Investigation of EEG non-linearity in dementia and Parkinson's disease

Approximate entropy and auto mutual information analysis of the electroencephalogram in Alzheimer’s disease patients

“…A possible explanation for this result might be that the inspection of different time scales provides an advantage in comparison to the use of other non-linear measures based on one time scale only when analysing physiological signals [9], [20], [31]. Our results are consistent with previous studies showing changes in the EEG of AD patients in comparison to age-matched control subjects with different non-linear metrics [1], [24], [25], [39], [44]. The abnormalities in the AD patients' EEG could be explained by a change of the dynamics in the brain.…”

“…The investigations of the electrical brain activity have revealed possible medical applications, since analysis based on non-linear dynamics yields information unavailable using traditional EEG spectral-band analysis [39]. Moreover, it has been shown that non-linear analysis is useful to characterize the EEG in different pathological states like epilepsy [27], schizophrenia [41], or the Creutzfeldt-Jakob [6] and Parkinson's diseases [44]. This has given rise to the possibility that the underlying mechanisms of the brain function may be explained in a more appropriate way by non-linear dynamics.…”

Analysis of regularity in the EEG background activity of Alzheimer's disease patients with Approximate Entropy

“…Most of these studies have been carried out applying the D 2 (Stam et al, 1995;Besthorn et al, 1995Besthorn et al, , 1997Jeong et al, 1998;Jelles et al, 1999;Jeong et al, 2001a) or the first positive Lyapunov exponent (Jeong et al, 1998(Jeong et al, , 2001a. Measures such as D 2 , K-S entropy, the Lyapunov spectrum and related algorithms have been much studied in the presence of noise and limited data.…”

“…the brain (Andrzejak et al, 2001). Many studies are known in which non-linear time series analysis techniques were applied to different kinds of EEGs from humans, such as recordings from healthy volunteers at rest , sleep (Babloyantz et al, 1985), during periods of cognitive activity (Theiler and Rapp, 1996), or from patients with acute ischemic stroke (Hwa and Ferree, 2002) or with diseases like Alzheimer's (Stam et al, 1995;Jelles et al, 1999), Parkinson's (Pezard et al, 2001), Creutzfeldt-Jakob (Babloyantz and Destexhe, 1988), epilepsy (Hornero et al, 1999), depression (Nandrino et al, 1994) and schizophrenia (Fell et al, 1995) in comparison with control subjects.…”

“…However, the most frequently used non-linear method is the correlation dimension (D 2 ), a measure of dimensional complexity of the underlying system (Grassberger and Procaccia, 1983a). Results showed that AD patients had lower D 2 values than controls (Stam et al, 1995;Jeong et al, 1998Jeong et al, , 2001a. Furthermore, Besthorn et al (1995) showed that a lower D 2 was correlated with increased severity of dementia and also found that this method correctly classified AD patients and controls with an accuracy of 70% (Besthorn et al, 1997).…”