A comparative SPECT study of regional brain perfusion in patients with Alzheimer's disease, progressive supranuclear palsy, and corticobasal degeneration

Abstract

To investigate the underlying mechanism of dementing illnesses that comprise tauopathy, we evaluated the regional cerebral blood flow (rCBF) of patients with Alzheimer's disease (AD), corticobasal degeneration (CBD), and progressive supranuclear palsy (PSP), and of normal control subjects using single-photon emission computed tomography (SPECT) with 123I-iodoamphetamine as the tracer. rCBF was evaluated semiquantitatively by using the ratio of the RI count to the occipital region count, and the asymmetry index. Compared with the normal controls, AD patients showed significantly decreased rCBF in the inferior and lateral prefrontal, temporal, and posterior parietal cortices, while CBD patients showed significant rCBF reduction in the inferior prefrontal, anterior cingulate, medial premotor, temporal, posterior parietal, and sensorimotor cortices, thalamus, and basal ganglia. PSP patients showed no rCBF reduction in any region. Compared with PSP patients, CBD patients showed significant rCBF reduction in the sensorimotor cortex. Compared with CBD patients, AD patients showed significant rCBF reduction in the posterior parietal cortex, while rCBF in the sensorimotor cortex of the CBD patients was significantly decreased compared to the AD patients. Asymmetry of rCBF was observed in the lateral prefrontal and posterior parietal cortices of the AD patients and in the inferior prefrontal and sensorimotor cortices of the CBD patients. In conclusion, AD patients were characterized by reduced rCBF in the temporoparietal cortex. Although the magnitude of the rCBF reduction was mild in CBD, the decreases extended widely over the subcortical/cortical areas.