Some older adults don't develop the key biomarkers of Alzheimer's, even in their 80s and 90s. Scientists try to crack the code about what protects their brains.
There are a lot of unanswered questions about Alzheimer’s, but one thing the Alzheimer’s community knows well is that getting older is the disease’s greatest known risk factor. Generally, the buildup of beta-amyloid and tau tangles in the brain — key biomarkers of neurodegeneration — increase as people age; abnormal levels of these proteins are linked to the onset of Alzheimer’s.
However, a recent study correlated memory performance and brain scans of individuals 80 and older and found that some people are ‘super agers’ — individuals who performed remarkably well in memory tasks, even in advanced age. A brain scan of these cognitively sharp octogenarians revealed that they had a limited build-up of beta-amyloid plaques and tau tangles, akin to the brains of healthy younger people.
“In our study, we observed that super agers do not appear to accumulate aging-associated proteins, such as tau and amyloid pathology,” lead researcher of the study and postdoctoral fellow at University Hospital Cologne in Germany, Merle Hoenig said in a news release. “In contrast, normal agers did present tau pathology, arguing that this ‘proteinopathy’ may be part of the normal aging process.”
The case of a Colombian woman, covered by the New York Times, can highlight one reason why some individuals are seemingly unaffected by this aging process.
Aliria Rosa Piedrahita de Villegas, a resident of Colombia, carried the region-specific mutation in the PSEN1 gene, which causes early-onset Alzheimer’s. While it was expected that she would develop the disease in her 40s, she did not experience any symptoms until much later, at the age of 72.
Researchers link this anomaly to the rare mutation of two genes — dubbed the Christchurch mutation, after Christchurch, New Zealand, where it was first observed — in her genetic profile. Ever since this finding, scientists are attempting to understand and replicate the protective effects of this mutation.
What becomes clear, however, is that the genetic predisposition of a person may aid in their evasion of Alzheimer’s disease. Hoeing highlights how the new findings necessitate further exploration of the ‘molecular signature’ of people who are resistant to dementia-related conditions.
While the preventive role of genes is being investigated, there are many things one can do to prevent or delay the onset of dementia. In a BrainTalk with Being Patient, Dr. Claudia Kawas, professor of neurology, neurobiology, and behavior at the University of California, Irvine, outlined a few steps that everybody can take to reduce their risk from Alzheimer’s.
“It could be [that genes play a role],” Kawas told Being Patient. “But it could also be an environmental resiliency.” According to a 2020 report published in The Lancet, getting exercise and eating a healthy diet are among the lifestyle factors that could reduce one’s likelihood of neurodegeneration late in life.
According to Kawas, another factor could be social interaction. During the current pandemic, social isolation has become a common phenomena. “[The effect of social engagement] is always minimized in our head,” Kawas said. “It doesn’t sound real scientific or it’s not a pill. But engaging with other people probably contributes more to brain health than we generally admit … It’s a very important kind of brain activity.”