Associations Between ApoEε4 Carrier Status and Serum BDNF Levels—New Insights into the Molecular Mechanism of ApoEε4 Actions in Alzheimer’s Disease

Insufficient neurotrophic support increases the risk for developing Alzheimer’s disease (AD). Mounting evidence has confirmed the association of brain-derived neurotrophic factor (BDNF) and apolipoprotein E (ApoE) with AD. As both BDNF and ApoE are suggested to be involved in modulating brain integrity, the present study is aiming to investigate the associations between these two factors. In this study, 110 AD patients and 120 cognitively normal controls (NC) were recruited for measurement of serum BDNF levels and ApoE genotyping. Serum BDNF levels in the AD group were significantly lower than that in the NC group, reflecting insufficient neurotrophic supply in AD patients. We further found that ApoE e4+/− and e4+/+ subjects had significantly lower serum BDNF levels than e4−/− subjects in the whole cohort and the NC group, suggesting altered BDNF metabolism in ApoE e4 carriers. Further analysis indicated possible interactions between ApoEe4 and BDNF in their co-effects on AD and mini-mental state examination (MMSE) scores. Our findings imply that the possible involvement of ApoE e4 in BDNF metabolism might be another molecular mechanism underlying the contribution of ApoE e4 to the development of AD.