A New Blood Test Could Help Transform Alzheimer’s Treatment
Recent progress in clinical trials for Alzheimer’s disease has more or less been non-existent lately, especially after Pfizer revealed earlier this month that it will stop pursuing treatments for the disorder.
However, a recent study in Nature that reports on a screening test that could improve the success of Alzheimer’s drug research could be the news the field was waiting for, writes Scientific American.
The findings suggest that a simple blood test can accurately predict levels of a protein called amyloid beta in the brain that begins appearing early in the course of the disease before symptoms appear. The build-up of this protein is a key pathological feature of Alzheimer’s, and determining the degree to which someone’s brain is riddled with the molecule is essential for designing effective clinical trials.
Right now, the only way to measure amyloid in a living person is either via costly positron emission tomography imaging (PET scan) or by sampling cerebrospinal fluid (CSF) with a lumbar puncture, or spinal tap. Being able to introduce a blood test, would offer a cheaper, and far less invasive means of determining a patient’s amyloid status. Furthermore, it could even encourage more patients to enter clinical trials, as well as help researchers, distinguish people with brewing Alzheimer’s from those with other forms of dementia.
Senior study author, Katsuhiko Yanagisawa, director general of the National Center for Geriatrics and Gerontology in Japan, strongly believes that enough amyloid penetrates the blood-brain barrier to make its way into the bloodstream to be a useful measure of cognitive function.
“We think amyloid blood tests could replace costly, invasive amyloid tests, especially when it comes to detecting preclinical Alzheimer’s,” he explained. “We hope our biomarker better facilitates clinical trials for Alzheimer’s by improving enrollment of participants.”
In order to measure the amount of amyloid in the bloodstream, he and his colleagues used a technique called immunoprecipitation with mass spectrometry, which deploysantibodies to bind and identify proteins. The study included 121 people from Japan and 252 from Australia, and both groups involved individuals with normal brain function, mild cognitive impairment and Alzheimer’s. They discovered that the amount of amyloid present in the blood correlated with the degree of cognitive problems, and that blood amyloid levels also correlated with findings in the same patients from PET scans and spinal fluid measures.
Yanagisawa believes hat a simple amyloid blood test would allow for the recruitment of clinical trials of new drugs in a larger share of the population, as opposed to only those with access to advanced academic centers. Scaling up trial numbers should also help trials more accurately represent the actual population.
“This does seem to be an important study,” added James Hendrix, who was not involved in the new research and is director of Global Science Initiatives for the Alzheimer’s Association, the largest nonprofit funder of Alzheimer’s research. “It is from a top research team. It is a decently large sample size. And most important, they are correlating their results to PET and CSF. That cross-validation to other techniques is great to see – we haven’t seen this before for a blood test in Alzheimer’s.”
Also in agreement with such a view is neurologist, William Hu, from Emory University, who explained, “The findings are promising as reliable blood biomarkers can lead to early detection with a relatively straightforward procedure and lower costs. Yet he cautions the accuracy of amyloid PET scanning – the standard against which the blood test is being measured – remains controversial, compared true gold standard of Alzheimer’s, a postmortem inspection of brain tissue.”
He goes on to point out that the overall levels of amyloid differed between the Japanese and Australian groups. “I believe the technology will need further development and standardisation to provide more accurate amyloid measures,” he added.
For researchers, the development of such a test would make it a lot easier for researchers to identify people at risk for the disease in whom treatment and preventative measures could be more effective.
Yanagisawa and colleagues are in the process of extending and expanding their study in hopes of bringing an amyloid blood test closer to routine clinical use. Multiple authors have even filed for patents for the technique.
“It’s good to see this type of study advance, as we desperately need noninvasive and low-cost markers for Alzheimer’s disease,” Hedrix concluded. “But still, at this point, it is not ready for prime time.”