By 2030, an estimated 65.7 million people are predicted to be affected by Alzheimer’s disease (AD), a 30 million person jump from today’s total. But, there’s increasing evidence that biomarkers coupled with the correct imaging technique may provide crucial insights into the disease.
A group of international researchers summarized their understanding of the most commonly used and accurate imaging techniques for AD-related signs, along with the most current liquid biomarkers used in the early diagnosis and signaling of possible progression of Alzheimer’s, in a paper published online Jan. 4 in Experimental Gerontology.
Below are some of their most noteworthy findings:
MRI may be best used for early diagnosis
While the use of MRI in distinguishing AD subjects from control groups with a reasonable accuracy has been established science, sMRI can predict the future development of AD with an 80 percent accuracy, according to the study.
MRI can also reveal the disease progression of AD from cognitive normalcy to mild cognitive impairment (MCI) and ultimately to Alzheimer’s.
Furthermore, authors note that decline in hippocampal volume—visualized through MRI— correlates with the clinical progression of the disease.
“Hippocampal volumetry is the best established structural biomarker for AD in the field of imaging, particularly for early diagnosis, and appears to be suitable for risk stratification in MCI cohorts and follow up in AD patients aiming for treatment trials,” wrote Otávio Toledo Nóbrega with the Medical Centre for the Elderly at University Hospital, University of Brasília in Brazil and colleagues.
PET may be more costly than effective
“At present, it is not clear whether the diagnostic accuracy of amyloid PET can prevail…in terms of accuracy. However, despite the drawback side of the high cost of performing PET, it is conceivable that coupled usage of these imaging techniques will, in a near future, contribute in determining pathological profiles that better suit prevention or disease-modifying therapy studies and in assisting clinical diagnosis,” wrote Nóbrega et al.
Imaging tracers show promise
Tau imaging is one of the most highly anticipated areas of development for understanding AD pathology is imaging tracers. Tau imaging is among the most promising PET modality because of the participation of tau protein in AD pathophysiology.
Additional complex PET compounds are being developed that “could become a biomarker of gene expression, determining genetic and/or epigenetic signatures…and [in] helping pharmaceutical companies to identify the best individuals to undergo clinical trials of HDAC-inhibitors-which have been proposed as treatment for degenerative diseases,” according to Nóbrega et al.
Combined approaches are key
“To date, we conclude that amyloid-pathology markers (low CSF Aβ42 and high Aβ42 deposition), followed by tauopathic scores, can predict abnormalities in typical high-risk individuals, whereas FDG PET and MRI volumetric measures tend to show more informativeness closer to or within the prodromal stage,” wrote Nóbrega et al.
“…combination of neurochemical, fluid biomarkers (t-tau, p-tau, Aβ42) with imaging markers as MRI-based tests (hippocampal and whole brain volumetry) are currently undergoing multicenter evaluation in controlled diagnostic phase IIb studies to determine the sensitivity and specificity of the markers and to make an initial assessment of their positive and negative predictive values,” added Nóbrega and colleagues.
There is still much to be learned
“There is still much room for studies to shed some light into the informativeness of fluid and imaging biomarker for early and differential diagnosis of the complex and challenging Alzheimer's disease,” wrote Nóbrega et al.