The EEG Study Based On The Complexity Analysis Of Alzheimer’s Disease, Mild Cognitive Impairment And Normal Elderly

ObjectiveTo find an objective dignostic indicator and the characteristics of EEG complexity of elderly subjects with different cognitive functional status from Alzheimer’s disease(AD)、mild cognition impairment (MCI) to the normal, EEG Lempel-Ziv complexity (LZC) was calculated.MethodFrom the neurological clinic inpatients in Tianjin Medical University General Hospital,60patients were selected,30patients with AD for AD group;30MCI patients for MCI group;20normal age、education matched volunteers were involved. All subjects with eye closed performed EEG in rest state. More than10.24s’ datas(2048points) were chosen for Lemple-Zie Complexity(LZC) calculation on MATLAB7.0software platform by self program.Results①AD group had the lowest LZC value in the three groups, while the normal gained the highest.②LZC values of AD group in all channels, whole brain(the average of all channels), bilateral hemisphere, bilateral frontal and temporal areas were significantly lower than those in the normal control gorup (P<0.05, P<0.001); and showed larged decline(>23%) in F7(the left anterior temporal), F8(the right anterior temporal), T3(the left temporal), T4(right temporal), F3(the left frontal), F4(the right frontal), C3(the left central), P3(the left parietal).③Except T6, the remaining channels, the whole brain, bilateral hemisphere, left and right frontotemporal area’s LZC value were significantly higher than the AD group (P<0.05, P<0.001);④Comparied with the normal control group, MCI group had the notablly lower LZC values existed in F3, C3, C4, P3, P4, F7, T3, T4, T5, the whole brain, lefe hemisphere, the left and right temporal region, the left forntal ares’s (P<0.05, P<0.01).⑤In AD group, the LZC value of the FP1, FP2, F7, F8channels have statistically lower values than the others. Conclusions1. In the healthy elderly, LZC values in dominant hemisphere and the cognitive related areas were higher than that in right hemispere and other brain areas. This result suggest that these brain regions play more important role in information processing.2. The EEG complexity value can reflect the change of brain function to some degree, and can be used as an objective detection indicator for evaluation of cognitive function.3. The degradation of brain function seems not synchronized, and in cognitive-related brain areas such as:the frontal, temporal lobe, degradation is more obviouslly than other brain regions.4. The MCI patients with abormal LZC values in temporal and frontal lobe have a certain degree relation with the occurrence of AD.