability and increased heart rate, subjective stress and cortisol. Whole-brain analyses comparing fMRI activity during experimental versus control MIST conditions revealed stress-related activation in regions including the anterior insula, dorsal anterior cingulate cortex, and dorsolateral prefrontal cortex and deactivations in the hippocampus, ventral striatum, and putamen. Region of Interest analyses found that during acute stress (a) hippocampal deactivation corresponded to heightened cortisol release, (b) trait anxiety was associated with increased hippocampal and ventral striatum activation and decreased putamen activity, and (c) males exhibited greater putamen deactivation than females. These results provide novel evidence that the MIST is an effective stressor for adolescents. Associations between the neural acute stress response, other biological factors, and trait anxiety highlight the importance of these neurobiological mechanisms in understanding anxiety disorders.

Repeatability of Neural and Autonomic Responses to Acute Psychosocial Stress

FMRI Montreal Imaging Stress Tasks (MIST) have been shown to activate endocrine and autonomic stress responses that are mediated by a prefrontal cortex (PFC)-hippocampus-amygdala circuit. However, the stability of the neurobehavioral responses over time and the ability to monitor response to clinical interventions has yet to be validated. The objective of this study was to compare the fMRI and physiologic responses to acute psychosocial stress in healthy volunteers during initial and follow-up visits approximately 13 weeks later, simulating a typical duration of clinical intervention. We hypothesized that responses to stress would remain highly conserved across the 2 visits in the absence of an intervention. 15 healthy volunteers completed a variant of control math task (CMT) and stress math task (SMT) conditions based on MIST. Neural responses were modeled using an event-related design with estimates for math performance and auditory feedback for each task condition. For each visit, measures of stress reactivity included differential fMRI and heart rate (SMT-CMT), as well as salivary alpha-amylase before and after scanning sessions. The results revealed that differential fMRI, as well as increased heart rate and salivary alpha-amylase from before and after scanning remained similar between visits. Intraclass correlation coefficient (ICC) values revealed areas of reliable task-dependent BOLD fMRI signal response across visits for peaks of clusters for the main effect of condition (SMT vs CMT) within dorsal anterior cingulate cortex (ACC), insula, and hippocampus regions during math performance and within subgenual ACC, posterior cingulate cortex, dorsolateral PFC regions during auditory feedback. Given that the neurobehavioral response to acute stress remained highly conserved across visits in the absence of an intervention, this study confirms the utility for MIST for assessing longitudinal changes in controlled trials that can identify underlying neurobiological mechanisms involved in mediating the efficacy of stress-reduction interventions.

Relationship between neural responses to stress and mental health symptoms in psychogenic nonepileptic seizures after traumatic brain injury

OBJECTIVE

To utilize traumatic brain injury (TBI) as a model for investigating functioning during acute stress experiences in psychogenic nonepileptic seizures (PNES) and to identify neural mechanisms underlying the link between changes in processing of stressful experiences and mental health symptoms in PNES.

METHODS

We recruited 94 participants: 50 with TBI only (TBI-only) and 44 with TBI and PNES (TBI + PNES). Participants completed mood (Beck Depression Inventory-II), anxiety (Beck Anxiety Inventory), and posttraumatic stress disorder (PTSD) symptom (PTSD Checklist-Specific Event) assessments before undergoing functional magnetic resonance imaging during an acute psychosocial stress task. Linear mixed-effects analyses identified clusters of significant interactions between group and neural responses to stressful math performance and stressful auditory feedback conditions within limbic brain regions (volume-corrected α = .05). Spearman rank correlation tests compared mean cluster signals to symptom assessments (false discovery rate-corrected α = .05).

RESULTS

Demographic and TBI-related measures were similar between groups; TBI + PNES demonstrated worse clinical symptom severity compared to TBI-only. Stressful math performance induced relatively greater reactivity within dorsomedial prefrontal cortex (PFC) and right hippocampal regions and relatively reduced reactivity within left hippocampal and dorsolateral PFC regions for TBI + PNES compared to TBI-only. Stressful auditory feedback induced relatively reduced reactivity within ventral PFC, cingulate, hippocampal, and amygdala regions for TBI + PNES compared to TBI-only. Changes in responses to stressful math within hippocampal and dorsal PFC regions were correlated with increased mood, anxiety, and PTSD symptom severity.

SIGNIFICANCE

Corticolimbic functions underlying processing of stressful experiences differ between patients with TBI + PNES and those with TBI-only. Relationships between these neural responses and symptom assessments suggest potential pathophysiologic mechanisms in PNES.

The effect of sleep on the salivary cortisol response to acute stressors: a review and suggestions

There have been steadily increasing studies on the relationship between sleep and stress. However, the findings regarding the effects of sleep on the acute stress response have been inconsistent. Elevated, blunted, or unchanged salivary cortisol stress response have been reported. Therefore, this study conducted a systematic review of previous studies to provide a comprehensive summary of the factors that influence the effects of sleep on the salivary cortisol stress response. We conducted a comprehensive electronic literature search in PubMed, PsycINFO, PsycARTICLES, Web of Science, MEDLINE, and EMBASE for human studies published in English (up to June 2019). Finally, 17 articles with participants aged 6.4-72 years were included in this review. We assessed the following factors: designing factors (sleep measurement, stress induction, cortisol sampling period, and time intervals between sleep measurement and the acute stress task), analyzing factors (cortisol analysis), and participants' characteristics (age, sex, and background stress levels); subsequently, we explained conflicting findings across the current literature. Further, we provide study design, analysis, and report suggestions for optimal assessment of the effects of sleep on the acute stress response. This summary of influencing factors and suggestions for future studies could help elucidate the impact of sleep on stress and advance the field.

Brain Marker Links Stress and Nicotine Abstinence

BACKGROUND

Subjective stress is a well-documented predictor of early smoking relapse, yet our understanding of stress and tobacco use is limited by reliance on self-reported measures of stress. We utilized a validated functional neuroimaging paradigm to examine whether stress exposure during early abstinence alters objective measures of brain function.

METHODS

Seventy-five participants underwent blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) during the Montreal Imaging Stress Task (MIST) on two occasions: once during smoking satiety and once following biochemically confirmed 24-hour abstinence (order counterbalanced). The primary outcome measure was brain response during stress (vs. control) blocks of the MIST, assessed using whole-brain analysis corrected for multiple comparisons using clusters determined by Z ≥ 3.1.

RESULTS

Abstinence (vs. satiety) was associated with significantly increased activation in the left inferior frontal gyrus, a brain region associated with inhibitory control. Abstinence-induced change in brain response to stress was positively associated with change in self-reported stress.

CONCLUSIONS

This study provides objective evidence that the brain response to stress is altered during the first 24 hours of a quit attempt compared to smoking satiety.

IMPLICATIONS

These results point to the potential value of inoculating smokers with stress management training prior to a quit attempt.

Associations between brain activity and endogenous and exogenous cortisol - A systematic review

To arrive at a coherent understanding of the relation between glucocorticoids and the human brain, we systematically reviewed the literature for studies examining the associations between endogenous or exogenous cortisol and human brain function. Higher levels of endogenous cortisol during psychological stress were related to increased activity in the middle temporal gyrus and perigenual anterior cingulate cortex (ACC), decreased activity in the ventromedial prefrontal cortex, and altered function (i.e., mixed findings, increased or decreased) in the amygdala, hippocampus and inferior frontal gyrus. Moreover, endogenous cortisol response to psychological stress was related to increased activity in the inferior temporal gyrus and altered function in the amygdala during emotional tasks that followed psychological stress. Exogenous cortisol administration was related to increased activity in the postcentral gyrus, superior frontal gyrus and ACC, and altered function in the amygdala and hippocampus during conditioning, emotional and reward-processing tasks after cortisol administration. These findings were in line with those from animal studies on amygdala activity during and after stress.

Incivility and the clinical learner

The impact of incivility in terms of individual and team performance in clinical environments is increasingly acknowledged and supported by a growing evidence base. However, clinical environments are not just areas where patient care is delivered, they are also rich, key learning arenas for healthcare professionals. To date, the potential impact of incivility in clinical environments on healthcare professional learning and development has not been comprehensively explored. This article provides an overview of the physiological mechanisms that inhibit learning and memory recall in individuals experiencing or observing incivility and social stress. It establishes a clear need for focus on the impact of incivility on clinical learners and educators and further evidence for the need for clinical environments in which civility is firmly rooted into the pervading culture.

Stress-induced changes in modular organizations of human brain functional networks

Humans inevitably go through various stressful events, which initiates a chain of neuroendocrine reactions that may affect brain functions and lead to psychopathological symptoms. Previous studies have shown stress-induced changes in activation of individual brain regions or pairwise inter-regional connectivity. However, it remains unclear how large-scale brain network is reconfigured in response to stress. Using a within-subjects design, we combined the Trier Social Stress Test and graph theoretical method to characterize stress-induced topological alterations of brain functional network. Modularity analysis revealed that the brain network can be divided into frontoparietal, default mode, occipital, subcortical, and central-opercular modules under control and stress conditions, corresponding to several well-known functional systems underpinning cognitive control, self-referential mental processing, visual, salience processing, sensory and motor functions. While the frontoparietal module functioned as a connector module under stress, its within-module connectivity was weakened. The default mode module lost its connector function and its within-module connectivity was enhanced under stress. Moreover, stress altered the capacity to control over information flow in a few regions important for salience processing and self-referential metal processing. Furthermore, there was a trend of negative correlation between modularity and stress response magnitude. These findings demonstrate that acute stress prompts large-scale brain-wide reconfiguration involving multiple functional modules.

Increasing Deactivation of Limbic Structures Over Psychosocial Stress Exposure Time

BACKGROUND

Understanding the interplay between central nervous system and hypothalamic-pituitary-adrenal axis responses to stress in humans is assumed to be essential to contribute to the central question of stress research, namely how stress can increase disease risk. Therefore, the present study used a neuroimaging stress paradigm to investigate the interplay of 3 stress response domains. Furthermore, we asked if the brain's stress response changes over exposure time.

METHODS

In a functional magnetic resonance imaging study, changes in brain activation, cortisol levels, affect, and heart rate in response to an improved ScanSTRESS protocol were assessed in 67 young, healthy participants (31 females).

RESULTS

Stress exposure led to significant increases in cortisol levels, heart rate, and negative affect ratings as well as to activations and deactivations in (pre)limbic regions. When cortisol increase was used as a covariate, stronger responses in the hippocampus, amygdala, medial prefrontal cortex, and cingulate gyrus were observed. Responses within the same regions predicted negative affect ratings. Remarkably, an increasing deactivation over the two ScanSTRESS runs was found, again, in the same structures. A reanalysis of an independent sample confirmed this finding.

CONCLUSIONS

For the first time, reactions in a cluster of (pre)limbic structures was consistently found to be associated with changes in cortisol and negative affect. The same neural structures showed increasing deactivations over stress exposure time. We speculate that investigating possible associations between exposure-time effects in neural stress responses and stress-related interindividual differences (e.g., chronic stress) might be a promising new avenue in stress research.

Reflective and Reflexive Stress Responses of Older Adults to Three Gaming Experiences In Relation to Their Cognitive Abilities: Mixed Methods Crossover Study

BACKGROUND

The gamification of digital health provisions for older adults (eg, for rehabilitation) is a growing trend; however, many older adults are not familiar with digital games. This lack of experience could cause stress and thus impede participants' motivations to adopt these technologies.

OBJECTIVE

This crossover longitudinal multifactorial study aimed to examine the interactions between game difficulty, appraisal, cognitive ability, and physiological and cognitive responses that indicate game stress using the Affective Game Planning for Health Applications framework.

METHODS

A total of 18 volunteers (mean age 71 years, SD 4.5; 12 women) completed a three-session study to evaluate different genres of games in increasing order of difficulty (S₁-BrainGame, S₂-CarRace, and S₃-Exergame). Each session included an identical sequence of activities (t₁-Baseline, t₂-Picture encode, t₃-Play, t₄-Stroop test, t₅-Play, and t₆-Picture recall), a repeated sampling of salivary cortisol, and time-tagged ambulatory data from a wrist-worn device. Generalized estimating equations were used to investigate the effect of session×activity or session×activity×cognitive ability on physiology and cognitive performance. Scores derived from the Montreal Cognitive Assessment (MoCA) test were used to define cognitive ability (MoCA-high: MoCA>27, n=11/18). Kruskal-Wallis tests were used to test session or session×group effects on the scores of the postgame appraisal questionnaire.

RESULTS

Session×activity effects were significant on all ambulatory measures (χ²₁₀>20; P<.001) other than cortisol (P=.37). Compared with S₁ and S₂, S₃ was associated with approximately 10 bpm higher heart rate (P<.001) and approximately 5 muS higher electrodermal activity (P<.001), which were both independent of the movement caused by the exergame. Compared with S₁, we measured a moderate but statistically significant drop in the rate of hits in immediate recall and rate of delayed recall in S₃. The low-MoCA group did not differ from the high-MoCA group in general characteristics (age, general self-efficacy, and perceived stress) but was more likely to agree with statements such as digital games are too hard to learn. In addition, the low-MoCA group was more likely to dislike the gaming experience and find it useless, uninteresting, and visually more intense (χ²₁>4; P<.04). Group differences in ambulatory signals did not reach statistical significance; however, the rate of cortisol decline with respect to the baseline was significantly larger in the low-MoCA group.

CONCLUSIONS

Our results show that the experience of playing digital games was not stressful for our participants. Comparatively, the neurophysiological effects of exergame were more pronounced in the low-MoCA group, suggesting greater potential of this genre of games for cognitive and physical stimulation by gamified interventions; however, the need for enjoyment of this type of challenging game must be addressed.

Effects of stress on functional connectivity during verbal processing

Effects of stress on functional connectivity (FC) in specific language processing regions of the brain during verbal fluency tasks were explored. Roles of gender and serotonin transporter gene polymorphisms (5-HTTLPR), associated with stress susceptibility, were also examined to understand their effect. Forty-five healthy volunteers (Mean age: 19.6 ± 1.6 years; 28 females) participated. Functional magnetic resonance imaging was carried out while participants performed letter and category fluency tasks. These tasks were interposed with the Montreal Imaging Stress Test to induce stress or a no-stress control task. Buccal swabs collected were used to genotype for the presence of polymorphisms on the SLC6A4 gene known to contribute to atypical stress responses. Significant variations in strength of FC were noted between several ROIs, including left inferior frontal gyrus and left middle temporal gyrus. Overall, males showed regional increases in FC strength over long and short distances during task under stress. Additionally, variability in effects of stress on task performance was associated with effects of stress on FC. Results suggest that long distance FC may be strengthened to compensate for additional cognitive load of the stressor but that specific short distance functional connections may be strengthened in a gender specific manner. Additionally, FC may serve as a marker for effects of stress on performance. This is the first study exploring stress effects on language tasks with imaging markers. Future studies will need to explore stress susceptible populations and establish the role of FC as a marker, with implications for targeted therapeutic interventions.

Neurobiological mechanisms underlying sex-related differences in stress-related disorders: Effects of neuroactive steroids on the hippocampus

Men and women differ in their vulnerability to a variety of stress-related illnesses, but the underlying neurobiological mechanisms are not well understood. This is likely due to a comparative dearth of neurobiological studies that assess male and female rodents at the same time, while human neuroimaging studies often don't model sex as a variable of interest. These sex differences are often attributed to the actions of sex hormones, i.e. estrogens, progestogens and androgens. In this review, we summarize the results on sex hormone actions in the hippocampus and seek to bridge the gap between animal models and findings in humans. However, while effects of sex hormones on the hippocampus are largely consistent in animals and humans, methodological differences challenge the comparability of animal and human studies on stress effects. We summarise our current understanding of the neurobiological mechanisms that underlie sex-related differences in behavior and discuss implications for stress-related illnesses.

Affective Game Planning for Health Applications: Quantitative Extension of Gerontoludic Design Based on the Appraisal Theory of Stress and Coping

User retention is the first challenge in introducing any information and communication technologies (ICT) for health applications, particularly for seniors who are increasingly targeted as beneficiaries of such technologies. Interaction with digital technologies may be too stressful to older adults to guarantee their adoption in their routine selfcare. The second challenge, which also relates to adoption, is to supply empirical evidence that support the expectations of their beneficial outcomes. To address the first challenge, persuasive technologies such as serious games (SGs) are increasingly promoted as ludic approaches to deliver assistive care to older adults. However, there are no standards yet to assess the efficacy of different genres of games across populations, or compare and contrast variations in health outcomes arising from user interface design and user experience. For the past 3 decades, research has focused either on qualitative assessment of the appeal of digital games for seniors (by game designers) or on the quantitative evaluation of their clinical efficacy (by clinical researchers). The consensus is that interindividual differences play a key role in whether games can be useful or not for different individuals. Our challenge is to design SGs that retain their users long enough to sustain beneficial transfer effects. We propose to add a neuropsychological experimental framework (based on the appraisal theory of stress and coping) to a Gerontoludic design framework (that emphasizes designing positive and meaningful gaming experience over benefit-centric ones) in order to capture data to guide SG game development. Affective Game Planning for Health Applications (AGPHA) adds a model-driven mixed-methods experimental stage to a user-centered mechanics-dynamics-aesthetics game-design cycle. This intersectoral framework is inspired by latest trends in the fields of neuroimaging and neuroinformatics that grapple with similar challenges related to the psychobiological context of an individual's behaviors. AGPHA aims to bring users, designers, clinicians, and researchers together to generate a common data repository that consists of 4 components to define, design, evaluate, and document SGs. By unifying efforts under a standard approach, we will accelerate innovations in persuasive and efficacious ICTs for the aging population.

Neural response to stress and perceived stress differ in patients with left temporal lobe epilepsy

Patients with epilepsy are often able to predict seizure occurrence subsequent to an acute stress experience. However, neuroimaging investigations into the neural basis of this relationship or the potential influence of perceived life stress are limited. The current study assessed the relationship between perceived stress and the neurobehavioral response to stress in patients with left temporal lobe epilepsy (LTLE) and healthy controls (HCs) using heart rate, salivary cortisol level, and functional magnetic resonance imaging and compared these effects between HCs and LTLE. Matched on perceived stress levels, groups of 36 patients with LTLE and 36 HCs completed the Montreal Imaging Stress Task, with control and stress math task conditions. Among LTLEs, 27 reported that prior (acute) stress affected their seizures (LTLES+), while nine did not (LTLES-). The results revealed that increased perceived stress was associated with seizure frequency in LTLE. Further, cortisol secretion was greater in LTLE, but did not vary with perceived stress as observed in HCs. A linear mixed-effects analysis revealed that as perceived stress increased, activation in the hippocampal complex (parahippocampal gyrus and hippocampus) decreased during stressful math in the LTLES+, increased in HCs, but did not vary in the LTLES-. Task-based functional connectivity analyses revealed LTLE differences in hippocampal functional connectivity with sensory cortex specific to stressor modalities. We argue that the current study demonstrates an inhibitory hippocampal mechanism underlying differences in resilience to stress between HCs and LTLE, as well as LTLE patients who report stress as a precipitant of seizures.

Work-related social support modulates effects of early life stress on limbic reactivity during stress

Early life stress (ELS) affects stress- reactivity via limbic brain regions implicated such as hippocampus and amygdala. Social support is a major protective factor against ELS effects, while subjects with ELS experience reportedly perceive less of it in their daily life. The workplace, where most adults spend a substantial amount of time in their daily lives, might serve as a major resource for social support. Since previous data demonstrated that social support attenuates stress reactivity, we here used a psychosocial stress task to test the hypothesis that work-related social support modulates the effects of ELS. Results show decreased amygdala reactivity during stress in ELS subjects who report high levels of work- related social support, thereby indicating a signature for reduced stress reactivity. However, this effect was only observable on the neural, but not on the behavioral level, since social support had no buffering effect regarding the subjective experience of stress in daily life as well as regarding feelings of uncontrollability induced by the stress task. Accordingly, our data suggest that subjects with ELS experiences might benefit from interventions targeted at lowering their subjective stress levels by helping them to better perceive the availability of social support in their daily lives.

Effects of genetic and environmental risk for schizophrenia on hippocampal activity and psychosis-like behavior in mice

Schizophrenia is a serious mental illness most notably characterized by psychotic symptoms. In humans, psychotic disorders are associated with specific hippocampal pathology. However, animal model systems for psychosis often lack this pathology, and have been weak in providing a representation of psychosis. We utilized a double-risk model system combining genetic risk with environmental stress. We hypothesized these factors will induce hippocampal subfield pathology consistent with human findings, as well as behavioral phenotypes relevant to psychosis. To address this, we exposed wild-type and transgenic Disc1 dominant negative (Disc1-deficient) mice to maternal deprivation. In adulthood, hippocampal subfields were examined for signs of cellular and behavioral pathology associated with psychosis. Mice exposed to maternal deprivation showed a decrease in dentate gyrus activity, and an increase in CA3/CA1 activity. Furthermore, results demonstrated a differential behavioral effect between maternal deprivation and Disc1 deficiency, with maternal deprivation associated with a hyperactive phenotype and impaired prepulse inhibition, and Disc1 deficiency causing an impairment in fear conditioning. These results suggest distinct consequences of environmental and genetic risk factors contributing to psychosis, with maternal deprivation inducing a state more wholly consistent with schizophrenia psychosis. Further research is needed to determine if this pathology is causally related to a specific behavioral phenotype. The development of a strong inference animal model system for psychosis would satisfy a high medical need in schizophrenia research.

Stress-induced hippocampus Npas4 mRNA expression relates to specific psychophysiological patterns of stress response

Neuronal Per-Arnt-Sim (PAS) domain protein 4 (Npas4) is a key protein that intervenes in GABA synapse scaling and neurotrophicity enhancing. Since GABA and neurotrophicity are implicated in stress response and Npas4-deficient rodents exhibit behavioral alterations, an investigation was designed in rats to verify whether stress-induced spontaneous hippocampus Npas4 mRNA expression would be associated with specific patterns of stress response. The rats were exposed to one of three stressor levels: no stress (CTL, n = 15), exposure to a footshock apparatus (Sham, S, n = 40) and footshock (F, n = 80). After stress exposure the S and F rats were tested in an activity cage, and subsequently in an elevated plus maze (EPM), just prior to the sacrifice. Using cluster analysis, the animals already assigned to a stress level were also distributed into 2 subgroups depending on their Npas4 mRNA levels. The low (L) and high (H) Npas4 expression subgroups were identified in the S and F groups, the CTL group being independent of the Npas4 levels. The Npas4 effect was studied through the interaction between stress (S and F) and Npas4 level (L and H). The biological stress response was similar in H and L rats, except blood corticosterone that was slightly lower in the H rats. The H rats were more active in the actimetry cage and presented higher levels of exploration in the EPM. They also exhibited higher hippocampus activation, as assessed by the c-fos, Egr1 and Arc mRNA levels. Therefore high Npas4 expression favors stress management.

How the brain connects in response to acute stress: A review at the human brain systems level

The brain's response to stress is a matter of extensive neurocognitive research in an attempt to unravel the mechanistic underpinnings of neural adaptation. In line with the broadly defined concept of acute stress, a wide variety of induction procedures are used to mimic stress experimentally. We set out to review commonalities and diversities of the stress-related functional activity and connectivity changes of functional brain networks in healthy adults across procedures. The acute stress response is consistently associated with both increased activity and connectivity in the salience network (SN) and surprisingly also with increased activity in the default mode network (DMN), while most studies show no changes in the central executive network. These results confirm earlier findings of an essential, coordinating role of the SN in the acute stress response and indicate a dynamic role of the DMN whose function is less clear. Moreover, paradigm specific brain responses have to be taken into account when investigating the role and the within and between network connectivity of these three networks.

The effect of mild acute stress during memory consolidation on emotional recognition memory

Stress during consolidation improves recognition memory performance. Generally, this memory benefit is greater for emotionally arousing stimuli than neutral stimuli. The strength of the stressor also plays a role in memory performance, with memory performance improving up to a moderate level of stress and thereafter worsening. As our daily stressors are generally minimal in strength, we chose to induce mild acute stress to determine its effect on memory performance. In the current study, we investigated if mild acute stress during consolidation improves memory performance for emotionally arousing images. To investigate this, we had participants encode highly arousing negative, minimally arousing negative, and neutral images. We induced stress using the Montreal Imaging Stress Task (MIST) in half of the participants and a control task to the other half of the participants directly after encoding (i.e. during consolidation) and tested recognition 48h later. We found no difference in memory performance between the stress and control group. We found a graded pattern among confidence, with responders in the stress group having the least amount of confidence in their hits and controls having the most. Across groups, we found highly arousing negative images were better remembered than minimally arousing negative or neutral images. Although stress did not affect memory accuracy, responders, as defined by cortisol reactivity, were less confident in their decisions. Our results suggest that the daily stressors humans experience, regardless of their emotional affect, do not have adverse effects on memory.

Biomarkers, designs, and interpretations of resting-state fMRI in translational pharmacological research: A review of state-of-the-Art, challenges, and opportunities for studying brain chemistry

A decade of research and development in resting-state functional MRI (RSfMRI) has opened new translational and clinical research frontiers. This review aims to bridge between technical and clinical researchers who seek reliable neuroimaging biomarkers for studying drug interactions with the brain. About 85 pharma-RSfMRI studies using BOLD signal (75% of all) or arterial spin labeling (ASL) were surveyed to investigate the acute effects of psychoactive drugs. Experimental designs and objectives include drug fingerprinting dose-response evaluation, biomarker validation and calibration, and translational studies. Common biomarkers in these studies include functional connectivity, graph metrics, cerebral blood flow and the amplitude and spectrum of BOLD fluctuations. Overall, RSfMRI-derived biomarkers seem to be sensitive to spatiotemporal dynamics of drug interactions with the brain. However, drugs cause both central and peripheral effects, thus exacerbate difficulties related to biological confounds, structured noise from motion and physiological confounds, as well as modeling and inference testing. Currently, these issues are not well explored, and heterogeneities in experimental design, data acquisition and preprocessing make comparative or meta-analysis of existing reports impossible. A unifying collaborative framework for data-sharing and data-mining is thus necessary for investigating the commonalities and differences in biomarker sensitivity and specificity, and establishing guidelines. Multimodal datasets including sham-placebo or active control sessions and repeated measurements of various psychometric, physiological, metabolic and neuroimaging phenotypes are essential for pharmacokinetic/pharmacodynamic modeling and interpretation of the findings. We provide a list of basic minimum and advanced options that can be considered in design and analyses of future pharma-RSfMRI studies. Hum Brain Mapp 38:2276-2325, 2017. © 2017 Wiley Periodicals, Inc.

The hippocampal response to psychosocial stress varies with salivary uric acid level

Uric acid is a naturally occurring, endogenous compound that impacts mental health. In particular, uric acid levels are associated with emotion-related psychopathology (e.g., anxiety and depression). Therefore, understanding uric acid's impact on the brain would provide valuable new knowledge regarding neural mechanisms that mediate the relationship between uric acid and mental health. Brain regions including the prefrontal cortex, amygdala, and hippocampus underlie stress reactivity and emotion regulation. Thus, uric acid may impact emotion by modifying the function of these brain regions. The present study used functional magnetic resonance imaging (fMRI) during a psychosocial stress task to investigate the relationship between baseline uric acid levels (in saliva) and brain function. Results demonstrate that activity within the bilateral hippocampal complex varied with uric acid concentrations. Specifically, activity within the hippocampus and surrounding cortex increased as a function of uric acid level. The current findings suggest that uric acid levels modulate stress-related hippocampal activity. Given that the hippocampus has been implicated in emotion regulation during psychosocial stress, the present findings offer a potential mechanism by which uric acid impacts mental health.

Interindividual differences in stress sensitivity: basal and stress-induced cortisol levels differentially predict neural vigilance processing under stress

Stress exposure is known to precipitate psychological disorders. However, large differences exist in how individuals respond to stressful situations. A major marker for stress sensitivity is hypothalamus-pituitary-adrenal (HPA)-axis function. Here, we studied how interindividual variance in both basal cortisol levels and stress-induced cortisol responses predicts differences in neural vigilance processing during stress exposure. Implementing a randomized, counterbalanced, crossover design, 120 healthy male participants were exposed to a stress-induction and control procedure, followed by an emotional perception task (viewing fearful and happy faces) during fMRI scanning. Stress sensitivity was assessed using physiological (salivary cortisol levels) and psychological measures (trait questionnaires). High stress-induced cortisol responses were associated with increased stress sensitivity as assessed by psychological questionnaires, a stronger stress-induced increase in medial temporal activity and greater differential amygdala responses to fearful as opposed to happy faces under control conditions. In contrast, high basal cortisol levels were related to relative stress resilience as reflected by higher extraversion scores, a lower stress-induced increase in amygdala activity and enhanced differential processing of fearful compared with happy faces under stress. These findings seem to reflect a critical role for HPA-axis signaling in stress coping; higher basal levels indicate stress resilience, whereas higher cortisol responsivity to stress might facilitate recovery in those individuals prone to react sensitively to stress.

Cortisol response and psychological distress predict susceptibility to false memories for a trauma film

For eyewitness testimony to be considered reliable, it is important to ensure memory remains accurate following the event. As many testimonies involve traumatic, as opposed to neutral, events, it is important to consider the role of distress in susceptibility to false memories. The aim of this study was to investigate whether cortisol response following a stressor would be associated with susceptibility to false memories. Psychological distress responses were also investigated, specifically, dissociation, intrusions, and avoidance. Participants were allocated to one of three conditions: those who viewed a neutral film (N = 35), those who viewed a real trauma film (N = 35), and a trauma "reappraisal" group where participants were told the film was not real (N = 35). All received misinformation about the film in the form of a narrative. Participants provided saliva samples (to assess cortisol) and completed distress and memory questionnaires. Cortisol response was a significant predictor of the misinformation effect. Dissociation and avoidance were related to confabulations. In conclusion, following a stressor an individual may differ with regard to their psychological response to the event, and also whether they experience a cortisol increase. This may affect whether they are more distressed later on, and also whether they remember the event accurately.

Ketamine interactions with biomarkers of stress: a randomized placebo-controlled repeated measures resting-state fMRI and PCASL pilot study in healthy men

Ketamine, an NMDA receptor antagonist, is increasingly used to study the link between glutamatergic signaling dysregulation and mood and chronic pain disorders. Glutamatergic neurotransmission and stress corticosteroids (cortisol in human) are critical for Ca(2+) mediated neuroplasticity and behavioral adaptation. The mechanisms of action of glutamatergic neurotransmission and stress corticosteroids on the NMDA-receptors of the hippocampus have been long investigated in animals, but given little attention in human studies. In this randomized single-blinded placebo-controlled crossover study (12 healthy young men), five sets of resting-state fMRI (RSFMRI), pseudocontinuous arterial spin labeling (PCASL), and corresponding salivary cortisol samples were acquired over 4h, at given intervals under pharmacokinetically-controlled infusion of subanesthetic ketamine (20 & 40mg/70kg/h). An identical procedure was repeated under a sham placebo condition. Differences in the profile of ketamine versus placebo effect over time were examined. Compared to placebo, ketamine mimicked a stress-like response (increased cortisol, reduced calmness and alertness, and impaired working memory). Ketamine effects on the brain included a transient prefrontal hyperperfusion and a dose-related reduction of relative hippocampal perfusion, plus emerging hyperconnectivity between the hippocampus and the occipital, cingulate, precuneal, cerebellar and basal ganglia regions. The spatiotemporal profiles of ketamine effects on different hippocampal subnetworks suggest a topographically dissociable change in corticohippocampal functional connectivity. We discuss our findings in the context of the negative feedback inhibition theory of the hippocampal stress-control. This pilot study provides a methodological framework for multimodal functional neuroimaging under resting-state conditions, which may be generalized for translational studies of glutamatergic- or stress-related etiology of neuropsychiatric disorders.

A low cortisol response to acute stress is related to worse basal memory performance in older people

Age-related memory decline has been associated with a faulty regulation of the hypothalamus-pituitary-adrenal axis (HPA-axis). The aim of this study was to investigate whether the magnitude of the stress-induced cortisol increase is related to memory performance when memory is measured in non-stressful conditions. To do so, declarative and working memory performance were measured in 31 men and 35 women between 55 and 77 years of age. On a different day, the magnitude of their cortisol response to acute psychosocial stress was measured. The relationship between the cortisol response and memory performance was U shaped: a low cortisol response to stress was related to poorer declarative and working memory performance, whereas those who did not increase their cortisol levels and those who had the largest cortisol increase had better declarative and working memory capabilities. Sex did not moderate these relationships. These results suggest that a low cortisol response to stress could reflect a defective HPA-axis response to stressors that is accompanied by poorer memory performance. Conversely, a high cortisol response seems to reflect a correct functioning of the HPA-axis and may protect against memory deficits in the later stages of human life.

Early life stress modulates oxytocin effects on limbic system during acute psychosocial stress

Early life stress (ELS) is associated with altered stress responsivity, structural and functional brain changes and an increased risk for the development of psychopathological conditions in later life. Due to its behavioral and physiological effects, the neuropeptide oxytocin (OXT) is a useful tool to investigate stress responsivity, even though the neurobiological underpinnings of its effects are still unknown. Here we investigate the effects of OXT on cortisol stress response and neural activity during psychosocial stress. Using functional magnetic resonance imaging in healthy subjects with and without a history of ELS, we found attenuated hormonal reactivity and significantly reduced limbic deactivation after OXT administration in subjects without a history of ELS. Subjects who experienced ELS showed both blunted stress reactivity and limbic deactivation during stress. Furthermore, in these subjects OXT had opposite effects with increased hormonal reactivity and increased limbic deactivation. Our results might implicate that reduced limbic deactivation and hypothalamic-pituitary-adrenal axis responsivity during psychosocial stress are markers for biological resilience after ELS. Effects of OXT in subjects with a history of maltreatment could therefore be considered detrimental and suggest careful consideration of OXT administration in such individuals.

Biological and psychological markers of stress in humans: focus on the Trier Social Stress Test

Validated biological and psychological markers of acute stress in humans are an important tool in translational research. The Trier Social Stress Test (TSST), involving public interview and mental arithmetic performance, is among the most popular methods of inducing acute stress in experimental settings, and reliably increases hypothalamic-pituitary-adrenal axis activation. However, although much research has focused on HPA axis activity, the TSST also affects the sympathetic-adrenal-medullary system, the immune system, cardiovascular outputs, gastric function and cognition. We critically assess the utility of different biological and psychological markers, with guidance for future research, and discuss factors which can moderate TSST effects. We outline the effects of the TSST in stress-related disorders, and if these responses can be abrogated by pharmacological and psychological treatments. Modified TSST protocols are discussed, and the TSST is compared to alternative methods of inducing acute stress. Our analysis suggests that multiple readouts are necessary to derive maximum information; this strategy will enhance our understanding of the psychobiology of stress and provide the means to assess novel therapeutic agents.

Distribution of the glucocorticoid receptor in the human amygdala; changes in mood disorder patients

Exposure to stress activates the hypothalamic-pituitary-adrenal (HPA) axis that stimulates glucocorticoid (GC) release from the adrenal. These hormones exert numerous effects in the body and brain and bind to a.o. glucocorticoid receptors (GR) expressed in the limbic system, including the hippocampus and amygdala. Hyperactivity of the HPA axis and disturbed stress feedback are common features in major depression. GR protein is present in the human hypothalamus and hippocampus, but little is known-neither in healthy subjects nor in depressed patients-about GR expression in the amygdala, a brain structure involved in fear and anxiety. Since chronic stress in rodents affects GR expression in the amygdala, altered GR protein level in depressed versus healthy controls can be expected. To test this, we investigated GR-α protein expression in the post-mortem human amygdala and assessed changes in ten major or bipolar depressed patients and eight non-depressed controls. Abundant GR immunoreactivity was observed in the human amygdala, both in neurons and astrocytes, with a similar pattern in its different anatomical subnuclei. In major depression, GR protein level as well as the percentage of GR-containing astrocytes was significantly higher than in bipolar depressed patients or in control subjects. Taken together, the prominent expression of GR protein in the human amygdala indicates that this region can form an important target for corticosteroids and stress, while the increased GR expression in major, but not bipolar, depression suggests possible involvement in the etiology of major depression.

Idle behaviors of the hippocampus reflect endogenous cortisol levels in youth

OBJECTIVE

Compelling evidence indicates that disruption in functional connectivity (FC) in brain networks underlies many psychiatric and developmental disorders. Current theory posits that biological (i.e., cortisol) and environmental (i.e., stress) experiences in early life are strong determinants in the development of functional brain systems and formative in the genesis of such disorders. The objective of this study was to examine the extent to which individual differences in cortisol concentrations during FC magnetic resonance imaging (MRI) would map onto variability in hippocampal to default mode network (DMN) connectivity in typically developing youth.

METHOD

Salivary cortisol and FC MRI data were collected concurrently in 33 scan-naive 7- to 15-year-old participants. Twenty-nine of these participants previously completed the Trier Social Stress Test. Hippocampal to DMN FC and endogenous cortisol variability during MRI were examined. A possible association between MRI cortisol and cortisol response to the Trier Social Stress Test during the preceding visit or a participant's ratings of anxiety during MRI was tested.

RESULTS

There were significant positive relations between MRI cortisol levels and measurements in the following 3 areas: hippocampal to DMN FC during the resting state, cortisol levels during the Trier Social Stress Test, and fear/anxiety ratings during MRI. Fear/anxiety ratings during MRI also related to self-reported anxiety on standardized measurements.

CONCLUSIONS

This study shows for the first time that FC of the hippocampus is altered with changing cortisol responsivity in youth. Altered FC during the resting state may represent altered alertness or monitoring resulting from variation in glucocorticoid function in youth, which carries implications for the effect of stress on response monitoring and decision making.

Temporal association of stress sensitivity and symptoms in individuals at clinical high risk for psychosis

BACKGROUND

Increased sensitivity and exposure to stress are associated with psychotic symptoms in schizophrenia and its risk states, but little is known about the co-evolution of stress sensitivity and exposure with positive and other symptoms in a clinical high-risk (CHR) cohort.

METHOD

A combined cross-sectional and longitudinal design was used to examine the associations over time of stress sensitivity and exposure (i.e. life events) with 'prodromal' symptoms in a cohort of 65 CHR patients assessed quarterly for up to 4 years, and at baseline in 24 healthy controls similar in age and gender.

RESULTS

Impaired stress tolerance was greater in patients, in whom it was associated over time with positive and negative symptoms, in addition to depression, anxiety and poor function. By contrast, life events were comparable in patients and controls, and bore no association with symptoms. In this treated cohort, there was a trajectory of improvement in stress tolerance, symptoms and function over time.

CONCLUSIONS

Impaired stress tolerance was associated with a wide range of 'prodromal' symptoms, consistent with it being a core feature of the psychosis risk state. Self-reported life events were not relevant as a correlate of clinical status. As in other treated CHR cohorts, most patients improved over time across symptom domains.

Glucocorticoid receptor protein expression in human hippocampus; stability with age

The glucocorticoid receptor (GR) exerts numerous functions in the body and brain. In the brain, it has been implicated, amongst others, in feedback regulation of the hypothalamic-pituitary-adrenal axis, with potential deficits during aging and in depression. GRs are abundantly expressed in the hippocampus of rodent, except for the Ammon's horn (CA) 3 subregion. In rhesus monkey however, GR protein was largely absent from all hippocampal subregions, which prompted us to investigate its distribution in human hippocampus. After validation of antibody specificity, we investigated GRα protein distribution in the postmortem hippocampus of 26 human control subjects (1-98 years of age) and quantified changes with age and sex. In contrast to monkey, abundant GR-immunoreactivity was present in nuclei of almost all neurons of the hippocampal CA subfields and dentate gyrus (DG), although neurons of the CA3 subregion displayed lower levels of immunoreactivity. Colocalization with glial fibrillary acidic protein confirmed that GR was additionally expressed in approximately 50% of the astrocytes in the CA regions, with lower levels of colocalization (approximately 20%) in the DG. With increased age, GR expression remained stable in the CA regions in both sexes, whereas a significant negative correlation was found with age only in the DG of females. Thus, in contrast to the very low levels previously reported in monkey, GR protein is prominently expressed in human hippocampus, indicating that this region can form an important target for corticosteroid effects in human.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.