En español | A study presented today at the Alzheimer's Association International Conference 2019 suggests researchers may be one step closer to a potential breakthrough for treating the devastating and widespread disease — a simple blood test to detect proteins that accumulate in the brains of patients with Alzheimer's disease, causing neuron death.
A blood test that recognizes such a biomarker for Alzheimer's in the brain could “revolutionize clinical trials today and in the future,” says Maria Carrillo, chief science officer of the Alzheimer's Association. “And think of the implications for clinical practice once we have a therapeutic."
In that event, as she describes it, patients could one day get a quick blood test during their annual checkup to see if they have elevated biomarkers for Alzheimer's. Those who do would then be referred to a specialist to begin a course of treatment as soon as possible.
In the new study, researchers at the National Center for Geriatrics and Gerontology in Japan developed a prototype for a blood test that “reliably” picked up the accumulation of amyloid precursor protein (APP) with 93 percent specificity in the blood of 201 patients with mild cognitive impairment, Alzheimer's disease, or non-Alzheimer's dementia. It also picked up the protein in some subjects who were cognitively normal. (While amyloid plaque is considered a reliable biomarker of Alzheimer's, some of those with the plaque never go on to develop signs of the disease.)
Last year the same group of researchers found that blood biomarkers of this kind of amyloid protein were as reliable as the current gold standard of diagnosing Alzheimer's with positron-emission tomography (PET) or measuring the protein through cerebrospinal fluid. A blood test is much less invasive and more cost effective than a PET scan.
The new blood test developed in Japan may also be more efficient at picking up preclinical stages of Alzheimer's disease, according to the study. This would enable earlier intervention. Currently, changes in amyloid protein can exist for as long as two decades before the point at which a patient would be clinically diagnosed with Alzheimer's disease.
"Clinical trials haven't succeeded up until now, likely because we need to find a novel therapeutic and be able to catch people early in the disease before it is established and becomes a runaway train,” says Barry Greenberg, director of the Alzheimer's Disease Translational Center at Johns Hopkins School of Medicine.
Some of those hearing news of the blood test remain cautious, citing the need for the study to be replicated in a larger, more diverse population, or noting that a blood test that detects other Alzheimer's biomarkers, such as viruses or a protein called tau, might turn out to be better biomarkers to target in a blood test going forward.
Ultimately, “we need effective biomarkers at all stages of disease — before and after onset of symptoms — to both measure progression and test potential therapies to see if they slow or perhaps reverse the progression,” says Eliezer Masliah, director of the National Institute on Aging's Division of Neuroscience.