Association between Adipokines and Biomarkers of Alzheimer's Disease: A Cross-Sectional Study.

Background: Adipose tissue dysfunction has been implicated in the pathophysiology of Alzheimer's disease. However, the involvement of adipokines, particularly adiponectin, remains unclear. Objective: To compare serum and cerebrospinal fluid (CSF) levels of adiponectin, leptin and leptin-to-adiponectin ratio in patients within the spectrum of Alzheimer's disease and evaluate their relationship with classical biomarkers and their value as markers of progression. Methods: Amnestic mild cognitive impairment (MCI, n= 71) and Alzheimer's dementia (AD, n= 53) subjects were consecutively recruited for serum and CSF adiponectin and leptin determination using an analytically validated commercial enzyme-linked immunosorbent assay (ELISA). Correlations were explored using adjusted Spearman's correlation coefficients. A logistic regression model and ROC analysis were performed to evaluate the staging predictive value of adipokines. Results: Serum adiponectin was 33% higher in AD when compared to MCI patients. Adiponectin CSF levels, similar in both groups, were positively correlated with A beta(42) and cognitive function, though only in women. The area under the ROC curve was 0.673 (95%CI:0.57-0.78) for serum adiponectin as predictor of dementia stage and the cut-off 10.85 mu g/ml maximized the sum of specificity (87%) and sensitivity (44%). Conclusion: Although longitudinal studies are required, we hypothesize that higher serum adiponectin in AD patients constitutes a strategy to compensate possible central signaling defects. In addition, adiponectin might be specifically assigned to neuroprotective functions in women and eventually involved in the female-biased incidence of Alzheimer's disease.