P2‐410: Alzheimer's disease‐related changes in plasma brain‐derived neurotrophic factor levels: Data from the AIBL study

Abstract

Background: The relationship between brain-derived neurotrophic factor (BDNF) and Alzheimer's disease (AD) pathogenesis is yet to be fully elucidated. BDNF is critical for neuronal survival and function and represents a potential neuroprotective agent; somewhat expectedly, low levels have been measured in the AD brain post mortem. However, conflicting results have been reported in the blood fractions of AD patients, possibly reflecting differences in disease stage or measurement technique. These 'conflicting results' make it difficult to determine the suitability of BDNF as a blood biomarker of AD. A study investigating BDNF levels in a large well-characterised ageing cohort is lacking; our aim is to address this deficit. Methods: BDNF was measured in plasma fractions using the Milliplex-MAPHuman brain-derived protein panel (Millipore, USA). Assays were read on a Luminex xMAP reader system (Bio-Plex 200 System, Bio-Rad, USA). BDNF levels were compared between mild cognitively impaired (MCI) individuals, cognitively healthy controls, and AD patients. Levels were then analysed in conjunction with objective and subjective measurements of physical activity, extensive neuropsychological data, Pittsburgh Compound B positron emission tomography (PiB-PET), magnetic resonance imaging (MRI) and blood biomarker levels. Results: Plasma BDNF levels were measured in 1112 plasma samples. Preliminary analyses suggest our findings support the hypothesis that BDNF levels are altered in individuals with AD compared to cognitively healthy controls. Further analysis will establish the relationship between plasma BDNF and PiB-PET determined brain amyloid burden. Conclusions: To our knowledge, this study is the first to assess the relationship between brain amyloid burden and BDNF levels. Additional analysis is required to ascertain the suitability of BDNF as a candidate AD blood biomarker. The significance of our findings will be evaluated using longitudinal data from the AIBL study of ageing.