The miR-133b and miR-206 serum levels as a candidate biomarker in Alzheimer's patients with dyslipidemia

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by cognitive decline. Dyslipidemia, a risk factor for AD, may influence the expression of microRNAs (miRs) involved in AD pathogenesis. Thus, the aim of this study was to investigate the effect of dyslipidemia on the expression levels of miR-133b and miR-206 in AD patients with mild cognitive impairment. This study recruited a total of 45 subjects, who were subsequently divided into three distinct groups: the AD group (n = 15), the AD dyslipidemia group (n = 15), and the dyslipidemia group with normal cognitive status (n = 15). The Aβ_42/40 serum ratio was measured using an enzyme-linked immunosorbent assay. miR expression levels were determined by RT-qPCR. Clinicopathological characteristics, including Mini-Mental State Examination (MMSE) scores, Clinical Dementia Rating (CDR), and HDL levels, were also assessed. miR-133b levels were significantly reduced in the AD dyslipidemia group compared to the other two groups (p < 0.001), while miR-206 levels were markedly elevated (p < 0.001). Spearman correlation analysis revealed that miR-133b expression levels were positively associated with the Aβ_42/40 ratio (r = 0.799), MMSE scores (r = 0.578), and HDL levels (r = 0.768), while negatively associated with miR-206 levels (r = -0.461), CDR score (r = -0.539), and AD duration (r = -0.569). Conversely, miR-206 levels positively correlated with CDR and disease duration, but were inversely associated with miR-133b, MMSE, Aβ_42/40, and HDL. Serum miR-133b and miR-206 levels appear to be associated with AD pathology and clinical parameters in the early stages of the disease. The studied miR expression levels could serve as reliable biomarkers in AD patients with dyslipidemia.