March 20, 2019
Ophthalmology can help detect Alzheimer`s
Study suggests loss of blood vessels in retina reflect changes in brain health
Alzheimer`s is the most common type of dementia with no cure and treatment. It disrupts the daily life of a person. There are millions of people living with Alzheimer's disease and no viable treatments or noninvasive tools for early diagnosis. It is a burden on their families and the economy is heavy.
A study of more than 200 people at Duke Eye Center, USA published in a journal, namely, “Ophthalmology Retina”, suggests the loss of blood vessels in the retina could signal Alzheimer's disease. The study included eyes of 39 people with Alzheimer's disease, and it was found that web was less dense and even sparse in places. The differences in density were statistically significant after researchers controlled factors including age, sex, and level of education. Researchers at Duke Eye Center studied other changes in the retina that could signal trouble upstream in the brain, such as thinning of some of the retinal nerve layers.
Blood vessels were measured that couldn't be seen during a regular eye exam and it was done with relatively new non-invasive technology that takes high-resolution images of very small blood vessels within the retina in just a few minutes. It's possible that these changes in blood vessel density in the retina could mirror what's going on in the tiny blood vessels in the brain, perhaps before the doctors are able to detect any changes in cognition. The study found differences in the retinas of those with Alzheimer's disease when compared to healthy people and to those with mild cognitive impairment, often a precursor to Alzheimer's disease.
A US based doctor of Indian origin, Dilraj S. Grewal, M.D., a Duke Ophthalmologist and Retinal Surgeon and a Lead Author on the Study said, "We know that there are changes that occur in the brain in the small blood vessels in people with Alzheimer's disease, and because the retina is an extension of the brain, we wanted to investigate whether these changes could be detected in the retina using a new technology that is less invasive and easy to obtain. The Duke study used a noninvasive technology called optical coherence tomography angiography (OCTA). OCTA machines use light waves that reveal blood flow in every layer of the retina.”
An OCTA scan could even reveal changes in tiny capillaries – most less than half the width of a human hair – before blood vessel changes show up on a brain scan such as an MRI or cerebral angiogram, which highlight only larger blood vessels. Such techniques to study the brain are invasive and costly.
The ophthalmologists also suggested that ultimately, the goal would be to use this technology to detect Alzheimer's early, before symptoms of memory loss are evident, and be able to monitor these changes over time in participants of clinical trials studying new Alzheimer's treatments.
Expressing happiness over the development, Dr. S.P.S. Grewal, CEO, Grewal Eye Institute, said, “I believe that this a milestone in the history of mankind as early detection of Alzheimer's through an eye exam will not only help in reversing the symptoms wherever possible but an early treatment will also pave way for an accurate diagnosis, which otherwise becomes difficult if the disease is detected at a later stage. Additionally, this study shows the significance of regular eye check-ups since now it may lead to diagnosis of another diseases, including a dreaded one like Alzheimer.”