The effects of recurrent episodes of depression on startle responses

High-throughput screening of glucocorticoid-induced enhancer activity reveals mechanisms of stress-related psychiatric disorders

Exposure to stressful life events increases the risk for psychiatric disorders. Mechanistic insight into the genetic factors moderating the impact of stress can increase our understanding of disease processes. Here, we test 3,662 single nucleotide polymorphisms (SNPs) from preselected expression quantitative trait loci in massively parallel reporter assays to identify genetic variants that modulate the activity of regulatory elements sensitive to glucocorticoids, important mediators of the stress response. Of the tested SNP sequences, 547 were located in glucocorticoid-responsive regulatory elements of which 233 showed allele-dependent activity. Transcripts regulated by these functional variants were enriched for those differentially expressed in psychiatric disorders in the postmortem brain. Phenome-wide Mendelian randomization analysis in 4,439 phenotypes revealed potentially causal associations specifically in neurobehavioral traits, including major depression and other psychiatric disorders. Finally, a functional gene score derived from these variants was significantly associated with differences in the physiological stress response, suggesting that these variants may alter disease risk by moderating the individual set point of the stress response.

Effects of maternal social isolation on adult rodent offspring cognition

Prenatal experiences can influence offspring physiology and behaviour through the lifespan. Various forms of prenatal stress impair adult learning and memory function and can lead to increased occurrence of anxiety and depression. Clinical work suggests that prenatal stress and maternal depression lead to similar outcomes in children and adolescents, however the long-term effects of maternal depression are less established, particularly in well controlled animal models. Social isolation is common in depressed individuals and during the recent COVID-19 pandemic. Accordingly, for this study we were interested in the effects of maternal stress induced via social isolation on adult offspring cognitive functions including spatial, stimulus-response, and emotional learning and memory that are mediated by different networks centered on the hippocampus, dorsal striatum, and amygdala, respectively. Tasks included a discriminative contextual fear conditioning task and cue-place water task. Pregnant dams in the social isolation group were single housed prior to and throughout gestation. Once offspring reached adulthood the male offspring were trained on a contextual fear conditioning task in which rats were trained to associate one of two contexts with an aversive stimulus and the opposing context remained neutral. Afterwards a cue-place water task was performed during which they were required to navigate to both a visible and invisible platform. Fear conditioning results revealed that the adult offspring of socially isolated mothers, but not controls, were impaired in associating a specific context with a fear-inducing stimulus as assessed by conditioned freezing and avoidance. Results from the water task indicate that adult offspring of mothers that were socially isolated showed place learning deficits but not stimulus-response habit learning on the same task. These cognitive impairments, in the offspring of socially isolated dams, occurred in the absence of maternal elevated stress hormone levels, anxiety, or altered mothering. Some evidence suggested that maternal blood-glucose levels were altered particularly during gestation. Our results provide further support for the idea that learning and memory networks, centered on the amygdala and hippocampus are particularly susceptible to the negative impacts of maternal social isolation and these effects can occur without elevated glucocorticoid levels associated with other forms of prenatal stress.

Rethinking the risk for depression using the RDoC: A psychophysiological perspective

Considering that the classical categorical approach to mental disorders does not allow a clear identification of at-risk conditions, the dimensional approach provided by the Research Domain Criteria (RDoC) is useful in the exploration of vulnerability to psychopathology. In the RDoC era, psychophysiological models have an important role in the reconceptualization of mental disorders. Indeed, progress in the study of depression vulnerability has increasingly been informed by psychophysiological models. By adopting an RDoC lens, this narrative review focuses on how psychophysiological models can be used to advance our knowledge of the pathophysiological mechanisms underlying depression vulnerability. Findings from psychophysiological research that explored multiple RDoC domains in populations at-risk for depression are reviewed and discussed. Future directions for the application of psychophysiological research in reaching a more complete understanding of depression vulnerability and, ultimately, improving clinical utility, are presented.

Unraveling the comorbidity of depression and anxiety in a large inpatient sample: Network analysis to examine bridge symptoms

BACKGROUND

Comorbidities in mental disorders are often understood by assuming a common cause. The network theory of mental disorders offers an alternative to this assumption by understanding comorbidities as mutually reinforced problems. In this study, we used network analysis to examine bridge symptoms between anxiety and depression in a large sample.

METHOD

Using data from a sample of patients diagnosed with both depression and an anxiety disorder before and after inpatient treatment (N = 5,614, mean age: 42.24, 63.59% female, average treatment duration: 48.12 days), network models of depression and anxiety symptoms are estimated. Topology, the centrality of nodes, stability, and changes in network structure are analyzed. Symptoms that drive comorbidity are determined by bridge node analysis. As an alternative to network communities based on categorical diagnosis, we performed a community analysis and propose empirically derived symptom subsets.

RESULTS

The obtained network models are highly stable. Sad mood and the inability to control worry are the most central. Psychomotor agitation or retardation is the strongest bridge node between anxiety and depression, followed by concentration problems and restlessness. Changes in appetite and suicidality were unique to depression. Community analysis revealed four symptom groups.

CONCLUSION

The estimated network structure of depression and anxiety symptoms proves to be highly accurate. Results indicate that some symptoms are considerably more influential than others and that only a small number of predominantly physical symptoms are strong candidates for explaining comorbidity. Future studies should include physiological measures in network models to provide a more accurate understanding.

Brain Correlates of Continuous Pain in Rheumatoid Arthritis as Measured by Pulsed Arterial Spin Labeling

OBJECTIVE

Central nervous system pathways involving pain modulation shape the pain experience in patients with chronic pain. The aims of this study were to understand the mechanisms underlying pain in patients with rheumatoid arthritis (RA) and to identify brain signals that may serve as imaging markers for developing targeted treatments for RA-related pain.

METHODS

Patients with RA and matched control subjects underwent functional magnetic resonance imaging, using pulsed arterial spin labeling. The imaging conditions included 1) resting state, 2) low-intensity stimulus, and 3) high-intensity stimulus. Stimuli consisted of mechanical pressure applied to metacarpophalangeal (MCP) joints with an automated cuff inflator. The low-intensity stimulus was inflation to 30 mm Hg. The high-intensity stimulus was the amount of pressure required to achieve a pain intensity rating of 40 on a 100-point scale for each RA patient, with the same amount of pressure used in the matched control.

RESULTS

Among RA patients, regional cerebral blood flow (rCBF) in the medial frontal cortex and dorsolateral prefrontal cortex increased during both low-pressure and high-pressure stimulation. No rCBF changes were observed in pain-free controls. Region-of-interest analyses in RA patients showed that baseline rCBF in the medial frontal cortex was negatively correlated with the pressure required for the high-intensity stimulus and positively correlated with pain induced by the low-intensity stimulus. Baseline rCBF was also marginally correlated with disease activity). Regional CBF during high pain was positively correlated with pain severity and pain interference.

CONCLUSION

In response to clinically relevant joint pain evoked by pressure applied to the MCP joint, neural processing in the medial frontal cortex increases and is directly associated with clinical pain in patients with RA.

Alteration of the affective modulation of the startle reflex during antidepressant treatment

Whereas the amplitude of the startle reflex varies with stimulus valence in the normal population, a lack of this affective modulation has been reported in patients with major depressive disorder. The present study sought to clarify blunted startle modulation as a feature of depression by comparing 16 patients diagnosed with major depression prior to and after 2 weeks of SSRI treatment, and 16 healthy controls. The affect-modulated startle reflex paradigm and the Self-Assessment Manikin were used to probe affective reactivity. In addition, a preliminary analysis of change in affective reactivity pattern was performed with depressed patients who could be assessed in the eighth week of treatment (n = 13). The control group showed a linear trend in response across valence categories, which was stable over sessions. Blunted affective reactivity was observed only in the patients and persisted after 2 weeks of treatment. Nevertheless, a linear trend could be detected in the eighth week of treatment. These findings confirm that the affective reactivity is blunted in depression and provide initial evidence for the lack of change in the early phase of SSRI antidepressant treatment. Nevertheless, in a small group, the emergence of a linear trend in response was evident later with treatment. Large-scale studies are required to assess the relation between the treatment response and the change in affective modulation of the startle reflex, as a potential biomarker.

Reduced positive emotion and underarousal are uniquely associated with subclinical depression symptoms: Evidence from psychophysiology, self-report, and symptom clusters

Multiple models of aberrant emotional processing in depression have been advanced. However, it is unclear which of these models best applies to emotional disturbances in subclinical depressive symptoms. The current study employed a battery of psychophysiological measures and emotional ratings in a picture-viewing paradigm to examine whether the underarousal, low positive emotion, heightened negative emotion, or emotion context insensitivity model of emotional dysfunction in subclinical depressive symptoms received greatest support. Postauricular reflex and skin conductance response potentiation for pleasant minus neutral pictures (measuring low positive emotion), overall skin conductance magnitude and late positive potential (LPP) amplitude (measuring underarousal), and pleasant minus aversive valence ratings (measuring emotion context insensitivity) and aversive minus neutral arousal ratings (measuring heightened negative emotionality) were all negatively related to depressive symptomatology. Of these, postauricular reflex potentiation and overall LPP amplitude were incrementally associated with depressive symptoms over the other measures. Postauricular reflex potentiation, overall skin conductance magnitude, and aversive minus neutral arousal ratings were incrementally associated with depressive symptomatology after controlling for other symptoms of internalizing disorders. Though no model was unequivocally superior, the low positive emotion and underarousal models received the most support from physiological measures and symptom reports, with self-report data matching patterns consistent with the emotion context insensitivity model.

Startle amplitude during unpleasant pictures is greater in veterans with a history of multiple-suicide attempts and predicts a future suicide attempt

Recent studies demonstrate that veterans exhibit higher suicide risk compared with the general U.S.

POPULATION

A prior suicide attempt is a well-documented predictor of suicide death. Despite increased attention to clinical risk factors of suicide and efforts to develop psychosocial interventions to reduce suicide risk, the underlying biological factors that confer this risk are not well understood. This study examined affect-modulated startle (AMS) during a series of intermixed unpleasant, neutral, and pleasant pictures in a sample of 108 demographically-matched veterans at low (passive ideators: n = 26) and high risk (active ideators: n = 29; single attempters: n = 28; and multiple attempters: n = 25) for suicide based on the Columbia Suicide Severity Rating Scale. An exploratory aim involved a longitudinal component in a subset of the high-risk sample that went on to participate in a randomized 6-month clinical trial. We investigated whether baseline AMS predicts a subsequent suicide attempt at 12-month follow-up. Compared with the other three groups, multiple attempters showed greater startle potentiation during unpleasant pictures and deficient overall startle habituation from early to later trials. The groups did not differ in startle during neutral or pleasant pictures, or self-reported picture valence. Greater startle during unpleasant pictures was associated with greater emotion dysregulation as measured by the Difficulties in Emotion Regulation Scale and a future suicide attempt assessed prospectively at 12-month follow-up. These findings suggest that startle potentiation during unpleasant pictures in multiple-suicide attempters is a promising psychophysiological biomarker of suicide risk and underscore the clinical importance of targeting emotion dysregulation in the treatment of patients at-risk for suicide.

The underlying neurobiology of key functional domains in young people with mood and anxiety disorders: a systematic review

BACKGROUND

Mood and anxiety disorders are leading causes of disability and mortality, due largely to their onset during adolescence and young adulthood and broader impact on functioning. Key factors that are associated with disability and these disorders in young people are social and economic participation (e.g. education, employment), physical health, suicide and self-harm behaviours, and alcohol and substance use. A better understanding of the objective markers (i.e. neurobiological parameters) associated with these factors is important for the development of effective early interventions that reduce the impact of disability and illness persistence.

METHODS

We systematically reviewed the literature for neurobiological parameters (i.e. neuropsychology, neuroimaging, sleep-wake and circadian biology, neurophysiology and metabolic measures) associated with functional domains in young people (12 to 30 years) with mood and/or anxiety disorders.

RESULTS

Of the one hundred and thirty-four studies selected, 7.6 % investigated social and economic participation, 2.1 % physical health, 15.3 % suicide and self-harm behaviours, 6.9 % alcohol and substance use, whereas the majority (68.1 %) focussed on clinical syndrome.

CONCLUSIONS

Despite the predominance of studies that solely examine the clinical syndrome of young people the literature also provides evidence of distinct associations among objective measures (indexing various aspects of brain circuitry) and other functional domains. We suggest that a shift in focus towards characterising the mechanisms that underlie and/or mediate multiple functional domains will optimise personalised interventions and improve illness trajectories.

Impact of Comorbid Depressive Disorders on Subjective and Physiological Responses to Emotion in Generalized Anxiety Disorder

Generalized anxiety disorder (GAD) and unipolar depressive disorders (UDD) have been shown to differ from each other in dimensions of affective functioning despite their high rates of comorbidity. We showed emotional film clips to a community sample (n = 170) with GAD, GAD with secondary UDD, or no diagnosis. Groups had comparable subjective responses to the clips, but the GAD group had significantly lower heart rate variability (HRV) during fear and after sadness, compared to controls. While HRV in the GAD and control groups rose in response to the sadness and happiness clips, it returned to baseline levels afterwards in the GAD group, potentially indicating lesser ability to sustain attention on emotional stimuli. HRV in the GAD + UDD group changed only in response to sadness, but was otherwise unvarying between timepoints. Though preliminary, these findings suggest comorbid UDD as a potential moderator of emotional responding in GAD.

The Power of Theory, Research Design, and Transdisciplinary Integration in Moving Psychopathology Forward

While the past few decades have seen much work in psychopathology research that has yielded provocative insights, relatively little progress has been made in understanding the etiology of mental disorders. We contend that this is due to an overreliance on statistics and technology with insufficient attention to adequacy of experimental design, a lack of integration of data across various domains of research, and testing of theoretical models using relatively weak study designs. We provide a conceptual discussion of these issues and follow with a concrete demonstration of our proposed solution. Using two different disorders - depression and substance use - as examples, we illustrate how we can evaluate competing theories regarding their etiology by integrating information from various domains including latent variable models, neurobiology, and quasi-experimental data such as twin and adoption studies, rather than relying on any single methodology alone. More broadly, we discuss the extent to which such integrative thinking allows for inferences about the etiology of mental disorders, rather than focusing on descriptive correlates alone. Greater scientific insight will require stringent tests of competing theories and a deeper conceptual understanding of the advantages and pitfalls of methodologies and criteria we use in our studies.

Heritability and molecular genetic basis of acoustic startle eye blink and affectively modulated startle response: a genome-wide association study

Acoustic startle responses have been studied extensively in relation to individual differences and psychopathology. We examined three indices of the blink response in a picture-viewing paradigm-overall startle magnitude across all picture types, and aversive and pleasant modulation scores-in 3,323 twins and parents. Biometric models and molecular genetic analyses showed that half the variance in overall startle was due to additive genetic effects. No single nucleotide polymorphism was genome-wide significant, but GRIK3 produced a significant effect when examined as part of a candidate gene set. In contrast, emotion modulation scores showed little evidence of heritability in either biometric or molecular genetic analyses. However, in a genome-wide scan, PARP14 produced a significant effect for aversive modulation. We conclude that, although overall startle retains potential as an endophenotype, emotion-modulated startle does not.

Aversive startle potentiation and fear pathology: Mediating role of threat sensitivity and moderating impact of depression

Enhanced startle reactivity during exposure to unpleasant cues (aversive startle potentiation; ASP) appears in the RDoC matrix as a physiological index of acute threat response. Increased ASP has been linked to focal fear disorders and to scale measures of dispositional fearfulness (i.e., threat sensitivity; THT+). However, some studies have reported reduced ASP for fear pathology accompanied by major depressive disorder (MDD) or pervasive distress. The current study evaluated whether (a) THT+ as indexed by reported dispositional fearfulness mediates the relationship between fear disorders (when unaccompanied by depression) and ASP, and (b) depression moderates relations of THT+ and fear disorders with ASP. Fear disorder participants without MDD showed enhanced ASP whereas those with MDD (or other distress conditions) showed evidence of reduced ASP. Continuous THT+ scores also predicted ASP, and this association: (a) was likewise moderated by depression/distress, and (b) accounted for the relationship between ASP and fear pathology without MDD. These findings point to a role for the RDoC construct of acute threat, operationalized dispositionally, in enhanced ASP shown by individuals with fear pathology unaccompanied by distress pathology.