Nonlinear dynamics of electroencephalography study in schizophrenic patients.
BACKGROUND
Few characteristic changes of linear electroencephalograph (EEG) have been reported in schizophrenia. The aim of the present study was to investigate the changes in temporal-spatial dimensional properties of EEG under different cognitive tasks in patients with schizophrenia.


METHODS
EEG was recorded by using EEG-1518K system and mapping system (Nihon Kohden Tomioka Corporation, Japan) in 45 schizophrenic patients and 47 healthy adults (normal control, NC) under five states: eyes closed, eyes open, mental arithmetic test with eyes closed, memory test with eyes open, and number cancellation test. Correlation dimension (D2) and point-wise correlation dimension (PD2) were calculated for all EEG analyses.


RESULTS
(1) There were no significant differences of D2 and PD2 between NC and schizophrenic patients under states of eyes open and closed. (2) Compared with NC, schizophrenic patients showed decreased performance of D2 in mental arithmetic test with eyes closed and number cancellation test (mental arithmetic test with eyes closed: Nc 5.9 ± 0.6, Sch 3.0 ± 0.8; number cancellation test: Nc 6.0 ± 0.6, Sch 4.4 ± 0.7; P < 0.05 or P < 0.01). (3) Schizophrenic patients also showed decrease performance of PD2 in mental arithmetic test with eyes closed, memory test with eyes open, and number cancellation test (mental arithmetic test with eyes closed: Nc 6.9 ± 0.7, Sch 4.0 ± 0.8; memory test with eyes open: Nc 6.6 ± 0.8, Sch 5.0 ± 0.9; number cancellation test: Nc 7.1 ± 0.7, Sch 4.8 ± 0.9; P < 0.05 or P < 0.01).


CONCLUSIONS
Nonlinear dynamic analysis provided a new approach in clinical investigation of EEG signals. It was helpful to further understand the cerebral mechanism in schizophrenic cognitive process.
Department of Electrophysiology, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai 200030, China.
Xing-shi
XS
Chen
Yi-feng
YF
Xu
Yun-xiang
YX
Tang
Yi-ru
YR
Fang
Chen
C
Zhang
Ming-dao
MD
Zhang
Fei-ying
FY
Lou
Jian-hua
JH
Liang
Chong
C
Chen
Xiao
X
Pan
Jin
J
Yan
Yi
Y
Cui
D000328:Adult; D003071:Cognition / Q000502:physiology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D012559:Schizophrenia / Q000503:physiopathology*