Abstract: Objective To determine the clinical significance of serum inflammatory markers and 25-hydroxyvitamin D in diagnosing and treating depression in patients with Alzheimer's disease （AD）. Methods Serum levels of inflammatory markers were measured by ELISA and 25 hydroxyvitamin D（25-OH-VD）by chemiluminescent immunoassay （CLIA） in 20 AD patients with depression,26 AD patients without depression and 24 eligible healthy volunteers. Participants were evaluated for cognitive function by the Mini-Mental State Examination（MMSE）scores. Results Serum levels of IL-6 and TNF-α in AD with depression group were significantly increased,and（25-OH-VD）was significantly decreased. There were significant differences between the three groups （P<0.01）. Pearson correlation analysis showed that MMSE score in AD with depression group was negatively correlated with the levels of IL-1β、IL-6 and TNF-α（r=-0.437、-0.371、-0.532, P<0.05）,and positively correlated with 25-OH-VD（r=0.512,P<0.05）. （25-OH-VD）was negatively correlated with IL-1β,IL-6 and TNF-α（r=-0.452、-0.441、-0.471, P<0.05）. Conclusion The marker levels of peripheral inflammatory IL-6 and TNF-α in AD patients with depression were significantly increased, and the level of（25-OH-VD）was significantly decreased. This may be closely related to cognitive impairment in AD patients.

Key words: Alzheimer's disease, Depression, Inflammatory factors, 25-hydroxyvitamin D, Cognitive impairment