APOE and Alzheimer disease: Serum levels of adiponectin were significantly lower in MCI and AD as compared to controls (p < 0.001). After controlling for age, educational level, and APOE genotype, adiponectin levels remained significantly reduced in these groups (p < 0.001). Circulating adiponectin levels did not predict cognitive decline in the elderly controls (i.e., progression from normal cognition to MCI) or progression to Alzheimer’s disease in subjects with MCI.