Researchers have long been searching for a biomarker for Alzheimer’s disease that will allow the disease to be detected before patients start exhibiting symptoms. Damage to the brain occurs long before the symptoms of Alzheimer’s disease start to be experienced, by which stage the disease has advanced considerably. If Alzheimer’s disease is detected earlier, interventions could slow the progression of the disease. In the United States there are around 5.4 million individuals with Alzheimer’s disease making it the leading cause of dementia. Estimates suggest that by 2050, that figure will rise to around 16 million.
A team of researchers at the University of Minnesota believe they may have identified such a biomarker, which can be detected using a non-invasive procedure that is quick and easy to perform.
The researchers used retinal hyperspectral imaging to identify biochemical changes that occur in the early stages of Alzheimer’s disease. The imaging technique involves analyzing light scatter changes in the retina.
The retina is considered to be a developmental extension of the brain, and since scans can easily be performed it is an ideal place to search for possible Alzheimer’s biomarkers. The researchers performed an analysis on patients with Alzheimer’s disease and healthy patients to identify possible biomarkers for Alzheimer’s disease. They searched for a protein that clusters to forms the plaques in the brain in Alzheimer’s patients. The imaging technique allowed the researchers to detect tiny quantities of the protein, which is indicative of early Alzheimer’s.
The researchers tested the imaging technique on 19 patients with varying stages of Alzheimer’s, from mild cognitive impairment to more advanced stages of the disease. The results were compared to healthy patients of the same age.
The researchers assessed light scatter changes in different areas of the retina and recorded the changes using a specialized camera and spectral imaging system.
The researchers found that the highest detectable light signal was in patients with mild cognitive impairment compared to the advanced stages of the disease. The retinal hyperspectral imaging signature correlated with memory scores of the mild cognitive impairment patients, and the retinal hyperspectral imaging signature was unaffected by pre-existing eye conditions such as glaucoma, peripapillary atrophy, and moderate cataracts.
“While Alzheimer’s disease cannot yet be treated with the intent to cure, early diagnosis with retinal screening can facilitate interventions with available therapeutics,” said Robert Vince, director of the UM Center for Drug Design, College of Pharmacy. “The rHSI technique has shown promise and could be particularly valuable for identifying high-risk individuals for Alzheimer’s disease by starting periodic retinal screening at an early age.”
The test takes around 10 minutes to perform and could be included in an annual eye examination. Interventions could then take place, which could add several years of productive, quality time to a patient’s life.
A pre-clinical trial has been conducted along with a pilot study and the researchers are now working on more extensive clinical trials.
The study is detailed in the paper – In Vivo Assessment of Retinal Biomarkers by Hyperspectral Imaging: Early Detection of Alzheimer’s Disease – which was recently published in the journal ACS Chemical Neuroscience. DOI: 10.1021/acschemneuro.9b00331