Serum Adiponectin in Alzheimer's Disease (AD): Association with AD Biomarkers and Cognitive Outcome

Background: The association between dementia and serum adiponectin has been evaluated in many studies; however, conclusions remain mixed. Objective: We investigated the cross-sectional associations of adiponectin with cognitive function and Alzheimer's disease (AD) biomarkers and whether serum adiponectin levels can predict cognitive outcomes. Methods: This study included 496 participants from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI1) with available serum adiponectin levels at baseline and >= 65 years of age. Subjects were stratified based on sex and apolipoprotein epsilon 4 (APOE4) carrier status to determine associations between adiponectin and cognitive function. The linear mixed model was used to analyze associations between adiponectin level and cognitive outcome in amnestic mild cognitive impairment (aMCI) patients. Results: Serum adiponectin levels were higher in aMCI and AD than in CN subjects among APOE4 non-carrier males (adiponectin in CN, aMCI, and AD: 0.54 +/- 0.24, 0.74 +/- 0.25, and 0.85 +/- 0.25, respectively, p < 0.001). In this group, serum adiponectin levels were associated with age (p = 0.001), ADAS13 (p < 0.001), memory function (p < 0.001), executive function (p < 0.001), total tau (p < 0.001), and phosphorylated tau (p < 0.001) measures in cerebrospinal fluid (CSF). Higher adiponectin level was not associated with cognitive outcome in aMCI patients in the linear mixed model analysis over 5.3 +/- 2.6 years of mean follow-up. Conclusion: Serum adiponectin level was associated with cognitive function and CSF AD biomarkers among APOE4 non-carrier males. However, serum adiponectin level was not associated with longitudinal cognitive function outcome in aMCI.