A simple eye test to detect Alzheimer’s disease
Alzheimer’s Disease is a condition that affects a proportion of the population as they age. The incidence of Alzheimer’s will increase in people in the UK age. Although there is currently no absolute cure for Alzheimer’s, the rationale for early diagnosis is that it can help put into place the appropriate medical treatment that may slow down the disease. Slowing down the disease enables carers to provide a suitable supportive environment and support services at an earlier stage.
Researchers have discovered that a retinal scan can help diagnose Alzheimer disease years before the clinical symptoms start to emerge. Detecting the disease earlier with a retinal test can help patients be more involved in making plans for their care, as well as sorting out their legal and financial matters. In the early stages of Alzheimer’s, the patient is often very lucid and can understand what is going on.
Clinical symptoms of Alzheimer disease occur because of damage caused by proteins that build up in the patient’s brain resulting in loss of good connections between nerve cells. Ultimately, the patient loses those nerve cells and healthy brain tissue.
Until recently, it was not possible to make an entirely positive diagnosis of Alzheimer’s other than with a brain biopsy after death. However, physicians are now able to use a combination of medical history, analysis as the patient’s mood, their personality, and their mental status. Together with physical and neurological exams, brain imaging with MRI and blood tests, physicians can mostly rule out other possible causes of symptoms that may mimic Alzheimer’s in the early stage.
The eyes are a window to the body
A recent breakthrough by researchers at the Cedars-Sinai Medical Centre in the USA and by other institutes such as Imperial College London and the Western Eye Hospital have made diagnosis much more straightforward. The researchers have discovered that Alzheimer’s disease affects the retina of the eye in a similar way to which it affects the brain because the eye is an extension of the brain. Therefore, an eye scan can be used to detect key signs of Alzheimer’s long before patients have experienced noticeable symptoms.
The recent study by the Cedars-Sinai Medical Centre group published in the journal JCI Insight based its findings on a clinical trial looking at 16 Alzheimer’s disease patients. They were seeking to detect amyloid plaques that are the early signs of Alzheimer’s disease using non-invasive, inexpensive, and convenient retinal imaging in living patients. The investigator in charge was Maya Koronyo-Hamaoui, the Associate Professor in the Department of Neurosurgery in Bayer Medical Sciences. The imaging is still at an investigational stage and has to go through the US Food and Drug Administration for approval.
The OCT can be a more practical and less expensive way to scan for Alzheimer’s disease
The machine they use is an OCT, or optical coherence tomography, which is an established medical imaging technique used to observe the microscopic detail of layers of the retina. It can painlessly scan a patient’s retina and look for abnormalities. We have an OCT at Clinica London which we use daily. We one day hope to be able to use the OCT to detect Alzheimer disease.
The researchers used the technique called blue laser autofluorescence in conjunction with the OCT. Therefore it is an adaptation of our existing OCT specifically to look for the cellular components that will glow without an injection of a dye. At present, the only way to scan the brain of living people is by doing a PET scan to see whether amyloid and TAU are accumulating. But these scans are very much more expensive and invasive because it involves an injection of radioactive tracer that binds the proteins, making them glow during the scan. Using an OCT is very much more practical and attractive.
Watch this space. Professor Michaelides and Mr Jaheed Khan are our retinal experts here at Clinica London. They routinely examine patients and do many OCTs. They have a vast experience in the medical retina subspecialty.