Understanding the Link ​between
Mood, Anxiety, and Stress

This study explores how the body’s built-in defense responses—automatic reactions that help us respond to stress—may play a role in different types of anxiety. By looking at how these responses range from specific fears to more general feelings of distress and how they are impacted by retained reflexes, this research helps parents better understand how anxiety can show up in children. Enjoy!

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Abstract

Guided by the diagnostic nosology, anxiety patients are expected to show defensive hyperarousal during affective challenge, irrespective of the principal phenotype. In the current study, patients representing the whole spectrum of anxiety disorders (i.e., specific phobia, social phobia, panic disorder with or without agoraphobia, obsessive-compulsive disorder, generalized anxiety disorder (GAD), posttraumatic stress disorder(PTSD)), and healthy community control participants, completed an imagery-based fear elicitation paradigm paralleling conventional intervention techniques. Participants imagined threatening and neutral narratives as physiological responses were recorded. Clear evidence emerged for exaggerated reactivity to clinically relevant imagery—most pronounced in startle reflex responding. However, defensive propensity varied across principal anxiety disorders. Disorders characterized by focal fear and impairment (e.g., specific phobia) showed robust fear potentiation. Conversely, for disorders of long-enduring, pervasive apprehension and avoidance with broad anxiety and depression comorbidity (e.g., PTSD secondary to cumulative trauma, GAD), startle responses were paradoxically diminished to all aversive contents. Patients whose expressed symptom profiles were intermediate between focal fearfulness and broad anxious-misery in both severity and chronicity exhibited a still heightened but more generalized physiological propensity to respond defensively. Importantly, this defensive physiological gradient—the inverse of self-reported distress—was evident not only between but also within disorders. These results highlight that fear circuitry could be dysregulated in chronic, pervasive anxiety, and preliminary functional neuroimaging findings suggest that deficient amygdala recruitment could underlie attenuated reflex responding. In summary, adaptive defensive engagement during imagery may be compromised by long-term dysphoria and stress—a phenomenon with implications for prognosis and treatment planning. Depression and Anxiety 29:264–281, 2012.

Keywords: imagery, anxiety disorders, specific phobia, social phobia, panic, agoraphobia, GAD, comorbidity, depression, PTSD, trauma, chronicity, emotional reactivity, blunting, diagnostic subtypes, psychophysiology, startle, fMRI, neuroimaging

EMOTIONS AS ACTION DISPOSITIONS

From the perspective of natural science, human emotions include three measurable response classes: verbal reports of experience, overt actions, and associated physiological mobilization.[1] Several theorists have proposed[2–4] that primitive survival reflexes are the foundation for emotion’s physiological mobilization and action. That is, humans and other animals approach elements that sustain life (appetitive motivation) and fight or flee amidst threats to continued existence (defensive motivation). Humans, however, seldom react as directly as do less complex species. With the development of higher order cortices, emerged enhanced capacity for inhibition and delay, and evaluation of alternatives and outcomes. Nevertheless, primitive reactance is adumbrated in muscles and glands, supported by neural circuits deep within the brain and widely shared among species. For this reason, emotions (fear and anger; joy and desire) are considered action dispositions[5] and as such are often most evident when humans are overtly passive, but mobilized somatically and autonomically for actions that may never actually manifest.

ANXIETY, DEFENSIVE PHYSIOLOGY, AND THE DSM-IV

Throughout the diagnostic nosology,[6] anxiety disorders are fundamentally conceptualized as disruptions of emotional processing, more specifically of exaggerated propensities to respond defensively to stimuli typically perceived as mildly threatening or even innocuous. Based on the supposition that emotional experience of fear and/or anxiety includes not only subjective distress and behavior (i.e., escape/avoidance) but accompanying physiological activation, the canon lists for each diagnosis at least one physiological symptom intended to reflect arousal secondary to disorder-related distress. Notably, prototypical physiological activation patterns have not been identified for respective disorders, suggesting that physiological hyperarousal is an undifferentiated constituent of clinical anxiety—similarly heightened across symptom presentations.

INTERNALIZING SYMPTOMATOLOGY: A DISCERNIBLE UNDERLYING STRUCTURE?

Epidemiological phenotypic[7–11] and genotypic[12–14] factor analytic studies of anxiety and mood disorder comorbidity have revealed a common internalizing dimension, typically expressed as one of two classes of disorders, circumscribed fear versus pervasive anxiety and sadness. Phobic disorders (specific and social phobia) are conceptualized as expressions of underlying fear pathology whereas generalized anxiety disorder (GAD), dysthymia, and depression, showing strong common affinity, reflect latent anxious-misery/distress.

Although epidemiological data have provided compelling evidence of focal fearfulness and broad anxiety as organizing concepts, there is a paucity of complementary objective evidence. Recently, the National Institute of Mental Health has initiated the Research Domain Criteria Project (RDoC[15–18]) to promote investigation of basic mechanisms underlying mental illness, unconstrained by conventional diagnostic boundaries, with the aim of explicating endophenotypes[19] or response measures (e.g., reaction time, autonomic and startle reflexes, brain circuit connectivity)—presumably informative indices of the elementary organic dysfunction (e.g., gene expression).

Consistent with the aims of the RDoC, in this review, we integrate recent results from a psychophysiological investigation of the full range of anxiety spectrum disorders, evaluating reflex outputs from the brain’s fear/defense circuitry during aversive imagery. Following a brief review of somatovisceral and functional neuroimaging patterns elicited by imagery, we consider observed defensive profiles both within as well as between anxiety disorders toward the goal of determining the relative influence of disorder-specific as well as nonspecific features in defensive mobilization.

MENTAL IMAGERY AS A WINDOW INTO EMOTIONAL EXPERIENCE

Mental imagery, especially of an affectively laden narrative, in which the participant imagines the engaging role of active protagonist, has been a productive means of instantiating observable affective dispositions.[20–22] From hundreds of unselected participants, we have collected normative ratings of pleasure and arousal for a wide range of narrative scripts (Affective Norms for English Text,[23]) and found the same pattern that emerged for pictures (International Affective Picture System,[24]). These data attest that despite the effort involved in generating a mental image, emotional narratives prime motivational dispositions analogously to external percepts. In fact, physiological arousal during threat imagery parallels anticipatory reactions to in vivo threat,[21] similarly mobilizing the autonomic nervous system (e.g., heart rate, skin conductance), communicating distress through facial musculature (e.g., corrugator “frown” muscle), prompting somatic reflexive action (e.g., startle potentiation),[22] enhancing attention allocation (e.g., electrocortical activity[25]), and yielding verbal evaluations of intense aversion. Not surprisingly, imagery has been incorporated into empirically supported treatments of fear and anxiety to selectively prompt clinically relevant distress with the goal of promoting habituation and, ultimately, extinction. Aversive imagery, indeed, is a component in numerous conventional behavioral methodologies implemented to treat the entire anxiety spectrum (e.g., specific phobia,[26] panic disorder,[27] posttraumatic stress disorder (PTSD),[28, 29] GAD[30]). Script-driven imagery is an especially flexible tool in experimental and therapeutic contexts as it permits presentation of not only standard, but also personal threat challenges, the latter being essential given the idiosyncratic nature of human experience and consequent fear and apprehension.

MOTIVATIONAL CIRCUITRY AND EMOTIONAL IMAGERY

The use of imagery to elicit clinically pertinent distress is premised on the expectation that imagining frightening narratives activates brain circuitry implicated in animal models of human fear.[31] In a series of functional neuroimaging studies[32–34] from our laboratory, we have observed a corticolimbic network that reliably activates during aversive relative to neutral imagery even in nonclinical samples. These distributed neural sources are consistent with Bioinformational Theory,[35] which conceptualizes emotional imagery as episodes encoded in memory via associative networks including (1) stimulus or sensory representations (cues perceived in the context), (2) meaning representations (semantic information “about” the context), and (3) response representations (behavior and physiology that occur in the context). The response representation or procedural knowledge is of particular significance for the action mobilization characteristic of emotional engagement. It is these efferent memories that are most directly connected to the brain’s motivational system (appetitive or defensive), presumably intrinsic to the pronounced physiological arousal evidenced in the psychophysiological laboratory. Guided by this conception, response dispositions primed during aversive imagery should be observable in neural substrates. Accordingly, blood-oxygen level dependent (BOLD) signal increases have reliably emerged in supplementary and presupplementary motor areas, precentral gyrus, and cerebellum[31–33]—regions involved in planning and executing motor action. Corresponding enhancements have been demonstrated in ventrolateral inferior frontal gyrus and dorsal medial prefrontal and dorsal parietal cortex, perhaps reflecting semantic elaboration and sensory integration subserving the generation of a vivid mental image of the self. Importantly, in contrast to imagery of simple visual scenes[36] or motor execution,[37] enhanced defensive motivation was clearly evidenced by middle temporal lobe, insula, and amygdala recruitment—activation that strongly covaried with subjective arousal (Fig. 1). Functional connectivity analyses further confirmed that these premotor and motivational regions contribute to a network of coordinated cortico-cortical and corticolimbic loops sensitive to the emotional intensity of imagined narratives.[38]

Figure 1.