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. The gene discussed is ADIPOQ; the disease is early-onset autosomal dominant Alzheimer disease.