Finding earlier and more definitive ways to diagnose AD has been the subject of significant amounts of research, and testing advances have been seen in the last decade with expanded use of positron emission tomography (PET) and magnetic resonance imaging (MRI), as well as in the identification of biomarkers in cerebrospinal fluid (CSF) and more recently serum. While limited, some of these diagnostic advances are available to the public, though typically at a high price.A high-level overview of emerging diagnostic strategies can be found below.
Volumetric DataIn simple terms, volume changes in specific brain regions can predict the likelihood of progression from mild cognitive impairment (MCI) to AD. These volume assessments can be done by radiologists or with the help of FDA-approved MRI volumetric data software packages such as Neuroquant and Neuoreader. Hippocampal volume changes in particular are regarded as an important AD biomarker. 3 Because of limited sensitivity of this measure in diagnosing AD, however, MRI studies are regarded as a contributor to the diagnostic process but not sufficient in themselves for determining a diagnosis. 4
Diffusion Tensor ImagingDiffusion Tensor Imaging (DTI) is an advanced neuroimaging technique that uses the diffusion properties of water molecules to generate magnetic resonance images that correspond to changes in macroscopic axonal organization. This technique can be used to evaluate the structure of vertical cellular micro-circuits, termed "minicolumns." Previous studies have demonstrated that minicolumns are known to be altered in a somewhat predictable and progressive manner during aging, MCI, and AD. 5 Additionally, pathologic changes of cortex columnar architecture are associated with increased plaque load and cognitive decline. 6 With the aid of proprietary software, DTI can be measured and used as a marker of neurodegeneration.
PET ScanPathologic species of two proteins, amyloid-β (Aβ) and hyperphosphorylated tau accumulate in the brains of persons with AD. PET scans are able to assess for both proteins and serve as a reliable biomarker. Amyloid accumulation precedes clinically significant cognitive changes and tau accumulation progresses in step with cognitive decline, suggesting the value of PET scans for diagnosis and measurement of disease progression. 7
CSF and Blood TestsCerebrospinal fluid (CSF), accessible through lumbar puncture, surrounds the brain. Changes in the levels of Aβ and tau proteins in the CSF develop decades before the onset of clinically significant AD. 8 Among the tests of CSF developed during recent decades, the most prominent are CSF Aβ42:Aβ40 ratio and the CSF tau phosphorylated at threonine 181 (P-tau181). CSF P-tau217, measurable in the peripheral circulation, is hoped to provide a biomarker with very high sensitivity and specificity. 9Because blood is more easily accessed than CSF, C2N Diagnostics in St. Louis, Missouri has developed and released a blood test called PrecivityAD which is available in most of the U.S. and to the European U...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.