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以及相应的身体不满意是神经性贪食症（BN）和阈下进食障碍（其他特定进食障碍[OSFED]）的核心诊断特征。饮食失调的认知模型表明，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、解释和注意过程，这些过程被认为是与饮食失调典型的行为（如身体检查、身体回避和病态饮食行为）有关的重要因素。与此同时，眼动研究表明，患有（亚）临床饮食失调症的女性会优先处理与体重变化相关的身体部位，或者主观上不喜欢的身体部位（而不是喜欢的）。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对身体不满意之间存在因果关系，因为对自我定义的不吸引人的身体部位的注意力再训练会减少，而对身体不满意的女性对身体部位的注意力再训练会增加对身体的满意度。但是，后一种工作比较困难，需要更广泛的再培训。最近的研究表明，经颅直流电刺激（tDCS）对背外侧前额叶皮层（dlPFC）的皮质刺激可以改善注意偏倚，增加注意再训练的效果。因此，本项目的目的是研究积极的身体相关注意再训练是否会减少BN和阈下BN （OSFED）女性对不吸引人的身体部位的选择性注意，提高身体满意度，以及tDCS是否可以增强这些效果。为此我们将招募80 BN的女性或BN-OSFED根据dsm - 5标准,将比较他们一群40体重和年龄匹配的女人没有终身饮食失调对注意分配对三个自我界定的大多数(联合国)吸引力self-body部分及其神经生理学签名通过结合眼动跟踪和脑电图(EEG)范式以及结合近红外光谱(NIRS)和眼动跟踪模式。随后，在双盲受试者比较中，只有BN/BN- osfed患者在重复的身体相关注意再训练（AR）或相应的注意再训练控制条件（AR- cc）中进行主动tDCS或假性tDCS，以增加对自我定义的有吸引力的身体部位的选择性加工。最后一次训练结束后，再用实验范式评估自我定义的三个最（不）吸引人的自我身体部位的注意力分配。在实验阶段、训练前后以及四周和三个月的随访期间，将通过问卷对身体不满程度进行评估。

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.