پردازش هیجانی در مقابله با اختلال استرس پس از ضربه: مقایسه با افراد نرمال و افراد دچار آسیب های روانی

Emotional numbing (EN) symptoms are an important but poorly understood component of the response to trauma. To try to demonstrate EN, this laboratory study examined subjective and psychophysiological emotion responses to standardized visual stimuli in combat veterans with posttraumatic stress disorder (PTSD), combat veterans without PTSD, and nontraumatized controls. PTSD subjects showed no evidence of generalized reduction in subjective or psychophysiological emotion responses. In response to a subset of more evocative stimuli, PTSD subjects reported less experience of Positive Emotions, and more experience of Negative Emotions than controls. For controls, valence and arousal were uncorrelated, while they were negatively correlated for PTSD subjects. Verbal and nonverbal subjective emotion measures were positively correlated for all subject groups, but there was little correlation between subjective emotion measures and psychophysiological indices. Viewing time was positively correlated with Positive Emotions for PTSD subjects, and with Negative Emotions for combat controls.

Diminished or blunted emotional responding, sometimes called “emotional numbing” (EN), constitutes one of the central symptoms in posttraumatic stress disorder (PTSD; American Psychiatric Association 1994 and Horowitz 1986). Symptoms of EN include diminished interest in activities, feeling detached or estranged from others, and restricted range of affect (American Psychiatric Association, 1994). While blunted emotional responses are defined in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) as part of the avoidance cluster of PTSD symptoms, their exact nature remains elusive (Litz, 1992). Recent findings that EN is best predicted not by the intensity of other avoidant symptoms, but by the intensity of self-reported hyperarousal symptoms (Litz et al., 1997), as well as factor analytic evidence that self-report items and structured interview responses focusing on avoidance may actually measure separate avoidance and numbing factors Amdur & Liberzon in press and King, Leskin, King, & Weathers 1998, further suggest that the true nature of EN symptoms is poorly understood. The cause of EN is equally unclear. These symptoms might occur because PTSD subjects behaviorally or cognitively avoid stimuli that would evoke emotions, or due to “depletion of biological and psychological emotional processing resources” (Litz et al., 1997). Along with EN, subjects with PTSD experience seemingly conflicting symptoms: intense affect states in which they feel overwhelmingly angry, sad, frightened, hyperaroused, and hypervigilant. It is unclear how EN and hyperemotionality co-exist in the same patient. It is possible that EN occurs cyclically, alternating with states of intense affect (as suggested by Horowitz, 1986), or that EN occurs concurrently with hyperemotionality, or that there are subtypes of PTSD, one with predominantly EN symptoms and the other predominantly hyperemotional. Furthermore, patients with PTSD often find it difficult to verbalize their emotional states (“alexithymia”; Hyer, Woods, & Boudwyns 1991, Krystal 1988, Krystal, Giller, & Cicchetti 1986 and Wehmer, Brejnak, Lumley, & Stettner 1995). This suggests that there might be a discrepancy between the semantic report and the subjective or bodily experiences of the patient. Consequently, the present study employs both physiological and self-report measures of emotional responding. EN, being a broad and loosely defined concept, has been difficult to study. Alternative conceptualizations of EN have been proposed, including: (a) a generalized deficit in emotional responding, (b) a deficit in emotional responding to positive events only, and (c) a deficit in certain emotion responses only (Litz, 1992). To further elucidate this complex phenomenon, an operational description of EN is needed that would include a set of measurable changes in specific response parameters, which occur in reaction to clearly defined emotional stimuli. This definition should specify whether there is a reduction in emotion frequency or intensity, and whether it occurs in subjective, physiological, or behavioral components of the emotion response. PTSD subjects report EN symptoms in response to structured clinical interviews and written tests, and often appear to have reduced facial expressiveness when examined clinically. As yet, there has not been a laboratory study documenting blunting of subjective and psychophysiological (expressive or visceral) emotion responses in PTSD. In the present study we manipulated affective stimuli in a laboratory setting and assessed subjects' responses to these standard stimuli across subjective and psychophysiological channels. The measurement of subjective emotion states can be performed using both “dimensional” and “discreet” conceptualization of emotions. The discreet conceptualization postulates the presence of a set of “basic” emotion states from which other emotions are built (analogous to the way “primary” colors can blend to form a wide variety of other colors; e.g., Ekman 1992, Ekman 1994, Izard 1992, Izard 1994 and Nathanson 1992 ; Tompkins 1962 and Tompkins 1963), while dimensional theories identify orthogonal factors that organize, explain, or simplify the classification of specific emotions (e.g., Russell, 1980). In particular, valence (i.e., pleasant vs. unpleasant) and arousal (calming vs. arousing) seem to be two orthogonal dimensions that have received much support, both in studies of physiological (e.g., Lang, Greenwald, Bradley, & Hamm, 1993) and subjective (e.g., Larsen & Diener 1992 and Reisenzein 1994) emotional responses. Rather than try to address this debate, we measured subjective aspects of emotion using both a set of discreet emotions and measures of emotion dimensions. We hypothesized that while the Valence and Arousal dimensions might be orthogonal for normal subjects, they would be negatively correlated for subjects with PTSD because arousal itself would be experienced as unpleasant. Psychophysiological components of the emotional response have been studied in PTSD, using measures of skin conductance response (SCR), heart rate (HR), and frontalis muscle electromyogram (EMG), in response to a variety of stimuli including standardized combat sounds or pictures, combat-related words (McNally et al., 1987), and individualized combat “scripts.” Subjects with PTSD tend to have larger HR responses Blanchard, Kolb, Pallmeyer, & Gerardi 1982, Blanchard, Kolb, Gerardi, Ryan, & Pallmeyer 1986, Blanchard, Kolb, Taylor, & Wittrock 1989, Malloy, Fairbank, & Keane 1983, McFall, Murburg, Ko, & Veith 1990 and Pallmeyer, Blanchard, & Kolb 1986 and SCR and frontalis EMG responses Orr et al. 1993, Pitman et al. 1990 and Pitman et al. 1987 than controls. Similar results have been found using a civilian trauma population (Shalev, Orr, & Pitman, 1993). If we define psychophysiological response “gain” as the strength of emotion response to a stimulus of a specific magnitude (as suggested by Cacioopo et al., 1992), these PTSD-specific findings do not support a generalized reduction in response gain for PTSD subjects, and demonstrate selectively heightened response gain for stimuli that evoke traumatic memories. This seems to contradict, at least in the realm of psychophysiology, the presence of EN. Similarly, in an unpublished study examining emotion responses to pleasant imagery, Orr (1991) found no differences in “the capacity to experience non-trauma related emotions” in Vietnam veterans with and without PTSD. However, in a different study, PTSD subjects appeared to have difficulty in appraising the emotions presented in audiotaped dialogues (Zimmering, Caddell, Fairbank, & Keane, 1984), suggesting possible difficulty in accessing emotional responses. Therefore, the available data suggest that, while the majority of PTSD patients endorse the presence of EN in self-reports, laboratory evidence for EN is scarce at best. The “elusiveness” of EN could be a result of specificity in the stimuli that evoke it, and/or specificity in the components of emotional responses. That is, EN may only occur in response to certain stimuli, and at the same time, may only occur in certain emotion response systems. Alternatively, EN could represent a mismatch or desynchrony between various components of emotional responses. For example, desynchrony could occur between physiological responses and subjective reports of specific emotion states (e.g., self-reported numbing accompanied by heightened visceral or expressive emotion responses), or between verbal reports of emotion states and nonverbal indicators of valence and arousal experiences (e.g., nonverbal ratings of stimuli as pleasant in the absence of verbal reports of experiencing pleasure). An example of desynchrony can be found in the personality literature on repressive coping style. When exposed to threatening conditions, some people (i.e., repressors) say they are calm and relaxed, even though physiological assessments indicate they are more anxious than other people in the same condition. This desynchrony between self-report and physiological measures of emotion, found in subjects with a repressive coping style, has been demonstrated in a number of studies Asendorpf & Scherer 1983, Gudjonsson 1981, Jamner & Schwartz 1986 and Weinberger, Schwartz, & Davidson 1979. We used simultaneous measures of different components of emotion responses (verbal, nonverbal, psychophysiological, and behavioral) in order to assess desynchrony. The present study was set up to examine emotional functioning in subjects with PTSD and two control groups: one with combat experience but no PTSD, and the other with no exposure to trauma. We examined subjective, psychophysiological, and behavioral aspects of emotion responses to a variety of standard emotionally evocative stimuli in an attempt to answer the following questions: (a) Do subjects with PTSD have less frequent and less intense emotion experiences than controls, in response to all stimuli? (b) Do the emotional experiences of subjects with PTSD differ from those of controls in response to only the most evocative stimuli? (c) Do subjects with PTSD have more desynchrony between subjective, visceral, and expressive emotion responses, or between verbal and nonverbal reports of subjective emotional experience? (d) Do subjects with PTSD have a different relationship between the Valence and Arousal dimensions of emotion than controls? (e) Do subjects with PTSD have patterns of stimulus viewing time indicating that they avoid distressing or arousing stimuli more t