title: Activation-flow coupling differentiates between vascular and Alzheimer type of dementia.
abstract: The activation-flow coupling describes a mechanism, which adapts local cerebral blood flow in accordance with the underlying neuronal activity. It was suggested that the mechanism helps in differentiation between Alzheimer and vascular type of dementia. We combined EEG and Doppler techniques and assessed integrity of the activation-flow coupling in the occipital cortex utilizing a visual stimulation task. Alzheimer patients (MMSE: 18+/-8 points, DemTect 5+/-4 points) without signs of vascular lesions on a MRI scan and vascular demented patients (MMSE: 20+/-6 points, DemTect 6+/-3 points; MRI Fazekas score 7+/-3 points) were compared with data from an age-matched control group. Evoked flow velocity responses in the posterior cerebral artery were analysed according to a control system model specifying the parameters gain, attenuation, natural frequency and rate time. Evoked potentials were analysed for the N(75)-P(100) amplitude difference. Vascular demented patients exhibited a significant decreased gain parameter and increased attenuation parameter indicating severe cerebrovascular dysfunction. Also, the potential amplitudes were significantly decreased indicating neuronal damage due to the vascular disease process. Alzheimer patients did not differ in parameters as compared to the control group supporting other reports of intact occipital function at this stage of disease. Simultaneous assessment of electrical as well as vascular integrity might help in differentiating the most frequent forms of dementia.
authors.affiliation: Department of Neurology, Justus-Liebig University of Giessen, Am Steg 14, 35392 Giessen, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Rosengarten
authors.forename: Sönke
authors.initials: S
authors.lastname: Paulsen
authors.forename: Sandor
authors.initials: S
authors.lastname: Molnar
authors.forename: Reiner
authors.initials: R
authors.lastname: Kaschel
authors.forename: Bernd
authors.initials: B
authors.lastname: Gallhofer
authors.forename: Manfred
authors.initials: M
authors.lastname: Kaps
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015140:Dementia, Vascular / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000379:methods; D004734:Energy Metabolism / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D010775:Photic Stimulation; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011237:Predictive Value of Tests; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods