Cerebral blood flow changes in response to visual stimulation in
demented patients
H.A. Buchtel, R.A. Koeppe, J. Mountz, N.L. Foster, S. Berent, B.
Giordani and D.E. Kuhl.
VA Medical Center, Ann Arbor and University of
Michigan Departments of Psychiatry, Internal Medicine, Division of
Nuclear Medicine, Neurology, and Psychology.
The visual-spatial disorders that are commonly seen in dementia
are usually attributed to a disturbance of higher-order mechanisms rather
than to reduced responsiveness of the visual system. However, EEG evoked
potentials are slowed or reduced in amplitude in patients with
Alzheimer's Disease (AD) and Parkinson's Disease (PD) with dementia. To
test the possibility that visual-spatial deficits seen in dementia may be
secondary to reduced input to higher cortical centers, we carried out
[O-15]-water activation PET scans with two groups of demented patients
(PD with dementia, N=5; probable AD; N=5), and two control groups (normal
control subjects, N=7; and cognitively intact patients with PD, N=4).
Overall metabolic values were lower for the patient groups compared to
normals, and stimulation effects were significantly lower in association
cortices for the demented patients compared to the non-demented
individuals. We are uncertain if the effect observed would entirely
account for the behavioral findings in visual-spatial tasks, and plan to
study these phenomena further. We do feel that responsiveness in the
visual system should not be excluded as one of the factors contributing
to cognitive deficits in demented patients.
Sponsored in part by NIH RO1 NS24896 to D.E. Kuhl
http://www-personal.umich.edu/~gusb/snabstract.html