A recent study published in ACS Chemical Neuroscience suggests the use of retinal hyperspectral imaging technology as a biomarker for detecting early degenerative alterations in the retina associated with Alzheimer's disease.
Study: In Vivo Assessment of Retinal Biomarkers by Hyperspectral Imaging: Early Detection of Alzheimer’s Disease. Image Credit: nobeastsofierce/Shutterstock.com
The retina is used as a window to assess Alzheimer's disease since it is a developmental extension of the brain. Alzheimer patients’ retinas have structural abnormalities including weakening of the retinal nerve fibre layer and modifications to the retinal vasculature. These modifications occur in the later stages of illness and are not particular biomarkers for Alzheimer's disease.
Importance of Preclinical Alzheimer's Disease Detection
Alzheimer's disease (AD) is the most common cause of dementia. Forty-seven million individuals globally are impacted currently by dementia. Alzheimer's disease is defined by the alterations in the composition of tau- and amyloid-protein. These changes start to occur years before brain shrinkage and cognitive deterioration. The identification of biomarkers for early preclinical stages is the holy grail of Alzheimer's disease management. Mass population screening is required in the future for preclinical Alzheimer's disease detection.
Limitations of Current Diagnosis Methods
Detection of Alzheimer's disease needs a quick, non-invasive, and inexpensive technique. Identifying preclinical Alzheimer's disease is extremely helpful in creating anti-AD treatments to stop the illness before it manifests clinically. Unfortunately, no practical biomarker exists currently that meets the aforementioned criteria.
The quantification of amyloid-beta (A) using positron emission tomography (PET) is a standard cognitive evaluation method for patients with cognitive and behavioural deficits. This technique is expensive, time-consuming, and invasive, which makes it unsuitable for routine population screening even though it helps in the identification of patients at risk.
Detection of Retinal Morphological Changes in Alzheimer's Patients
Multiple cross-sectional studies have revealed retinal morphological changes in Alzheimer's disease patients. These changes include alterations to the retinal vasculature, retinal cell loss, optic disc, deposition of inclusion bodies, and thinning of the retinal nerve fibre layer. These changes are observed using retinal imaging techniques such as angiography (OCTA), optical coherence tomography (OCT), and confocal scanning laser.
Utilization of Retinal Hyperspectral Imaging of Mice Cells for Identification of Alzheimer's Disease
Retinal hyperspectral imaging of mice cells produces strong feasibility results for the identification of early aggregation events of Alzheimer's disease. More et al. described that live animal imaging observations translate to retinal imaging in humans. Determining the utility of the aforementioned occurrence can be used as an optical marker for early-stage Alzheimer's disease. Non-invasive retinal imaging to detect atrophy and degenerative alterations in the brain is of great interest for population screening.
The researchers used retinal hyperspectral imaging to acquire distinctive spectral signatures that have correlated with the development of disease in mice. They introduced modifications in retinal hyperspectral imaging for detecting and analysing light scatter alterations in patients’ retinas. This research establishes the groundwork for future retinal hyperspectral imaging-based retinal biomarker research for Alzheimer's disease as well as for extensive prospective longitudinal clinical trials to assess their applicability in preclinical treatment.
The success of the retinal hyperspectral imaging approach as a biomarker for the early-stage detection of Alzheimer's disease is demonstrated in this study. Retinal hyperspectral imaging offered a potent spectral signature (MMSE = 22) in the early stages of the disease. The necessary equipment used was comparable to that needed for standard fundus imaging, except for the custom-made optics needed for spectral characterisation of retinal tissue.
No adverse effects or problems were reported throughout this research. These findings add to information regarding retinal imaging for the detection of Alzheimer's disease by integrating a biomarker sensitive to amyloid aggregation before it leads to the formation of insoluble plaques.
The molecular pathology that underlies Alzheimer-related cognitive disease begins years or decades before clinical presentation. This fact is now widely acknowledged with advances in the understanding of Alzheimer's disease pathology and related neurodegeneration. As a result, there is an urgent need to find biomarkers sensitive to these early pathological events. Retinal hyperspectral imaging, a non-invasive, low-cost technology without the use of exogenous agents for the spectral characterization of such occurrences in humans is described for the first time in this study.
Potential of Hyperspectral Imaging for Early Alzheimer's Detection
Retinal hyperspectral imaging can be a useful tool for Alzheimer's disease clinical trials in identifying presymptomatic in conjunction with currently available biomarkers. Retinal hyperspectral imaging-enabled sufficiently early diagnosis will enable intervention with current medications, potentially extending the patient's life by years.
The retinal hyperspectral imaging method created by the researchers has shown promise for early Alzheimer's disease identification. Such a non-invasive, low-cost population screening technique is useful for people at high risk since they can start receiving frequent monitoring at a young age.
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More, S. S., Beach, J. M., McClelland, C., Mokhtarzadeh, A., & Vince, R. (2019). In Vivo Assessment of Retinal Biomarkers by Hyperspectral Imaging: Early Detection of Alzheimer’s Disease. ACS Chemical Neuroscience, 10(11), 4492–4501. https://pubs.acs.org/doi/10.1021/acschemneuro.9b00331