Altered serum levels of adipokines and insulin in probable Alzheimer's disease.

Cerebral hypometabolism of glucose, weight loss, and decreased food intake are characteristic features of sporadic Alzheimer's disease (AD). A systematic study on the serum levels of adipokines and insulin, the major hormones regulating energy metabolism, food intake, and body weight, in sporadic AD is necessary. The present study compares the serum levels of leptin, adiponectin, and insulin, measured by commercially available immuno-assay kits, between controls and sporadic AD subjects. The results show a conspicuous decrease in the level of leptin, a dramatic rise in the level of adiponectin, and also a statistically significant increase in insulin level, in the blood of AD subjects, with respect to controls. The changes in the serum levels of adiponectin and insulin in AD are positively correlated with the severity of dementia. Likewise, the serum level of leptin in AD subjects is negatively correlated with the degree of dementia. The changes in the levels of adipokines and insulin have implications in the amyloid pathology, neurodegeneration, and hypometabolism of glucose existing in the AD brain.