The role of prefrontal-subcortical circuitry in negative bias in anxiety: Translational, developmental and treatment perspectives

Chemogenetic inhibition of prefrontal cortex inputs to dorsal raphe reduces anxiety behaviors in male rat model of fetal alcohol spectrum disorder

Prenatal ethanol exposure (PE) causes Fetal Alcohol Spectrum Disorders (FASD), characterized by cognitive, behavioral, and emotional deficits, including anxiety and depression. PE-induced alteration in the function of dorsal raphe nucleus (DRN) serotonin (5-HT) neurons is thought to be major contributing factor for increased anxiety. However, the precise neuronal circuits involved are unknown. Using electrophysiology, optogenetics, chemogenetics, and behavioral approaches, we find that PE preferentially potentiates medial prefrontal cortex (mPFC) glutamatergic inputs, but not lateral habenula (LHb), to DRN 5-HT neurons projecting to mPFC. Additionally, PE also increases the strength of LHb but not mPFC excitatory inputs to DRN 5-HT neurons projecting to central amygdala (Ce). This input and target selective effect of PE was mediated by a circuit-specific increase in nitric oxide (NO) signaling. Importantly, chemogenetic inhibition of mPFC-DRN neuronal circuit blunted anxiety-like behaviors in PE rats. As such, our results unraveled the DRN neuronal circuitries affected by PE, which gate FASD-induced anxiety-like behaviors.

Symptomatic Pathways of Comorbid Depression, Anxiety, and Stress Among Adolescents Exposed to Childhood Trauma-Insights from the Network Approach

Background

Childhood trauma can have a long-lasting influence on individuals and contribute to mental disorders, including depression and anxiety. Depression, anxiety, and stress are highly comorbid among adolescents with the trauma experience. Yet, the evolution of comorbidity remains unclear. To fill this gap, the current study aimed to explore the symptomatic and changing patterns of depression, anxiety, and stress among adolescents exposed to childhood trauma.

Methods

A total of 1548 college students (females = 782 (50.98%), Meanage = 19.59, SDage = 1.14) in China completed the Childhood Trauma Questionnaire (CTQ) and the Depression, Anxiety, and Stress Scales (DASS-21), and 942 students (Females = 516 (54.78%), Meanage = 19.57, SDage = 1.16) met the selection standard based on the cut-off scores of the CTQ. The symptomatic network and directed acyclic graph (DAG) network approaches were used.

Results

The results revealed that males reported experiencing significantly more physical abuse, physical neglect, emotional neglect, and sexual abuse compared to females. However, females scored significantly higher than males on "Worried" (DASS9), "Agitated" (DASS11), "Panic" (DASS15), and "Scared" (DASS20). No significant difference between genders was observed in the network structure and global strength. Meanwhile, among all participants, "Down-hearted" and "Agitated" appeared to be the most interconnected symptoms, the bridge symptoms in the symptom network, as well as the most vital symptoms in the directed acyclic graph network. Apart from that, "Panic" also served as the most prominent symptom in the directed acyclic graph network.

Conclusion

The results suggested that intervention targeted at assisting adolescents in developing more adaptive coping strategies with stress and regulating emotion could benefit the alleviation of comorbid depression, anxiety, and stress.

Amygdala activity after subchronic escitalopram administration in healthy volunteers: A pharmaco-functional magnetic resonance imaging study

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are used for the treatment of several conditions including anxiety disorders, but the basic neurobiology of serotonin function remains unclear. The amygdala and prefrontal cortex are strongly innervated by serotonergic projections and have been suggested to play an important role in anxiety expression. However, serotonergic function in behaviour and SSRI-mediated neurobiological changes remain incompletely understood.

AIMS

To investigate the neural correlates of subchronic antidepressant administration.

METHODS

We investigated whether the 2- to 3-week administration of a highly selective SSRI (escitalopram) would alter brain activation on a task robustly shown to recruit the bilateral amygdala and frontal cortices in a large healthy volunteer sample. Participants performed the task during a functional magnetic resonance imaging acquisition before (n = 96) and after subchronic escitalopram (n = 46, days of administration mean (SD) = 15.7 (2.70)) or placebo (n = 40 days of administration mean (SD) = 16.2 (2.90)) self-administration.

RESULTS

Compared to placebo, we found an elevation in right amygdala activation to the task after escitalopram administration without significant changes in mood. This effect was not seen in the left amygdala, the dorsomedial region of interest, the subgenual anterior cingulate cortex or the right fusiform area. There were no significant changes in connectivity between the dorsomedial cortex and amygdala or the subgenual anterior cingulate cortex after escitalopram administration.

CONCLUSIONS

To date, this most highly powered study of subchronic SSRI administration indicates that, contrary to effects often seen in patients with anxiety disorders, subchronic SSRI treatment may increase amygdala activation in healthy controls. This finding highlights important gaps in our understanding of the functional role of serotonin.

Nutritional Modulation of the Gut-Brain Axis: A Comprehensive Review of Dietary Interventions in Depression and Anxiety Management

Mental health is an increasing topic of focus since more than 500 million people in the world suffer from depression and anxiety. In this multifactorial disorder, parameters such as inflammation, the state of the microbiota and, therefore, the patient's nutrition are receiving more attention. In addition, food products are the source of many essential ingredients involved in the regulation of mental processes, including amino acids, neurotransmitters, vitamins, and others. For this reason, this narrative review was carried out with the aim of analyzing the role of nutrition in depression and anxiety disorders. To reach the review aim, a critical review was conducted utilizing both primary sources, such as scientific publications and secondary sources, such as bibliographic indexes, web pages, and databases. The search was conducted in PsychINFO, MedLine (Pubmed), Cochrane (Wiley), Embase, and CinAhl. The results show a direct relationship between what we eat and the state of our nervous system. The gut-brain axis is a complex system in which the intestinal microbiota communicates directly with our nervous system and provides it with neurotransmitters for its proper functioning. An imbalance in our microbiota due to poor nutrition will cause an inflammatory response that, if sustained over time and together with other factors, can lead to disorders such as anxiety and depression. Changes in the functions of the microbiota-gut-brain axis have been linked to several mental disorders. It is believed that the modulation of the microbiome composition may be an effective strategy for a new treatment of these disorders. Modifications in nutritional behaviors and the use of ergogenic components are presented as important non-pharmacological interventions in anxiety and depression prevention and treatment. It is desirable that the choice of nutritional and probiotic treatment in individual patients be based on the results of appropriate biochemical and microbiological tests.

Multiple faces of anxiety: a frontal lobe perspective

Marked dysregulation of the human prefrontal cortex (PFC) and anterior cingulate cortex (ACC) characterises a variety of anxiety disorders, and its amelioration is a key feature of treatment success. Overall treatment response, however, is highly variable, and about a third of patients are resistant to treatment. In this review we hypothesise that a major contributor to this variation in treatment response are the multiple faces of anxiety induced by distinct forms of frontal cortex dysregulation. Comparison of findings from humans and non-human primates reveals marked similarity in the functional organisation of threat regulation across the frontal lobes. This organisation is discussed in relation to the 'predatory imminence continuum' model of threat and the differential engagement of executive functions at the core of both emotion generation and regulation strategies.

Amygdala biomarkers of treatment response in major depressive disorder: An fMRI systematic review of SSRI antidepressants

Functional neuroimaging studies have demonstrated abnormal activity and functional connectivity (FC) of the amygdala among individuals with major depressive disorder (MDD), which may be rectified with selective serotonin reuptake inhibitor (SSRI) treatment. This systematic review aimed to identify changes in the amygdala on functional magnetic resonance imaging (fMRI) scans among individuals with MDD who received SSRIs. A search for fMRI studies examining amygdala correlates of SSRI response via fMRI was conducted through OVID (MEDLINE, PsycINFO, and Embase). The end date was April 4th, 2023. In total, 623 records were screened, and 16 studies were included in this review. While the search pertained to SSRIs broadly, the included studies were escitalopram-, citalopram-, fluoxetine-, sertraline-, and paroxetine-specific. Decreases in event-related amygdala activity were found following 6-to-12-week SSRI treatment, particularly in response to negative stimuli. Eight-week courses of SSRI pharmacotherapy were associated with increased event-related amygdala FC (i.e., with the prefrontal [PFC] and anterior cingulate cortices, insula, thalamus, caudate nucleus, and putamen) and decreased resting-state effective connectivity (i.e., amygdala-PFC). Preliminary evidence suggests that SSRIs may alter amygdala activity and FC in MDD. Additional studies are needed to corroborate findings. Future research should employ long-term follow-ups to determine whether effects persist after treatment termination.

Approach-avoidance reinforcement learning as a translational and computational model of anxiety-related avoidance

Although avoidance is a prevalent feature of anxiety-related psychopathology, differences in the measurement of avoidance between humans and non-human animals hinder our progress in its theoretical understanding and treatment. To address this, we developed a novel translational measure of anxiety-related avoidance in the form of an approach-avoidance reinforcement learning task, by adapting a paradigm from the non-human animal literature to study the same cognitive processes in human participants. We used computational modelling to probe the putative cognitive mechanisms underlying approach-avoidance behaviour in this task and investigated how they relate to subjective task-induced anxiety. In a large online study (n = 372), participants who experienced greater task-induced anxiety avoided choices associated with punishment, even when this resulted in lower overall reward. Computational modelling revealed that this effect was explained by greater individual sensitivities to punishment relative to rewards. We replicated these findings in an independent sample (n = 627) and we also found fair-to-excellent reliability of measures of task performance in a sub-sample retested 1 week later (n = 57). Our findings demonstrate the potential of approach-avoidance reinforcement learning tasks as translational and computational models of anxiety-related avoidance. Future studies should assess the predictive validity of this approach in clinical samples and experimental manipulations of anxiety.

Attributional negativity bias and acute stress disorder symptoms mediate the association between trauma history and future posttraumatic stress disorder

Individuals who have experienced more trauma throughout their life have a heightened risk of developing posttraumatic stress disorder (PTSD) following injury. Although trauma history cannot be retroactively modified, identifying the mechanism(s) by which preinjury life events influence future PTSD symptoms may help clinicians mitigate the detrimental effects of past adversity. The current study proposed attributional negativity bias, the tendency to perceive stimuli/events as negative, as a potential intermediary in PTSD development. We hypothesized an association between trauma history and PTSD symptom severity following a new index trauma via heightened negativity bias and acute stress disorder (ASD) symptoms. Recent trauma survivors (N =189, 55.5% women, 58.7% African American/Black) completed assessments of ASD, negativity bias, and lifetime trauma 2-weeks postinjury; PTSD symptoms were assessed 6 months later. A parallel mediation model was tested with bootstrapping (10,000 resamples). Both negativity bias, Path b1 : β = -.24, t(187) = -2.88, p = .004, and ASD symptoms, Path b2 : β = .30, t(187) = 3.71, p < .001, fully mediated the association between trauma history and 6-month PTSD symptoms, full model: F(6, 182) = 10.95, p < .001, R 2 = .27; Path c': β = .04, t(187) = 0.54, p = .587. These results suggest that negativity bias may reflect an individual cognitive difference that can be further activated by acute trauma. Moreover, negativity bias may be an important, modifiable treatment target, and interventions addressing both acute symptoms and negativity bias in the early posttrauma period may weaken the link between trauma history and new-onset PTSD.

Self-Compassion and Anxiety in Adolescents with and without Anxiety Disorder

Previous studies have linked self-compassion to mental health, specifically anxiety, in non-clinical adolescents, suggesting that self-compassion can be a protective factor against anxiety. This study compared the overall level of self-compassion and (un)compassionate self-responding in adolescents with and without an anxiety disorder and assessed the association between self-compassion and anxiety. This cross-sectional study included adolescents (12-19 years) with an anxiety disorder (N = 23) and a reference group (N = 28). Participants completed the Self-Compassion Scale (SCS) and State Trait Anxiety Inventory (STAI). Results showed that overall self-compassion and uncompassionate self-responding were significantly lower and higher in the clinical than the reference group, respectively, while compassionate self-responding did not differ between groups. In the clinical group, only uncompassionate self-responding was significantly associated with higher anxiety. In the reference group, uncompassionate self-responding showed a significant positive association with anxiety, and compassionate self-responding showed a significant negative association with anxiety. Although the results suggest that low uncompassionate self-responding may buffer against anxiety, the role of compassionate and uncompassionate self-responding remains unclear. An alternative explanation is that the uncompassionate self-responding items measure the presence of psychopathology in adolescents with an anxiety disorder. More research on the construct validity of the SCS uncompassionate self-responding scale is needed.

Active immunotherapy against pathogenic Cis pT231-tau suppresses neurodegeneration in traumatic brain injury mouse models

Traumatic brain injury (TBI), characterized by acute neurological impairment, is associated with a higher incidence of neurodegenerative diseases, particularly chronic traumatic encephalopathy (CTE), Alzheimer's disease (AD), and Parkinson's disease (PD), whose hallmarks include hyperphosphorylated tau protein. Recently, phosphorylated tau at Thr231 has been shown to exist in two distinct cis and trans conformations. Moreover, targeted elimination of cis P-tau by passive immunotherapy with an appropriate mAb that efficiently suppresses tau-mediated neurodegeneration in severe TBI mouse models has proven to be a useful tool to characterize the neurotoxic role of cis P-tau as an early driver of the tauopathy process after TBI. Here, we investigated whether active immunotherapy can develop sufficient neutralizing antibodies to specifically target and eliminate cis P-tau in the brain of TBI mouse models. First, we explored the therapeutic efficacy of two different vaccines. C57BL/6 J mice were immunized with either cis or trans P-tau conformational peptides plus adjuvant. After rmTBI in mice, we found that cis peptide administration developed a specific Ab that precisely targeted and neutralized cis P-tau, inhibited the development of neuropathology and brain dysfunction, and restored various structural and functional sequelae associated with TBI in chronic phases. In contrast, trans P-tau peptide application not only lacked neuroprotective properties, but also contributed to a number of neuropathological features, including progressive TBI-induced neuroinflammation, widespread tau-mediated neurodegeneration, worsening functional deficits, and brain atrophy. Taken together, our results suggest that active immunotherapy strategies against pathogenic cis P-tau can halt the process of tauopathy and would have profound clinical implications.

The prefrontal cortex, pathological anxiety, and anxiety disorders

Anxiety is experienced in response to threats that are distal or uncertain, involving changes in one's subjective state, autonomic responses, and behavior. Defensive and physiologic responses to threats that involve the amygdala and brainstem are conserved across species. While anxiety responses typically serve an adaptive purpose, when excessive, unregulated, and generalized, they can become maladaptive, leading to distress and avoidance of potentially threatening situations. In primates, anxiety can be regulated by the prefrontal cortex (PFC), which has expanded in evolution. This prefrontal expansion is thought to underlie primates' increased capacity to engage high-level regulatory strategies aimed at coping with and modifying the experience of anxiety. The specialized primate lateral, medial, and orbital PFC sectors are connected with association and limbic cortices, the latter of which are connected with the amygdala and brainstem autonomic structures that underlie emotional and physiological arousal. PFC pathways that interface with distinct inhibitory systems within the cortex, the amygdala, or the thalamus can regulate responses by modulating neuronal output. Within the PFC, pathways connecting cortical regions are poised to reduce noise and enhance signals for cognitive operations that regulate anxiety processing and autonomic drive. Specialized PFC pathways to the inhibitory thalamic reticular nucleus suggest a mechanism to allow passage of relevant signals from thalamus to cortex, and in the amygdala to modulate the output to autonomic structures. Disruption of specific nodes within the PFC that interface with inhibitory systems can affect the negative bias, failure to regulate autonomic arousal, and avoidance that characterize anxiety disorders.

Selective serotonin reuptake inhibitor treatment retunes emotional valence in primate ventral striatum

Selective serotonin reuptake inhibitors (SSRIs) are widely used to treat psychiatric disorders with affective biases such as depression and anxiety. How SSRIs exert a beneficial action on emotions associated with life events is still unknown. Here we ask whether and how the effectiveness of the SSRI fluoxetine is underpinned by neural mechanisms in the ventral striatum. To address these issues, we studied the spiking activity of neurons in the ventral striatum of monkeys during an approach-avoidance task in which the valence assigned to sensory stimuli was manipulated. Neural responses to positive and negative events were measured before and during a 4-week treatment with fluoxetine. We conducted PET scans to confirm that fluoxetine binds within the ventral striatum at a therapeutic dose. In our monkeys, fluoxetine facilitated approach of rewards and avoidance of punishments. These beneficial effects were associated with changes in tonic and phasic activities of striatal neurons. Fluoxetine increased the spontaneous firing rate of striatal neurons and amplified the number of cells responding to rewards versus punishments, reflecting a drug-induced positive shift in the processing of emotionally valenced information. These findings reveal how SSRI treatment affects ventral striatum neurons encoding positive and negative valence and striatal signaling of emotional information. In addition to a key role in appetitive processing, our results shed light on the involvement of the ventral striatum in aversive processing. Together, the ventral striatum appears to play a central role in the action of SSRIs on emotion processing biases commonly observed in psychiatric disorders.

Modulating emotion processing using transcranial alternating current stimulation (tACS) - A sham-controlled study in healthy human participants

As an emerging non-invasive neuromodulation technique, transcranial alternating current stimulation(tACS) has been reported to be used in mood regulation, cognitive modulation and brain trauma recovery by applying specific frequency currents. However, the neuromodulatory mechanisms and effects of tACS on emotion processing are unclear. In this study, a single-blind experiment with 44 healthy subjects in 1:1 randomized groups (experimental group given 10 Hz-tACS and control group given sham-stimulation) was conducted. The effects of tACS applied to the prefrontal lobe on the brain's emotional state and emotional cognitive processing in response to emotional stimulation patterns were explored by designing two experimental paradigms of an 8-minute open and closed eye resting task and an emotional face oddball task. Power spectrum and event-related potentials were extracted to explore the effect of tACS on brain rhythm modulation and attention modulation. It was found that the experimental group showed significantly enhanced alpha rhythm in the whole brain range after tACS, especially in the parieto-occipital lobe. The rate of misclassification of neutral emotions into negative emotions was significantly lower and the amplitude of P2 and P3 of event-related potentials were significantly higher when performing the emotional face task after tACS, while the control group did not have this phenomenon. These results suggest that tACS can modulate and enhance alpha rhythm activity by synchronizing alpha oscillations in the frontoparietal attention network, thereby improving subjects' negative emotion cognitive bias and enhancing their emotion processing by increasing early and late levels of emotional attention.

Does non-invasive brain stimulation modulate emotional stress reactivity?

Excessive emotional responses to stressful events can detrimentally affect psychological functioning and mental health. Recent studies have provided evidence that non-invasive brain stimulation (NBS) targeting the prefrontal cortex (PFC) can affect the regulation of stress-related emotional responses. However, the reliability and effect sizes have not been systematically analyzed. In the present study, we reviewed and meta-analyzed the effects of repetitive transcranial magnetic (rTMS) and transcranial direct current stimulation (tDCS) over the PFC on acute emotional stress reactivity in healthy individuals. Forty sham-controlled single-session rTMS and tDCS studies were included. Separate random effects models were performed to estimate the mean effect sizes of emotional reactivity. Twelve rTMS studies together showed no evidence that rTMS over the PFC influenced emotional reactivity. Twenty-six anodal tDCS studies yielded a weak beneficial effect on stress-related emotional reactivity (Hedges’ g = −0.16, CI_95% = [−0.33, 0.00]). These findings suggest that a single session of NBS is insufficient to induce reliable, clinically significant effects but also provide preliminary evidence that specific NBS methods can affect emotional reactivity. This may motivate further research into augmenting the efficacy of NBS protocols on stress-related processes.

How Representative are Neuroimaging Samples? Large-Scale Evidence for Trait Anxiety Differences Between fMRI and Behaviour-Only Research Participants

Over the past three decades, functional magnetic resonance imaging (fMRI) has become crucial to study how cognitive processes are implemented in the human brain. However, the question of whether participants recruited into fMRI studies differ from participants recruited into other study contexts has received little to no attention. This is particularly pertinent when effects fail to generalize across study contexts: for example, a behavioural effect discovered in a non-imaging context not replicating in a neuroimaging environment. Here, we tested the hypothesis, motivated by preliminary findings (N = 272), that fMRI participants differ from behaviour-only participants on one fundamental individual difference variable: trait anxiety. Analysing trait anxiety scores and possible confounding variables from healthy volunteers across multiple institutions (N = 3317), we found robust support for lower trait anxiety in fMRI study participants, consistent with a sampling or self-selection bias. The bias was larger in studies that relied on phone screening (compared with full in-person psychiatric screening), recruited at least partly from convenience samples (compared with community samples), and in pharmacology studies. Our findings highlight the need for surveying trait anxiety at recruitment and for appropriate screening procedures or sampling strategies to mitigate this bias.

Whole blood serotonin levels in healthy elderly are negatively associated with the functional activity of emotion-related brain regions

Understanding the role of neuromodulators of socio-affective processing is important to ensure psychological wellbeing during older years. Here, we investigated the link between blood serotonin levels and brain and behavioral responses to emotional information in healthy elderly. A priori regions of interest (ROI) were selected due to their role in emotion processing and their dense serotonergic innervation. Correlation analyses were performed between ROI-specific responses to emotional stimuli and whole blood serotonin levels. We found significant negative associations between serotonin and functional activity for the bilateral insula, dorsal anterior cingulate cortex and subgenual gyrus. No association with behavioral measures survived correction for multiple testing. Our results mirror prior pharmacological and genetic work on the link between serotonin and emotional brain reactivity in younger adults. Given the involvement of serotonin in several age-related changes, our study encourages future research to characterize the role of this neuromodulator in emotion processing across the lifespan.

Irritability Is Associated With Decreased Cortical Surface Area and Anxiety With Decreased Gyrification During Brain Development

Background: Brain development is of utmost importance for the emergence of psychiatric disorders, as the most severe of them arise before 25 years old. However, little is known regarding how early transdiagnostic symptoms, in a dimensional framework, are associated with cortical development. Anxiety and irritability are central vulnerability traits for subsequent mood and anxiety disorders. In this study, we investigate how these dimensions are related to structural changes in the brain to understand how they may increase the transition risk to full-blown disorders. Methods: We used the opportunity of an open access developmental cohort, the Healthy Brain Network, to investigate associations between cortical surface markers and irritability and anxiety scores as measured by parents and self-reports. Results: We found that in 658 young people (with a mean age of 11.6) the parental report of irritability is associated with decreased surface area in the bilateral rostral prefrontal cortex and the precuneus. Furthermore, parental reports of anxiety were associated with decreased local gyrification index in the anterior cingulate cortex and dorsomedial prefrontal cortex. Conclusions: These results are consistent with current models of emotion regulation network maturation, showing decreased surface area or gyrification index in regions associated with impaired affective control in mood and anxiety disorders. Our results highlight how dimensional traits may increase vulnerability for these disorders.

Transcranial electric stimulation as a neural interface to gain insight on human brain functions: current knowledge and future perspective

The use of brain-stimulation approaches in social and affective science has greatly increased over the last two decades. The interest in social factors has grown along with technological advances in brain research. Transcranial electric stimulation (tES) is a research tool that allows scientists to establish contributory causality between brain functioning and social behaviour, therefore deepening our understanding of the social mind. Preliminary evidence is also starting to demonstrate that tES, either alone or in combination with pharmacological or behavioural interventions, can alleviate the symptomatology of individuals with affective or social cognition disorders. This review offers an overview of the application of tES in the field of social and affective neuroscience. We discuss issues and challenges related to this application and suggest avenue for future basic and translational research.

Elevated Amygdala Activity in Young Adults With Familial Risk for Depression: A Potential Marker of Low Resilience

BACKGROUND

Amygdala overactivity has been frequently observed in patients with depression, as well as in nondepressed relatives of patients with depression. A remaining unanswered question is whether elevated amygdala activity in those with familial risk for depression is related to the presence of subthreshold symptoms or to a trait-level vulnerability for illness.

METHODS

To examine this question, functional magnetic resonance imaging data were collected in nondepressed young adults with (family history [FH+]) (n = 27) or without (FH-) (n = 45) a first-degree relative with a history of depression while they viewed images of "looming" or withdrawing stimuli (faces and cars) that varied in salience by virtue of their apparent proximity to the subject. Activation of the amygdala and 2 other regions known to exhibit responses to looming stimuli, the dorsal intraparietal sulcus (DIPS) and ventral premotor cortex (PMv), were measured, as well as levels of resilience, anxiety, and psychotic and depressive symptoms.

RESULTS

Compared with the FH- group, the FH+ group exhibited significantly greater responses of the amygdala, but not the dorsal intraparietal sulcus or ventral premotor cortex, to looming face stimuli. Moreover, amygdala responses in the FH+ group were negatively correlated with levels of resilience and unrelated to levels of subthreshold symptoms of psychopathology.

CONCLUSIONS

These findings indicate that elevated amygdala activity in nondepressed young adults with a familial history of depression is more closely linked to poor resilience than to current symptom state.

Endocannabinoid Signaling Collapse Mediates Stress-Induced Amygdalo-Cortical Strengthening

Functional coupling between the amygdala and the dorsomedial prefrontal cortex (dmPFC) has been implicated in the generation of negative affective states; however, the mechanisms by which stress increases amygdala-dmPFC synaptic strength and generates anxiety-like behaviors are not well understood. Here, we show that the mouse basolateral amygdala (BLA)-prelimbic prefrontal cortex (plPFC) circuit is engaged by stress and activation of this pathway in anxiogenic. Furthermore, we demonstrate that acute stress exposure leads to a lasting increase in synaptic strength within a reciprocal BLA-plPFC-BLA subcircuit. Importantly, we identify 2-arachidonoylglycerol (2-AG)-mediated endocannabinoid signaling as a key mechanism limiting glutamate release at BLA-plPFC synapses and the functional collapse of multimodal 2-AG signaling as a molecular mechanism leading to persistent circuit-specific synaptic strengthening and anxiety-like behaviors after stress exposure. These data suggest that circuit-specific impairment in 2-AG signaling could facilitate functional coupling between the BLA and plPFC and the translation of environmental stress to affective pathology.

Prefrontal Regulation of Threat-Elicited Behaviors: A Pathway to Translation

Regions of the prefrontal and cingulate cortices play important roles in the regulation of behaviors elicited by threat. Dissecting out their differential involvement will greatly increase our understanding of the varied etiology of symptoms of anxiety. I review evidence for altered activity within the major divisions of the prefrontal cortex, including orbitofrontal, ventrolateral, dorsolateral, and ventromedial sectors, along with the anterior cingulate cortex in patients with clinical anxiety. This review is integrated with a discussion of current knowledge about the causal role of these different prefrontal and cingulate regions in threat-elicited behaviors from experimental studies in rodents and monkeys. I highlight commonalities and inconsistencies between species and discuss the current state of our translational success in relating findings across species. Finally, I identify key issues that, if addressed, may improve that success in the future.

Altered learning under uncertainty in unmedicated mood and anxiety disorders

Anxiety is characterized by altered responses under uncertain conditions, but the precise mechanism by which uncertainty changes the behaviour of anxious individuals is unclear. Here we probe the computational basis of learning under uncertainty in healthy individuals and individuals suffering from a mix of mood and anxiety disorders. Participants were asked to choose between four competing slot machines with fluctuating reward and punishment outcomes during safety and stress. We predicted that anxious individuals under stress would learn faster about punishments and exhibit choices that were more affected by those punishments, thus formalizing our predictions as parameters in reinforcement learning accounts of behaviour. Overall, the data suggest that anxious individuals are quicker to update their behaviour in response to negative outcomes (increased punishment learning rates). When treating anxiety, it may therefore be more fruitful to encourage anxious individuals to integrate information over longer horizons when bad things happen, rather than try to blunt their responses to negative outcomes.

Novel pharmacological targets in drug development for the treatment of anxiety and anxiety-related disorders

Current medication for anxiety disorders is suboptimal in terms of efficiency and tolerability, highlighting the need for improved drug treatments. In this review an overview of drugs being studied in different phases of clinical trials for their potential in the treatment of fear-, anxiety- and trauma-related disorders is presented. One strategy followed in drug development is refining and improving compounds interacting with existing anxiolytic drug targets, such as serotonergic and prototypical GABAergic benzodiazepines. A more innovative approach involves the search for compounds with novel mechanisms of anxiolytic action using the growing knowledge base concerning the relevant neurocircuitries and neurobiological mechanisms underlying pathological fear and anxiety. The target systems evaluated in clinical trials include glutamate, endocannabinoid and neuropeptide systems, as well as ion channels and targets derived from phytochemicals. Examples of promising novel candidates currently in clinical development for generalised anxiety disorder, social anxiety disorder, panic disorder, obsessive compulsive disorder or post-traumatic stress disorder include ketamine, riluzole, xenon with one common pharmacological action of modulation of glutamatergic neurotransmission, as well as the neurosteroid aloradine. Finally, compounds such as D-cycloserine, MDMA, L-DOPA and cannabinoids have shown efficacy in enhancing fear-extinction learning in humans. They are thus investigated in clinical trials as an augmentative strategy for speeding up and enhancing the long-term effectiveness of exposure-based psychotherapy, which could render chronic anxiolytic drug treatment dispensable for many patients. These efforts are indicative of a rekindled interest and renewed optimism in the anxiety drug discovery field, after decades of relative stagnation.

Reliability of Fronto-Amygdala Coupling during Emotional Face Processing

One of the most exciting translational prospects for brain imaging research is the potential use of functional magnetic resonance imaging (fMRI) 'biomarkers' to predict an individual's risk of developing a neuropsychiatric disorder or the likelihood of responding to a particular intervention. This proposal depends critically on reliable measurements at the level of the individual. Several previous studies have reported relatively poor reliability of amygdala activation during emotional face processing, a key putative fMRI 'biomarker'. However, the reliability of amygdala connectivity measures is much less well understood. Here, we assessed the reliability of task-modulated coupling between three seed regions (left and right amygdala and the subgenual anterior cingulate cortex) and the dorsomedial frontal/cingulate cortex (DMFC), measured using a psychophysiological interaction analysis in 29 healthy individuals scanned approximately two weeks apart. We performed two runs on each day of three different emotional face-processing tasks: emotion identification, emotion matching, and gender classification. We tested both between-day reliability and within-day (between-run) reliability. We found good-to-excellent within-subject reliability of amygdala-DMFC coupling, both between days (in two tasks), and within day (in one task). This suggests that disorder-relevant regional coupling may be sufficiently reliable to be used as a predictor of treatment response or clinical risk in future clinical studies.

Mental disorders and the risk of adult violent and psychological victimisation: a prospective, population-based study

AIMS

Psychiatric patients are at increased risk to become victim of violence. It remains unknown whether subjects of the general population with mental disorders are at risk of victimisation as well. In addition, it remains unclear whether the risk of victimisation differs across specific disorders. This study aimed to determine whether a broad range of mood, anxiety and substance use disorders at baseline predict adult violent (physical and/or sexual) and psychological victimisation at 3-year follow-up, also after adjustment for childhood trauma. Furthermore, this study aimed to examine whether specific types of childhood trauma predict violent and psychological victimisation at follow-up, after adjustment for mental disorder. Finally, this study aimed to examine whether the co-occurrence of childhood trauma and any baseline mental disorder leads to an incrementally increased risk of future victimisation.

METHODS

Data were derived from the first two waves of the Netherlands Mental Health Survey and Incidence Study-2 (NEMESIS-2): a psychiatric epidemiological cohort study among a nationally representative adult population. Mental disorders were assessed using the Composite International Diagnostic Interview version 3.0. Longitudinal associations between 12 mental disorders at baseline and violent and psychological victimisation at 3-year follow-up (n = 5303) were studied using logistic regression analyses, with adjustment for sociodemographic characteristics and childhood trauma. Furthermore, the moderating effect of childhood trauma on these associations was examined.

RESULTS

Associations with victimisation varied considerably across specific mental disorders. Only alcohol dependence predicted both violent and psychological victimisation after adjustment for sociodemographic characteristics and childhood trauma. Depression, panic disorder, social phobia, generalised anxiety disorder and alcohol dependence predicted subsequent psychological victimisation in the fully adjusted models. All types of childhood trauma independently predicted violent and psychological victimisation after adjustment for any mental disorder. The presence of any childhood trauma moderated the association between any anxiety disorder and psychological victimisation, whereas no interaction between mental disorder and childhood trauma on violent victimisation existed.

CONCLUSIONS

The current study shows that members of the general population with mental disorders are at increased risk of future victimisation. However, the associations with violent and psychological victimisation vary considerably across specific disorders. Clinicians should be aware of the increased risk of violent and psychological victimisation in individuals with these mental disorders - especially those with alcohol dependence - and individuals with a history of childhood trauma. Violence prevention programmes should be developed for people at risk. These programmes should not only address violent victimisation, but also psychological victimisation.