[Cerebral hemodynamic difference between early- and late-onset Alzheimer's disease by circumferential profile analysis with 123I-IMP brain SPECT].

We conducted investigation to determine whether early- and late-onset Alzheimer's disease differ pathophysiologically. Five patients with the early-onset (65 years and under) of the disease and 11 with the late-onset (65 years and over) of the disease were studied by single photon emission CT (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP). Circumferential profile analysis (CPA) was performed to examine differences in the predominant hypoperfusion in the temporoparietal lobe, which is considered to be functionally damaged the most in Alzheimer's disease. The Xm values, calculated from gradients between the motor sensory or occipital cortices and temporoparietal cortex in the circumferential profile curve, were compared in both groups. The Xm values for the patients with early- and late-onset Alzheimer's disease were 6.81 +/- 2.10 (count/degree) and 3.28 +/- 1.58, respectively, the difference being significant. Our results suggest that functional abnormalities in the temporoparietal area severer in early- than late-onset Alzheimer's disease and that the application of CPA to IMP SPECT is useful to elucidate the pathophysiological difference between each of the disease.