Brain activation elicited by acute stress: An ALE meta-analysis

Association of Lower Rostral Anterior Cingulate GABA+ and Dysregulated Cortisol Stress Response With Altered Functional Connectivity in Young Adults With Lifetime Depression: A Multimodal Imaging Investigation of Trait and State Effects

OBJECTIVE

Preclinical work suggests that excess glucocorticoids and reduced cortical γ-aminobutyric acid (GABA) may affect sex-dependent differences in brain regions implicated in stress regulation and depressive phenotypes. The authors sought to address a critical gap in knowledge, namely, how stress circuitry is functionally affected by glucocorticoids and GABA in current or remitted major depressive disorder (MDD).

METHODS

Multimodal imaging data were collected from 130 young adults (ages 18-25), of whom 44 had current MDD, 42 had remitted MDD, and 44 were healthy comparison subjects. GABA+ (γ-aminobutyric acid and macromolecules) was assessed using magnetic resonance spectroscopy, and task-related functional MRI data were collected under acute stress and analyzed using data-driven network modeling.

RESULTS

Across modalities, trait-related abnormalities emerged. Relative to healthy comparison subjects, both clinical groups were characterized by lower rostral anterior cingulate cortex (rACC) GABA+ and frontoparietal network amplitude but higher amplitude in salience and stress-related networks. For the remitted MDD group, differences from the healthy comparison group emerged in the context of elevated cortisol levels, whereas the MDD group had lower cortisol levels than the healthy comparison group. In the comparison group, frontoparietal and stress-related network connectivity was positively associated with cortisol level (highlighting putative top-down regulation of stress), but the opposite relationship emerged in the MDD and remitted MDD groups. Finally, rACC GABA+ was associated with stress-induced changes in connectivity between overlapping default mode and salience networks.

CONCLUSIONS

Lifetime MDD was characterized by reduced rACC GABA+ as well as dysregulated cortisol-related interactions between top-down control (frontoparietal) and threat (task-related) networks. These findings warrant further investigation of the role of GABA in the vulnerability to and treatment of MDD.

Sex-based differences in brain morphometry under chronic stress: A pilot MRI study

Background

Sex-based differences are known to be a significant feature of chronic stress; however, the morphological mechanisms of the brain underlying these differences remain unclear. The present study aimed to use magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) to investigate the effects of sex on gray matter volume (GMV) changes under conditions of chronic stress.

Methods

A total of 32 subjects were included for analysis in the present study: 16 participants experiencing chronic stress and 16 healthy controls. T1-weighted (T1WI) images from a 3 T MRI scanner were extracted from the OpenfMRI database. Images were segmented into gray matter using VBM analysis. A two-way analysis of variance (ANOVA) with a 2 × 2 full factorial design was used to evaluate the main and interaction effects of chronic stress and sex on GMV changes, and then post hoc testing was used to verify each simple effect.

Results

Two-way ANOVA showed a chronic stress × sex interaction effect on GMV. Simple effects analysis indicated that the GMV of the bilateral pre- and post-central gyri, the right cuneus and superior occipital gyrus was decreased in males, whereas that of the bilateral pre- and post-central gyri, the right superior occipital gyrus and the left middle frontal gyrus and orbital middle frontal gyrus was increased in females, under chronic stress. Additionally, in the control group, the GMV of the bilateral pre- and post-central gyri, the right cuneus and superior occipital gyrus was greater in males than females. While in the chronic stress group, the above sex-based differences were no longer significant.

Conclusions

This study preliminarily shows that there are significant differences in gray matter volume changes between males and females under chronic stress. These findings provide a basis for future studies investigating the volumetric mechanisms of sex differences under chronic stress.

Neural substrates of affective temperaments: An intersubject representational similarity analysis to resting-state functional magnetic resonance imaging in nonclinical subjects

Previous research has suggested that certain types of the affective temperament, including depressive, cyclothymic, hyperthymic, irritable, and anxious, are subclinical manifestations and precursors of mental disorders. However, the neural mechanisms that underlie these temperaments are not fully understood. The aim of this study was to identify the brain regions associated with different affective temperaments. We collected the resting-state functional magnetic resonance imaging (fMRI) data from 211 healthy adults and evaluated their affective temperaments using the Temperament Evaluation of Memphis, Pisa, Paris and San Diego Autoquestionnaire. We used intersubject representational similarity analysis to identify brain regions associated with each affective temperament. Brain regions associated with each affective temperament were detected. These regions included the prefrontal cortex, anterior cingulate cortex (ACC), precuneus, amygdala, thalami, hippocampus, and visual areas. The ACC, lingual gyri, and precuneus showed similar activity across several affective temperaments. The similarity in related brain regions was high among the cyclothymic, irritable, and anxious temperaments, and low between hyperthymic and the other affective temperaments. These findings may advance our understanding of the neural mechanisms underlying affective temperaments and their potential relationship to mental disorders and may have potential implications for personalized treatment strategies for mood disorders.

Stress priming transcranial direct current stimulation (tDCS) enhances updating of emotional content in working memory

Transcranial direct current stimulation (tDCS) targeting the prefrontal cortex has emerged as a valuable tool in psychiatric research. Understanding the impact of affective states, such as stress at the time of stimulation, on the efficacy of prefrontal tDCS is crucial for advancing tDCS interventions. Stress-primed tDCS, wherein stress is used as a priming agent, has the potential to modulate neural plasticity and enhance cognitive functions, particularly in emotional working memory. However, prior research using stress-primed tDCS focused solely on non-emotional working memory performance, yielding mixed results. In this sham-controlled study, we addressed this gap by investigating the effects of stress-primed bifrontal tDCS (active versus sham) on both non-emotional and emotional working memory performance. The study was conducted in 146 healthy individuals who were randomly assigned to four experimental groups. The Trier Social Stress Test (TSST) or a control variant of the test was used to induce a stress versus control state. The results showed that stress priming significantly enhanced the effects of tDCS on the updating of emotional content in working memory, as evidenced by improved accuracy. Notably, no significant effects of stress priming were found for non-emotional working memory performance. These findings highlight the importance of an individual's prior affective state in shaping their response to tDCS, especially in the context of emotional working memory.

Alterations of functional brain activity and connectivity in female nurses working on long-term shift

AIM

To investigate the alterations of functional brain activity and connectivity in female nurses working on long-term shifts and explore their correlations with work-related psychological traits.

DESIGN

An exploratory cross-sectional study.

METHODS

Thirty-five female nurses working on long-term shifts (shift nurses) and 35 female nurses working on fixed days (fixed nurses) were enrolled. After assessing the work-related psychological traits, including burnout, perceived stress, anxiety, and depression of nurses, the fractional amplitude of low-frequency fluctuations (fALFF) and region of interest (ROI)-based functional connectivity (FC) analyses were performed to investigate the differences of brain spontaneous activity and functional connectivity between these two groups of nurses. Thereafter, correlations between the functional brain parameters (fALFF and FC) and clinical metrics were investigated among the shift nurses.

RESULTS

Compared to fixed nurses, shift nurses had higher burnout, perceived stress and depression scores, lower fALFF in the right dorsolateral prefrontal cortex (dlPFC), left and right superior parietal lobule (SPL), bilateral anterior cingulate cortex (ACC), and higher fALFF in the right superior/middle temporal gyrus, as well as decreased FC between the right dlPFC (the selected ROI) and bilateral ACC, left and right inferior frontal/orbitofrontal gyrus (IFG/IOFG), right SPL, and left middle occipital gyrus (voxel-level p < 0.001, cluster level p < 0.05, GRF correction). Correlation analyses demonstrated that the fALFF value of the right dlPFC was significantly correlated with the burnout and anxiety scores, the FC value of the right dlPFC-right SPL was correlated with the perceived stress and burnout scores, the FC value of the right dlPFC-right IFG/IOFG was correlated with the burnout score in shift nurses (p < 0.05).

CONCLUSION

Shift nurses had work-related altered functional activity and connectivity in the right frontoparietal network, which provided objective and visualised evidence to clarify the hazards of long-term shift work on female nurses.

PATIENT OR PUBLIC CONTRIBUTION

Seventy nurses participated deeply as subjects in this study. These findings are expected to draw managers' attention to the harmful influences of shift work on nurses.

Role of hippocampus and orbitofrontal cortex in the association of interdependent self-construal with an acute stress response

Empirical evidence indicates that high interdependent self-construal (InterSC) is correlated with exaggerated acute stress responses; however, the underlying neural correlates remain unclear. Considering the regulatory effect of the prefrontal cortex and limbic system on the acute stress response, the primary aim of this study was to investigate the role of the orbitofrontal cortex (OFC) and hippocampus (HIP) in the relationship between InterSC and acute stress responses. Forty-eight healthy college students underwent a modified version of the Montreal imaging stress task (MIST), while brain activity was recorded using functional magnetic resonance imaging (fMRI). Participants' saliva samples and subjective stress feelings were collected before, during, and after the MIST. Additionally, participants' self-construal was measured using questionnaires. Results revealed that InterSC was positively correlated with the activation of OFC, which, in turn, was associated with higher subjective stress feelings. A higher InterSC was also significantly associated with an enhanced salivary cortisol response in those with lower HIP activity. Furthermore, the HIP moderated the indirect effect of InterSC on subjective stress feelings by moderating the effect of InterSC on neural activity in the OFC. This indicated the mediation of the OFC was stronger in those with higher neural activity in the HIP than in those with lower activity in the HIP. In summary, the current study proposed an important role of the OFC-HIP regions in the relationship between InterSC and acute stress responses, making contribution to broadening the field of personality and stress and deepening our understanding of individual differences in acute stress responses.

From childhood adversity to latent stress vulnerability in adulthood: the mediating roles of sleep disturbances and HPA axis dysfunction

Childhood adversity is a prominent predisposing risk factor for latent stress vulnerability, expressed as an elevated likelihood of developing stress-related psychopathology upon subsequent exposure to trauma in adulthood. Sleep disturbances have emerged as one of the most pronounced maladaptive behavioral outcomes of childhood adversity and are also a highly prevalent core feature of stress-related psychopathology, including post-traumatic stress disorder (PTSD). After reviewing the extensive literature supporting these claims, the current review addresses the notion that childhood adversity-induced sleep disturbances may play a causal role in elevating individuals' stress vulnerability in adulthood. Corroborating this, sleep disturbances that predate adult trauma exposure have been associated with an increased likelihood of developing stress-related psychopathology post-exposure. Furthermore, novel empirical evidence suggests that sleep disturbances, including irregularity of the sleep-wake cycle, mediate the link between childhood adversity and stress vulnerability in adulthood. We also discuss cognitive and behavioral mechanisms through which such a cascade may evolve, highlighting the putative role of impaired memory consolidation and fear extinction. Next, we present evidence to support the contribution of the hypothalamic-pituitary-adrenal (HPA) axis to these associations, stemming from its critical role in stress and sleep regulatory pathways. Childhood adversity may yield bi-directional effects within the HPA stress and sleep axes in which sleep disturbances and HPA axis dysfunction reinforce each other, leading to elevated stress vulnerability. To conclude, we postulate a conceptual path model from childhood adversity to latent stress vulnerability in adulthood and discuss the potential clinical implications of these notions, while highlighting directions for future research.

Multi-trajectory analysis uncovers latent associations between psychological and physiological acute stress response patterns

Encounter with an acute stressor elicits multiple physiological and psychological response trajectories that spread at different times-scales and directions. Associating a single physiological response trajectory with a specific psychological response has remained a challenge, due to putative interactions between the different stress response pathways. Hence, multidimensional analysis of stress response trajectories may be better suited to account for response variability. To test this, 96 healthy female participants underwent a robust acute laboratory stress induction procedure while their psychological [positive and negative affect (PANAS)] and physiological [heart rate (HR), heart rate variability (HRV), saliva cortisol (CORT)] responses were recorded before, during and after stress. Combining these data using unsupervised group-based multi-trajectory modelling uncovered three latent classes that best accounted for variability across psychological and physiological stress response trajectories. These classes were labelled based on their psychological response patterns as: A prototypical response group that depict a moderate increase in negative and decrease in positive affect during stress, with both patterns recovering after stress offset (n = 55); A heightened response group that depict excessive affective responses during stress that recover after stress offset (n = 24); and a lack of recovery group that depict a moderate increase in negative and decrease in positive affect during stress, with both patterns not recovering after stress offset (n = 17). With respect to physiological acute stress trajectories, all three groups exhibited comparable increases in HR and CORT during stress that recovered after stress offset, yet only the prototypical group expressed the expected stress-induced reduction in HRV, while the other two groups exhibited blunted HRV response. Critically, focusing on a single physiological stress response trajectory, including HRV, did not account for psychological response variability and vice versa. Taken together, a multi-trajectory approach may better account for the multidimensionality of acute stress response and uncover latent associations between psychological and physiological response patterns. Compared to the other two groups, the prototypical group also exhibited significantly lower overall stress scores based on the DASS-21 scale. This, alongside the uncovered response patterns, suggest that latent psycho-physiological associations may shed light on stress response adaptivity or lack thereof.