A person who cannot smell is said to have anosmia. Anosmia is the loss of the sense of smell, either total or partial. It can occur suddenly in life, or be present from birth. There are various causes of anosmia, and it can have a significant impact on a person’s quality of life. Understanding anosmia and what it means to lose the sense of smell is important for both the individuals affected and those around them. This article will provide an overview of anosmia, including its causes, effects, and how we can help people with this condition.
What is Anosmia?
Anosmia refers to the inability to perceive smells. It differs from hyposmia, which is a decreased ability to smell. With full anosmia, an individual is unable to detect any smells at all. This not only means they cannot identify familiar odors like coffee or perfume, but also that they cannot detect warning odors like smoke, gas leaks, or spoiled food.
Anosmia can affect one nostril or both. When it only affects one nostril, it is known as unilateral anosmia. When it affects both nostrils, it is termed bilateral anosmia. Bilateral anosmia – the complete loss of smell function in both nostrils – is the most common type.
Types of Anosmia
There are three main types of anosmia:
- Congenital anosmia – Present from birth
- Acquired anosmia – Develops during life after previous normal sense of smell
- Transient anosmia – Temporary loss of smell
Congenital anosmia occurs when a person is born without a sense of smell. This may be due to abnormal development of the olfactory bulb which contains the nerve receptors responsible for detecting odors.
Acquired anosmia develops later in life after having a normal sense of smell. This is the most common type of anosmia. Causes can include head trauma, respiratory infections, or chronic sinus disease among other things.
Transient anosmia is a temporary loss of smell that often occurs when congested from a cold. It resolves once the congestion clears.
Causes of Anosmia
There are several possible causes of lost or reduced sense of smell:
Nasal and Sinus Disease
Chronic nasal and sinus disease is one of the most common causes of anosmia. Persistent inflammation from conditions like nasal polyps, allergies, or chronic sinusitis can damage the olfactory nerves. This interferes with the ability to perceive odors.
Respiratory Infections
Viruses and bacteria can cause temporary loss of smell. The viruses that cause upper respiratory infections like colds and flu can infect and injure the olfactory neurons. Bacteria that cause sinus or middle ear infections can also damage smell function.
Head Trauma
Injuries to the head from events like car accidents, falls, or sports injuries may disrupt smell function. Even concussions from seemingly minor blows can lead to anosmia by harming nerves or areas of the brain stem involved in smell.
Exposure to Toxins
Smell loss can occur after exposure to harmful toxins like pesticides, solvents, metals, and gases. These agents can damage olfactory nerve pathways when inhaled. Chronic tobacco use has also been linked to increased anosmia risk.
Neurodegenerative Disease
Anosmia is an early symptom of Parkinson’s and Alzheimer’s disease. Loss of smell can precede the onset of movement or memory issues by several years as neurons degenerate.
Aging
Smell function naturally declines with age. Anosmia becomes more common in the elderly as the number of nerve receptors in the nose diminish over time. By age 80, up to 75% of people will have some degree of smell loss.
Radiation Therapy
Radiation treatments for head and neck cancers can damage the olfactory epithelium lining the nasal cavity that contains smell receptors. This disrupts the ability to detect odors.
Medications
Some medications like antihistamines, decongestants, antidepressants, and antipsychotics can interfere with smell perception as a side effect. Antibiotics that disrupt the nasal microbiome may also contribute.
Psychiatric Disorders
Smell loss can be associated with conditions like schizophrenia, depression, and bipolar disorder. The underlying mechanisms are not well understood.
Surgery
Nasal or sinus surgery, even when performed expertly, can sometimes disrupt smell function if nerves are cut. Occasionally, anosmia is done deliberately to treat untreatable nasal conditions.
Zinc Deficiency
Zinc is needed for the enzymes involved in smell perception. Deficiency can lead to anosmia, so can be reversed with supplementation.
Genetic Disorders
Rare genetic syndromes such as Kallmann syndrome can cause smell loss along with other symptoms. Genetic mutations affecting olfactory neurons may also play a role.
Effects of Anosmia
Losing one’s sense of smell can have wide-ranging impacts:
Safety Concerns
Anosmia strips away the ability to detect dangers through scent. This includes the inability to smell smoke from a fire, leaking gas, or spoiled foods. Extra care must be taken to visually assess the environment.
Taste Impairment
Smell and taste are intimately linked. Most flavors are produced by odor molecules stimulating smell receptors at the back of the mouth. Without smell, foods tend to taste bland and flavorless.
Decreased Appetite
With foods lacking in flavor appeal, people with anosmia often experience a decreased appetite. Unintended weight loss can result if food intake becomes inadequate.
Depression
Loss of pleasurable food aromas and odors in nature can contribute to mood changes and depression. There are strong nostalgic links between scent and memory.
Social Isolation
The inability to smell one’s own body odor or bad breath can lead to anxiety in social settings. Some people withdraw due to self-consciousness about undetectable offensive smells.
Relationship Stress
Partners rely on scent cues like pheromones for attraction. The loss can impair sexual intimacy and cause relationship disruptions.
Diagnosing Anosmia
To diagnose anosmia, physicians will take a medical history and perform an examination of the nose and sinuses. Specialized smell tests may also be used:
Imaging
CT scans or MRIs can reveal sinus disease, tumors, or other structural problems that may be contributing to anosmia.
Endoscopy
A camera probe inserted in the nose during endoscopy allows visualization of the nasal passages and olfactory region to pinpoint causes.
Smell Testing
Formal smell testing involves identifying common odorants like coffee, oranges, leather, and so on. This evaluates the degree of smell loss.
Biopsies
rarely, a small sample of tissue from the olfactory nerve may be analyzed under a microscope to assess nerve damage.
Treating Anosmia
Treatment options depend on the underlying cause:
Medications
Oral steroids may help some types of smell loss by reducing inflammation. Topical sodium citrate drops may also aid recovery.
Surgery
Surgery can remove sources of blockages like nasal polyps or correct structural deformities.
Smell Training
Repeated exposure to strong odors may help retrain damaged smell pathways through neuroplasticity.
Psychotherapy
Counseling for depression or anxiety related to the smell loss may be advised. Joining a support group also helps some.
Olfactory Amplification
Devices like the nasal ranger can amplify odors to detectable levels to aid with safety and food flavors.
Zinc Supplements
Zinc supplementation can restore smell if deficiency is the cause. Levels normalize after several months.
Unfortunately, anosmia has no definitive cure for many causes. But treatments focused on quality of life improvements can make a major positive impact.
Adapting to Life with Anosmia
Though challenging, people can adapt and thrive living with smell loss utilizing the following tips:
- Install smoke and gas detectors in the home and workspace
- Use stove timers to monitor cooking food
- Eliminate use of scented products like candles or air fresheners
- Add spices, herbs, sauces to enhance food flavors
- Focus more on food textures than taste
- Let others know about the condition to avoid embarrassment
- Use visual signs rather than scent for tasks like checking hygiene
- Try a nasal ranger device to amplify odors
- Join an anosmia support group
Supporting a Loved One with Anosmia
For family and friends of someone with smell loss:
- Have patience, it can be devastating
- Offer emotional support and a listening ear
- Give reminders about groceries, laundry, and self-care
- Cook foods with more seasoning or marinades
- Install safety devices around the home
- Suggest trying nasal amplification tools
- Remind them you care about more than just their smell
Prognosis
The prognosis for anosmia depends greatly on the underlying cause:
- With head trauma, smell typically recovers within 6-12 months but can be permanent
- After upper respiratory infections, smell returns within weeks as congestion resolves
- For chronic sinus disease, smell improvement is variable after treatment
- Idiopathic cases have a poor prognosis if persisting months to years
- Smell loss is usually permanent from aging or neurological conditions
Though challenging, smell retraining therapy may help recovery in some individuals if applied diligently.
Key Takeaways on Anosmia
- Anosmia refers to complete loss of smell function
- It has numerous possible causes including infections, injury, aging, and more
- Loss of smell can impair safety, taste, appetite, and relationships
- Treatment aims to address underlying causes when possible
- People can adapt with lifestyle adjustments and sensory aids
- Support groups and smell training can aid coping
Though difficult, smell loss does not have to be devastating. With practical adaptations, creativity in the kitchen, and support from loved ones, it is possible to regain enjoyment in life after anosmia.
Frequently Asked Questions
What percentage of people have anosmia?
About 5% of people have anosmia. It becomes much more common later in life, affecting over half of people by age 80.
Can anosmia be cured?
For some types like head trauma or zinc deficiency, smell loss can be successfully restored. But in many cases like aging or neurodegenerative disease, anosmia is unfortunately permanent.
Is anosmia considered a disability?
Yes, loss of smell that affects daily functioning and safety can be considered a disability. Reasonable accommodations may be needed in some settings.
Can you drive with anosmia?
People with anosmia can drive using extra visual precautions. Some choose to install gas odor detectors in their vehicles for added safety. Driving ability is evaluated on a case-by-case basis.
How do you test for anosmia?
Smell testing involves attempting to identify common odors like coffee, lemon, smoke, etc. Failure indicates some degree of anosmia. Imaging and endoscopy also help evaluate causes.
Conclusion
Anosmia, the complete loss of smell, can significantly impact quality of life. But with compassion, understanding of its causes and effects, and practical adaptations, it is possible to find enjoyment and thrive despite smell loss. Support groups, smell training, and technologies that amplify odors can all help people with anosmia regain confidence and safety in their environment. While at times frustrating, anosmia does not have to mean giving up all of life’s pleasures.