There have been a number of new biomarkers identified recently that could lead to development of blood tests for Alzheimer's disease, but few have actually been validated in the clinic, and findings have been hard to duplicate. Researchers from across the U.S. have identified a number of blood biomarkers and used the multicenter Alzheimer's Disease Neuroimaging Initiative (ADNI) as a resource to confirm their results in a larger group of people.
Using proteomics to measure 190 proteins in blood samples from two groups totaling 600 people, including healthy volunteers and people with Alzheimer's disease or mild cognitive impairment (MCI; believed to be a precursor to Alzheimer's disease), the team found 17 biomarkers linked with MCI or Alzheimer's disease. By matching these with biomarkers found in 566 people who had taken part in the ADNI studies, the researchers narrowed their results down to four markers--apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide. These markers also correlated with levels of beta amyloid in cerebrospinal fluid, which has previously been used as a biomarker in the disease.
"Reliability and failure to replicate initial results have been the biggest challenge in this field," says lead author William Hu of Emory University School of Medicine. "We demonstrate here that it is possible to show consistent findings."
Blood tests for Alzheimer's disease and for MCI would be useful for clinicians by reducing the need for invasive tests such as spinal taps or costly imaging techniques. They could aid definitive diagnosis and allow earlier treatment, which would give patients and their families relief from symptoms. Though these results suggest that tests are a step closer, further research is still needed to be able to differentiate Alzheimer's disease from other dementias, and to make sure that the biomarkers are practical and reliable.
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