Are Retinal Tests Able to Identify Early-Onset Alzheimer’s?
According to The Alzheimer’s Association, In 2021, 6.2 million Americans were living with Alzheimer’s Disease. 1 in every 9 people (11.3%) above the age of 65 has Alzheimer’s Disease, and these percentages only increase with age, leaving 35 percent of people above the age of 85 with Alzheimer’s or Dementia. For those who do not know, Dementia is a general term for the loss of memory and other thinking abilities, severe enough to interfere with daily life. Alzheimer’s is the most common type of Dementia, and it affects not just memory but behavior. Mainly recognized in adults above the age of 60, our current form of diagnosing Alzheimer’s is waiting until people become overly forgetful or begin to act out of character. Although early detection is occasionally possible through brain scans, this method is expensive and unsuitable for most.
My uncle Steven was only 51 when he was diagnosed with Alzheimer’s. Although caught decently early, his changes in behavior and short-term memory loss were apparent. Often asking a question only minutes after he had previously been told the answer, my family was devastated. Before being diagnosed, my uncle was the CFO of a Fortune 500 company and was always seen as a mentally and physically strong man. Having no choice but to retire young and focus on his health was a hard truth for all of us to accept.
Sad and confused about how this had happened, I did extensive research on the causes of Alzheimer’s. Although there are multiple possible causes and factors that play into the development of Alzheimer’s disease, one way is through inheritance. Early-onset Alzheimer’s diseases, like my uncle’s, can be inherited genetically. Humans typically have 46 chromosomes in each cell of their body. Each of these chromosomes contains anywhere between 20,000 and 250,000 genes. Usually having two copies of each chromosome, one copy comes from the mother’s egg and the other from the father’s sperm. Each egg and the sperm are haploid, meaning they contain 23 chromosomes. When the sperm fertilizes the egg, two copies of each chromosome and gene are present. Although some genes are required from both parents to be passed onto their offspring, Alzheimer’s is inherited in an autosomal dominant pattern. This is one of the many ways that disorders can be passed down through families, and it means that only one parent needs to have the abnormal gene for you to get the disease. Thus people who inherit one copy of the APOE e4 allele have a significant chance of developing Alzheimer’s. However, those who inherit two copies of their allele are at even greater risk. It is important to note that not all people with the disease have the e4 allele, and not all people with the allele develop Alzheimer’s. Because in most cases, an infected person inherits the gene from an infected parent, it is not likely that my uncle developed Alzheimer’s genetically as no one else in my family tree ever had the disease.
Moving forward with my research, I looked into possible treatments; unfortunately, most drugs are still in trial or only applicable to individuals diagnosed before any level of severe memory loss occurs. While this is a sign of good progress, I can’t help but feel there must be some better solution to diagnose Alzheimer’s before it becomes too late. Thankfully, Dr. Ashleigh Barrett-Young and her team agreed.
Working at Otago’s Dunedin Multidisciplinary Health and Development Research Unit, Barrett-Young and her team of researchers have investigated the retina’s potential to indicate Alzheimer’s earlier in life. As stated by Barrett-Young, “In the near future, it’s hoped that artificial intelligence will be able to take an image of a person’s retina and determine whether that person is at risk for Alzheimer’s long before they begin showing symptoms, and when there is a possibility of treatment to mitigate the symptoms.” The Dunedin study analyzed the retinal nerve fiber layer (RNFL) and Ganglion cell layer (GCL) of 865 people at the age of 45. Dr. Barret-Young and her team reported that thicker RNFL and GCL were associated with better cognitive performance, while a thinner RNFL was linked to a more significant decline in processing speed. Adding to their report, “These findings suggest that RNFL could be an indicator of overall brain health. This highlights the potential for optical scans to aid in the diagnosis of cognitive decline.” Since treatment for Alzheimer’s is yet to be discovered, the ability to identify the disease in preclinical stages could allow the possibility of aid before it’s too late. Although further studies are required to determine if retinal scans can predict precisely Alzheimer’s, or just the expected cognitive decline of the brain, researchers have hope.
So, while this solution sadly offers no benefit to my uncle, I feel hopeful that this new diagnosis technique will be beneficial for the millions of people who would have had family members or friends combating Alzheimer’s disease but caught it early enough to intervene and do something about it.