Quantitative EEG in early Alzheimer's disease patients - power spectrum and complexity features.

Institute for Psychology, Hungarian Academy of Sciences, Budapest, Hungary.
International Journal of Psychophysiology (Impact Factor: 2.04). 05/2008; 68(1):75-80. DOI: 10.1016/j.ijpsycho.2007.11.002
Source: PubMed

ABSTRACT The goal of this study was to investigate the EEG signs of early stage Alzheimer's disease (AD) by conventional analyses and by methods quantifying linear and nonlinear EEG-complexity. The EEG was recorded in 12 mild AD patients and in an age-matched healthy control group (24 subjects) in both eyes open and eyes closed conditions. Frequency spectra, Omega-complexity and Synchronization likelihood were calculated on the data. In the patients a significant decrease of the relative alpha and increase of the theta power were found. Remarkably increased Omega-complexity and lower Synchronization likelihood were observed in AD in the 0.5-25 Hz frequency ranges. It is concluded that both spectral- and EEG-complexity changes can be found already in the early stage of AD in a wide frequency range. Application of conventional EEG analysis methods in combination with quantification of EEG-complexity may improve the chances of early diagnosis of AD.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Changes in the electroencephalogram (EEG) characteristics in experienced Zen meditation practitioners (n = 23) during 40 minutes of meditation were compared with those in the matched controls (n = 23) taking a rest for 40 minutes. Averaged complexity index ([image omitted] ) evaluation and spectral analysis were measured in three intervals: the first, middle and the last 5-min segments of Zen meditation or relaxing rest. Significant increase in frontal alpha-1 (8-10 Hz) and occipital beta power was found during meditation as compared with the EEG under the rest, whereas an average increase of theta power was observed in the controls. In meditation, brain dynamics exhibited high [image omitted] , which correlated with more beta activity. Control subjects showed no significant change in [image omitted] level. This distinction became more significant during the last 5 minutes of meditation over most electrodes. Deeper meditation state has been reported as having implications of increased beta power that can be more prominent by the approach of [image omitted] estimation. Our results substantiate the idea that long-term training with Zen-Buddhist meditation induces changes in the electro-cortical activity of the brain.
    Journal of Medical Engineering & Technology 02/2009; 33(4):314-21.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Alzheimer's disease (AD) is an irreversible brain disorder which represents the most common form of dementia in western countries. An early and accurate diagnosis of AD would enable to develop new strategies for managing the disease; however, nowadays there is no single test that can accurately predict the development of AD. In this sense, only a few studies have focused on the magnetoencephalographic (MEG) AD connectivity patterns. This study compares brain connectivity in terms of linear and nonlinear couplings by means of spectral coherence and cross mutual information function (CMIF), respectively. The variables defined from these functions provide statistically significant differences (p < 0.05) between AD patients and control subjects, especially the variables obtained from CMIF. The results suggest that AD is characterized by both decreases and increases of functional couplings in different frequency bands as well as by an increase in regularity, that is, more evident statistical deterministic relationships in AD patients' MEG connectivity. The significant differences obtained indicate that AD could disturb brain interactions causing abnormal brain connectivity and operation. Furthermore, the combination of coherence and CMIF features to perform a diagnostic test based on logistic regression improved the tests based on individual variables for its robustness.
    Annals of Biomedical Engineering 01/2011; 39(1):524-36. · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Over the past few years there has been an increased interest in studying the underlying neural mechanism of attention and cognitive brain activity. This paper aims towards identifying and analyzing distinct responses in an auditory working memory paradigm, as independent components with variable latency, frequency and phase characteristics. The event-related nature of components (either phase or non-phase-locked) over multiple trials is thoroughly examined through intertrial coherence measures. Furthermore, the functional coupling of independent components is investigated through the concept of partial directed coherence depicted as a directed graph. Using these tools, the paper compares issues of activation, connectivity and directionality in the synchronization maps of two populations, of control and Alzheimer's subjects. The results on real data from an oddball experiment verify and further enhance the findings of previous studies and illustrate the potential of the proposed analysis framework.
    Journal of neuroscience methods 02/2011; 197(2):302-14. · 2.30 Impact Factor


Available from
Jun 3, 2014