Australasian Science: Australia's authority on science since 1938

Blood Test for Alzheimer’s

By Stephen Luntz

A blood test providing prior warning of Alzheimer’s disease may be on its way following the identification of markers that signal the presence of beta-amyloid plaques in the brain.

Earlier this year Dr Samantha Burnham of CSIRO Preventative Health co-authored a Lancet paper showing that the beta-amyloid plaques used to diagnose Alzheimer’s disease appear an average of 17 years before the clinical onset of dementia. However, identification of the plaques relied on highly expensive neuroimaging or invasive extraction of spinal fluid.

Burnham has now published a paper in Molecular Psychiatry showing that a combination of nine blood markers correlate with positron emission tomography tests that can detect the presence of the plaques. “We hope our continued research will lead to the development of a low-cost, minimally invasive population-based screening test for Alzheimer’s,” Burnham says.

In order to make the test a reality she says studies in wider population samples are required “to establish that it doesn’t also pick up other diseases such as Parkinson’s”. Logistical questions such as the platform to be used by pathology labs also need to be resolved.

While some researchers have questioned whether plaques are the first evidence of Alzheimer’s (AS, June 2013, pp.6-7), Burnham says these were done in rodents. “Animal models may only replicate one aspect of a pathology, so for example they might have the same cognitive path but not the same plaque path.”

Current treatments for Alzheimer’s alleviate symptoms rather than slowing the progress of the disease, making them of little use to anyone diagnosed before symptoms have appeared. However, Burnham says: “A poll in the Sydney Morning Herald found that most people would want to know if they have Alzheimer’s so they could put care plans in place, maybe retire early and take the trip of a lifetime.”

Moreover, Burnham says that a reliable early test is necessary if treatments are to be applied effectively. “Once you have cell death it is unlikely you can reverse it. We need to be able to get in beforehand to modify the disease.”