is the lack of olfaction
, or an absence of the ability to smell. It can be either temporary or permanent. A related term, hyposmia
, refers to a decrease in the ability to smell, while hyperosmia
refers to an increased ability to smell. Some people may be anosmic for one particular odor
. This is called "specific anosmia" and may be genetically based.
While termed as a disability, anosmia is often viewed in the medical field as a trivial problem. This is not always the case — esthesioneuroblastoma is a very rare cancerous tumor originating in or near the olfactory nerve.
Anosmia can be diagnosed by doctors by using scratch-n-sniff
odor tests or by using commonly available odors such as coffee
Anosmia can have a number of detrimental effects. Patients with sudden onset anosmia may find food less appetizing, though congenital anosmics rarely complain about this. Loss of smell can also be dangerous because it hinders the detection of gas leaks, fire, body odor, and spoiled food. The common view of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.
Losing an established and sentimental smell memory (e.g. the smell of grass, of the grandparents' attic, of a particular book, of loved ones, or of oneself) has been known to cause feelings of depression.
Loss of olfaction may lead to the loss of libido, though this may not apply to congenital anosmics.
Often people who have congenital anosmia report that they pretended to be able to smell as children because they thought that smelling was something that older/mature people could do, or did not understand the concept of smelling but did not want to appear different from others. When children get older, they often realize and report to their parents that they do not actually possess a sense of smell, much to the surprise of their parents.
A temporary loss of smell can be caused by a stuffy nose
or infection. In contrast, a permanent loss of smell may be caused by death of olfactory receptor neurons
in the nose, or by brain injury
in which there is damage to the olfactory nerve
or damage to brain areas that process smell (see olfactory system
). The lack of the sense of smell at birth, usually due to genetic factors, is referred as congenital anosmia.
Anosmia may very occasionally be an early sign of degenerative brain diseases such as Parkinson's disease
and Alzheimer's disease
. Another specific cause of permanent loss could be from damage to olfactory receptor neurons due to use of certain types of nasal spray
, i.e. those that cause vasoconstriction of the nasal microcirculation. To avoid such damage and subsequent risk of loss of smell from vasoconstricting nasal sprays, they should be used for only a short amount of time and only when absolutely necessary. Non-vasoconstricting sprays, such as those used to treat allergy related congestion are safe to use for extended periods of time. Anosmia can also be caused by nasal polyps. These polyps are found in people with allergies, histories of sinusitis & family history. Individuals with Cystic Fibrosis often develop nasal polyps.
Causes of anosmia include: