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Cerebral metabolic response to passive audiovisual stimulation in patients with Alzheimer's disease and healthy volunteers assessed by PET

Pietrini, Pietro and Alexander, Gene E. and Furey, Maura L. and Dani, Alessio and Mentis, Marc J. and Horwitz, Barry and Guazzelli, Mario and Schapiro, Mark B. and Rapoport, Stanley I. Cerebral metabolic response to passive audiovisual stimulation in patients with Alzheimer's disease and healthy volunteers assessed by PET. Journal of Nuclear Medicine, 41 (4). pp. 575-583. ISSN 0161-5505 (2000)

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Abstract

Alzheimer'sdiseaseis associated with reductions in resting-state brain metabolism, as measured by PET, progressing with dementia severity. The purpose of this study was to see to what extent brain regions with reduced resting-state metabolicrates in Alzheimer patients could be activated by a passive audiovisual stimulation test and to compare the result with activation in age-matched healthy volunteers. The extent of activation in Alzheimer's disease is considered to reflect the integrity of synapticfunction, or inherent viability, and the potential responsiveness of the Alzheimer brain to drug therapy. Methods: Regional cerebral metabolicrates for glucose (rCMRgc,in mg/ 100 9 tissue/mm) were measured in the resting state (eyes and ears covered) and during passive audio visual stimulation (watch ing a movie) in 15 otherwise healthy Alzheimer patients of differing dementia severity (Maths Dementia Rating Scale score, 23—128) and in 14 age-matched healthy volunteers (score, 141 ±3) using PET with 2 sequential injections of FDG. Results: In the volunteers, audio visual stimulation caused significant rCMRgc increases in visual and auditory cortical areas but significant decreases in frontal areas. In the mildly demented patients, rCMRgc responses were within 2 SDs of the mean in volunteers. However, the magnitude of the rCMRgc responses during stimulation declined significantly with dementia severity in the right occipitotemporal, right and left occipital association, and left calcarine cortical regions. Conclusion: Functional brain responsiveness, evaluated by a passive audio visual stimulation paradigm with PET, is with in normal limits in mildly demented Alzheimer patients but fails with worsening dementia severity. Declining responsiveness may account for the limited success of neurotransmitter replacement therapy in Alzheimer patients with moderate-to-severe dementia.

Item Type: Article
Uncontrolled Keywords: PET; FDG; dementia; brain; activation; cognition
Subjects: R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Research Area: Computer Science and Applications
Depositing User: Ms T. Iannizzi
Date Deposited: 12 Apr 2016 08:17
Last Modified: 12 Apr 2016 08:17
URI: http://eprints.imtlucca.it/id/eprint/3404

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