Abstract
We analysed the electroencephalogram (EEG) from Alzheimer’s disease (AD) patients with two nonlinear methods: approximate entropy (ApEn) and auto mutual information (AMI). ApEn quantifies regularity in data, while AMI detects linear and nonlinear dependencies in time series. EEGs from 11 AD patients and 11 age-matched controls were analysed. ApEn was significantly lower in AD patients at electrodes O1, O2, P3 and P4 (p < 0.01). The EEG AMI decreased more slowly with time delays in patients than in controls, with significant differences at electrodes T5, T6, O1, O2, P3 and P4 (p < 0.01). The strong correlation between results from both methods shows that the AMI rate of decrease can be used to estimate the regularity in time series. Our work suggests that nonlinear EEG analysis may contribute to increase the insight into brain dysfunction in AD, especially when different time scales are inspected, as is the case with AMI.
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Abbreviations
- AD:
-
Alzheimer’s disease
- AMI:
-
Auto mutual information
- ApEn:
-
Approximate entropy
- AUC:
-
Area under the ROC curve
- CMI:
-
Cross mutual information
- D 2 :
-
Correlation dimension
- EEG:
-
Electroencephalogram
- L1:
-
Largest Lyapunov exponent
- LZ:
-
Lempel-Ziv
- MI:
-
Mutual information
- MMSE:
-
Mini-mental state examination
- MSE:
-
Multiscale entropy
- ROC:
-
Receiver operating characteristic
- SampEn:
-
Sample entropy
- SD:
-
Standard deviation
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Acknowledgments
This work was supported by grant projects VA102A06 and VA108A06 from Consejería de Educación de la Junta de Castilla y León and by a grant project from Ministerio de Educación y Ciencia and FEDER grant MTM 2005-08519-C02-01.
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Abásolo, D., Escudero, J., Hornero, R. et al. Approximate entropy and auto mutual information analysis of the electroencephalogram in Alzheimer’s disease patients. Med Biol Eng Comput 46, 1019–1028 (2008). https://doi.org/10.1007/s11517-008-0392-1
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DOI: https://doi.org/10.1007/s11517-008-0392-1