OBJECTIVE: We examined the hypothesis that cognitive dysfunction in Alzheimer's disease is associated with abnormal spontaneous fluctuations of EEG synchronization levels during an eyes-closed resting state. METHODS: EEGs were recorded during an eyes-closed resting state in Alzheimer patients (N=24; 9 males; mean age 76.3 years; SD 7.8; range 59-86) and non-demented subjects with subjective memory complaints (N=19; 9 males; mean age 76.1 years; SD 6.7; range: 67-89). The mean level of synchronization was determined in different frequency bands with the synchronization likelihood and fluctuations of the synchronization level were analysed with detrended fluctuation analysis (DFA). RESULTS: The mean level of EEG synchronization was lower in Alzheimer patients in the upper alpha (10-13Hz) and beta (13-30Hz) band. Spontaneous fluctuations of synchronization were diminished in Alzheimer patients in the lower alpha (8-10Hz) and beta bands. In patients as well as controls the synchronization fluctuations showed a scale-free pattern. CONCLUSIONS: Alzheimer's disease is characterized both by a lower mean level of functional connectivity as well as by diminished fluctuations in the level of synchronization. The dynamics of these fluctuations in patients and controls was scale-free which might point to self-organized criticality of neural networks in the brain. SIGNIFICANCE: Impaired functional connectivity can manifest itself not only in decreased levels of synchronization but also in disturbed fluctuations of synchronization levels.
OBJECTIVE: We examined the hypothesis that cognitive dysfunction in Alzheimer's disease is associated with abnormal spontaneous fluctuations of EEG synchronization levels during an eyes-closed resting state. METHODS: EEGs were recorded during an eyes-closed resting state in Alzheimerpatients (N=24; 9 males; mean age 76.3 years; SD 7.8; range 59-86) and non-demented subjects with subjective memory complaints (N=19; 9 males; mean age 76.1 years; SD 6.7; range: 67-89). The mean level of synchronization was determined in different frequency bands with the synchronization likelihood and fluctuations of the synchronization level were analysed with detrended fluctuation analysis (DFA). RESULTS: The mean level of EEG synchronization was lower in Alzheimerpatients in the upper alpha (10-13Hz) and beta (13-30Hz) band. Spontaneous fluctuations of synchronization were diminished in Alzheimerpatients in the lower alpha (8-10Hz) and beta bands. In patients as well as controls the synchronization fluctuations showed a scale-free pattern. CONCLUSIONS:Alzheimer's disease is characterized both by a lower mean level of functional connectivity as well as by diminished fluctuations in the level of synchronization. The dynamics of these fluctuations in patients and controls was scale-free which might point to self-organized criticality of neural networks in the brain. SIGNIFICANCE: Impaired functional connectivity can manifest itself not only in decreased levels of synchronization but also in disturbed fluctuations of synchronization levels.
Authors: E Cavedo; S Lista; Z Khachaturian; P Aisen; P Amouyel; K Herholz; C R Jack; R Sperling; J Cummings; K Blennow; S O'Bryant; G B Frisoni; A Khachaturian; M Kivipelto; W Klunk; K Broich; S Andrieu; M Thiebaut de Schotten; J-F Mangin; A A Lammertsma; K Johnson; S Teipel; A Drzezga; A Bokde; O Colliot; H Bakardjian; H Zetterberg; B Dubois; B Vellas; L S Schneider; H Hampel Journal: J Prev Alzheimers Dis Date: 2014-12
Authors: Wajid Mumtaz; Syed Saad Azhar Ali; Mohd Azhar Mohd Yasin; Aamir Saeed Malik Journal: Med Biol Eng Comput Date: 2017-07-13 Impact factor: 2.602
Authors: Andrew A Fingelkurts; Alexander A Fingelkurts; Heikki Rytsälä; Kirsi Suominen; Erkki Isometsä; Seppo Kähkönen Journal: Hum Brain Mapp Date: 2007-03 Impact factor: 5.038
Authors: Markus Waser; Heinrich Garn; Reinhold Schmidt; Thomas Benke; Peter Dal-Bianco; Gerhard Ransmayr; Helena Schmidt; Stephan Seiler; Günter Sanin; Florian Mayer; Georg Caravias; Dieter Grossegger; Wolfgang Frühwirt; Manfred Deistler Journal: J Neural Transm (Vienna) Date: 2015-09-28 Impact factor: 3.575