February 2002
Have you ever wondered what your life would belike if you did not have one of your five senses? At some point inour lives we have all seen a blind or deaf person but how often do wewonder what it would be like if we were in their shoes? Many peopletake their senses for granted, not giving much thought to the factthat something as simple as bumping your head the wrong way orgetting a cold could take away your sense of smell forever. Anosmiais the total loss of the sense of smell and affects approximately twomillion Americans (Wuensch,2001). Of all the five senses, smellseems to be the least appreciated due to our society's beliefs thatsight and hearing are more important for survival (Gillyatt, 1997).For most people, once they start to notice a decrease in theirhearing or sight they go to the doctor almost immediately to fix theproblem. However, because the sense of taste and smell are so closelyrelated, many people attribute the problem to a lack of taste and donot see their doctor until the damage is irreversible (Thomson,2001). Anosmia is a condition in which although there are mild cases,more serious cases do exist which may jeopardize the victim's life.This disorder not only affects the person's life and safety, but alsohas psychological effects as well . In any case, anosmia should notonly be taken seriously, but resaerch should be continued in thehopes of finding better treatments.
Lacking a sense of smell has similarpsychological effects as those related to losing one's sight orhearing. For example, many blind people feel cut off from the worldand isolated. This case is also seen in many people with anosmia.Some people with anosmia feel physically and socially vulnerable aswell as victimized (Toller, 1999). Others feel unhappy with theinability to detect pleasurable food smells, and as a result manyanosmics develop eating problems and even lose interest in eating(Toller, 1999). On the other hand, some people will constantly eattrying to satisfy their need for taste and put on an excess ofunhealthy weight. Another issue to consider when discussing anosmiais safety. Probably one of the most important safety aspects of allpeople is the ability to smell fire. Anosmics may be in greaterdanger with these situations. They should be encouraged to check thebatteries in their smoke detectors often, and consider having theirnatural gas checked by a professional monthly, since people withanosmia would not be able to detect the smell of a gas leak(Gillyatt, 1997). When using cleaning products and paint supplies,they should be reminded to keep the room adequately ventilated toprevent becoming woozy or nauseated, which could lead to anotherdangerous situation. Some other less serious aspects to take intoconsideration are their daily routines, such as personal hygiene orpreventing food from spoiling (Thomson, 2001). One way to preventfood poisoning is to write the dates on leftover food or to throw itaway if they are not sure.
Anosmia has many causes ranging from a minorhead injury or cold to more serious illnesses like Alzheimer'sdisease. The following are examples that fall on the less seriousside of the spectrum. Age is one factor that not only affects yoursense of smell but the other four senses as well. It has beenestimated that "half of everyone age 60 and over has some loss ofsmell" (Thomson, 2001). While age plays a role in anosmia it is alsonormal to notice a lack of smell due to a cold, allergies, or otherminor viral infections. In some cases, cold viruses can damage theolfactory system causing the loss of smell to last even after thecold is over (Thomson, 2001). In this instance, since there are noproven treatments for reversing olfactory nerve damage, the patient'sbest hope may be spontaneous recovery (Thomson, 2001). Jobs are alsorisk factors for anosmia. For example, many fire fighters experiencea loss of smell due to constant exposure to toxic chemicals andsmoke. This example holds true for anyone in a profession who workswith harsh chemicals on a regular basis.
While the risk factors above may not seem veryserious, there are other issues that in some cases are lifethreatening. For example, one of the first things most doctorseliminate is the occurrence of head trauma due to the fact that"about 10% of people with a head injury experience some loss ofsmell" (Thomson, 2001). Head injuries can cause the brain to joltwhich thins out the delicate axons that run from the olfactoryneurons to the brain (Wuensch, 2001). In many cases, not only thelocation of the injury, but also the degree of the trauma isimportant. The loss of smell is more likely to occur if the personlost consciousness or fractured their skull during the accident(Ogawa and Rutka, 1999). Many times people will regain their sense ofsmell after the axons regenerate; however, the condition can also bepermanent. Obstructions and inflammation in the nasal cavity alsoeffect one's sense of smell. One type of obstruction in the nasalcavity is called nasal polyps. This obstruction can occur when thelining of the sinuses swells up and protrudes into the nasal cavity(Thomson, 2001). More serious causes of anosmia are certain brainpathologies like Alzheimer's disease. Morgan (2000) states thatpatients diagnosed with Alzheimer's disease have plaques, tangles,and cell loss in the areas of the brain associated with olfactoryfunction. In the case of Alzheimer's disease, researchers have usedfMRI's to observe the extent of activity when specific brain regionsare activated by olfactory stimuli (Andrew et al., 2001). Theirfindings have suggested that, compared to younger people, elderlypeople with Alzheimer's have decreased activation in the olfactorycortex located in the right side of the brain (Andrew et al., 2001).However, the left side of the brain reached significant levels ofactivation(Andrew et al., 2001). These results have also been seen inother research cases. For example, researchers in New York used smelltests and fMRI's to locate the areas which were affected by odors(Thomson, 2001). They found that while Alzheimer's patients haddifficulty identifying odors and they also had damage on the rightside of their brain (Thomson, 2001).
The amount of research being done in the areaof anosmia and other olfactory disorders is very small. In the past,researchers have used such brain imaging technologies as fMRI's, PETscans and CT scans to observe different areas affected by olfactorydysfunctions. As pointed out above, the use of fMRI's is useful indetecting anosmia in such disorders as Alzheimer's disease. By usingthe paired-subtraction technique researchers are able to identify theareas related to olfactory functions and how these areas are affectedby Alzheimer's and even Parkinson's disease. Such researching groupsas Andrew et al. used fMRI's to observe areas of the brain in twelveAlzheimer's patients (Andrew et al., 2001). In the present,researchers are still exploring how anosmia is related to the brainpathologies of Alzheimer's and Parkinson's disease. "Their work couldlead to smell-based diagnostic tests for these diseases, as well asfresh insights into how they develop" (Thomson, 2001).
Anosmia is a difficult disorder to treat dueto the lack of informative research. The less serious cases have ahigher chance of being treated and cured. For example, antihistamineswill help clear a stuffy nose during allergy season and most coldmedicines also clear the nasal passages. For certain infections, suchas sinusitis and upper respiratory infections, prescription drugsusually result in the best treatment. However, although people canregain smell, permanent damage can still result even in these lightcases. When moving on to the more serious cases of anosmia, likeAlzheimer's or Parkinson's disease; treatments become less and lessreliable due to the minimal amount of research in this area. In oneresearch study, it was found that both Parkinson's and a loss ofsmell had been traced to low levels of dopamine (Thomson, 2001).However, they also found that when patients were given levodopa, asubstance that increases dopamine levels, the sense of smell did notimprove. Although trial and error research studies usually providenegative results, they still aid in the study of anosmia and moveresearchers closer to a cure.
The MRI studies performed by the researchersabove provide useful information about the effects of anosmia,especially in Alzheimer's disease. For this reason, looking furtherinto other diseases such a schizophrenia, epilepsy, or even cancermay provide further evidence of damaged olfactory functioning. Whileantihistamines and prescription drugs provide relief of temporarysymptoms, anosmia is a serious disorder that should continue to beresearched to foresee treatments in the serious conditions as well.Finding treatments for anosmics who have more serious damage couldnot only save lives, but also help them regain a sense of worth andrelieve the depression that accompanies this disorder.
Andrew, Bryant, Critchley, Fukuda, Howard,Jackson, Ouldred, Suckling, Suzuki, Swift, & Williams (2001).Functional magnetic resonance imaging of odor indentification: Theeffect of aging. Journals of Gerontology, 56A(12),M756-760.
Gillyatt, P., (1997). Loss of smell: when thenose doesn't know. Harvard Health Letter, 22, 6-8.
Morgan (2000). Olfactory event-relatedpotentials in Alzheimer's disease. Dissertation AbstractsInternational, 61(5-B), 2773.
Ogawa & Rutka (1999). Olfactorydysfunction in head ingured workers. Acta Oto-Laryngologica,119(540), 50-57.
Thomson, Corp. (2001). Senses- Loss ofSmell: How it happens and what it means. HarvardCollege.
Toller, Van (1999). Assessing the impact ofanosmia: review of a questionnaire's findings. Chemical Senses,24(6), 705-712.
Wuensch, L. (2001, November 10). How frequentis anosmia? [Online]. Available: http://www.personal.ecu.edu/wuenschk/anos-freq.htm