Concurrent and prospective associations between negative social-evaluative beliefs, safety behaviours, and symptoms during and following cognitive behavioural group therapy for social anxiety disorder.

BACKGROUND: Improving the delivery of cognitive-behavioural therapy (CBT) for social anxiety disorder (SAD) requires an in-depth understanding of which cognitive and behavioural mechanisms drive change in social anxiety symptoms (i.e., social interaction anxiety) during and after treatment. The current study explores the dynamic temporal associations between theory-driven cognitive and behavioural mechanisms of symptom change both during and following group CBT. METHODS: A randomized controlled trial of imagery-enhanced CBT (n = 51) versus traditional verbal CBT (n = 54) for social anxiety was completed in a community mental health clinic setting. This study included data collected from 12-weekly sessions and a 1-month follow-up session. Mixed models were used to assess magnitude of change over the course of treatment. Cross-lagged panel models were fit to the data to examine temporal relationships between mechanisms (social-evaluative beliefs, safety behaviours) and social interaction anxiety symptoms. RESULTS: Participants in both CBT groups experienced significant improvements across all cognitive, behavioural, and symptom measures, with no significant differences in the magnitude of changes between treatments. During treatment, greater social-evaluative beliefs (fear of negative evaluation, negative self-portrayals) at one time point (T) were predictive of more severe SAD symptoms and safety behaviours at T+1. Social-evaluative beliefs (fear of negative evaluation, probability and cost of social failure) and safety behaviours measured at post-treatment were positively associated with SAD symptoms at the 1-month follow-up. CONCLUSIONS: The current study identifies social-evaluative beliefs that may be important targets for symptom and avoidance reduction during and following CBT. Assessment of these social-evaluative beliefs throughout treatment may be useful for predicting future SAD symptoms and avoidance, and for adapting treatment to promote optimal change for patients.

Quantifying dynamic facial expressions under naturalistic conditions.

Facial affect is expressed dynamically - a giggle, grimace, or an agitated frown. However, the characterisation of human affect has relied almost exclusively on static images. This approach cannot capture the nuances of human communication or support the naturalistic assessment of affective disorders. Using the latest in machine vision and systems modelling, we studied dynamic facial expressions of people viewing emotionally salient film clips. We found that the apparent complexity of dynamic facial expressions can be captured by a small number of simple spatiotemporal states - composites of distinct facial actions, each expressed with a unique spectral fingerprint. Sequential expression of these states is common across individuals viewing the same film stimuli but varies in those with the melancholic subtype of major depressive disorder. This approach provides a platform for translational research, capturing dynamic facial expressions under naturalistic conditions and enabling new quantitative tools for the study of affective disorders and related mental illnesses.

Impacts of imagery-enhanced versus verbally-based cognitive behavioral group therapy on psychophysiological parameters in social anxiety disorder: Results from a randomized-controlled trial.

Social anxiety disorder (SAD) is associated with marked physiological reactivity in social-evaluative situations. However, objective measurement of biomarkers is rarely evaluated in treatment trials, despite potential utility in clarifying disorder-specific physiological correlates. This randomized controlled trial sought to examine the differential impact of imagery-enhanced vs. verbal-based cognitive behavioral group therapy (IE-CBGT, n = 53; VB-CBGT, n = 54) on biomarkers of emotion regulation and arousal during social stress in people with SAD (pre- and post-treatment differences in heart rate variability (HRV) and skin conductance). We acquired psychophysiological data from randomized participants across four social stress test phases (baseline, speech preparation, speech, interaction) at pre-treatment, and 1- and 6-months post-treatment. Analyses revealed that IE-CBGT selectively attenuated heart rate as indexed by increases in median heart rate interval (median-RR) compared to VB-CBGT at post-treatment, whereas one HRV index showed a larger increase in the VB-CBGT condition before but not after controlling for median-RR. Other psychophysiological indices did not differ between conditions. Lower sympathetic arousal in the IE-CBGT condition may have obviated the need for parasympathetic downregulation, whereas the opposite was true for VB-CBGT. These findings provide preliminary insights into the impact of imagery-enhanced and verbally-based psychotherapy for SAD on emotion regulation biomarkers.

Imagery-enhanced v. verbally-based group cognitive behavior therapy for social anxiety disorder: a randomized clinical trial.

BACKGROUND: Cognitive behavior therapy (CBT) is effective for most patients with a social anxiety disorder (SAD) but a substantial proportion fails to remit. Experimental and clinical research suggests that enhancing CBT using imagery-based techniques could improve outcomes. It was hypothesized that imagery-enhanced CBT (IE-CBT) would be superior to verbally-based CBT (VB-CBT) on pre-registered outcomes. METHODS: A randomized controlled trial of IE-CBT v. VB-CBT for social anxiety was completed in a community mental health clinic setting. Participants were randomized to IE (n = 53) or VB (n = 54) CBT, with 1-month (primary end point) and 6-month follow-up assessments. Participants completed 12, 2-hour, weekly sessions of IE-CBT or VB-CBT plus 1-month follow-up. RESULTS: Intention to treat analyses showed very large within-treatment effect sizes on the social interaction anxiety at all time points (ds = 2.09-2.62), with no between-treatment differences on this outcome or clinician-rated severity [1-month OR = 1.45 (0.45, 4.62), p = 0.53; 6-month OR = 1.31 (0.42, 4.08), p = 0.65], SAD remission (1-month: IE = 61.04%, VB = 55.09%, p = 0.59); 6-month: IE = 58.73%, VB = 61.89%, p = 0.77), or secondary outcomes. Three adverse events were noted (substance abuse, n = 1 in IE-CBT; temporary increase in suicide risk, n = 1 in each condition, with one being withdrawn at 1-month follow-up). CONCLUSIONS: Group IE-CBT and VB-CBT were safe and there were no significant differences in outcomes. Both treatments were associated with very large within-group effect sizes and the majority of patients remitted following treatment.

Altered resting-state functional connectome in major depressive disorder: a mega-analysis from the PsyMRI consortium.

Major depressive disorder (MDD) is associated with abnormal neural circuitry. It can be measured by assessing functional connectivity (FC) at resting-state functional MRI, that may help identifying neural markers of MDD and provide further efficient diagnosis and monitor treatment outcomes. The main aim of the present study is to investigate, in an unbiased way, functional alterations in patients with MDD using a large multi-center dataset from the PsyMRI consortium including 1546 participants from 19 centers ( www.psymri.com ). After applying strict exclusion criteria, the final sample consisted of 606 MDD patients (age: 35.8 ± 11.9 y.o.; females: 60.7%) and 476 healthy participants (age: 33.3 ± 11.0 y.o.; females: 56.7%). We found significant relative hypoconnectivity within somatosensory motor (SMN), salience (SN) networks and between SMN, SN, dorsal attention (DAN), and visual (VN) networks in MDD patients. No significant differences were detected within the default mode (DMN) and frontoparietal networks (FPN). In addition, alterations in network organization were observed in terms of significantly lower network segregation of SMN in MDD patients. Although medicated patients showed significantly lower FC within DMN, FPN, and SN than unmedicated patients, there were no differences between medicated and unmedicated groups in terms of network organization in SMN. We conclude that the network organization of cortical networks, involved in processing of sensory information, might be a more stable neuroimaging marker for MDD than previously assumed alterations in higher-order neural networks like DMN and FPN.

A longitudinal assessment of the bivalent fear of evaluation model with social interaction anxiety in social anxiety disorder.

BACKGROUND: The Bivalent Fear of Evaluation Model proposes that the fears of positive and negative evaluation each uniquely contribute to social anxiety severity. However, the debate continues as to whether these are distinct constructs, and, if so, the degree of influence each has on social anxiety severity. This study used a longitudinal evaluation of these relationships in a clinical sample to identify whether the two fears differentially change over time and differentially relate to social anxiety severity. METHODS: Individuals with a social anxiety disorder (N = 105) completed measures of fears of negative and positive evaluation weekly, and social interaction anxiety monthly, for 12 weeks. Temporal relationships were assessed using residual dynamic structural equation modeling. RESULTS: Fears of positive and negative evaluation both predicted the future status of the other (ϕ = 0.18, 95% credibility interval [0.10-0.28] and ϕ = 0.22 [0.12-0.35], respectively). Fear of negative evaluation (ϕ = 0.16 [0.05-0.28]) but not positive evaluation (ϕ < 0.01 [-0.09 to 0.10]) directly predicted future social anxiety severity. Fear of positive evaluation only indirectly predicted anxiety severity via fear of negative evaluation. CONCLUSIONS: Previous fears of negative evaluation could not fully explain future fears of positive evaluation (or vice-versa), which is consistent with the two constructs being likely distinct in social anxiety disorder. Given its more direct relationship with social anxiety severity, fear of negative evaluation should be targeted in treatment, as this could both directly reduce social anxiety severity and minimize the indirect impact of fear of positive evaluation.

Imagery Rescripting for Anxiety Disorders and Obsessive-Compulsive Disorder: Recent Advances and Future Directions.

PURPOSE OF REVIEW: This review describes imagery rescripting (ImRs) and its clinical application to anxiety disorders and obsessive-compulsive disorder (OCD). Variations in ImRs delivery, clinical evidence, and theories of potential mechanisms of change are also reviewed. Finally, we propose a future research agenda. RECENT FINDINGS: There is some evidence that ImRs affects memory processes and schemas. ImRs is associated with reductions in cognitive-affective, physiological and behavioural symptoms of social anxiety disorder and reductions in OCD-related distress and OCD symptoms. ImRs for other anxiety disorders has not been evaluated. While ImRs appears to be an effective intervention for social anxiety disorder and OCD, more research is needed to (a) systematically compare ImRs to established interventions, (b) evaluate ImRs for other anxiety disorders, (c) test theorized mechanisms of change, and (d) evaluate the impact of moderating factors and treatment variations on therapeutic outcomes.

The impact of methodological and measurement factors on transdiagnostic associations with intolerance of uncertainty: A meta-analysis.

Intolerance of uncertainty is a dispositional trait associated with a range of psychological disorders, but the influence of methodological factors on theses associations remains unknown. The first aim of this meta-analysis was to quantify the strengths of the association between IU and symptoms of generalised anxiety disorder, social anxiety disorder, panic disorder, agoraphobia, obsessive compulsive disorder, depression, and eating disorders. The second aim was to assess the influence of methodological factors on these relationships, including clinical (vs. non-clinical) status, age group, sex, IU measure, and symptom measure. We extracted 181 studies (N participants = 52,402) reporting 335 independent effect sizes (Pearson's r). Overall, there was a moderate association between IU and symptoms (r = 0.51, 95% CI = 0.50-0.52), although heterogeneity was high (I2 = 83.50, p < .001). Some small but significant moderator effects emerged between and within disorders. Effect sizes were not impacted by sample size. The results indicate that IU has robust, moderate associations with a range of disorder symptoms, providing definitive evidence for the transdiagnostic nature of IU.

Repetitive Negative Thinking as a Transdiagnostic Predictor of Depression and Anxiety Symptoms in Adolescents.

Repetitive negative thinking (RNT) is a transdiagnostic process associated with numerous emotional disorders. Most measures of RNT are disorder-specific, limiting utility in comorbid populations. Transdiagnostic measures of RNT have been developed in adults and are associated with anxiety and depression. However, a transdiagnostic measure is needed to assess RNT in adolescents as a potential vulnerability factor for emotional disorders. This study validates a transdiagnostic measure of RNT-Repetitive Thinking Questionnaire-10 (RTQ-10)-in adolescents ( N = 840, Mage = 15.7 years). Exploratory and confirmatory factor analyses supported a unidimensional structure. The RTQ-10 manifested good internal consistency and measurement invariance across genders and age. RNT was equally associated with anxiety and depression symptoms irrespective of gender or age. Convergent validity was demonstrated by correlations with disorder-specific measures of RNT. These findings support the RTQ-10 as a reliable and valid transdiagnostic measure of RNT in adolescents.

Attenuated Psychophysiological Reactivity following Single-Session Group Imagery Rescripting versus Verbal Restructuring in Social Anxiety Disorder: Results from a Randomized Controlled Trial.

BACKGROUND: The effectiveness of psychotherapies for social anxiety disorder (SAD) is typically evaluated using self- and clinician-reported symptom change, while biomarkers of treatment response are rarely measured. The current study aimed to compare biomarkers of response following two brief group interventions for SAD. METHODS: This randomized controlled trial evaluated the effectiveness of single-session group interventions for SAD (n = 58) - imagery rescripting (IR) and verbal restructuring (VR) versus waitlist control (WC). The IR intervention guided participants to rescript autobiographical memories through visualization whilst the VR intervention focused on thought challenging. Trial outcomes included change in psychophysiological reactivity (heart rate variability (HRV) and electrodermal responding) to social stress, and symptom-based measures (social interaction anxiety, negative self-portrayal, cognitive avoidance, repetitive negative thinking, memory modification, anxious behaviors). RESULTS: Psychophysiological reactivity was selectively attenuated following IR treatment, compared to VR and WC groups. The specific influence of the imagery-based intervention in modulating autonomic reactivity was evident across HRV parameters, including the standard deviation of intervals between heartbeats (IR vs. WC, d = 0.67, p = 0.021; IR vs. VR, d = 0.58, p = 0.041), and high frequency power - an indicator of parasympathetically mediated emotion regulation (IR vs. WC, d = 0.75, p = 0.034; IR vs. VR, d = 0.95, p = 0.006). Few group differences were observed across self-report measures. CONCLUSION: The current study highlights the specificity of brief imagery-based interventions in influencing psychophysiological reactivity in SAD and establishes the sensitivity of objective markers of treatment response in quantifying change over symptom-based measurements.

White matter alterations in the internal capsule and psychomotor impairment in melancholic depression.

Emerging evidence suggests that structural brain abnormalities may play a role in the pathophysiology of melancholic depression. We set out to test whether diffusion-derived estimates of white matter structure were disrupted in melancholia in regions underpinning psychomotor function. We hypothesized that those with melancholia (and evidencing impaired psychomotor function) would show disrupted white matter organization in internal capsule subdivisions. Diffusion magnetic resonance imaging (dMRI) data were acquired from 22 melancholic depressed, 23 non-melancholic depressed, and 29 healthy control participants. Voxel-wise fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) values were derived for anterior, posterior, and retrolenticular limbs of the internal capsule and compared between groups. Neuropsychological (reaction time) and psychomotor functioning were assessed and correlated against FA. Fractional anisotropy was distinctly increased, whilst RD was decreased, in the right anterior internal capsule in those with melancholia, compared to controls. The right anterior limb of the internal capsule correlated with clinical ratings of psychomotor disturbance, and reduced psychomotor speed was associated with increased FA values in the right retrolenticular limb in those with melancholia. Our findings highlight a distinct disturbance in the local white matter arrangement in specific regions of the internal capsule in melancholia, which in turn is associated with psychomotor dysfunction. This study clarifies the contribution of structural brain integrity to the phenomenology of melancholia, and may assist future efforts seeking to integrate neurobiological markers into depression subtyping.

Transdiagnostic assessment of repetitive negative thinking and responses to positive affect: Structure and predictive utility for depression, anxiety, and mania symptoms.

BACKGROUND: Repetitive negative thinking (RNT) is a cognitive process that is repetitive, passive, relatively uncontrollable, and focused on negative content, and is elevated in emotional disorders including depression and anxiety disorders. Repetitive positive thinking is associated with bipolar disorder symptoms. The unique contributions of positive versus negative repetitive thinking to emotional symptoms are unknown. The first aim of this study was to use confirmatory factor analyses to evaluate the psychometrics of two transdiagnostic measures of RNT, the Repetitive Thinking Questionnaire (RTQ-10) and Perseverative Thinking Questionnaire (PTQ), and a measure of repetitive positive thinking, the Responses to Positive Affect (RPA) Questionnaire. The second aim was to determine incremental predictive utility of these measures. METHOD: All measures were administered to a sample of 2088 undergraduate students from the Netherlands (n = 992), Australia (n = 698), and America (n = 398). RESULTS: Unidimensional, bifactor, and three-factor models were supported for the RTQ-10, PTQ, and RPA, respectively. A common factor measured by all PTQ items explained most variance in PTQ scores suggesting that this measure is essentially unidimensional. The RNT factor of the RTQ-10 demonstrated the strongest predictive utility, although the PTQ was also uniquely although weakly associated with anxiety, depression, and mania symptoms. The RPA dampening factor uniquely predicted anxiety and depression symptoms, suggesting that this scale is a separable process to RNT as measured by the RTQ-10 and PTQ. LIMITATIONS: Findings were cross-sectional and need to be replicated in clinical samples. CONCLUSIONS: Transdiagnostic measures of RNT are essentially unidimensional, whereas RPA is multidimensional. RNT and RPA have unique predictive utility.

Social anxiety disorder: looking back and moving forward.

Fifty years have passed since social anxiety disorder (SAD) was first differentiated from other phobias. In the years since research has largely aligned with the zeitgeist of categorical classificatory frameworks, and has spanned identifying causes, maintenance factors and innovative interventions. Despite significant advances in the field, the capacity to conceptualise SAD as an independent entity is limited given the heterogeneity and dimensionality of diagnostic criteria, high rates of comorbidity, and non-specificity of aetiological mechanisms, maintaining factors and approaches to treatment. The Research Domain Criteria (RDoC) initiative was developed in an effort to overcome the inherent limitations posed by descriptive diagnostic systems - particularly in terms of reliability and validity - and in doing so seeks to facilitate research into underlying pathophysiological and behavioural mechanisms that cut across traditional diagnostic boundaries. The RDoC framework is furnished with a 'matrix', which in essence corresponds to a set of research principles that attempt to reconcile neuroscience and psychopathology. This review outlines a rationale for integrating SAD research with the RDoC approach, and offers examples of how future studies may wish to frame hypotheses and design experiments as the field moves towards classifying dimensions of psychopathology through a mechanistic understanding of underlying neurobiological and behavioural processes.

Assessing the efficacy of imagery-enhanced cognitive behavioral group therapy for social anxiety disorder: Study protocol for a randomized controlled trial.

Cognitive behavior group therapy (CBGT) is effective for social anxiety disorder (SAD), but a substantial proportion of patients do not typically achieve normative functioning. Cognitive behavioral models of SAD emphasize negative self-imagery as an important maintaining factor, and evidence suggests that imagery is a powerful cognitive mode for facilitating affective change. This study will compare two group CBGT interventions, one that predominantly uses verbally-based strategies (VB-CBGT) and another that predominantly uses imagery-enhanced strategies (IE-CBGT), in terms of (a) efficacy, (b) mechanisms of change, and (c) cost-effectiveness. This study is a parallel groups (two-arm) single-blind randomized controlled trial. A minimum of 96 patients with SAD will be recruited within a public outpatient community mental health clinic in Perth, Australia. The primary outcomes will be self-reported symptom severity, caseness (SAD present: yes/no) based on a structured diagnostic interview, and clinician-rated severity and life impact. Secondary outcomes and mechanism measures include blind observer-rated use of safety behaviors, physiological activity (heart rate variability and skin conductance level) during a standardized speech task, negative self-beliefs, imagery suppression, fear of negative and positive evaluation, repetitive negative thinking, anxiety, depression, self-consciousness, use of safety behaviors, and the EQ-5D-5L and TiC-P for the health economic analysis. Homework completion, group cohesion, and working alliance will also be monitored. The outcomes of this trial will inform clinicians as to whether integrating imagery-based strategies in cognitive behavior therapy for SAD is likely to improve outcomes. Common and distinct mechanisms of change might be identified, along with relative cost-effectiveness of each intervention.

Out-of-sync: disrupted neural activity in emotional circuitry during film viewing in melancholic depression.

While a rich body of research in controlled experiments has established changes in the neural circuitry of emotion in major depressive disorders, little is known as to how such alterations might translate into complex, naturalistic settings--namely involving dynamic multimodal stimuli with rich contexts, such as those provided by films. Neuroimaging paradigms employing dynamic natural stimuli alleviate the anxiety often associated with complex tasks and eschew the need for laboratory-style abstractions, hence providing an ecologically valid means of elucidating neural underpinnings of neuropsychiatric disorders. To probe the neurobiological signature of refined depression subtypes, we acquired functional neuroimaging data in patients with the melancholic subtype of major depressive disorder during free viewing of emotionally salient films. We found a marked disengagement of ventromedial prefrontal cortex during natural viewing of a film with negative emotional valence in patients with melancholia. This effect significantly correlated with depression severity. Such changes occurred on the background of diminished consistency of neural activity in visual and auditory sensory networks, as well as higher-order networks involved in emotion and attention, including bilateral intraparietal sulcus and right anterior insula. These findings may reflect a failure to re-allocate resources and diminished reactivity to external emotional stimuli in melancholia.

Disrupted effective connectivity of cortical systems supporting attention and interoception in melancholia.

IMPORTANCE: Patients with melancholia report a distinct and intrusive dysphoric state during internally generated thought. Melancholia has long been considered to have a strong biological component, but evidence for its specific neurobiological origins is limited. The distinct neurocognitive, psychomotor, and mood disturbances observed in melancholia do, however, suggest aberrant coordination of frontal-subcortical circuitry, which may best be captured through analysis of complex brain networks. OBJECTIVE: To investigate the effective connectivity between spontaneous (resting-state) brain networks in melancholia, focusing on networks underlying attention and interoception. DESIGN, SETTING, AND PARTICIPANTS: We performed a cross-sectional, observational, resting-state functional magnetic resonance imaging study of 16 participants with melancholia, 16 with nonmelancholic depression, and 16 individuals serving as controls at a hospital-based research institute between August 30, 2010, and June 27, 2012. We identified 5 canonical resting-state networks (default mode, executive control, left and right frontoparietal attention, and bilateral anterior insula) and inferred spontaneous interactions among these networks using dynamic causal modeling. MAIN OUTCOMES AND MEASURES: Graph theoretic measures of brain connectivity, namely, in-degree and out-degree of each network and edge connectivity, between regions composed our principal between-group contrasts. RESULTS: Melancholia was characterized by a pervasive disconnection involving anterior insula and attentional networks compared with participants in the control (Mann-Whitney, 189.00; z = 2.38; P = .02) and nonmelancholic depressive (Mann-Whitney, 203.00; z = 2.93; P = .004) groups. Decreased effective connectivity between the right frontoparietal and insula networks was present in participants with melancholic depression compared with those with nonmelancholic depression (χ2 = 8.13; P = .004). Reduced effective connectivity between the insula and executive networks was found in individuals with melancholia compared with healthy controls (χ2 = 8.96; P = .003). CONCLUSIONS AND RELEVANCE: We observed reduced effective connectivity in resting-state functional magnetic resonance imaging between key networks involved in attention and interoception in melancholia. We propose that these abnormalities underlie the impoverished variety and affective quality of internally generated thought in this disorder.

Scene unseen: Disrupted neuronal adaptation in melancholia during emotional film viewing.

Impairments in attention and concentration are distinctive features of melancholic depression, and may diminish the ability to shift focus away from internal dysphoric states. Disrupted brain networks may underlie the inability to effectively disengage from interoceptive signals in this disorder. This study investigates changes in effective connectivity between cortical systems supporting attention, interoception, and perception in those with melancholic depression when shifting attention from rest to viewing dynamic film stimuli. We hypothesised that those with melancholia would show impaired attentional shifting from rest to emotional film viewing, captured in neuronal states that differed little across conditions. Functional magnetic resonance imaging (fMRI) data were acquired from 48 participants (16 melancholic depressed, 16 non-melancholic depressed, and 16 healthy controls) at rest and whilst viewing emotionally salient movies. Using independent component analysis, we identified 8 cortical modes (default mode, executive control, left/right frontoparietal attention, left/right insula, visual and auditory) and studied their dynamics using dynamic causal modelling. Engagement with dynamic emotional material diminished in melancholia and was associated with network-wide increases in effective connectivity. Melancholia was also characterised by an increase in effective connectivity amongst cortical regions involved in attention and interoception when shifting from rest to negative film viewing, with the converse pattern in control participants. The observed involvement of attention- and insula-based cortical systems highlights a potential neurobiological mechanism for disrupted attentional resource allocation, particularly in switching between interoceptive and exteroceptive signals, in melancholia.

Bias and discriminability during emotional signal detection in melancholic depression.

BACKGROUND: Cognitive disturbances in depression are pernicious and so contribute strongly to the burden of the disorder. Cognitive function has been traditionally studied by challenging subjects with modality-specific psychometric tasks and analysing performance using standard analysis of variance. Whilst informative, such an approach may miss deeper perceptual and inferential mechanisms that potentially unify apparently divergent emotional and cognitive deficits. Here, we sought to elucidate basic psychophysical processes underlying the detection of emotionally salient signals across individuals with melancholic and non-melancholic depression. METHODS: Sixty participants completed an Affective Go/No-Go (AGN) task across negative, positive and neutral target stimuli blocks. We employed hierarchical Bayesian signal detection theory (SDT) to model psychometric performance across three equal groups of those with melancholic depression, those with a non-melancholic depression and healthy controls. This approach estimated likely response profiles (bias) and perceptual sensitivity (discriminability). Differences in the means of these measures speak to differences in the emotional signal detection between individuals across the groups, while differences in the variance reflect the heterogeneity of the groups themselves. RESULTS: Melancholic participants showed significantly decreased sensitivity to positive emotional stimuli compared to those in the non-melancholic group, and also had a significantly lower discriminability than healthy controls during the detection of neutral signals. The melancholic group also showed significantly higher variability in bias to both positive and negative emotionally salient material. CONCLUSIONS: Disturbances of emotional signal detection in melancholic depression appear dependent on emotional context, being biased during the detection of positive stimuli, consistent with a noisier representation of neutral stimuli. The greater heterogeneity of the bias across the melancholic group is consistent with a more labile disorder (i.e. variable across the day). Future work will aim to understand how these findings reflect specific individual differences (e.g. prior cognitive biases) and clarify whether such biases change dynamically during cognitive tasks as internal models of the sensorium are refined and updated in response to experience.

Loss of light in the eyes: a window to melancholia.

Melancholia has long evaded attempts at clarifying underlying biological signals. Techniques that have attempted differentiation of melancholia from the non-melancholic conditions have largely weighted a greater contribution of biological factors to melancholia. More recently, several avenues of research have highlighted the potential utility of visual electrophysiological technologies in clarifying disease processes, driven by reports of those with melancholia that life loses its 'colour', and by clinical observations that such patients often 'lose the light in their eyes' during an episode. This led to the development of our hypothesis that melancholia may be able to be measured through the eyes reflected by disrupted dopaminergic signaling in the retina, thus allowing clarification of any hypodopaminergic contribution to the disorder. We report on research from visual neuroscience and research localizing key brain structures as well as consider likely genetic contributions to propose a unique paradigm for pursuing the biological basis of melancholic depression.