There is an urgent need to identify non-invasive biomarkers for the detection of 
sporadic Alzheimer's disease (AD). We previously studied microRNAs (miRNAs) in 
AD autopsy brain samples and reported a connection between miR-137, -181c, -9, 
-29a/b and AD, through the regulation of ceramides. In this study, the potential 
role of these miRNAs as diagnostic markers for AD was investigated. We 
identified that these miRNAs were down-regulated in the blood serum of probable 
AD patients. The levels of these miRNAs were also reduced in the serum of AD 
risk factor models. Although the ability of these miRNAs to conclusively 
diagnose for AD is currently unknown, our findings suggest a potential use for 
circulating miRNAs, along with other markers, as non-invasive and relatively 
inexpensive biomarkers for the early diagnosis of AD, however, with further 
research and validation.