Augmentative effects of tDCS on a body-related attentional retraining in women with bulimia nervosa

身材和体重对自尊的高估和相应的身体不满是神经性暴食症(BN)和阈值下BN(其他指定的进食或进食障碍[OSFED])的核心诊断特征。进食障碍的认知模型表明，显著的刺激，如与自我身体的接触或与另一个身体的比较，激活了选择性记忆、解释和注意力过程，被认为是与进食障碍典型相关的行为的重要组成部分，如身体检查、身体回避和病理性进食行为。相应地，眼动研究表明，患有(亚)临床饮食障碍的女性优先处理通常与体重变化有关的身体部位，或她们主观上不喜欢的身体部位(与喜欢的部位相比)。值得注意的是，实验证据表明，对身体部位的选择性注意偏差与身体不满之间存在因果联系，因为重新训练对自我定义的不好看的身体部位的注意力会减少，而重新训练对有吸引力的身体部位的注意力会提高对身体不满意的女性的身体满意度。然而，后者的难度更大，需要更广泛的再训练。最近的证据表明，经颅直流电刺激(TDC)刺激背外侧前额叶皮质(DlPFC)可以改善注意偏向，增加注意再训练的效果。因此，本项目的目的是调查积极的与身体相关的注意再训练是否减少了对不好看的身体部位的选择性注意，并提高了患有BN和阈值下BN的女性(OSFED)的身体满意度，为此，我们将招募80名符合DSM-5标准的患有BN或BN-OSFED的女性，并将她们与40名体重和年龄匹配、没有终生进食障碍的女性进行比较，通过结合眼睛跟踪和脑电(EEG)范式以及结合近红外光谱(NIRS)和眼睛跟踪范式，将注意力分配到三个自定义的最具吸引力的(不)自我身体部位及其神经生理特征。随后，只有患有BN/BN-OSFED的患者将在重复的身体相关注意再训练(AR)期间接受积极的tDCs或假的tDCs，该AR旨在增加对自定义吸引力身体部位的选择性加工，或者在受试者之间的双盲比较中分别接受各自的注意力再训练控制条件(AR-CC)。在最后一次训练后，将通过实验范式再次评估对三个自定义的最具(不)吸引力的身体部位的注意力分配。在实验期间、训练前后以及四周和三个月的随访中，将通过问卷调查来评估身体的不满意程度。

Overvaluation of shape and weight on self-esteem and corresponding body dissatisfaction are a core diagnostic feature of both bulimia nervosa (BN) and subthreshold BN (Other Specified Feeding or Eating Disorder [OSFED]). Cognitive models of eating disorders suggest that salient stimuli such as the exposure with the self-body or the comparison with another body activate selective memory, interpretation and attentional processes, assumed to substantially contribute to behavior typically associated with eating disorders such as body checking, body avoidance and pathological eating behavior. In accordance, eye movement studies showed that women with a (sub)clinical eating disorder preferentially process body parts typically associated with weight change or body parts which they subjectively dislike (compared to like). Of note, experimental evidence suggests a causal link between the selective attentional bias for body parts and body dissatisfaction, in that a retraining of attention towards self-defined unattractive body parts reduces, while a retraining of attention towards attractive body parts increases body satisfaction in body dissatisfied women. However the latter was shown to be more difficult, needing a more extensive retraining.Recent evidence suggests that the cortical stimulation of the dorsolateral prefrontal cortex (dlPFC) by transcranial direct current stimulation (tDCS) can ameliorate attentional biases and increase the effects of attentional retraining. Therefore, the aim of the present project is to investigate whether a positive body-related attentional retraining reduces selective attention for unattractive body parts and increases body satisfaction in a group of women with BN, as well as subthreshold BN (OSFED), and whether these effects can be enhanced by tDCS.To this end we will recruit a total of 80 women with BN or BN-OSFED according to DSM-5 criteria and will compare them to a group of 40 weight and age matched women without lifetime eating disorders with regard to attention allocation towards three self-defined most (un)attractive self-body parts and its neurophysiological signatures by means of a combined eye tracking and electroencephalogram (EEG) paradigm as well as a combined near-infrared spectroscopy (NIRS) and eye tracking paradigm. Subsequently, only patients with BN/BN-OSFED will be administered active tDCS or sham tDCS during a repeated body-related attentional retraining (AR) which aims to increase the selective processing of self-defined attractive body parts, or a respective attentional retraining control condition (AR-CC) in a double-blind between-subject comparison. After the last training session, attention allocation towards the three self-defined most (un)attractive self-body parts will be assessed once more by the experimental paradigms. Body dissatisfaction will be assessed by questionnaires at the experimental sessions, prior to and after the training and at four-week and three months follow-up.