Body representations in schizophrenia: an alteration of body structural description is common to people with schizophrenia while alterations of body image worsen with passivity symptoms

Introduction: Individuals with schizophrenia, particularly those with passivity symptoms, often feel that their actions and thoughts are controlled by an external agent. Recent evidence has elucidated the role of body representations in the aetiology of passivity symptoms, yet one representation – body structural description – has not yet been examined. Additionally, body image has rarely been examined outside of bodily illusions (e.g., rubber hand experiments) and external validation is required. Methods: Body structural description was assessed with an in-between task and a matching body parts by location task, and body image with a questionnaire examining body distortion experiences (containing subscales assessing boundary loss, depersonalisation and body size distortions). Individuals with schizophrenia (20 with current, 12 with past and 21 with no history of passivity symptoms) and 48 healthy controls participated in the study. Results: People with schizophrenia (as a group) made more errors on the in-between task, but not on the matching body parts by location task. Individuals with current passivity symptoms reported greater distortions on all subscales relative to the other clinical samples, except for experiences of boundary loss which were common to both passivity symptom groups. Conclusions: The results indicate that body structural description may be altered in schizophrenia generally and body image alterations are worsened in passivity symptoms, and these alterations likely contribute to the emergence of passivity symptoms.

引言：精神分裂症患者，尤其是存在被动症状（passivity symptoms）者，常感到自身的动作与思维被外部媒介所控制。近期研究已阐明躯体表征在被动症状病因学中的作用，但躯体结构描述（body structural description）这一表征维度尚未得到相关探讨。此外，躯体意象（body image）的相关研究极少脱离躯体错觉（bodily illusions，如橡胶手实验（rubber hand experiments））范畴开展，且仍需外部验证。
研究方法：本研究通过两项任务评估躯体结构描述能力，分别为中间位置判断任务（in-between task）与躯体部位位置匹配任务（matching body parts by location task）；躯体意象则通过考察躯体扭曲体验的问卷进行评估，该问卷包含评估边界丧失（boundary loss）、人格解体（depersonalisation）与躯体大小扭曲（body size distortions）的三个子量表。本研究共纳入53名精神分裂症患者：其中20名当前存在被动症状、12名既往存在被动症状、21名无被动症状病史，另纳入48名健康对照者参与实验。
研究结果：整体而言，精神分裂症患者群体在中间位置判断任务中的出错率更高，但在躯体部位位置匹配任务中未表现出该差异。相较于其余临床样本，当前存在被动症状的患者在所有子量表上报告的躯体扭曲程度均更高，仅边界丧失体验在两类存在被动症状的患者群体中无显著差异。
研究结论：本研究结果显示，精神分裂症患者普遍存在躯体结构描述能力异常，且伴被动症状的患者其躯体意象异常程度更为严重，上述异常或与被动症状的发生存在关联。