AbstractBackgroundAlzheimer’s disease (AD) is the most common neurodegenerative disease, that characterize a long preclinical phase. Therefore, improving the early diagnosis of the disease is crucial. Biological and cognitive markers that will help improve the accurate diagnosis of the disease, understanding the underlying etiology of the clinical syndrome and that can be useful in clinical trial recruitment are constantly sought. It has been suggested that changes in miRNAs expression may predict the onset of cognitive decline. Measuring miRNA in the blood could be a promising approach for the early detection of AD. The literature data have indicated that circulating miRNAs could reflect the early neurodegenerative changes and predict the MCI/AD onset during the pre‐symptomatic stage. This study aims to evaluate the concentration of the miRNA‐451a in patients with AD and compare it with classical biomarkers for the disease.MethodA total of 30 individuals, including 15 patients with AD and 15 non‐demented controls, were enrolled in the study. miRNA was isolated from serum samples, and it was hybridized with the biotin‐labeled specific DNA oligonucleotide. The RNA hybrids were then transferred onto a stationary solid phase coated with a monoclonal antibody specific to matched RNA‐biotin hybrids. The absorbance of the complex was proportional to the concentration of miRNA‐451a present in the serum sample. The classical AD biomarkers, such as Aβ‐42, Aβ‐42/Aβ‐40, tau, and pTau181, were assessed in the cerebrospinal fluid (CSF) by immunoenzyme assays.ResultThe significantly higher concentrations of miRNA451a in AD patients in comparison to non‐demented controls were revelded. Moreover, the elevated level of miRNA451a correlated significantly with Aβ‐42/Aβ‐40 ratio and tau protein in the whole study group.ConclusionPresented results indicate that miRNA451a deregulation may be important in the initiation of AD‐related neurodegeneration, but these investigations need to be further clarified using a larger study group.AcknowledgementThe study was conducted with the use of equipment purchased by Medical University of Białystok as part of the RPOWP 2007‐2013 funding, Priority I, Axis 1.1, contract No. UDA‐RPPD.01.01.00‐20‐001/15‐00 dated 26.06.2015.