Two preliminary studies presented at the Alzheimer's Association International Conference in Copenhagen discussed new methods to detect Alzheimer s disease (AD) before the disease becomes clinically evident. Both research teams examined the relationship between changes in the eye specifically, changes in the retina and lens, respectively and the brain. They used the presence of beta-amyloid plaque, a protein hallmark of AD, within the eye to predict the development of the degenerative brain disease. Beta-amyloid accumulation in the brain occurs well before memory and dementia symptoms. Therefore, researchers hope that an eye test that might mirrors an individual s beta-amyloid spread in the brain can aid with both early detection of the disease and early points of intervention to slow down or prevent AD.
A team from Australia conducted one of the studies, in which they fluorescently tagged beta-amyloid in the retina with curcumin, thereby staining retinal beta-amyloid protein yellow. Then, a novel imaging system was used to detect the protein the retina. A US based company, Cogonoptix Inc., led the second study, in which beta-amyloid staining was performed in the lens of the eye. Laser scanning was used to detect beta-amyloid levels. Both techniques show that beta-amyloid concentration in the eye reflects that seen in the brain by PET imaging, thereby serving as an early predictor of AD.
Of note, Alzheimer s is not defined by beta-amyloid presence alone, as it includes a complex combination of dementia and neurological symptoms. Therefore, these studies offer extremely preliminary evidence that eye tests can serve as tools to forecast disease progression.
These new eye tests join other early detection methods for the brain disease also revealed at the meeting--smell tests. Researcher from Columbia University found that poor performance in smell tests is highly associated with Alzheimer s incidence. Another group from Harvard Medical School found that poor sense of smell is linked to smaller brain volumes in areas associated with memory.
Early detection of AD is highly sought by medical researchers because it can lead to better monitoring of the disease and new therapies. The head of a UK based charity, Alzheimer s Research UK, Dr. Simon Ridley says, "It is difficult to diagnose Alzheimer's disease accurately and, in many cases, by the time the symptoms have developed, damage has already been going on in the brain for a number of years. The development of a quick, cheap, non-invasive test to detect Alzheimer's would be an important step in helping people to receive an early diagnosis, and helping to improve clinical trials so that potential new treatments have the best chance of success.
Dr. Doug Brown, Director of Research at Alzheimer s Society adds, These studies provide proof of principle that scanning the eye for amyloid could give us insight about what is going on in the brain. However as they are only preliminary studies, the eye scans will need further validation before they could be used on people with dementia."
