Université Lille Nord de France, Lille, France.
PLoS One. 2012;7(2):e30449. doi: 10.1371/journal.pone.0030449. Epub 2012 Feb 27.
Early diagnosis of young adults at risk of schizophrenia is essential for preventive approaches of the illness. Nevertheless, classic screening instruments are difficult to use because of the non-specific nature of the signs at this pre-onset phase of illness. The objective of the present contribution was to propose an innovating test that can probe the more specific symptom of psychosis, i.e., the sense of agency, which is defined as being the immediate experience of oneself as the cause of an action. More specifically, we tested whether motor agency is abnormal in early psychosis.
Thirty-two young symptomatic patients and their age-matched controls participated in the study. 15 of these patients were at ultra high-risk for developing psychosis (UHR), and 17 patients were suffering from first-episode psychosis (FEP). Patients' neurocognitive capacities were assessed through the use of seven neuropsychological tests. A motor agency task was also introduced to obtain an objective indicator of the degree of sense of agency, by contrasting force levels applied during other and self-produced collisions between a hand-held objet and a pendulum.
As reported in the literature for adult controls, healthy adolescents used more efficient force levels in self than in other-imposed collisions. For both UHR and FEP patients, abnormally high levels of grip force were used for self-produced collisions, leading to an absence of difference between self and other. The normalized results revealed that motor agency differentiated patients from controls with a higher level of sensitivity than the more classic neuropsychological test battery.
This study is in favour of the existence of an abnormal sense of agency early in the psychotic illness. Because it is quick and none verbal, motor agency may be a valuable tool to use in complement to classic interviews, especially when investigating complex ineffable experiences that are difficult to explicitly describe.
对于精神分裂症的早期诊断，对于疾病的预防措施至关重要。然而，由于疾病发病前阶段的体征具有非特异性，因此经典的筛查工具难以使用。本研究的目的是提出一种创新的测试方法，以探测更具体的精神病症状，即自我感，它被定义为对自身作为行动原因的即时体验。更具体地说，我们测试了运动自我感在早期精神病中的是否异常。
32 名有症状的年轻患者及其年龄匹配的对照组参加了这项研究。其中 15 名患者处于发展为精神病的超高风险（UHR）状态，17 名患者患有首发精神病（FEP）。通过使用七种神经心理学测试来评估患者的神经认知能力。还引入了一项运动自我感任务，通过对比手持物体与摆锤之间的自我产生和他人产生的碰撞中施加的力水平，获得自我感程度的客观指标。
正如成人对照组文献中报道的那样，健康青少年在自我产生的碰撞中使用的力水平比他人施加的力水平更有效。对于 UHR 和 FEP 患者，自我产生的碰撞中使用的握力水平异常高，导致自我和他人之间没有差异。归一化结果表明，运动自我感比更经典的神经心理学测试组合更能区分患者和对照组，具有更高的敏感性。
这项研究支持在精神病早期存在异常自我感。由于它快速且非言语，运动自我感可能是一种有价值的工具，可以与经典访谈相结合使用，特别是在调查难以明确描述的复杂、难以言喻的体验时。
