Alzheimer's disease. Age at onset and single-photon emission computed tomographic patterns of regional cerebral blood flow
W. J. Jagust, B. R. Reed, J. P. Seab and T. F. Budinger
Department of Neurology, Martinez Veterans Affairs Medical Center, CA 94553.
We performed this study to determine whether early- and late-onset
Alzheimer's disease differ physiologically. Ten patients with a presenile
(before 65 years old) onset of the disease and 16 with senile onset of the
disease were evaluated clinically and neuropsychologically and studied with
single photon emission computed tomography using the blood flow tracer
[123I]N-isopropyl-p-iodoamphetamine. Although the presenile subjects had
more severe neuropsychological abnormalities in all realms of cognitive
function, including language, and showed greater reductions in regional
blood flow than the older patients, they were also more severely demented,
thus complicating interpretation of the results. Two indexes of cerebral
perfusion, a ratio of regional flow compared with occipital flow and a
left-right asymmetry index, demonstrated relative left frontal
hypoperfusion in presenile- but not senile-onset patients and did not
appear to be an artifact of the severity differences. Although no asymmetry
of cognitive function was noted, the perfusion asymmetry provides
biological evidence for an alteration in left-hemisphere function in
patients with the early onset of Alzheimer's disease.
