Biomarkers Potentially Diagnose Alzheimer's Disease Early

A blood test that offers promise as a way to detect Alzheimer's disease (AD) at its earliest onset has been evaluated.

The test has the potential to detect distinct metabolic signatures in blood plasma that are synonymous with the disease years before patients begin showing cognitive decline.

Scientists at the Mayo Clinic (Rochester, Minnesota, USA) analyzed cerebrospinal fluid and plasma samples from 45 people in the Mayo Clinic Alzheimer's Disease Center, 15 with no cognitive decline, 15 with mild cognitive impairment (MCI) and 15 with AD. The team applied a liquid chromatography/mass spectrometry-based nontargeted metabolomics approach to determine global metabolic changes in plasma and cerebrospinal fluid (CSF) from the same individuals with different AD severity.

Metabolomics assesses what is happening in the body at a given time and at a fine level of detail, giving scientists insight into the cellular processes that underlie a disease. In this case, the metabolomic profiles showed changes in metabolites related to mitochondrial function and energy metabolism, further confirming that altered mitochondrial energetics is at the root of the disease process.

Metabolic profiling detected a total of significantly altered 342 plasma and 351 CSF metabolites, of which 22% were identified. Based on the changes of more than 150 metabolites, they found 23 altered canonical pathways in plasma and 20 in CSF in MCI compared with cognitively normal (CN) individuals with a false discovery rate of less than 0.05. The time-of-flight mass spectrometry was performed using the Agilent 6220 (Agilent Technologies, Santa Clara, CA, USA).

Eugenia Trushina, PhD, a Mayo Clinic pharmacologist, and lead author of the study, said, “We want to use these biomarkers to diagnose the Alzheimer's disease before symptoms appear, which can be decades before people start exhibiting memory loss. The earlier we can detect the disease, the better treatment options we will be able to offer." Dr. Trushina hopes that the identified changes in the metabolic pathways could lead to a panel of biomarkers, which can eventually be used on a larger scale for early diagnosis, and monitoring of Alzheimer's progression. The study was published on May 20, 2013, in the journal Public Library of Science ONE.

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