Auditory delta event-related oscillatory responses are decreased in Alzheimer's disease.
BACKGROUND
Visual delta event-related (ERO) and evoked oscillations (EO) of Alzheimer patients (AD) are different than healthy. In the present study, the analysis is extented to include auditory ERO and EO in AD. The rationale is to reveal whether the auditory ERO delta responses are also reduced, and whether this is a general phenomenon in Alzheimer patients upon applying stimuli with cognitive load.


METHODS
Thirty-four mild AD subjects [17 de-novo and 17 medicated (cholinergic)] and seventeen healthy controls were included. Auditory oddball paradigm and sensory auditory stimuli were applied to the subjects. Oscillatory responses were analyzed by measuring maximum amplitudes in delta frequency range (0.5-3.5 Hz).


RESULTS
Auditory delta ERO (0.5-3.5 Hz) responses of healthy controls were higher than either de-novo AD or medicated AD group, without a difference between two AD subgroups. Furthermore, the auditory EO after presentation of tone bursts yielded no group difference.


CONCLUSIONS
Our findings imply that delta ERO is highly unstable in AD patients in comparison to age-matched healthy controls only during the cognitive paradigm. Our results favor the hypothesis that neural delta networks are activated during cognitive tasks and that the reduced delta response is a general phenomenon in AD, due to cognitive impairment.
Department of Neurology, Dokuz Eylül University, Izmir, Turkey. gorsev.yener@deu.edu.tr
G G
GG
Yener
B
B
Güntekin
D Necioglu
DN
Örken
E
E
Tülay
H
H
Forta
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Başar
D000161:Acoustic Stimulation / Q000379:methods / Q000523:psychology; D000368:Aged; D000544:Alzheimer Disease / Q000188:drug therapy / Q000503:physiopathology*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D003700:Delta Rhythm / Q000187:drug effects / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology
D002800:Cholinesterase Inhibitors