Blood test for Alzheimer's close

[Posted: Fri 10/08/2012 by Gillian Tsoi www.irishhealth.com]

Scientists have come closer to developing a blood test that will detect Alzheimer's disease.

The possibility of a cheap, convenient test for this form of dementia has been on the horizon for several years.

Scientists in the US have now found a group of markers that hold up in statistical analyses in three independent groups of patients.

The researchers measured the levels of 190 proteins in the blood of 600 people, who signed up for their study.

The study participants consisted of both healthy volunteers and people who had been diagnosed with Alzheimer's disease or mild cognitive impairment (MCI). MCI, considered a signal for Alzheimer's disease, causes a slight decline in brain function.

A subset of the 190 protein levels were significantly different in people with MCI or Alzheimer's. 

When those markers were checked against data from 566 people participating in the multicenter Alzheimer's Disease Neuroimaging Initiative, only four markers remained: apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide.

Changes in levels of these four proteins in blood also correlated with measurements from the same patients of the levels of proteins [beta-amyloid] in cerebrospinal fluid that previously have been connected with Alzheimer's.

The analysis grouped together people with MCI, who are at high risk of developing Alzheimer's, and full Alzheimer's.

"We were looking for a sensitive signal," says William Hu, assistant professor of neurology at Emory University School of Medicine in Georgia, who led the study.

"MCI has been hypothesized to be an early phase of Alzheimer's disease, and sensitive markers that capture the physiological changes in both MCI and Alzheimer's disease would be most helpful clinically."

Neurologists currently diagnose Alzheimer's disease based mainly on clinical symptoms. Additional information can come from PET brain imaging, which tends to be expensive, or analysis of a spinal tap, which can be painful.

"Though a blood test to identify underlying Alzheimer's disease is not quite ready for prime time given today's technology, we now have identified ways to make sure that a test will be reliable," said Hu.

"In the meantime, the combination of a clinical exam and cerebrospinal fluid analysis remains the best tool for diagnosis in someone with mild memory or cognitive troubles."

The study was carried out by researchers from the University of Pennsylvania and Washington University in St Louis.

It was published in the August issue of the journal Neurology.

For more information on Alzheimer's disease, visit the Irishhealth.com Alzheimer's clinic.