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JAMA Otolaryngology–Head & Neck Surgery | Original Investigation Factors Associated With Phantom Odor Perception Among US Adults Findings From the National Health and Nutrition Examination Survey
Kathleen E. Bainbridge, PhD, MPH; Danita Byrd-Clark, BBA; Donald Leopold, MD
Invited Commentary page 814 IMPORTANCE Phantom odor perception can be a debilitating condition. Factors associated with phantom odor perception have not been reported using population-based epidemiologic data.
OBJECTIVE To estimate the prevalence of phantom odor perception among US adults 40 years and older and identify factors associated with this condition.
DESIGN, SETTING, AND PARTICIPANTS In this cross-sectional study with complex sampling design, 7417 adults 40 years and older made up a nationally representative sample from data collected in 2011 through 2014 as part of the National Health and Nutrition Examination Survey.
EXPOSURES Sociodemographic characteristics, cigarette and alcohol use, head injury, persistent dry mouth, smell function, and general health status.
MAIN OUTCOMES AND MEASURES Phantom odor perception ascertained as report of unpleasant, bad, or burning odor when no actual odor exists.
RESULTS Of the 7417 participants in the study, 52.8% (3862) were women, the mean (SD) age was 58 (12) years, and the prevalence of phantom odor perception occurred in 534 participants, which was 6.5% of the population (95% CI, 5.7%-7.5%). Phantom odor prevalence varied considerably by age and sex. Women 60 years and older reported phantom odors less commonly (7.5% [n = 935] and 5.5% [n = 937] among women aged 60-69 years and 70 years and older, respectively) than younger women (9.6% [n = 1028] and 10.1% [n = 962] among those aged 40-49 years and 50-59 years, respectively). The prevalence among men varied from 2.5% (n = 846) among men 70 years and older to 5.3% (n = 913) among men 60 to 69 years old. Phantom odor perception was 60% (n = 1602) to 65% (n = 2521) more likely among those with an income-to-poverty ratio of less than 3 compared with those in the highest income-to-poverty ratio group (odds ratio [OR], 1.65; 95% CI, 1.06-2.56; and OR, 1.60; 95% CI, 1.01-2.54 for income-to-poverty ratio <1.5 and 1.5-2.9, respectively). Health conditions associated with phantom odor perception included persistent dry mouth (OR, 3.03; 95% CI, 2.17-4.24) and history of head injury (OR, 1.74; 95%
CI, 1.20-2.51). Author Affiliations: National Institute on Deafness and Other CONCLUSIONS AND RELEVANCE An age-related decline in the prevalence of phantom odor Communication Disorders, National perception is observed in women but not in men. Only 11% (n = 64) of people who report Institutes of Health, Bethesda, Maryland (Bainbridge); Social & phantom odor perception have discussed a taste or smell problem with a clinician. Scientific Systems, Inc, Silver Spring, Associations of phantom odor perception with poorer health and persistent dry mouth point Maryland (Byrd-Clark); University of to medication use as a potential explanation. Prevention of serious head injuries could have Vermont Medical Center, Burlington (Leopold). the added benefit of reducing phantom odor perception. Corresponding Author: Kathleen E. Bainbridge, PhD, MPH, National Institute on Deafness and Other Communication Disorders, 6001 Executive Blvd, MSC 9670, Bethesda, JAMA Otolaryngol Head Neck Surg. 2018;144(9):807-814. doi:10.1001/jamaoto.2018.1446 MD 20892-7180 (bainbridgek@mail Published online August 16, 2018. .nih.gov).
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he perception of phantom odors is a qualitative olfac- tory dysfunction whereby affected individuals per- Key Points ceive odors in the absence of an external stimulus. The T Question How does the prevalence of phantom odor perception sensation is typically unpleasant and described with terms such vary by age, sex, socioeconomic position, health status, health as “foul,”“rotten,”or “chemical.”There are few epidemiologi- behaviors, smell function, and oral and sinonasal symptoms cal studies of phantom odor perception. Prevalence esti- among US adults? mates are in the range of 5% to 6%1,2 and may be greater among Findings In this cross-sectional study of 7417 adults, the women. Phantom odor perception has been correlated with prevalence of phantom odor perception was 6.5% (n = 534) and depression3,4 and has been described in relation to migraine was greater among women, younger age groups, and those of aura,5 radiation therapy,6 sinonasal disease, post–upper re- lower socioeconomic position. Phantom odor perception was spiratory tract viral infection,7 and head trauma,8 although more common among those with poorer health, a history of head most evidence has been limited to case reports and small clini- injury, or dry mouth symptoms. cal studies. The biological mechanism of phantom odor per- Meaning Epidemiologic characterization may provide clues to ception is thought to arise from aberrant peripheral olfactory cause and alert clinicians to the importance of this disorder. sensory neurons9 signaling perception centers in the brain, or overactive brain cells creating the perception.9,10 Reports of egory. Income-to-poverty ratio was defined as the ratio of re- phantom odors have not been correlated with objective mea- ported total family income to the US Census Bureau’s poverty sures of olfactory loss.2,11 Phantom odor symptoms may dis- threshold, which varies by size of family and age of family appear, improve, or worsen over time,12 and treatments are not members. A person with an income-to-poverty ratio of 1.5, for reliably effective.9,13 example, belongs to a family with an income that is 50% above To our knowledge, the epidemiology of phantom odor per- the poverty threshold. Income-to-poverty ratio has a defined ception in the United States has never been described. The ob- maximum value of 5; persons whose income-to-poverty ratio jective of the present study was to use recent national survey exceeds that are assigned a value of 5. data to evaluate associations between phantom odor percep- People who reported never having smoked 100 ciga- tion and sociodemographic factors, certain health behaviors, rettes in their lifetime were classified as having never smoked. and health conditions among middle-aged and older US adults. Among the others, smoking status was defined as currently smoke every day, currently smoke some days, or former smoker. Alcohol use was classified using a threshold of 12 al- Methods coholic beverages in the past year. Frequency of alcohol use was categorized as 0, 1 to 2 days/week, and 3 to 7 days/week, Study Population based on self report. Data were collected in 2011 through 2014 as part of the National Participants assessed their general health status as excel- Health and Nutrition Examination Survey conducted by the lent, very good, good, fair, or poor. Participants also reported National Center for Health Statistics. The cross-sectional sur- on specific physical health conditions experienced over the past vey used a stratified, multistage, probability cluster design that 12 months, including nasal congestion from allergies, cold or resulted in a nationally representative sample of the nonin- flu lasting longer than a month, and persistent dry mouth. Life- stitutionalized, civilian US population. Study participants were time history of lost consciousness due to head injury, broken interviewed in their homes and underwent a physical exami- nose, or other serious face or skull injury, and greater than 2 nation at a mobile examination center. Adults 40 years and sinus infections were assessed from interview questions. For older were eligible for the interview question on phantom survey years 2013 through 2014, reduced smell function was odors. Of 7418 eligible adults, 7417 had nonmissing data on assessed for 3519 participants with an 8-item odor identifica- phantom odor perception. The demographic and other char- tion test in a mobile examination center. Odorants presented acteristics are detailed in Table 1. Overall response rates for the were strawberry, smoke, soap, chocolate, natural gas, leather, interviewed sample were 72.6% in the 2011-2012 period and grape, and onion. Reduced smell function was defined as fewer 71.0% in the 2013-2014 period. Survey protocols were ap- than 6 correctly identified odorants.14 proved by the National Center for Health Statistics Research Ethics Review Board. Study participants provided written in- Statistical Analysis formed consent. Frequency distributions of sociodemographic and certain health factors were computed for those who did and did not report Measures phantom odors. For each level of each factor, we computed the Phantom odor perception was measured with a single ques- difference (95% CI) in the proportion exhibiting that character- tion: “Do you sometimes smell an unpleasant, bad, or burn- istic between those with phantom odor perception and those ing odor when nothing is there?” Sociodemographic charac- without. We estimated the unadjusted prevalence (95% CI) of teristics, including age, sex, and educational attainment, were phantom odor perception overall, stratified by age and sex, and obtained during in-home interviews. Race/ethnic back- stratified by various health conditions. The 95% CIs serve to de- ground information was collected routinely as part of ongo- termine the range within which point estimates would fall on re- ing national surveillance. Participants reported their own race peated sampling. Independent correlates of phantom odor per- and ethnicity and were allowed to select more than 1 cat- ception were identified using a parsimonious multiple logistic
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Table 1. Frequency Distribution of Sociodemographic and Behavioral Characteristics Overall and by Phantom Odor Perception in a Sample of US Population, NHANES 2011-2014
Participants, Phantom Odor Perception, No. (%) No. (Weighted Percentage Difference Characteristic %) (n = 7417)a Yes (n = 534) No (n = 6883) (95% CI) Age, y 40-49 1934 (29.3) 160 (33.4) 1774 (29.0) 4.4 (−3.3 to 12.1) 50-59 1852 (29.5) 144 (32.5) 1708 (29.2) 3.3 (−3.8 to 10.3) 60-69 1848 (22.0) 145 (21.7) 1703 (22.1) −0.4 (−6.2 to 5.4) ≥70 1783 (19.2) 85 (12.4) 1698 (19.7) −7.3 (−11.0 to −2.6) Race/ethnicity Non-Hispanic white 3046 (71.2) 194 (63.5) 2852 (71.7) −8.2 (−14.4 to −2.1) Non-Hispanic black 1777 (10.7) 151 (14.4) 1626 (10.5) 3.9 (0.4-7.5) Non-Hispanic Asian 894 (4.8) 31 (2.7) 863 (4.9) −2.2 (−3.5 to −1.0) Mexican American 803 (6.1) 75 (8.7) 728 (6.0) 2.8 (−0.1 to 5.7) Other Hispanic 737 (5.0) 67 (7.0) 670 (4.8) 2.2 (−0.4 to 4.8) Other race/multiracial 160 (2.2) 16 (3.7) 144 (2.1) 1.6 (−0.9 to 4.0) Sex Male 3555 (47.2) 178 (32.0) 3377 (48.2) −16.3 (−21.4 to −11.2) Female 3862 (52.8) 356 (68.0) 3506 (51.8) 16.3 (11.2-21.4) Education <9th Grade 856 (6.2) 78 (8.5) 778 (6.1) 2.4 (−0.3 to 5.2) 9th Grade to
regression model. All variables that were examined in the bivari- corporating 4-year sample interview or examination weights. The able analysis were also examined in the multivariable analysis. prevalence of phantom odor perception stratified by reduced With the bivariable analysis as our guide, we fit variables sequen- smell function was estimated using 2-year sample examination tially into the model, allowing significant variables to remain in weights. the multivariable model until entering additional variables iden- tified them as not independently associated.15 We report effect sizes as odds ratio (OR) (95% CI). An age-by-sex interaction was Results entered to test whether sex modified the observed age associa- tion. Analyses were performed using SAS, version 14.2 (SAS In- Based on the findings of this study, we estimated the preva- stitute Inc) and SUDAAN, version 11.0.1 (RTI International), in- lence of phantom odor perception as 6.5% (n = 534) (95% CI,
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Table 2. Prevalence of Phantom Odor Perception by Health Characteristic in a Sample of the US Population 40 Years and Older, NHANES 2011-2014
Participants, No. Phantom Odor Perception (Weighted %) Characteristic (n = 7417)a Participants, No. Prevalence, % (95% CI) Overall 7417 (100) 534 6.5 (5.7-7.5) General health status Excellent/very good 2094 (40.0) 84 4.2 (3.3-5.3) Good 2610 (39.6) 169 5.8 (4.4-7.5) Fair/poor 1793 (20.4) 227 13.4 (11.2-15.9) Head injury, ever Yes 948 (15.6) 112 10.8 (8.5-13.6) No 6469 (84.4) 422 5.7 (4.8-6.8) Nose/face/skull injury, ever Yes 1037 (17.9) 98 7.9 (6.4-9.7) No 6380 (82.1) 436 6.2 (5.2-7.4) >2 sinus infections, ever Yes 2280 (40.2) 243 8.5 (6.9-10.4) No 5137 (59.8) 291 5.2 (4.5-6.0) Nasal congestion, past 12 mo Yes 2055 (28.7) 257 10.6 (8.6-13.0) No 5362 (71.3) 277 4.9 (4.2-5.7) Persistent cold/flu, past 12 mo Yes 478 (6.1) 79 16.1 (11.6-21.9) No 6939 (93.9) 455 5.9 (5.2-6.8) Persistent dry mouth, past 12 mo Abbreviation: NHANES, National Yes 1115 (13.1) 204 17.4 (13.7-21.9) Health and Nutrition Examination No 6302 (86.9) 330 4.9 (4.2-5.7) Survey. Reduced smell functionb a Missing data account for totals that do not equal 7417. Yes 630 (13.5) 33 5.6 (3.5-8.9) b Data available for only n = 3519 No 2889 (86.5) 217 7.2 (5.8-9.0) in 2013 to 2014.
5.7%-7.5%) among US adults 40 years and older (Table 2). Only reported phantom odors had an income-to-poverty ratio of less 11.1% (n = 64) of people who reported phantom odors have dis- than 3 (or 300% of poverty level) compared with 46.1% cussed a taste or smell problem of any kind with a clinician. (n = 3749) of those who did not report phantom odors. The frequency distribution of sociodemographic and health Almost 20% (n = 1309) of US adults reported smoking ev- behavior characteristics is summarized in Table 1, along with ery day or on some days. Of those who reported phantom odors, the difference (95% CIs) between the absolute percentage 25.3% (n = 130) had a history of current or former cigarette among people who reported phantom odors and those who did smoking compared with 17.8% (n = 1179) among those who did not. People who reported phantom odors were less likely to not report phantom odors. Overall use of alcohol did not vary be older than 70 years than those who did not report phan- between those who reported phantom odors and those who tom odors (12.4% [n = 85] vs 19.7% [n = 1698]). A greater pro- did not, but people who reported phantom odors were less portion of those who reported phantom odors were non- likely to consume alcohol at least 3 days per week (11.3% Hispanic black (14.4% [n = 151] vs 10.5% [n = 1626] among those [n = 49] vs 21.1% [n = 936]). who did not experience phantom odors). Non-Hispanic white The Figure displays the prevalence of phantom odor per- individuals (n = 2852 [71.7%]) and non-Hispanic Asian indi- ception by age group and sex in the study population. Women viduals (n = 863 [4.9%]) were represented in greater propor- had about 2 times greater prevalence of phantom odor per- tions among those who did not report phantom odors com- ception than men at every age group. Nonoverlapping CIs in pared with those who did (n=194 [63.5%] and n=31 [2.7%] the 40 to 49 and 50 to 59 years age groups indicated statisti- among non-Hispanic white individuals and non-Hispanic Asian cally significant sex differences. We noted a declining preva- individuals, respectively). Women made up 52.8% (n = 3862) lence of phantom odors by age, which was more pronounced of the national sample among adults 40 years and older. Two- in women than it was in men. thirds (68.0% [n = 356]) of adults who reported phantom odors The frequency distribution of potentially correlated health were women. People who reported phantom odors were less conditions and the corresponding prevalence of phantom odor likely to have more than a high school education than those perception are summarized in Table 2. Adults in fair or poor who did not report phantom odors (48.0% [n = 218] vs 62.2% health represented 20.4% (n = 1793) of the population. More [n = 3609]). Moreover, two-thirds (n = 762) of people who than 13% (n = 227) of people in fair or poor health reported
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Figure. Prevalence of Phantom Odor Perception by Age Group and Sex Table 3. Multivariable-Adjusted ORs for the Association of Phantom Odor Perception and Independent Risk Factors 20 Among a Sample of US Adults 40 Years and Older, NHANES 2011-2014a
Men Women Characteristic aOR (95% CI) Age, y 15 40-49 Men 2.32 (1.25-4.28) Women 5.12 (2.77-9.44) 10 50-59 Men 1.83 (0.94-3.57) Prevalence, % Prevalence,
5 Women 4.51 (2.03-10.02) 60-69 Men 2.28 (0.96-5.39) 0 Women 3.18 (1.61-6.27) 40-49 50-59 60-69 70-79 ≥70 Age, y Men 1 [Reference] Data collected in 2011 through 2014 as part of the National Health and Nutrition Women 1.64 (0.86-3.15) Examination Survey included 7417 adults 40 years and older as a nationally Income-to-poverty ratio representative sample. Whiskers indicate 95% CIs. <1.5 1.65 (1.06-2.56) 1.5 to <3 1.60 (1.01-2.54) phantom odors compared with 5.8% (n = 169) among those in 3 to <5 1.03 (0.55-1.93) good health and 4.2% (n = 84) among those in very good or ex- 5 1 [Reference] cellent health. People who reported persistent dry mouth had General health status more than 3 times the prevalence of reporting phantom odors Excellent/very good 1 [Reference] as those who did not (17.4% [n = 204] vs 4.9% [n = 330]). More Good 1.22 (0.85-1.74) than 10% (n = 112) of people who had lost consciousness from Fair/poor 2.27 (1.66-3.08) a head injury reported phantom odors compared with 5.7% Persistent dry mouth (n = 422) of those without a history of head injury. Almost one- Yes 3.03 (2.17-4.24) fifth of the population (n = 1037) reported a history of injury No 1 [Reference] to their nose, face, or skull but no greater prevalence of phan- Head injury/loss of consciousness tom odor perception. Reduced smell function or suboptimal Yes 1.74 (1.20-2.51) performance on an odor identification test was identified in No 1 [Reference] 13.5% (n = 630) of the population. Individuals with reduced smell function had somewhat, but not significantly, lower Abbreviations: aOR, adjusted odds ratio; NHANES, National Health and prevalence of phantom odor perception. Nutrition Examination Survey. a In Table 3, we detail estimates for the strength of inde- The total population for this multivariable-adjusted analysis was 5963. pendent associations of phantom odors with demographic factors and health conditions, adjusted for all variables re- 95% CI, 1.06-2.56). Adults in fair/poor health were more than maining in the model. We observed that the strength of the as- twice as likely to report phantom odors than those in excel- sociation between age and phantom odor perception varies lent or very good health (aOR, 2.27; 95% CI, 1.66-3.08). People markedly by sex. Men in younger age groups (40-49, 50-59, with persistent dry mouth had 3 times the odds of reporting and 60-69 years) were twice as likely to report phantom odors phantom odors (aOR, 3.03; 95% CI, 2.17-4.24). History of head as men 70 years and older, but this association was statisti- injury with loss of consciousness was associated with 74% cally significant for only the men aged 40 to 49 years (ad- greater odds of phantom odor perception (aOR, 1.74; 95% CI, justed OR [aOR], 2.32; 95% CI, 1.25-4.28). Among women, how- 1.20-2.51). ever, we observed a strong graded inverse correlation between the likelihood of phantom odor perception and age. Com- pared with men 70 years and older, women in this age group Discussion had no greater likelihood of phantom odor perception, but women in the younger age groups (40-49, 50-59, and 60-69 To our knowledge, the present study is the first population- years) had 5 (aOR, 5.12; 95% CI, 2.77-9.44), 4 (aOR, 4.51; 95% based epidemiologic analysis of phantom odor perception CI, 2.03-10.02), and 3 (aOR, 3.18; 95% CI, 1.61-6.27) times the using nationally representative data from the United States. odds of phantom odor perception, respectively. Compared with We estimated the prevalence to be 6.5% among adults 40 years people in the highest socioeconomic category (income-to- and older. This estimate is somewhat greater than the 4.9% poverty ratio of 5), those with an income-to-poverty ratio of prevalence observed in 1 Swedish community, although adults less than 3 had 60% to 65% greater likelihood of experiencing in the Swedish study were 60 years and older.2 When we lim- phantom odors (aOR, 1.60; 95% CI, 1.01-2.54; and aOR, 1.65; ited our sample to include only US adults 60 years and older,
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we corroborated the prevalence of phantom odor perception smoking and phantom odor perception. People who drink al- to be 5.4% (95% CI, 4.3%-6.8%). We observed that younger age cohol were not more likely than people who abstain to report and lower socioeconomic class were independently and posi- phantom odors. However, when alcohol use was broken down tively associated with phantom odor perception. Two-thirds by drinking days per week, we found that people who drink of people who experienced phantom odors were women, which more frequently have fewer reports of phantom odors, but this is consistent with the sex ratio observed in the Swedish association was not robust to adjustment for dry mouth symp- population-based data.2 People reporting fair to poor health toms. Recent pathobiologic evidence suggested no de- were more likely to report phantom odor perception than those creased neurogenesis in the olfactory bulb when comparing a in good health. Adults with persistent dry mouth or history of group with a 30-year history of high-volume alcohol use with serious head injury were more likely to report phantom odor a group with modest alcohol consumption.26 perception independent of reported health status. We observed a strong association between phantom odor Phantom odor perception is an olfactory disturbance in perception and symptoms of persistent dry mouth. Our measure which individuals perceive an odor in the absence of a stimu- of persistent dry mouth may have captured people with Sjogren lus. The cause of this condition is unknown. People with phan- syndrome, an autoimmune disorder that has been associated tom odor perception may have a neural signaling imbalance with reduced smell function27,28 but not, to our knowledge, with that allows nonsense olfactory signals to reach the central ner- phantom odors. With 13% of adults reporting dry mouth symp- vous system. The sensation may originate in the peripheral ner- toms, this measure may also be an indicator of medication use. vous system at the level of the olfactory sensory neurons, may A variety of medications have been implicated in olfactory dys- reflect damage to the olfactory nerve, or may originate in the function, including chemotherapeutic agents, antihypertensive central brain.16 We found phantom odor perception to be in- agents, antibiotics, and antidepressants.29 Self-reported general versely associated with age predominantly among women. If health is an indicator of individual health that is strongly corre- phantom odors are the result of aberrant peripheral neurons, lated with mortality, particularly among people who have indi- an age-related loss of olfactory sensory neurons may explain cators of circulatory disease.30 Sjölund et al2 observed a modest an age-related decline in phantom odor perception consis- association between a nonspecific indicator of cardiovascular risk tent with an age-related decline in odor sensitivity.17,18 Rea- burden and phantom odor perception using data collected as part sons for the sex difference or the age-related decline are un- of a community-based study in Sweden. Again, medication use clear. could explain correlations with fair or poor general health in our Black and Hispanic people are overrepresented among data and with cardiovascular risk in the Swedish data. Assess- people who report phantom odors. However, when we ac- ing associations with medication use was beyond the scope of counted for the greater prevalence of phantom odors among the current study. Finally, we observed no association between people of lower socioeconomic position, we observed no dif- reduced smell function based on an odor identification test, ference across race/ethnic groups. The greater prevalence of which corroborates evidence from the Swedish study.2 phantom odor perception among people of lower socioeco- nomic position may reflect greater exposure to environmen- Limitations tal toxins.19 Socioeconomic indices such as family income We acknowledge limitations to our study. It is possible that our are inversely associated with exposure to fine particulate measure of phantom odor perception misclassified people who matter and other ambient air pollutants, and poor indoor air have burning mouth syndrome or oral phantom sensations. quality.19,20 Lower socioeconomic status could also be a marker However, when we conducted a sensitivity analysis reclassi- for a number of health conditions understood to be associ- fying 13 people who also reported burning or other taste phan- ated with phantom odors, such as migraine or primary toms, there was no difference in the results. We do not have headache.21 Nonfatal injury rates also vary inversely with so- information on intensity, duration, or periodicity of the phan- cioeconomic status.22,23 Given the association we observed be- tom odor perception. We have no data regarding health con- tween phantom odors and severe head trauma, it is possible ditions, including seizures, primary headache, migraine head- that our measure of low income may be capturing injuries that ache, and serious mental illness, which could serve to explain have damaged the olfactory neurons, the olfactory bulb, or the the age, sex, and income patterns we describe. Data were not cerebral cortex, despite no loss of consciousness. Alterna- collected on adults younger than 40 years. We might expect tively, the inverse association between phantom odors and in- some misclassification in the reporting of medical condi- come may reflect differential reporting of nonfatal head inju- tions. The misclassification of severe head trauma, in particu- ries by social class.24 lar, could be differential, which would bias our point esti- Evidence from a recent review suggests that current but mate in an unpredictable direction. However, the positive not former smoking is related to subjective measures of olfac- association we report is biologically plausible and consistent tory dysfunction. Phantom odors were not considered among with earlier reports of olfactory dysfunction, including phan- the olfactory conditions in the review.25 We observed greater tom odors, among people with head trauma.31 These cross- prevalence of phantom odor perception among people who sectional data are not able to discern the temporal relation- currently smoke, compared with former or never smokers. ship of phantom odors with any of the correlated factors. For However, after adjustment for cigarette smoking being more example, living with and finding no relief from phantom odors common among younger people and those of lower socioeco- could lead people to report fair or poor health. Finally, the nomic status, we no longer observed an association between sample design does not allow for adults who are institution-
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alized or serving in the military. People hospitalized with head groups, and those of lower socioeconomic position. Phan- trauma and frail elderly people living in nursing facilities are tom odors are reported more commonly among those in not represented. poorer health and among those who have persistent dry mouth. Head injury is strongly associated with phantom odor perception, and rates of traumatic brain injury seen in 32 Conclusions emergency departments have been steadily increasing. Response to treatment for loss of odor sensitivity has been To our knowledge, this is the first observational study of shown to depend on duration of symptoms.33 Only 11% of phantom odor perception using nationally representative people who report phantom odors have discussed a taste or survey data and the largest epidemiological investigation of smell problem of any kind with a clinician. Increased aware- this condition to date. We estimate the prevalence of phan- ness of phantom odor perception as a clinical problem and tom odor perception at 6.5% among US adults 40 years and the risk factors associated with this condition may contrib- older. Among US adults 40 years and older, phantom odor ute to more affected individuals seeking guidance or treat- perception is more common among women, younger age ment for this condition.
ARTICLE INFORMATION Nutrition Examination Survey (NHANES). Chem 14. Hoffman HJ, Rawal S, Li C-M, Duffy VB. New Accepted for Publication: May7,2018. Senses. 2016;41(1):69-76. doi:10.1093/chemse chemosensory component in the U.S. National /bjv057 Health and Nutrition Examination Survey Published Online: August 16, 2018. (NHANES): first-year results for measured olfactory doi:10.1001/jamaoto.2018.1446 2. Sjölund S, Larsson M, Olofsson JK, Seubert J, Laukka EJ. Phantom smells: prevalence and dysfunction. Rev Endocr Metab Disord. 2016;17(2): Author Contributions: Dr Bainbridge had full correlates in a population-based sample of older 221-240. doi:10.1007/s11154-016-9364-1 access to all of the data in the study and takes adults. Chem Senses. 2017;42(4):309-318. doi:10 15. Hosmer DW, Lemeshow S. Applied Logistic responsibility for the integrity of the data and the .1093/chemse/bjx006 Regression. New York, NY: John Wiley & Sons; 1989. accuracy of the data analysis. Study concept and design: Bainbridge. 3. Philpott CM, Boak D. The impact of olfactory 16. Patel RM, Pinto JM. Olfaction: anatomy, Acquisition, analysis, or interpretation of data: All disorders in the United Kingdom. Chem Senses. physiology, and disease. Clin Anat. 2014;27(1):54-60. authors. 2014;39(8):711-718. doi:10.1093/chemse/bju043 doi:10.1002/ca.22338 Drafting of the manuscript: Bainbridge. 4. Croy I, Yarina S, Hummel T. Enhanced parosmia 17. Murphy C, Schubert CR, Cruickshanks KJ, Klein Critical revision of the manuscript for important and phantosmia in patients with severe depression. BE, Klein R, Nondahl DM. Prevalence of olfactory intellectual content: All authors. Psychol Med. 2013;43(11):2460-2464. doi:10.1017 impairment in older adults. JAMA. 2002;288(18): Statistical analysis: Bainbridge, Byrd-Clark. /S0033291713001773 2307-2312. doi:10.1001/jama.288.18.2307 Administrative, technical, or material support: 5. Jion YI, Grosberg BM, Evans RW. Phantosmia 18. Dong J, Pinto JM, Guo X, et al. The prevalence Byrd-Clark. and migraine with and without headache. Headache. of anosmia and associated factors among U.S. black Study supervision: Bainbridge. 2016;56(9):1494-1502. doi:10.1111/head.12890 and white older adults. J Gerontol A Biol Sci Med Sci. Conflict of Interest Disclosures: All authors have 6. Yang JC, Khakoo Y, Lightner DD, Wolden SL. 2017;72(8):1080-1086. doi:10.1093/gerona/glx081 completed and submitted the ICMJE Form for Phantosmia during radiation therapy: a report of 2 19. Ajmani GS, Suh HH, Wroblewski KE, et al. Fine Disclosure of Potential Conflicts of Interest and cases. J Child Neurol. 2013;28(6):791-794. doi:10 particulate matter exposure and olfactory none were reported. .1177/0883073812450616 dysfunction among urban-dwelling older US adults. Funding/Support: The National Institute on 7. Nordin S, Murphy C, Davidson TM, Quiñonez C, Environ Res. 2016;151:797-803. doi:10.1016/j.envres Deafness and Other Communication Disorders Jalowayski AA, Ellison DW. Prevalence and .2016.09.012 provided funding support for National Health and assessment of qualitative olfactory dysfunction in 20. Evans GW, Kantrowitz E. Socioeconomic status Nutrition Examination Survey chemosensory data different age groups. Laryngoscope. 1996;106(6): and health: the potential role of environmental risk collection via interagency agreements with the 739-744. doi:10.1097/00005537-199606000 exposure. Annu Rev Public Health. 2002;23:303-331. National Center for Health Statistics of the Centers -00014 doi:10.1146/annurev.publhealth.23.112001.112349 for Disease Control and Prevention and the University of Connecticut. Support for the 8. Mott AE, Leopold DA. Disorders in taste and 21. Coleman ER, Grosberg BM, Robbins MS. statistical analysis was provided by Social & smell. 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Invited Commentary Prevalence and Risk Factors for Olfactory Hallucinations The Phantom Menace David W. Hsu, MD; Jeffrey D. Suh, MD
Olfactory dysfunction can result in substantial reductions in among healthy individuals but range as widely as 0.8% to 25%.5 quality of life if left untreated. The presence of phantom smells, In a large Swedish study, Sjölund et al5 report a 4.9% overall or phantosmia, is a clinically distinct olfactory dysfunction prevalence among individuals 60 to 90 years old, with a higher where patients sense odors when no odor source is present.1 percentage of patients younger than 75 years reporting phan- The cause of phantosmia is toms smells. However, they qualify this finding with that fact
Related article page 807 not completely understood that 32% of these patients reported having phantosmia for more and has been most com- than 10 years. monly associated with head trauma, psychiatric conditions, In the study by Bainbridge and colleagues,3 data were col- chronic rhinosinusitis, epilepsy, and a number of neurologic lected in 2011 through 2014 as part of the National Health and and neurodegenerative disorders.2 Nutrition Examination Survey conducted by the National Cen- How do age, sex, socioeconomic position, health status, ter for Health Statistics. Of the 7417 participants, all 40 years and sinonasal symptoms affect reporting of phantom odors? and older, the prevalence of phantom odor perception was Are patients knowledgeable about olfactory hallucinations, and 6.5%. Women were found to have a higher prevalence of phan- if so, do they feel comfortable reporting them to their clini- tosmia, with younger women reporting it more frequently than cians? In this issue of JAMA Otolaryngology–Head & Neck older women.3,5 Two potential reasons for this finding are that Surgery, Bainbridge and colleagues investigate the preva- women are generally better than men at naming odors, and lence of phantosmia for adults in the United States and iden- women are more often negatively affected by environmental tify risk factors for developing phantom odor perception.3 odors.6,7 Women may have a heightened olfactory sensitivity Recent data suggest that olfactory dysfunction can pre- and lower threshold for reporting smell disturbances.5 date the clinical symptoms of several neurodegenerative dis- Phantosmia is also associated with medical conditions, ge- eases and neuropsychiatric disorders, which highlights the netics, and other factors such as smoking or occupational ex- importance of olfactory dysfunction as a marker for early in- posures. Several medical comorbidities have been impli- tervention. Neurodegenerative diseases such as Parkinson dis- cated, including epileptic seizures, schizophrenia, depression, ease, Alzheimer disease, and amyotrophic lateral sclerosis, and migraine, head trauma, or sinonasal problems.5 Olfactory hal- neuropsychiatric diseases such as anxiety disorders, depres- lucinations may originate from dysfunction of the peripheral sion, and schizophrenia have been associated with olfactory olfactory nervous system or in central brain regions, such as dysfunction.4 Age also plays an important role in general ol- the amygdala or the frontal cortex. Genetic variation can also factory dysfunction, with reported rates between 32% and 62% play a role in the development of phantom smells. The apoli- in older individuals compared with 6% to 17% in younger poprotein E ε4 allele and brain-derived neurotrophic factor populations.5 (BDNF) gene have been implicated in olfactory deficits.5 Fur- Phantom smells are a clinically distinct olfactory dysfunc- ther studies are required to further clarify potential genetic fac- tion that can be more troublesome for patients than a de- tors associated with phantosmia development. creased sense of smell.4 Most phantom smells are linked to The results of the study by Bainbridge and colleagues3 are negative smells, with the most frequently reported described novel and important. Phantosmia remains a difficult clinical as smoky or burnt.5 Although studies examining the preva- challenge in regard to diagnosis and management. Only a small lence of olfactory hallucinations are limited, several have percentage of people with phantom odor perception discuss shown the prevalence to range consistently from 4.9% to 8% their smell or taste issues with their clinicians. Increased aware-
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