Furthering the understanding of olfaction, prevalence of loss of smell and risk factors: a population-based survey (OLFACAT study)

Abstract

ObjectivesTo investigate olfaction in general population, prevalence of olfactory dysfunction and related risk factors.DesignCross-sectional population-based survey, distributing four microencapsulated odorants (rose, banana, musk and gas) and two self-administered questionnaires (odour description; epidemiology/health status).SettingThe survey was distributed to general population through a bilingual (Catalan, Spanish) newspaper in Catalonia (Spain), on December 2003.ParticipantsNewspaper readers of all ages and gender; 9348 surveys were analysed from the 10 783 returned.Main outcome measuresCharacteristics of surveyed population, olfaction by age and gender, smell self-perception and smell impairment risk factors. Terms normosmia, hyposmia and anosmia were used when participants detected, recognised or identified all four, one to three or none of the odours, respectively.ResultsSurvey profile was a 43-year-old woman with medium–high educational level, living in a city. Olfaction was considered normal in 80.6% (detection), 56% (recognition/memory) and 50.7% (identification). Prevalence of smell dysfunction was 19.4% for detection (0.3% anosmia, 19.1% hyposmia), 43.5% for recognition (0.2% anosmia, 43.3% hyposmia) and 48.8% for identification (0.8% anosmia, 48% hyposmia). Olfaction was worse (p<0.0001) in men than in women through all ages. There was a significant age-related smell detection decline however smell recognition and identification increased up to fourth decade and declined after the sixth decade of life. Risk factors for anosmia were: male gender, loss of smell history and poor olfactory self-perception for detection; low educational level, poor self-perception and pregnancy for recognition; and older age, poor self-perception and history of head trauma and loss of smell for identification. Smoking and exposure to noxious substances were mild protective factors for smell recognition.ConclusionsSense of smell in women is better than in men suggesting a learning process during life with deterioration in older ages. Poor self-perception, history of smell loss, head trauma and pregnancy are potential risk factors for olfactory disorders.

Smell–taste dysfunctions in extreme weight/eating conditions: analysis of hormonal and psychological interactions

“…Again, prospective design studies are here needed in order to demonstrate whether altered smell capacity is consequence of starvation or a trait. It is important to note that observed values in healthy controls included in the study were similar to those obtained in the general population in Spain [43], which reinforces the consistency of our results.…”

New chemosensory component in the U.S. National Health and Nutrition Examination Survey (NHANES): first-year results for measured olfactory dysfunction

“…Lower educational achievement also was reported as a risk factor of smell dysfunction in the National Social Life, Health and Aging Project, and explained some of racial/ethnicity differences between the sample of non-Hispanic whites and Hispanics [63]; similar associations were observed in the OLFACAT study, a large cohort study in Spain [60]. Low-income status, which is associated with poorer educational attainment, was reported in the Beaver Dam Offspring study [12] as a risk for olfactory dysfunction, which is consistent with the present findings.…”

“…The overall rate reported for NHANES 2012 is higher than the prevalence of 3.8 % ( n = 2838) reported in the Beaver Dam Offspring Study [12, 58] for younger participants, aged 21 to 84 years (mean age = 49 years), which utilized a technician-administered odor identification task, but less than the 19.1 % ( n = 1387) for the Skövde population-based study [16] of subjects aged 20+ years, which also was technician-administered, the 22.1 % ( n = 1277) for Dortmund Health Study [59] of subjects aged 25 to 75 years, which used an odor identification task, and the 20 % ( n = 10,783) from the OLFACAT study [60] of subjects aged 15+ years, which used a combined newspaper-solicited survey and self-administered procedures.…”

“…The correction for age and sex, may be calling attention to the importance of quitting smoking for an extended period of time, which may allow for the recovery from the effects of past smoking. In population-based studies with cross-sectional analysis, smoking has been associated with greater risk of olfactory dysfunction [11, 59] as well as no association with olfactory dysfunction [16] or as a small protective factor [60]. Differences in findings across these population-based studies could have result from how smoking was defined.…”

Olfactory and gustatory dysfunction in Myasthenia gravis: A study in Turkish patients

“…Men show lower scores of smell function than women [13]. Smell loss correlates stronger than taste loss with aging [14].…”