MiRNA -483-5p as a Potential Noninvasive Biomarker for Early Detection of Alzheimer's Disease.

Alzheimer's disease (AD) is an irreversible, progressive neurodegenerative disease that accounts for 62% of dementia cases in elderly. Early diagnosis of AD is crucial for successful treatment in order to slow disease progression and avoid deterioration. Current diagnostic tools for AD are unable to detect the disease in its early stage; in addition, they still have several limitations. Many studies have shown that microRNAs (miRNAs) are implicated in the pathogenesis of AD, and alterations of their levels in blood make them potential biomarkers for AD. We aimed to evaluate the plasma microRNA-483-5p as a non -invasive biomarker for early diagnosis of AD in mild cognitive impairment (MCI) stage in order to improve treatment outcomes. 40 patients with MCI and AD, and 20 apparently healthy controls were investigated. Plasma levels of miRNA -483-5p were measured by real time polymerase chain reaction (PCR) and expressed as fold change. Receiver operating characteristic (ROC) curve analysis was done to assess diagnostic performance of the assay. Plasma levels of miRNA-483-5p were higher in MCI and AD patients than controls (mean = 8.04, 2.84 and 0.21 respectively, P<0.001), and decreased in AD patients in comparison to MCI patients (mean = 2.84 and 8.04 respectively, P = 0.032). There were significant positive correlations between plasma levels of miRNA-483-5p and age (r = 0.338, P= 0.008) and Dementia Rating (DR) scale (r = 0.351, P = 0.026), and significant negative correlations between plasma levels of miRNA-483-5p and Functional Daily Living Activity (FDLA) scale (r = -0.441, P<0.001), Mini Mental State Examination(MMSE) (r = -0.478, P< 0.001) and Montreal Cognitive Assessment (MOCA) scale (r = -0.396, P= 0.002). ROC curves revealed that miRNA-483-5p has high diagnostic performance in differentiating MCI and AD patients from healthy controls with specificity 95%, 90% and sensitivity 85%, 90% respectively. In conclusion, miRNA-483-5p may be a promising non -invasive biomarker for early diagnosis of AD in MCI stage.