روابط غیر خطی بین اضطراب و پردازش بصری از چهره خود و دیگران در اختلال بدریخت انگاری

Individuals with body dysmorphic disorder (BDD) often experience anxiety, as well as perceptual distortions of appearance. Anxiety has previously been found to impact visual processing. This study therefore tested the relationship between anxiety and visual processing of faces in BDD. Medication-free participants with BDD (N=17) and healthy controls (N=16) viewed photographs of their face and a familiar face during functional magnetic resonance imaging. Blood–oxygen-level dependent signal changes in regions involved in anxiety (amygdala) and detailed visual processing (ventral visual stream—VVS) were regressed on anxiety scores. Significant linear relationships between activity in the amygdala and VVS were found in both healthy controls and individuals with BDD. There was a trend of a quadratic relationship between anxiety and activity in the right VVS and a linear relationship between anxiety and activity in the left VVS for the BDD sample, and this was stronger for own-face stimuli versus familiar-face. Results suggest that anxiety symptoms in BDD may be associated with activity in systems responsible for detailed visual processing. This may have clinical implications related to heightened perceptual distortions associated with anxiety.

Individuals with body dysmorphic disorder (BDD) are preoccupied with perceived appearance defects. They subsequently believe that they look disfigured and ugly, and suffer distress and functional impairment. BDD affects approximately 1–2% of the population (Otto et al., 2001, Rief et al., 2006 and Koran et al., 2008), and is associated with high lifetime rates of psychiatric hospitalization (48%) and suicide attempts (22–27.5%) (Phillips, 2007). Despite its prevalence and severity, little is known of the pathophysiology or neurobiology of BDD. Clinical observation suggests that patients focus primarily on details of their appearance at the expense of global or configural aspects, which may account for their perceptual distortions. Patients most often perceive “defects” of their face and head areas, such as skin, hair, and nose (Phillips, 2005), although perceived defects of other body parts are sometimes present. Neuropsychological data suggest that individuals with BDD demonstrate abnormal patterns of information processing consisting of selective recall of details rather than global features (Deckersbach et al., 2000). A previous functional magnetic resonance imaging (fMRI) study reported abnormal neural correlates of own-face processing in BDD relative to healthy controls. Results demonstrated correlations in the BDD group between BDD symptoms and activity in visual processing and frontostriatal systems (Feusner et al., 2010a and Feusner et al., 2010b). Participants in this study had varying degrees of anxiety, and in some cases comorbid generalized anxiety disorder (GAD), major depressive disorder (MDD) and/or dysthymia. The complex relationship between different symptom dimensions and brain pathophysiology is not entirely clear. Because lifetime prevalence of other Axis I comorbid disorders are high in BDD: 36–76% for major depressive disorder, 34–47% for social phobia, 21–39% for OCD, 16–26% for other anxiety disorders (including 18.8% for GAD (Zimmerman and Mattia, 1998)), and 10–32% for eating disorders (Gunstad and Phillips, 2003, Phillips et al., 2005 and Ruffolo et al., 2006), it is important to understand the relationship between co-occurring symptom dimensions and brain pathophysiology. Thus, the present study analyzed data from this previous study, focusing on the impact of a frequently comorbid psychiatric symptom: anxiety. We focus on the effects of anxiety in the present study because previous studies suggest that anxiety may influence visual processing. Degree of trait anxiety correlates with enhanced contrast detection (Laretzaki et al., 2008), and viewing fearful faces appears to enhance contrast sensitivity both independently of, and synergistically with, attention (Phelps et al., 2006). Several functional imaging studies have demonstrated that, in healthy controls (Bradley et al., 2003, Junghofer et al., 2005 and Sabatinelli et al., 2005) and social phobia (Goldin et al., 2009 and Straube et al., 2005), viewing of pictures with emotional content is associated with enhanced activation in the amygdala, as well as occipital and inferior temporal regions. Connections between the amygdala and the ventral visual stream (VVS) may carry top-down signals regarding emotional valence of stimuli to the visual cortex, resulting in enhanced visual processing of emotionally salient stimuli. Evidence of this comes from neuroimaging studies in which amygdala activation was found to correlate with activation in the visual cortex (Morris et al., 1998a, Morris et al., 1998b and Pessoa et al., 2002). In patients with amygdala damage this correlation is attenuated (Vuilleumier et al., 2004). Given these previous findings of anxiety effects on visual processing, and given the prevalence of the symptom of anxiety and evidence for abnormal visual processing in BDD, the primary objective of the current study was to use fMRI to determine the relationship between anxiety and neural systems associated with visual processing in individuals with BDD. We selected the VVS as our region of interest because of the importance of this region in visual processing, as well as the aforementioned correlations between activity in the amygdala and visual cortex in healthy controls. Although the fusiform face area has been implicated as an important region for face processing in prior studies (Kanwisher et al., 1997), we focused on the VVS as a whole because the relationship between anxiety/limbic system activity and activity in the visual system appears to encompass a broader visual processing network (Morris et al., 1998a, Morris et al., 1998b, Bradley et al., 2003, Vuilleumier et al., 2004, Junghofer et al., 2005 and Sabatinelli et al., 2005). We hypothesized that anxiety scores would correlate positively with activity in the VVS in individuals with BDD, as a result of a greater propensity for emotional arousal and therefore subsequent enhanced analytic and detailed visual processing, and that these relationships would be similar across BDD participants regardless of comorbid diagnoses of anxiety or depressive disorders. Although individuals with comorbid diagnoses will tend to have higher levels of anxiety (hence meeting threshold criteria for diagnosis), the effect of anxiety depending on comorbidity is more likely to be a quantitative rather than qualitative one. We also predicted that these relationships would be stronger for own-face relative to familiar-face stimuli because of greater emotional salience in BDD. Finally, we hypothesized that correlations between amygdala and VVS activity would be stronger for own-face relative to familiar-face viewing as a result of greater emotional salience. We predicted these correlations would be similar between BDD and healthy control groups, although the resultant effect in the BDD group would likely be heightened because they experience greater emotional arousal for their own face.