Changes in serum brain-derived neurotrophic factor levels in patients with Alzheimer's disease

Abstract

Objective To investigate changes in serum brain-derived neurotrophic factor(BDNF)levels in patients with Alzheimer's disease(AD). Methods Venous blood samples were collected from 40 AD patients, 40 amnestic mild cognitive impairment(aMCI)patients and 40 normal controls.Serum BDNF levels were analyzed by enzyme-linked immunosorbent assay(ELISA). The relationships of serum BDNF levels with age, gender, educational level, mini-mental state examination(MMSE)score and Beck depression scale-Ⅱ(BDⅠ-Ⅱ)score in AD patients were analyzed. Results Serum BDNF levels were lower in AD patients than in patients with aMCI and normal controls(4.6±1.9 μg/L vs.9.3±4.7 μg/L, 10.2±1.8 μg/L, F=71.083, P 0.05). Pearson correlation analysis showed that serum BDNF levels had a positive correlation with MMSE score(r=0.428, P<0.05). Conclusions Advanced age is associated with decreased serum levels of BDNF in AD patients.Decreased serum levels of BDNF in AD patients are related to the severity of cognitive impairment.There is no correlation between serum BDNF levels and depressive symptoms in AD patients. Key words: Alzheimer disease; Cognition disorders; Brain-derived neurotrophic factor