Cognitive dysfunction, as a common symptom among patients with chronic fatigue syndrome(CFS) and patients with fibromyalgia(FM), impacts on life quality, occupation and study of these patients. However, the neural correlates to the cognitive impairment are unknown. Event related potentials, which reflect the information processing objectively and constantly, provide possibility for taking a insight into and estimating the dysfunction. By summarizing and analyzing studies in event related potentials about chronic fatigue syndrome, fibromyalgia, we found that CFS patients were characterized with prolonged latency of N200 and P300 accompanied by decreased P300 amplitude when they performed on Oddball paradigm, fibromyalgia patients were characterized with lower P300 amplitude when they concentrated on Oddball task, meanwhile, fibromyalgia patients also showed decreased P100/N100, P200, P300, LPC in emotional word decision task and somatic pictures decision task. It's suggests that the cognitive dysfunction in CFS is mainly caused by slowed speed of information identification and classification, whereas in FM it's dysregulation in attention control system results in the cognitive dysfunction. Limitations in current studies and prospects on researches about cognitive dysfunction in CFS for future were also discussed.

Chronic fatigue syndrome; Fibromyalgia; Cognitive dysfunction; Event related potentials