Eye Exam Detects Signs of Alzheimer's Disease

The new research is a "small step forward," said Dr. Richard Isaacson, director of the Alzheimer's Prevention Clinic at NewYork-Presbyterian/Weill Cornell Medicine.

"But future studies need to focus on earlier stages of the disease," Isaacson said in an email. "We already have more definitive ways to diagnose dementia due to Alzheimer's, but we need to see if OTCA can be a useful cost-effective screening test for pre-symptomatic Alzheimer's."

 Using an ultrasensitive scanning technique, researchers can detect signs of Alzheimer's disease in the tiny blood vessels at the back of the eye, according to a new report.

Duke University researchers found that these small retinal blood vessels were altered in patients with Alzheimer's disease, but in not in those with mild cognitive impairment (MCI) or those with no signs of mental decline.

"Among the folks who had Alzheimer's there was a significant reduction in the density of the blood vessels in the superficial layer of the retina compared to controls and those with mild cognitive impairment," said Dr. Dilraj Grewal, an associate professor of ophthalmology at the Duke Eye Center. "We also found a reduction in the thickness of (of a specific layer of the retina) in Alzheimer's patients compared to controls and those with mild cognitive impairment."

The findings were reported March 11 online in Ophthalmology Retina, a publication of the American Academy of Ophthalmology.

"The retina is an extension of the brain," Grewal said. "And it's thought that changes that occur in the brain are mirrored in the retina. With any neurodegenerative disease, you lose nerve tissue. Along with a measurable loss of brain volume, there's a loss of the vasculature that supplies the brain. And because the retina is part of the central nervous system, the same changes occur there."

Practical Essentials

The current diagnosis of Alzheimer disease is made by clinical, neuropsychological, and neuroimaging assessments. Routine structural neuroimaging evaluation has long been based on nonspecific features such as atrophy, which is a late feature in the progression of the disease. More recently, a variety of imaging modalities, including structural and functional magnetic resonance imaging (MRI) and positron emission tomography (PET) studies of cerebral metabolism, have shown characteristic changes in the brains of patients with Alzheimer disease in prodromal and even presymptomatic states. ^[1, 2, 3]

Alzheimer disease was first described in 1907 by Alois Alzheimer. From its original status as a rare disease, Alzheimer disease has become one of the most common diseases in the aging population, ranking as the fourth most common cause of death. Alzheimer disease is a progressive neurodegenerative disorder characterized by the gradual onset of dementia. The pathologic hallmarks of the disease are beta-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs), and reactive gliosis. ^[4, 5, 6] (See the images below.)

fMRI revealing changes from Alzheimers Disease

Left Healthy Brain Right Alzheimer Brain  

                          

Coronal, T1-weighted magnetic resonance imaging (MRI) scan in a patient with moderate Alzheimer disease. Brain image reveals hippocampal atrophy, especially on the right side.

Eye Exam Detects Signs of Alzheimer's Disease: Using an ultrasensitive scanning technique, researchers can detect signs of Alzheimer's disease in the tiny blood vessels at the back of the eye, according to a new report.

Retinal fundus photography

Retina Fundus Camera

Using a high-definition eye scan developed especially for the study, researchers detected the crucial warning signs of Alzheimer's disease: amyloid-beta deposits, a buildup of toxic proteins. The findings represent a major advancement toward identifying people at high risk for the debilitating condition years sooner.

In addition to retinal imaging, there may be other ocular findings associated with Alzheimer's disease.

Low levels of amyloid-β and tau proteins, biomarkers of Alzheimer's disease (AD), in eye fluid were significantly associated with low cognitive scores, according to a new study published in the Journal of Alzheimer's Disease. Led by researchers at Boston Medical Center, the study is the first to connect these known AD protein biomarkers in the eye to mental status. These findings indicate that proteins in the eye may be a potential source for an accessible, cost-effective test to predict future Alzheimer's disease.

https://www.hindawi.com/journals/joph/2018/8538573/

https://www.ncbi.nlm.nih.gov/pubmed/25095818

https://www.sciencedirect.com/science/article/abs/pii/S0304394007002492