By National Institute on Aging, National Institutes of Health
Problems with sense of smell become more common as people get older:
- Twenty four and a half percent (15 million) of Americans 55 years old or older have a problem with their sense of smell.
- Thirty percent of Americans between the ages of 70 and 80 have a problem with their sense of smell.
- Nearly a third of people over 80 have a problem with their sense of smell.
A person's sense of smell generally declines when he or she is over 60. Only about one to two percent of people under the age of 65 will experience some problem with their sense of smell. Women of all ages are generally better at detecting odors than men.
Smell that declines with age is called presbyosmia and is not preventable. The sense of smell, or olfaction, is part of our chemical sensing system, along with the sense of taste. Normal smell occurs when odors around us, like the fragrance of flowers or the smell of baking bread, stimulate the specialized sensory cells, called olfactory sensory cells. Olfactory sensory cells are located in a small patch of tissue high inside the nose. Odors reach the olfactory sensory cells in two pathways. The first pathway is by inhaling, or sniffing, through your nose. When people think about smell, they generally think of this pathway.
The second pathway is less familiar. It is a channel that connects the roof of the throat region to the nose. When we chew our food, aromas are released that access olfactory sensory cells through this channel. If you are congested due to a head cold or sinus infection, this channel is blocked, which temporarily affects your ability to appreciate the flavors of food.
Odors are small molecules that are easily evaporated and released into the environment and that stimulate these sensory cells. Once the olfactory sensory cells detect the odor molecules, they send signals to our brain, where we identify the smell and its source.
For most people, a problem with smell is a minor irritation, but for others it may be a sign of a more serious disease or long-term health condition.
When people have a problem with smell, they may experience either total or partial loss of smell. They can also sometimes think they smell bad odors that are not actually present. Total smell loss is relatively rare. However, a diminished sense of smell occurs more often, especially in older adults. A diminished sense of smell may be temporary and treatable with medication. People with smell disorders usually have problems appreciating the subtle flavors of food, and say that food is less enjoyable.
Smell and taste are closely linked in the brain, but are actually distinct sensory systems. True tastes are detected by taste buds on the tongue and the roof of the mouth, as well as in the throat region, and are limited to sweet, salty, sour, bitter, savory and perhaps a few other sensations.
The loss of smell is much more common than the loss of taste, and many people mistakenly believe they have a problem with taste, when they are really experiencing a problem with their sense of smell. A loss in taste or smell is diagnosed by your doctor using special taste and smell tests.
The sense of smell gradually declines in older people. This is normal. Many older people are not even aware that they have a problem with their sense of smell because the changes occur gradually over several years. They may not even notice that they are experiencing a loss of smell until there is an incident in which they don't detect food that has spoiled or the presence of dangerous smoke.
When smell is impaired, some people change their eating habits. Some may eat too little and lose weight while others may eat too much and gain weight. Either way, there may be a long-term impact on one's overall health. Loss of smell may also cause us to eat too much sugar or salt to make our food taste better. This can be a problem for people with certain medical conditions, such as diabetes or high blood pressure. In severe cases, loss of smell can lead to depression.
Symptoms and Diagnosis
There are several types of smell disorders depending on how the sense of smell is affected. People who have smell disorders experience either a loss in their ability to smell or changes in the way they perceive odors.
Some people have hyposmia, which occurs when their ability to detect certain odors is reduced. This smell disorder is common in people who have upper respiratory infections or nasal congestion. This is usually temporary and goes away when the infection clears up.
Other people can't detect odor at all, which is called anosmia. This type of smell disorder is sometimes the result of head trauma in the nose region, usually from an automobile accident or chronic nasal or sinus infections. It can sometimes be caused by aging. In rare cases, anosmia is inherited.
Sometimes a loss of smell can be accompanied by a change in the perception of odors. This type of smell disorder is called dysosmia. Familiar odors may become distorted, or an odor that usually smells pleasant instead smells foul. Sometimes people with this type of smell disorder also experience headaches, dizziness, shortness of breath, or anxiety.
Still others may perceive a smell that isn't present at all, which is called phantosmia.
Your doctor may refer you to an otolaryngologist, a specialist in diseases of the ear, nose, and throat. After conducting a complete medical history and physical examination, your doctor may run special tests to determine the extent and nature of your smell disorder.
Some tests measure the smallest amount of odor you can detect. You also may receive a "scratch and sniff" test to determine how well you can identify various odors from a list of possibilities. In this test, the odor is embedded in a circular pad on a piece of paper and released when scratched.
Your doctor may ask you to compare the smells of different chemicals, or indicate how much the intensity of the smell grows when its concentration is increased. In this test, odors are presented through a face mask. By using these two types of tests, your doctor can determine if you have hyposmia, anosmia, or another type of smell disorder.
In some cases, your doctor may need to perform a nasal examination with a nasal endoscope, an instrument that illuminates and magnifies the areas of the nose where the problem may exist. This test can help identify the area and extent of the problem and help your doctor select the right treatment.
If your doctor suspects that upper regions of the nose and nasal sinuses that can't be seen by an endoscope are involved, he or she may order a specialized X-ray procedure, usually a CT scan, to look further into the nose and sinuses.
Treatment and Research
Although there is no treatment for presbyosmia -- loss of smell due to aging -- relief from smell disorders is possible for many older people. Depending on the cause of your problem with smell, your doctor may be able to treat it or suggest ways to cope with it. Scientists are studying how our sense of smell works so that new treatments can be developed.
Sometimes a certain medication causes a smell disorder, and improvement occurs when the medicine causing the problem is stopped or changed. Although certain medications can cause a loss of smell, others seem to improve smell and sometimes taste. An example of this is anti-allergy medicines.
If you take medications, ask your doctor if they can affect your sense of smell. If so, ask if you could substitute other medications or reduce the dose. Your doctor will work with you to get the medicine you need while trying to reduce unwanted side effects.
Your doctor may suggest oral steroid medications such as prednisone, which is usually used for a short period of time, or topical steroid sprays, which can be used for longer periods of time. Antibiotics are also used to treat nasal infections. The effectiveness of both steroids and antibiotics depends greatly on the severity and duration of the nasal swelling or infection. Often relief is temporary. Occasionally, the sense of smell returns to normal on its own without any treatment.
The National Institute on Aging (NIA), one of the 27 Institutes and Centers of the National Institute of Health (NIH) leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. In 1974, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people.