cognitive impairment to Alzheimer disease

Objective—To examine the utility of single photon emission computed tomography (SPECT) to predict conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Design—Longitudinal, prospective study. Setting—University-based memory disorders clinic. Participants—127 patients with MCI and 59 healthy comparison subjects followed for 1 to 9 years. Measurements—Diagnostic evaluation, neuropsychological tests, social/cognitive function, olfactory identification, apolipoprotein E genotype, MRI, and brain 99mTc HMPAO SPECT scan with visual ratings and region of interest (ROI) analyses were done. Results—Visual ratings of SPECT temporal and parietal blood flow did not distinguish eventual MCI converters to AD (n=31) from non-converters (n=96) but the global rating predicted conversion (41.9 % sensitivity and 82.3 % specificity, Fisher's exact test p=0.013). Blood flow in each ROI was not predictive, but when dichotomized at the MCI patients ' median value, low flow increased the hazard of conversion to AD for parietal (HR 2.96, 95%CI 1.16-7.53, p=0.023) an