Emotional Numbing 1 Word count: 1,436 EMOTIONAL NUMBING IN PTSD Vera Vine Kristalyn Salters - Pedneault Brett T. Litz National Center for PTSD Behavioral Science Division Veterans Affairs Boston Healthcare System Boston University School of Medicine Corresponding Auth or: Brett T. Litz, PhD National Center for PTSD (116B - 5) VA Boston Healthcare System 150 South Huntington Avenue Boston, MA 02130 Phone: 857 - 364 - 4131 Fax: 857 - 364 - 6523 Brett.Litz@va.gov Emotional Numbing 2 What is Emotional Numbing? Many people with posttraumatic stress d isorder (PTSD) report a compromised ability to experience and express emotions, a phenomenon called "emotional numbing” (EN). Formally, a cluster of t hree sets of disturbances and problems comprise EN in the current nosology for PTSD in DSM - IV : (a) markedl y diminished interest in significant activities; (b) feelings of detachment or estrangement from others; and (c) restricted range of affect. Although these three symptoms are listed under the “Cluster C” category in the DSM - IV (i.e., “ Persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness ”) , together with two symptoms representing effortful attempts to avoid trauma - related cues and experiences related to the trauma , recent studies suggest that the EN cluster is a un ique facet of PTSD The two remaining symptoms listed under the Cluster C category are “difficulty recalling aspects of the trauma” and “feeling as if one’s future will be cut short.” These symptoms are sometimes grouped together into the EN cluster in re search studies; however, they do not fit well into any conceptual or operational definition of emotional disturbances implicated by exposure to trauma. Inter est in EN has been growing in research , due in part to its impact on functioning and quality of l ife. Reports of EN are associated with considerable psychosocial functioning problems, including relationship distress, reduced participation in recreational activities, and difficulty meeting work, school, or homemaking responsibilities. Nevertheless, EN is under - researched and remains one of the least understood aspects of PTSD. For example, it is not known whether EN is global, or constrained to specific emotions or domains of emotional responding (i.e., subjective, physiological, behavioral). Further, t he DSM criteria do not specify whether EN is generalized across contexts or occurs only in response to certain states or Emotional Numbing 3 situations, or whether the emotional deficits relate to disruption of attention to emotional stimuli or the subsequent experience of em otion. One issue that has yet to be sufficiently acknowledged or researched is the possibility that the EN construct is not specific to PTSD, but is rather a symptom of comorbid disorder s , such as depression or substance abuse. This view is partially confi rmed by the high degree of content overlap and correlations between EN symptoms and these disorders Another important question is whether the “range of affect” in PTSD is “restricted” as the DSM - IV suggests Without question, p eople with PTSD often repo rt experienc ing more negative af fect and less positive affect, which might suggest a restriction in affect valenc e ; they also report lower arousal in response to positive cues, although most individuals with depression endorse this pattern, too. Yet, patie nts with PTSD also endorse a greater intensity of negative affect and greater arousal in response to traumatic cues and other unpleasant stimuli. Therefore, on its face, a global restricted affect interpretation is invalid. In addition, there is accumulati ng empirical evidence that disputes the restricted affect model Various studies have failed to demonstrate significant differences in self - reported positive affectivity between people with and without PTSD, whereas others have found significant PTSD - relat ed differences in subjective reports of emotional responding only when traumatized individuals are exposed to reminders of their trauma Research clarifying the nature of affective deficits will need to contend with the discrepancy between subjective repo rts of emotional responding in PTSD and levels of emotional numbing measured by other methods. Although individuals with PTSD report alterations in affect and arousal , individuals with and without PTSD have been indistinguishable physiologically One study of facial expressivity using electromyography ( EMG ) , which can Emotional Numbing 4 detect physiological impulses below the visually discernible threshold, found diminished zygomatic (i. e. , smiling) responses in p eople with PTSD, but only after they were exposed to cues relat ed to their trauma. Psychological Models of Emotional Numbing The conditioning model of EN suggests a link between chronic avoidance of trauma - related cues and trauma - cued emotional experiences on one hand and EN . Effortful strategies for avoiding the sit uations and cues that trigger trauma - related intrusive thoughts may fail as intrusions become more frequent, making confrontation with stressors inevitable. The conditioning model posits that the affective system needs to “ shut down ” as a final recourse ag ainst experiencing overwhelming distress A related model views EN as a consequence of the depletion of emotional resources due to chronic hyperarousal. This resource - depletion model derives its support from evidence that trauma - related hyperarousal sympto ms strongly predict elevated levels of EN. I nformation - processing models characterize EN as a phasic , context - dependent response triggered by intrusive thoughts and emotions related to the trauma. In these models, c ues reminiscent of the trauma trigger a network of trauma - related responses. Such responses can include physiological arousal and negative affective states, defensive/avoidance behaviors, and emotions, thoughts, or interpretations related to the traumatic event. While these responses are natural and may be protective during traumatic events themselves, they tend to be maladaptive in normal, non - threatening situations, because they render brain networks related to healthy responses (e.g., positive emotion , approach behaviors ) less available Accor ding to this model, t he overall capacity to ex perience and express emotions is fundamentally unaltered in PTSD ; the Emotional Numbing 5 repertoire of emotional experience and expression becomes narrowed only in trauma - related contexts. N eurobiology of Emotional Numbing The n eurobiological mechanisms of EN are not well known in part because of the ambiguity of the EN construct. The earliest biological model s describe d EN as comparable to the sequelae of exposure to unpredictable and/or uncontrollable stressors (e.g., electric shock) demonstrated in animal conditioning research In response to unconditioned aversive stimulation (e.g., electric shock) and in the presence of conditioned fear cues (e.g., a bell that is repeatedly paired with the shock), animals undergo a series of physiological responses , including serotonin depletion and naloxone - reversible opioi d brain chemical release, resulting in “stress - induced analgesia , ” which functions to minimize pain. Because stress - induced analgesia can be conditioned, several theorists have argued that EN is a result of conditioned fear - based opioid release in response to trauma tic conditioning and exposure to conditioned trauma - related cues (i.e., during intrusions of traumatic memories ). The biological substrates of EN have not been r igorously investigated using contemporary methods from the behavioral neurosciences; most of this work has instead focused on the negative emotional hyper - responsivity associated with PTSD. One exception is a small body of electrophysiology research showin g that EN severity correlates with diminished activity in the brain’s parietal lobe. This suggests that EN may be associated with deficits in attention or the ability to consciously allocate attentional resources, although it may be confounded by a similar relationship between parietal deficits and depression. Another line of research has suggested that affect ive disturbances in PTSD are the result of unusually strong inhibition of Emotional Numbing 6 traumatic memory - related emotional arousal, based on evidence of activation in brain regions typically involved in re - interpreting or suppressing thoughts during trauma recall Summary and Future Research There is no doubt that traumatic experiences are profoundly impactful, and that the emotional residue of trauma can last a li fetime. However, it appears that the construct of EN as defined in the nosology fails to capture the unique trauma - linked phenomenology of emotional behavior abnormalities and, not surprisingly, has failed to be confirmed empirically. Although the experien ce of EN is subjectively significant for individuals with PTSD, more research is needed to clarify its key features and underlying mechanisms. Specifically, future research should clarify the conditions under which emotional deficits occur, which emotions or domains of emotional responding are affected, and the role of neurobiological factors. Ultimately, this research will have value if it impacts early intervention and tertiary care . Research on treatment outcomes associated with EN is scarce, but there i s some indication that severe EN can make it difficult for individuals to benefit from treatments that are currently available. Some researchers have proposed that treatments targeting hyperarousal might indirectly alleviate EN symptoms, while others have called for the development of new treatments specifically targeting EN Recommended reading Flack, W. F., Litz, B. T., Hsieh, F. Y., Kaloupek, D. G, & Keane, T. M. (2000). Predictors of emotional numbing, revisited: A replication and extension. Journal o f Traumatic Stress, 13 , 611 - 618. Foa, E. B., Zinbarg, R., & Rothbaum, B. O. ( 1992 ). Uncontrollability and unpredictability in post - traumatic stress disorder: An animal model. Psychological Bulletin, 112 , 218 - 238. Emotional Numbing 7 Frewen, P. A., & Lanius, R. A. (2006). Towa rd a psychobiology of posttraumatic self - dysregulation: Reexperiencing, hyperarousal, dissociation, and emotional numbing. In R. Yehuda (Ed.), Psychobiology of posttraumatic stress disorder: A decade of progress (pp. 110 - 124). Boston: Annals of the New Yor k Academy of Sciences. Litz, B. T. (1992). Emotional numbing in combat - related post - traumatic stress disorder: A critical review and reformulation. Clinical Psychology Review, 12 , 417 - 432. Litz, B. T., & Gray, M. J. (2002). Emotional numbing in posttraumat ic stress disorder: Current and future research directions. Australian and New Zealand Journal of Psychiatry, 36 , 198 - 204.