RNA test could detect Alzheimer's disease
31 July 2013
A new RNA-based blood test can distinguish between people with
Alzheimer's disease and healthy controls. This type of test could be
used to help diagnose the disease and other degenerative disorders.
Alzheimer's disease, the most common form of dementia, can
currently only be diagnosed with certainty at autopsy, so the hunt
is on to find reliable, non-invasive biomarkers for diagnosis in the
living. Andreas Keller and colleagues focused on microRNAs (miRNAs),
small non-coding RNA molecules known to influence the way genes are
expressed, and which can be found circulating in bodily fluids
The team, from Saarland University and Siemens Healthcare
highlighted and tested a panel of 12 miRNAs, levels of which were
found to be different amongst a small sample of Alzheimer's patients
and healthy controls. In a much bigger sample, the test reliably
distinguished between the two groups. The research is described in
the open access journal Genome Biology.
Decent biomarkers need to be accurate, sensitive (able to
correctly identify people with the disease) and specific (able to
correctly pinpoint people without the disease). The new test scores
over 90% on all three measures. But whilst the test shows obvious
promise, it still needs to be validated for clinical use, and may
eventually work best when combined with other standard diagnostic
tools, such as imaging, the authors say.
As people with other brain disorders can sometimes show
Alzheimer's-like symptoms, the team also looked for the miRNA
signature in other patient groups. The test distinguished controls
from people with various psychological disorders, such as
schizophrenia and depression, with over 95% accuracy, and from
patients with other neurodegenerative disorders, such as mild
cognitive impairment and Parkinson's disease, with lower accuracy.
It also discriminated between Alzheimer's patients and patients with
other neurodegenerative disorders, with an accuracy of around 75%.
But by tweaking the miRNAs used in the test, researchers think
accuracy could be improved.
The work builds on previous studies highlighting the potential of
miRNAs as blood-based biomarkers for many diseases, including
numerous cancers, and suggests that miRNAs could yield useful
biomarkers for various brain disorders. But it also sheds light on
the mechanisms underpinning Alzheimer's disease. Two of the miRNAs
are known to be involved in amyloid precursor protein processing,
which itself is involved in the formation of plaques, a classic
hallmark of Alzheimer's disease. And many of the miRNAs are believed
to influence the growth and shape of neurons in the developing
1. Leidinger P, et al. A blood based 12-miRNA signature
of Alzheimer disease patients. Genome Biology 2013, 14:R75