Event-related potentials in Japanese childhood chronic fatigue syndrome

Article type: Research Article

Authors: Tomoda, Akemi | Mizuno, Kei | Murayama, Nobuki | Joudoi, Takako | Igasaki, Tomohiko | Miyazaki, Makoto | Miike, Teruhisa

Affiliations: Department of Child Developmental Sociology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan | Department of Child Development, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan | Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan | Department of Electrical and Computer Engineering, Kumamoto University, Kumamoto, Japan

Note: [] Correspondence: Akemi Tomoda, M.D., Ph.D., Department of Child Developmental Sociology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8566, Japan. Tel.: +81 96 373 5197; Fax: +81 96 373 5200; E-mail: tomo@kumamoto-u.ac.jp

Abstract: The aim of this study was to investigate cognitive functions such as allocation and information processing in patients with childhood type chronic fatigue syndrome (CCFS) using event-related potentials. A total of 190 healthy children as controls and 414 patients with CCFS participated in this study. Both patients and controls had (i) event-related potentials (including P300, P100, N150 and P200 measurements); (ii) component analysis of electrocardiographic R-R interval to evaluate autonomic function; and (iii) KANA-Pick-out test to evaluate frontal lobe function. The cutoff threshold defining abnormal P300 latency to target stimuli and amplitude to non-target stimuli was set at two standard deviations above the mean values of controls. Forty patients (classified as Type-I) had an abnormally-prolonged P300 latency to target stimuli, and 49 patients (classified as Type-II) had an abnormally-exaggerated P300 amplitude, and the remaining 325 patients whose P300 latency and amplitude ranged below the above-mentioned threshold were classified as Type-III. All patient groups had normal P100, N150 and P200 measurements. Component analysis of electrocardiographic R-R intervals revealed that the power of high-frequency components was lower in all patient groups, compared to controls. The score in KANA-Pick-out test was worse in all patient groups compared to controls; Type-I Group had the worst score and Type-II Group had the best score among the patients. Taken together, we speculate that abnormally-prolonged P300 latency to target stimuli might be associated with learning disability and abnormally-exaggerated P300 amplitude to non-target stimuli might be associated with hypersensitivity such as phobia in patients with CCFS. Psychosomatic symptoms in patients with CCFS might be associated with higher-order level cognitive dysfunction.

Keywords: Event-related potential, P300, childhood type chronic fatigue syndrome, electrocardiographic R-R interval, frontal lobe function

Journal: Journal of Pediatric Neurology, vol. 5, no. 3, pp. 199-208, 2007