Anosmia is the inability or loss of ability to smell things. It may be a total loss of smell, or inability to smell specific scents. Anosmia can have a detrimental effect on a person's life. This is exacerbated because it is not taken as seriously as other sensory deprivation disabilities. It can be just as dangerous because of the inability to sense danger signals such as smoke, toxic chemical smells or if food smells bad. The sense of smell is closely linked to memory and is one of the strongest cues to trigger detailed memories. Loss of this ability to remember via smell has been linked to depression. Smells also effect interpersonal interactions, sometimes on a subconscious level, as when hormones are involved.
Types
There are many different levels and causes of smell loss. Anosmia is the complete loss of the sense of smell. People with congenital anosmia are born without a sense of smell. The inability to sense a particular odor is called specific anosmia, which may also be genetic. Hyposmia is a decreased sensitivity to smells, while hyperosmia is increased senstivity. Dysosmia includes defective or impaired sense of smell, while parosmia is a distorted sense of smell. Phantosmia is smelling a phantom odor. Presbyosmia is a decrease in the sense of smell that happens as you get older. There are two widely used tests that have been developed to help diagnose anosmia. These are the University of Pennsylvania Smell Identification Test (UPSIT) scratch and sniff test developed by Dr. Richard Doty, and the Connecticut Chemosensory Clinical Research Center (CCCRC) test.
Causes - Medical
There are some medical conditions that cause anosmia or affect the sense of smell. Anosmia can be caused by sinus infections or other infections that affect the nose. This can cause a temporary loss of smell, or in severe cases, can cause permanent damage. Trauma to the head or nose can effect the sense of smell, especially if damage is caused to the frontal lobe, where smells are processed. Dental work can damage olfactory nerves. The sense of smell can also decrease and be completely lost as one ages.
Causes - Genetic
Certain genetic disorders can also affect the sens of smell. Kallmann's syndrome is a genetic disorder characterized by hypogonadism and congenital anosmia. Opitz-Frias syndrome is a rare congenital disorder that causes craniofacial anomalies, laryngotracheal disorders and heart defects. These can cause problems with breathing and the sense of smell. Sjogren's syndrome is an autoimmune disease that causes the immune system to attack the glands that produce tears and saliva. This leads to dry eyes, mouth, nose and throat which can effect the sense of smell. Some forms of epilepsy and psychological disorders such as schizophrenia and depression can also effect the sense of smell.
Causes - Chemical
Use of nasal spray, especially that containing zinc, has been linked to loss of smell. Exposure to other chemicals or irritants such as cigarette smoke can damage the sense of smell. Certain medications can cause hyposmia or dysosmia. Anosmia caused by medications or chemicals can be temporary.
Warning
There are a number of commonly prescribed drugs that can impair the sense of smell, these include antidepressants and anticonvulsants, antihistamines and cold medications, antihypertensives and heart medications, anti-inflammatories, antimicrobials, antineoplastics, bronchodilators and asthma medications, lipid-lowering drugs, muscle relaxants, vasodilators and radiation therapy of the head.
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