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
