Regional Cerebral Blood Flow Abnormalities in Nondemented Patients With Memory Impairment

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Abstract
Background. Patients with objective evidence of memory impairment have been considered to be at risk for developing Alzheimer's disease (AD). However, little is known about patterns of regional cerebral blood flow abnormalities and their prognostic significance in these patients. Methods. The authors retrospectively studied 28 nondemented subjects with memory loss and investigated patterns of blood flow abnormalities on single photon emission computed tomography (SPECT). Results. The patients were followed up for more than 2 years; during follow‐up, 14 patients (50%) developed AD. The onset of memory impairment in patients who progressed to AD was significantly earlier than in those who remained in a nondemented condition. SPECT data from the initial evaluation were analyzed by region of interest analysis and statistical parametric mapping. Interestingly, both groups of patients shared hypoperfusion in the medial temporal regions and the posterior cingulate. In addition to these regions, significant blood flow reduction in the parietal and anterior cingulate cortices was detected in patients who progressed to AD. Conclusions. These results demonstrate that (1) subjects with an earlier onset of memory loss have an increased risk for developing AD, (2) SPECT can be useful for distinguishing subjects with memory loss who will rapidly progress to AD from those who will not, and (3) perfusion impairment typical of AD was evident even in subjects with memory impairment who remained nondemented.