Development of diagnostic system for cognitive impairments in Parkinson's Disease

此前的研究表明，帕金森氏症(PD)患者的认知功能可能会受损。然而，到目前为止，只有与执行功能和记忆(程序记忆)有关的认知障碍被报道。在本研究中，我们使用行为分析和EEG(事件相关电位：事件相关电位)来检查帕金森病患者是否存在上述以外的认知障碍。得到了以下结果。(1)我们先前的研究表明，帕金森病患者对特定面部表情(恐惧和厌恶)的识别受到损害(Kan等人，2002年)。支持这一发现的是，我们最近使用事件相关电位的研究表明，帕金森病患者面部识别的独特性。使用偶极子追踪技术的事件相关电位研究表明，在面部表情识别任务中，杏仁核和运动前皮质不活跃，而正常对照组这些区域是活跃的。这一结果表明帕金森病患者的杏仁核以及基底神经节可能受损(Yoshimura et al.2005)。(2)最近，有关“心理理论”和“社会决策”的任务被用来评估额叶功能。由于假设帕金森病患者的额叶功能障碍，我们检查了帕金森病患者将如何执行这些任务。结果表明，帕金森病患者在一项要求他们推断他人想法/感受的心理理论任务中表现不佳，而且帕金森病患者的社会决策能力也受到损害(Oheda等人，正在准备中)。总之，本研究表明，帕金森病患者在面部表情识别和社会认知方面存在缺陷，执行功能和程序记忆也存在缺陷。此外，本研究还为我们提供了一种诊断工具，可以用来检查帕金森病患者除基底节区以外的其他部位的脑损害引起的临床症状。

Previous studies showed that cognitive functions could be impaired in patients with Parkinson's disease (PD). However, only cognitive impairments concerning executive functions and memory (procedural memory) were reported so far. In the present study, we examined whether or not PD patients have cognitive impairments other than those in the above, using behavior analysis and EEG (event-related potentials : ERP). The following results were obtained. (1) Our previous study showed that recognition of specific facial expressions (fear and disgust) is impaired in PD patients (Kan et al.2002). Supporting this finding, our recent study using ERP showed uniqueness of facial recognition in PD patients. The ERP study using dipole-tracing technique indicated that the amygdala and the pre-motor cortex were not active during the facial expression recognition task, whereas these areas were active in the normal control. The result suggests that the amygdala could be damaged in PD patients, as well as the basal ganglia (Yoshimura et al.2005). (2) Recently, the tasks concerning "theory of mind" and "social decision-making" are used to assess the frontal-lobe functions. Since it was hypothesized that the frontal lobe would be dysfunctioning in PD patients, we examined how PD patients would perform those tasks. The results showed that PD patients performed poorly in a "theory of mind" task in which they were asked to infer the thoughts/feelings of others, and that social decision-making was also impaired in PD patients (Oheda et al, in preparation).In conclusion, the present study demonstrated that PD patients have deficits in recognition of facial expressions and in social cognition, as well as deficits in executive functions and procedural memory. In addition, the present study provided us a diagnostic tool by which we can examine clinical symptoms caused by the brain damage in the areas other than the basal ganglia, in PD patients.