Is a Smell Test a Reliable Predictor of Early Stages of Alzheimer’s Disease?


Early detection of Alzheimer’s disease can change everything. Most infamously, the disease causes, memory loss, but can also cause balance issues, confusion, aggressive behavior, poor decision-making skills and depression. Because of the many complex symptoms caused by Alzheimer’s, it can be difficult to notice and attribute early-stage symptoms to the proper disease in time for preventive measures to have a real effect.

In addition, Alzheimer’s disease cannot actually be diagnosed with certainty until it has caused the death of a patient. The stakes are high for doctors and researchers to discover how to detect Alzheimer’s disease early. That is because preventive measures can be put in place, including registering seniors for new drug trials and caregiving adjustments that stimulate the brain and protect seniors from wandering because of confusion.



The Smell Test

An emerging way to test for Alzheimer’s disease is a simple smell test. Because Alzheimer’s disease causes plaques to develop on neurons in the brain, it cuts off communication from parts of the brain to other parts, making communication, memory and sensory understanding difficult. Many doctors have noticed over time that patients with Alzheimer’s disease felt that their food tasted less flavorful—a sign that their sense of smell may be affected. Although many senses can dull with age, such as hearing or vision, it became clear to some researchers that there was a pattern among Alzheimer’s disease patients of losing their sense of smell.

A research team at Columbia University recently published two studies focusing on this phenomenon and testing the hypothesis if a “smell test” could help doctors diagnose Alzheimer’s disease, especially in those without other more obvious symptoms. So far, the studies have shown a strong correlation between those who do poorly on the odor detection tests and those who experience cognitive decline. It is reasonable that this would work—the sense most strongly tied to memory and cognition, smell, is also tied in its decline to trouble with thinking and remembering. The area of the brain that interprets the information gathered by the sense of smell is one of the first that is affected by Alzheimer’s disease. That makes the sense of smell a perfect place to begin the search for simple, early diagnosis tools. (The next is the eye, which also has ties to similar parts of the brain.) Thus far, the simple smell test is as effective at diagnosing some type of cognitive decline as any existing test.


Why Such a Simple Test?


Rather than relying on costly and difficult diagnosis tests and procedures—like a PET scan or spinal tap—this kind of test allows physicians to apply at least a preliminary diagnosis for Alzheimer’s disease sufferers. It also means that rather than paying for and waiting on results that could take weeks or months to obtain, caregivers and physicians can work immediately to apply types of care that may help slow the progression of cognitive decline. Using items that typically have a strong and unique smell, such as coffee, smoke, peanut butter or berries, doctors can see how acute a patient’s sense of smell is. This test can be performed in a doctor’s office with simple tools, and is most likely to be used for early detection and referrals to neurologists, who can begin investigating a senior for causes of dementia.

Currently, the test cannot perfectly diagnose a case of Alzheimer’s disease. It is merely a simple way for doctors and loved ones to begin thinking about prevention and safety and to consider further testing. It is also a cost- and time-saving measure. A main reason why the test is not completely conclusive is that there are other causes for a poor sense of smell, especially if the patient smoked, is currently experiencing another illness which might diminish the sense of smell, or has had any type of head or brain trauma.

If you believe your loved one may have Alzheimer’s disease or another type of cognitive decline, make an appointment immediately with their doctor for testing. The earlier you catch and begin to treat dementia symptoms, the more likely that your loved one will be happier and healthier for longer. Do not use the smell test as a way to diagnose dementia at home; the only real results of the test should come from a physician.



Alzheimer’s Reading Room. Can a Smell Test Predict Early Stages of Alzheimer’s Disease?, October 31, 2016. Available at November 26, 2016.

Borelli, Lizette. Alzheimer’s Disease Sniff Test: Identifying Odors May Detect Early Memory Decline, Dementia. Medical Daily, July 27, 2016. Available at Retrieved November 27, 2016.

Hamilton, John. A Sniff Test For Alzheimer’s Checks For The Ability To Identify Odors. NPR, July 26, 2016. Available at November 27, 2016.

Sauer, Alissa. Can’t Smell Peanut Butter? Alzheimer’s May Be the Culprit., January 20, 2016. Available at Retrieved November 26, 2016.