A study published in 2012 suggested that cataracts and Alzheimer’s Disease are connected. The study authors believe that the delta-catenin protein is connected to the high prevalence of cataracts in Alzheimer’s patients. This protein is a key to cognitive development. It is also being studied for its role in the formation of some cancer types.
The Cataract Connection
The connection seems to exist with cortical cataracts. These are cataracts that develop on the outer edge of the lens, which can affect peripheral vision. The water content of the lens fibers can create fissures that look like the spokes of a bicycle wheel. Light is scattered when it enters the eye, causing vision difficulties.
The hypothesis is that the same genetic factors come into play when it comes to changes in the brain and the lenses of the eyes. It is possible that the lens of the eye can detect these brain changes early. By looking at cortical lens opacity in the middle of a person’s life and degeneration in the brain later in life, Alzheimer’s could possibly be predicted.
This was not proven in the 2012 multi-university study. However, a multigenerational study that began in 1948 referred to as the “Framingham Study” looked at over 1,000 people, comparing the results of eye examinations with cataracts and other conditions. There was a very strong correlation between Alzheimer’s disease and cataracts in that study.
What the researchers found was that the temporal horn enlarges in Alzheimer’s patients and those with temporal horn enlargement also saw increased delta-catenin deposits in the lens tissue. This protein buildup wasn’t seen in patients that didn’t have Alzheimer’s.
There is a lot of work left to do in this area, but there seems to be a link between cataracts and Alzheimer’s disease, and it is going back to changes in the brain and how it affects delta-catenin in the lens. It could be that cataracts become a predictor of Alzheimer’s disease.
The Disconnection
It is important to know that everyone who gets cataracts isn’t destined to develop Alzheimer’s. What has been shown in the studies is that there is something along the pathways to both disorders that share a commonality. Once the exact link is pinned down, the medical community could have a biomarker for Alzheimer’s, but even a biomarker doesn’t guarantee the development of the disease. All this information does is identify a higher risk, which, one day, could lead to ways to slow down the progression or even prevent Alzheimer’s when such methods become available.
More Information on the Study
The multi-university study was published in the Sept. 11, 2012, issue of PLoS ONE, a publication of The Public Library of Science. This open-access online journal is peer-reviewed and published monthly. It was conducted by Gyungah Jun, Carolina Koutras, Juliet A. Moncaster, Sudha Seshadri, Ann C. McKee, Jackqueline Buros, and Georges Levesque. The institutions represented in the study were the University of Toronto, Boston University Schools of Medicine and Public Health, and the University of Cambridge.
