目的：慢性疲勞 (Chronic fatigue syndrome, CFS) 是一種主訴為疲勞，但是無法以醫療因素來解釋的疾病。患者經常抱怨廣泛的認知功能受損，但在客觀的神經心理測驗的發現並不一致。本研究的第一個目的想經由事件相關電位 (event-related potential, ERPs) 的測量來了解CFS患者從事作業時間長、但難度簡單、測量持續性注意力 （sustained attention） 的認知作業時，訊息處理上是否有問題。本研究的第二個目的是測量患者進行作業時間短、但訊息處理上相當複雜、測量分配性注意力 (divided attention) 的作業時的訊息處理歷程。方法：本研究分別以10名CFS患者及9名健康受試為研究對象，測量他們進行較長時間（約30分鐘）的警覺作業(vigilance test)時的P300波形，以評估CFS患者在進行該作業時的認知資源或訊息處理速率是否有別於健康受試。另外，分別以6名CFS患者及5名健康受試為研究對象，測量他們進行呈現速率為4、3、2秒的Paced Auditory Serial Addition Task (PASAT) 時的ERPs波形。結果：警覺作業的ERPs的分析上，CFS患者的P300振幅及區域面積小於健康受試的，但CFS和健康受試在行為資料的測量上並沒有差異。PASAT的ERPs的分析上，CFS患者在FZ處的N130振幅(大小)大於健康受試，但N130的潛時、P230及N500的振幅及潛時上沒有差異、區域面積的測量上亦沒有差異，並且行為資料的測量上亦沒有差異。結論：CFS患者在進行較長時間的警覺作業時，中線位置 (FZ, CZ, PZ) P300的振幅及區域面積上小於健康受試者，顯示患者在tonic arousal低於健康受試。CFS患者在進行PASAT時所感受到的困難可能來自於早期知覺歷程的困難，而非較後面的訊息處理歷程。CFS患者可以依賴phasic arousal調節認知資源以達到警覺作業及PASAT的要求。

Objective: Chronic fatigue syndrome (CFS) is characterized by medically unexplained debilitating fatigue. Although patients with CFS usually report a wide range of cognitive complaints, neuropsychological studies found only mild dysfunctions. The first aim of present study was in an attempt to obtain neurophysiological evidence for cognitive dysfunction in CFS patients with event-related potentials (ERPs) recording during a prolonged cognitive task that required sustained attention. The second aim was to use ERPs recording to exploit the information processing of CFS patients while they were doing Paced Auditory Serial Addition Task (PASAT), a neuropsychological task of divided attention that commonly found impaired in patients with CFS. Methods: The ERPs were recorded from 10 patients with CFS and 9 healthy controls while they were doing a 30-minute vigilance task and from 6 patients with CFS and 5 health controls while they were doing PASAT (the presentation rates were 4, 3, and 2 seconds). Results: The patients with CFS compared to healthy controls had lower amplitude and area measurement of P300 while they were doing vigilance task. No difference in accuracy or reaction time was found. The amplitude of N130 at FZ was significantly higher in patients with CFS compared to healthy controls while they were doing PASAT, but there was no difference in N130 latency, P230 and N500 amplitude or latency, and no difference on area measurement. Also, no difference on behavior data between groups was found. Conclusion: The P300 amplitude and area measurement of patients with CFS tends to be smaller across electrode sites, implying that the tonic arousal is lower in patients with CFS. The difficulty in patients with CFS on PASAT comes form early process of information processing, not later process. Patients with CFS are able to modify their phasic arousal in response to presentation of vigilance task and PASAT.

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