Changing habits in anorexia nervosa – a randomized controlled trial (CHAiN)

神经性厌食症（Anorexia Nervosa， AN）是一种严重的精神障碍，其主要特征是严重限制食物摄入，导致体重过轻。多达4%的妇女在其一生中受到AN的影响，慢性病程伴严重的躯体后遗症是常见的，死亡率是所有精神障碍中最高的。不论采用何种治疗方法，治愈率低至中等，而减少率和复发率很高。现有治疗效果不理想的一个原因是，对这种疾病的病因和维持机制仍然知之甚少。然而，最近，一种神经生物学的机制模型已经被开发出来，该模型表明，AN中的许多问题行为（例如饮食限制，计算卡路里，身体检查，过度锻炼）是习惯性的，这意味着这些行为已经从目标导向转变为僵硬的，线索引出的，自动的行为，这些行为已经从积极或消极的后果中分离出来。与他的研究结果一致的是，神经成像研究表明，患有AN的患者在做出与食物有关的决策时，其背纹状体（一个调节习惯行为的大脑区域）的大脑活动增加。乔安娜·斯坦格拉斯（Joanna Steinglass）是拟议研究项目的合作者，她最近将这些发现转化为一种新颖的心理干预，专门针对AN （REaCH）中与饮食相关的习惯。在一项小型随机对照概念验证研究（n=22）中，该干预在减少与饮食相关的习惯强度（d=1.28）和自我报告的饮食失调精神病理（d=0.81）以及增加实验室膳食的热量摄入（d=1.16）方面优于积极对照组（支持性心理治疗）。基于这些有希望的初步发现，拟议研究项目的中心研究问题是，这种特定的干预措施是否确实改变了拟议的机制，并导致改善的临床结果。计划的研究是一项单中心随机对照优势试验，纳入n=110例AN患者，比较两个平行治疗组作为常规住院治疗的辅助治疗。主要结果将是在干预的每一周（4周）、治疗结束时和6个月随访时在基线时测量的体重指数（BMI）的变化。次要结果包括进一步的临床参数（自我报告的饮食失调精神病理学），替代测量（实验室膳食中的食物选择和热量摄入），以及干预所针对的机制变化（饮食相关习惯强度）。拟议的研究将提供具有直接临床意义和相关性的重要结果，以提高对an的病因和维持的理解。

Anorexia Nervosa (AN) is a serious mental disorder that is mainly characterized by severe restriction of food intake, resulting in underweight. AN affects up to 4% of women during their lifetime, a chronic course with severe somatic sequelae is common, and the mortality rate is the highest of any mental disorder. Irrespective of the treatment approach, recovery rates are low to moderate, whereas attrition and relapse rates are high. One reason for the unsatisfactory effectiveness of available treatments is that still relatively little is known about the etiology and maintenance of the disorder. However, recently, a neurobiologically informed, mechanistic model of AN has been developed which suggests that much of the problematic behaviors in AN (e.g. dietary restraint, counting calories, body checking, excessive exercising) are habitual, meaning that these have shifted from goal-directed to rigid, cue-elicited, automatic behaviors that have been uncoupled from positive or negative consequences. In line with his, neuroimaging research has shown that patients with AN show increased brain activity in the dorsal striatum (a brain region that mediates habitual behavior) during food-related decision-making. Joanna Steinglass, a collaborator on the proposed research project, has recently translated these findings into a novel psychological intervention that specifically targets eating-related habits in AN (REaCH). In a small randomized controlled proof-of-concept study (n=22), this intervention outperformed an active control group (supportive psychotherapy) in terms of reductions in eating-related habit strength (d=1.28) and self-reported eating disorder psychopathology (d=0.81), and increased caloric intake in a laboratory meal (d=1.16). Based on these promising preliminary findings, the central research question of the proposed research project is whether this specific intervention definitely changes the proposed mechanisms and leads to improved clinical results. The planned study is a mono-center randomized controlled superiority trial in n=110 patients with AN, comparing two parallel treatment arms as adjunct to inpatient treatment as usual. The primary outcome will be change in body mass index (BMI), measured at baseline, during each week of the intervention (4 weeks), at the end of treatment and at 6 months follow-up. Secondary outcomes comprise further clinical parameters (self-reported eating disorder psychopathology), surrogate measures (food choices and caloric intake in a laboratory meal), and changes in the mechanism(s) that are targeted by the intervention (eating-related habit strength). The proposed study will provide important results with both direct clinical implications and relevance for an improved understanding of the etiology and maintenance of AN.