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We’ve all heard that some people with COVID-19 lose their sense of smell. But there are lots of reasons why that can happen. It turns out that many viruses can temporarily diminish your sense of smell, in addition to COVID-19. Even the common cold virus can do it. Other common problems that can affect your smell include sinus disease, seasonal allergies, head injuries, and cigarette smoking.
Smell is usually one of the first senses affected by many types of dementia including Alzheimer’s disease, Parkinson’s disease dementia, and dementia with Lewy bodies. Together, these disorders are the cause of dementia in three out of four cases.
Why is smell diminished in these disorders? No one is exactly sure. One explanation may be that the place in the brain where smell is processed is right next to the hippocampus—the place in the brain where memory is processed. Since Alzheimer’s disease starts in this part of the temporal lobe and spreads, Alzheimer’s may simply spread quickly to the place in the brain where smell is processed. Another theory is that both Alzheimer’s disease and Parkinson’s disease may start with an unusual reaction to a viral infection—and the viral infection may start in the nose! But this is just a theory so please don’t worry that you’re going to develop one of these diseases because you have a cold.
Although at first blush losing one’s sense of smell may not seem like a big deal, most of what we “taste” is actually from our sense of smell. The tongue itself can only sense sweet, salty, sour, bitter, and spicy. Food is thus less appealing—one reason that many individuals with dementia lose weight. Diminished smell is also related to poor hygiene, because unpleasant smells of urine, feces, and body odor—which would normally cue individuals to bathe or change their clothes—go undetected.
Regarding foods, there are some things you can do to compensate for this loss of smell. First, try increasing the amount of flavoring. Does a recipe include a tablespoon of orange zest? Try two, three, or four tablespoons. Does another dish call for half a teaspoon of cinnamon? Try doubling or tripling the amount.
The second thing you can try is to increase the spiciness of foods. Because the “heat” of spices is not part of our sense of smell, your loved one will be able to taste the spiciness of curry powder, cayenne pepper, and tabasco sauce just fine. In addition to spicing up your cooking, you might also see if your loved one now enjoys more pungent, spicy foods such as Thai or Indian curries, even if they have never liked such foods in the past.
Key Question:
My father has dementia and he hasn’t been eating much lately. I make him his favorite foods but he takes one bite and says he’s not hungry.
The taste of food is mostly due to smell. So, if his smell is diminished the food may not taste good to him. Try increasing the amount of the flavors and spices to see if that makes the food more appetizing. Or try adding a bit of hot spices—those spicy flavors are on the tongue and are generally preserved. Experiment to find the new foods that he now likes best—they may be different from what he liked in the past.
© Andrew E. Budson, MD, 2021, all rights reserved.
References
Budson AE, O’Connor MK. Seven Steps to Managing Your Memory: What’s Normal, What’s Not, and What to Do About It, New York: Oxford University Press, 2017.
Budson AE, O’Connor MK. Six Steps to Managing Alzheimer’s Disease and Dementia: A Guide for Families, New York: Oxford University Press, 2021.
Budson AE, Solomon PR. Memory Loss, Alzheimer’s Disease, & Dementia: A Practical Guide for Clinicians, 3rd Edition, Philadelphia: Elsevier Inc., 2021.
