There are currently three FDA-approved amyloid positron emission tomography (PET) tracers designated for clinical use:
- florbetapir (Amyvid, Eli Lilly)
- flutemetamol (Vizamyl, GE Healthcare)
- florbetaben (Neuraceq, Piramal Imaging)
“While a PET scan is viewed by many as less invasive than lumbar puncture, it is much more costly and poses additional risks due to injection of a radioactive tracer. However, unlike CSF, amyloid imaging is able to provide information regarding regional patterns of pathology,” Burtea said.
She and colleagues are working to develop a new class of MRI contrast agents that would be able to bind specifically to amyloid plaques through functionalization with hexapeptides and cyclic heptapeptides. The imaging probe is composed of ultra small particles of iron oxide (USPIO).6
“Among the various USPIO derivatives screened in our study, USPIO coupled to a hydrophobic cyclic heptapeptide (USPIO-PHO) was the most effective and promising for human medicine,” Burtea said.
In a study published in Nature Medicine, Howard Federoff, MD, of Georgetown University Medical Center in Washington, D.C., and colleagues aimed to identify a blood biomarker that would allow physicians to identify patients who have very early AD and determine if currently available treatments are more effective when given earlier.4
“We discovered and validated a blood panel that predicted with greater than 90% accuracy, if a healthy person would develop mild cognitive impairment (MCI) or AD within three years,” Federoff said.
This blood panel may help mark the transition between preclinical states of AD where synaptic dysfunction and early neurodegeneration give rise to subtle cognitive changes, Federoff explained.However, additional investigations need to be completed to determine whether such blood tests can be used to screen a larger and more diverse population and to screen younger people to predict disease onset.
“Recent advances in AD biomarkers have increased the ability for early diagnosis of the disease. However, the relationship of presently known biomarkers with the cause of the disease needs further research as the molecular mechanism of the disease is not clear,” Chintamaneni said.
Beth Gilbert is a freelance health and science writer. She has an undergraduate degree in chemical engineering from Lehigh University and a Master’s in biomedical engineering from Columbia University.
This article was medically reviewed by Lindsey Marcellin, MD, MPH.
- Alzheimer’s Facts and Figures. Alzheimer’s Association. Available at: http://www.alz.org/alzheimers_disease_facts_and_figures.asp#prevalence. Accessed: November 19, 2014.
- Chintamaneni M, Bhaskar M. Biomarkers in Alzheimer’s disease: a review. ISRN Pharmacol. 2012;2012:984786.
- Khan TK, Alkon DL. Peripheral Biomarkers of Alzheimer’s Disease. J Alzheimers Dis. 2014;
- Mapstone M, Cheema AK, Fiandaca MS, et al. Plasma phospholipids identify antecedent memory impairment in older adults. Nat Med. 2014;20(4):415-8.
- Ferreira D, Rivero-santana A, Perestelo-pérez L, et al. Improving CSF Biomarkers’ Performance for Predicting Progression from Mild Cognitive Impairment to Alzheimer’s Disease by Considering Different Confounding Factors: A Meta-Analysis. Front Aging Neurosci. 2014;6:287.
- Ansciaux E, Burtea C, Laurent S, et al. In vitro and in vivo characterization of several functionalized ultrasmall particles of iron oxide, vectorized against amyloid plaques and potentially able to cross the blood-brain barrier: toward earlier diagnosis of Alzheimer’s disease by molecular imaging. Contrast Media Mol Imaging. 2014;
- Alzheimer’s and Dementia Testing for Earlier Diagnosis. Alzheimer’s Association. Available here: http://www.alz.org/research/science/earlier_alzheimers_diagnosis.asp. Accessed: November 19, 2014.