Scents and memories are intertwined, which is why the smell of baking cookies takes you straight back to your mother’s kitchen and a whiff of suntan lotion recalls childhood beach vacations. Though not everyone experiences a decline in the ability to smell, it is commonplace with age, and research suggests that a more-than-slight decline in this sense might foreshadow dementia or other health problems in the future.
What does your nose have to do with your brain? These two organs are biologically interconnected. Inside your nose are hundreds of scent receptors. When odor molecules released by, say, a bouquet of roses or a simmering pot of soup lock onto their receptors, sensory neurons fire in the brain. Those nerve cells release electrical signals that travel to the amygdala and hippocampus—parts of the brain involved in emotion and memory. This direct neural connection allows scents to be strongly etched into memory, especially when the memory is tied to something emotionally charged.
If your sense of smell diminishes (called hyposmia or, if it’s entirely gone, anosmia), your memories connected with smells might fade with it.
Sniffing out the science
Several studies have associated a loss of smell with cognitive decline. The authors of a 2025 study in JAMA Otolaryngology–Head & Neck Surgery followed 2,524 cognitively healthy older adults for 12 years. They found that every additional wrong answer on an odor identification test was associated with a 5 percent increased risk of death from all causes by the end of the study period. Dementia was one of the leading factors linking a lost sense of smell with dying.
The loss of brain volume is one potential reason why dementia might follow a diminished sense of smell. A 2023 study in Neurology compared odor identification test scores with brain volumes measured on MRI scans of 567 people ages 50 and older. The researchers also compared the odor identification scores with cognitive test results in 754 people. Participants who developed cognitive impairment or dementia scored worse on the odor identification tests than those who didn’t have cognitive issues. Those with higher odor identification scores had lost less volume in parts of the brain involved with thinking and memory.
In an earlier study of 515 older adults, people whose smelling ability rapidly declined were more likely to develop mild cognitive impairment or dementia. They also lost volume in areas of their brain related to memory. The authors say that smell testing might one day be a way to detect Alzheimer’s disease early, before cognitive symptoms appear.
Why smell diminishes with age
The older you get, the more likely you are to have difficulty smelling. According to the National Institute on Deafness and Other Communication Disorders, about 20 percent of Americans over the age of 40 report some alteration in their sense of smell, and rates increase in older age groups (with the highest rates among those over 80).
Age-related declines are permanent. As we get older, nerve endings in the nose start to degenerate and the production of mucus—which helps to capture odors—slows.
But a temporary loss of smell can happen at any age—for example, due to congestion from a cold, flu, Covid, or other upper respiratory infection. Certain medications, including some blood pressure drugs, can cause smell loss as a side effect.
Other health risks linked to smell loss
Cognitive decline isn’t the only negative health effect that has been associated with a diminished sense of smell. It’s possible that the same factors that contribute to olfactory impairment also increase the risks of the following conditions. Or losing your sense of smell may be an advanced warning sign that health troubles lie ahead.
- Parkinson’s disease. A loss of smell is one of the earliest and most common symptoms of this neurological disorder. Around 95 percent of people with Parkinson’s disease lose their sense of smell to some degree, sometimes years before movement symptoms begin.
- Depression. Older adults who have difficulty smelling are more likely to develop depression, which may have to do with connections between areas of the brain involved in both processes.
- Malnutrition. The senses of smell and taste are intertwined. An inability to smell can affect your enjoyment of food and potentially result in a poor diet that is lacking in recommended nutrients.
- Injuries. Your nose alerts you to dangers such as smoke, a gas leak, or spoiled food. Without a functioning sense of smell, your risk of injury or illness increases.
- Premature death. In a study of 3,503 adults, ages 40 and older, every one-point decrease on a smell test score correlated with an 18 percent higher risk of death. A decline in cognitive function and increased inflammation are possible reasons for the connection.
Smell check
If you suspect that your sense of smell has diminished, see your primary care doctor for an evaluation. Treating the underlying cause, if there is one, may correct the problem.
For age-related smell decline, the doctor may send you to an otolaryngologist (ear-nose-throat doctor) for an odor identification, or smell, test. It assesses your ability to recognize and identify different scents.
A program called olfactory training may offer a way to at least partially regain your sense of smell. During this treatment you smell different scents, such as lemon, orange, eucalyptus, rosemary, or cinnamon, for about 30 seconds at a time, twice a day, to retrain the connections between your nose and brain.
Olfactory training might one day offer a way to preserve memories, and possibly slow cognitive decline, although its effectiveness hasn’t yet been confirmed. A 2022 review of 20 studies published in Dementia looked at the effects of this therapy on people with various stages of dementia. Because the evidence was limited and not of high quality, the authors said it was hard to reach any conclusions about olfactory training, but the method is promising.
BOTTOM LINE: It’s not unusual to lose some sense of smell as you age. While difficulty perceiving odors doesn’t necessarily indicate a problem, research has linked a declining sense of smell with dementia, depression, and premature death. Even if your health isn’t compromised, not being able to smell can reduce your enjoyment of food and negatively affect your quality of life, so it’s worth discussing with your doctor. If you have lost your sense of smell, olfactory training may be worth trying. Although it isn’t proven to help, it won’t hurt either.
