Glaucoma is a leading cause of irreversible blindness in the United States and the world. The condition is a group of neurodegenerative eye diseases that leads to damage of the optic nerve and can lead to vision loss and possibly blindness. Like glaucoma, Alzheimer's is a neurodegenerative disease characterized by specific changes in the brain.
Both of these conditions affect the majority of older populations and involve selective loss of certain types of neurons, causing irreversible neuronal cell loss. And, both of these conditions are major public health concerns as the population ages.
Several decades ago in analyzing death certificates, researchers discovered there was a higher frequency of glaucoma in individuals with Alzheimer's disease. After that, several populations with Alzheimers were examined for the prevalence of glaucoma, and results showed an almost two-to-three-fold increase in glaucoma diagnosis.
Several studies later argued that having glaucoma did not produce an increased risk of Alzheimer's, and one study, in particular, indicated a decreased risk of Alzheimer's in individuals with glaucoma. Yet, more recently, researchers through their studies in France, showed that individuals with glaucoma were four times more likely to develop dementia.
In 2007, one study reported a potential common cause of both glaucoma and Alzheimer's disease. Scientifically, it has been shown that individuals with Alzheimer's could have retinal nerve fiber-layer thinning and loss of the retinal ganglion cells (neurons located near the inner surface of the retina of the eye) that compose the optic nerve, which are both hallmarks of glaucoma. Abnormal tau proteins, the hallmarks of Alzheimer's disease, have been found in the clear jellylike substance (vitreous jelly) that fills the space from the lens to the back of the eye in individuals with glaucoma.
Additionally, researchers who conducted a study in the Britain discovered the buildup of beta-amyloid (the same protein found in Alzheimer's) in the eye's retina, and in the brain tissue, which appeared to be linked to the development of both glaucoma and Alzheimer's.
Researchers, however, were very clear in stating in their conclusions that the abnormal accumulation of beta-amyloid proteins does not necessarily mean that an individual with Alzheimer's disease will have glaucoma or vice versa. It just means that the similarities between certain eye and brain tissue could explain why the buildup of beta-amyloid proteins can affect both the eye and the brain.
Lastly, while presenting her conclusions at Hawaiian Eye 2017 from her research, Dr. Yvonne Ou, of the University of California, San Francisco, stated that glaucoma severity was not associated with executive or cognitive function, adding that it was an exciting area for researchers who hope to "identify progression in Alzheimer’s using the retina as an ocular biomarker."
Overall, there are many conflicting reports as to whether those with glaucoma have an increased risk of developing Alzheimer's disease. So, more research is needed, which will eventually lead to better treatment alternatives for people who develop these two diseases.
Questions about Alzheimer's disease or related disorders can be sent to Dana Territo, the Memory Whisperer, owner of Dana Territo Consulting, LLC, at email@example.com.