Alzheimer's disease (AD) has historically been difficult to diagnose. Until somewhat recently, doctors could only identify it with certainty through a post-mortem exam, but in recent decades, research has made it easier for medical experts to diagnose AD with certainty—thanks to advances in brain imaging and a better understanding of the disease's warning signs.
You may notice one such red flag if you suddenly find yourself unable to do one thing in particular, according to a new study from researchers at the University of Chicago. They are now hopeful that by testing for this particular risk factor, doctors may reach that much-needed diagnosis sooner. Read on to learn which one thing could signal a heightened risk of Alzheimer's, and which other similar signs are also considered red flags.
If you suddenly can't do this, you may be at high risk of Alzheimer's.
Many people are aware that our memory and sense of smell are closely linked. Now, scientists are exploring how quickly losing one's sense of smell may help to predict memory loss in dementia patients.
A Jul. 2022 study published in the journal Alzheimer's&Dementia: The Journal of the Alzheimer's Association, found that a sudden decline in the ability to smell signals a loss of cognitive function, and forecasts certain structural changes in the brain which can lead to Alzheimer's disease, the most common form of dementia.
"This study provides another clue to how a rapid decline in the sense of smell is a really good indicator of what's going to end up structurally occurring in specific regions of the brain," Jayant M. Pinto, MD, a senior author of the study and a professor of surgery at the University of Chicago said via press release.
Here's how they did it.
Researchers reviewed anonymized patient data from 515 older adults who participated in Rush University's Memory and Aging Project (MAP). Beginning in 1997, these subjects were tested annually for their abilities to identify sample smells, and screened for signs of dementia. Using this information, the team looked for patterns that could predict dementia risk.
"Our idea was that people with a rapidly declining sense of smell over time would be in worse shape—and more likely to have brain problems and even Alzheimer's itself—than people who were slowly declining or maintaining a normal sense of smell," said Rachel Pacyna, a rising fourth-year medical student at the University of Chicago Pritzker School of Medicine and lead author of the study.
Poor sense of smell was linked with these physical changes in the brain.
The researchers learned that sudden changes in one's sense of smell were linked with physical changes associated with Alzheimer's disease. These include having smaller gray matter volume in the areas of the olfactory and memory-related areas of the brain, especially in the amygdala and entorhinal cortex.
"We were able to show that the volume and shape of grey matter in olfactory and memory-associated areas of the brains of people with rapid decline in their sense of smell were smaller compared to people who had less severe olfactory decline," explained Pinto.
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Smell tests may eventually become part of the dementia screening process.
There is no one diagnostic test that can definitively determine whether or not a person has Alzheimer's disease. However, doctors will typically perform a broader diagnostic workup which includes reviewing a patients' medical history and medications, administering memory and cognition tests, giving a physical and psychiatric evaluation, and performing brain scans, in order to support an Alzheimer's diagnosis and rule out other possible causes. Additionally, some doctors use vision and hearing tests as part of the screening process.
Now, the study authors are hopeful that someday, smell-tests may prove useful in screening for Alzheimer's disease—especially given that they are inexpensive, effective, and easy to use. "If we could identify people in their 40s, 50s and 60s who are at higher risk early on, we could potentially have enough information to enroll them into clinical trials and develop better medications," said Pacyna.