Exploring Racial Disparities for Alzheimer’s, Glaucoma

By Denise A. Valenti via Multibriefs

Over 15 years ago, one of the nation’s foremost glaucoma specialists provocatively asked in a review paper, "Glaucoma: Ocular Alzheimer's disease?" Stuart McKinnon, MD, an ophthalmologist with the Department of Ophthalmology at the University of Texas Health Science Center in San Antonio discussed many of the parallels of glaucoma to Alzheimer’s disease.

Animal studies have shown a high rate of the amyloid precursor molecules, which are attributed to Alzheimer’s disease, to also be a factor in induced glaucoma. Other neurotoxic molecules such as hyperphosphorylated tau are found in both diseases.

Researchers looking at both argue that glaucoma may be seen as a tau-related disease, tying it further to Alzheimer’s disease. Further, both glaucoma and Alzheimer’s disease sufferers often have lower than normal pressures in their cerebral spinal fluid.

A recently published research study adds yet another common element for the two diseases. The report in the Journal of the American Medical Association found that there were racial differences in the cerebrospinal fluid concentration of tau protein between African-American and white individuals.

There are implications in the expression of both Alzheimer’s disease and glaucoma in populations of color. Both diseases have a higher prevalence among African-Americans. The cerebrospinal fluid, its volume, pressure and physiology can influence the pressure and physiology of glaucoma.

The more recent work looked at the 1,255 participants in a study of health aging and Alzheimer’s disease. Within the study, there were 707 women and 548 men with an average age of 70.8 years.

There were 173 African-American participants and 1,082 non-Hispanic white participants, with the distribution of cognitive functioning similar across the groups. As the cerebral spinal fluid depletes of tau, it may be depositing in the brain or elsewhere. The study found that the concentrations of tau were significantly different, being lower for those African-Americans who also were genetically positive for the APOE E4 measure.

Researchers found that there were differences in the concentration of tau protein and lower cerebral spinal fluid concentrations of tau protein in African-Americans who also have positive genetic markers for Alzheimer’s disease.

This points to a race-dependent physiology contribution to disease expression. Poor vascular health does contribute to higher rates of glaucoma and Alzheimer’s disease in African-Americans. Large-population genetic studies show that while genetics play a role in glaucoma, there are other factors.

When it comes to neurodegenerative diseases, clearly there are relationships. Further, there are roles that genetics and race play. These are all critical factors as we study both glaucoma and Alzheimer’s disease.

Dr. Denise A. Valenti is a residency-trained, low-vision/blind-rehabilitation optometrist who has worked closely with sensory and cognitive impairment and the ability to safely drive as a clinical provider. Dr. Valenti provided direct clinical care for more than 25 years and currently is active in research and consultation related to vision, aging, neuroprocessing, cannabinoids, cognitive function and driving. She has additional education and expertise in the field of age-related neurodegenerative diseases with the emphasis on Parkinson's disease and Alzheimer's disease. She had been honored as the Alzheimer’s Disease Drug Discovery Foundation’s outstanding young researcher and was selected by the AARP as an exemplary gerontology scientist. Her research has included the study of imaging of retinal neural tissue using Optical Coherence Tomography (OCT) and functional assessment of neural processing in the visual system using Frequency Doubling Technology (FDT). The neurocognitive impact of cannabis is an active area of research as is the treatment potential for Alzheimer’s disease and Parkinson’s disease. She is the principal in the development of technology to detect impairment in the retina and lateral geniculate brain nuclei from cannabis consumption, Impairment Measurement: Marijuana and Driving (IMMAD). The company IMMAD provides education, services and technology for the responsible use of cannabis. Dr. Valenti lectures on marijuana, cannabis, cannabinoids and cognition both nationally and internationally.