Prevalence and Correlates of Olfactory Dysfunction in Old Age: A Population-Based Study

Abstract

Background:Olfactory dysfunction (OD) in old age is associated with poor health outcomes. Interrelationships among different correlates of OD can offer insights into the underlying mechanisms, but to date remain understudied.Methods:Odor identification performance and self-reported olfactory functioning were studied in 2,234 people aged 60–90 years, who were free of neurodegenerative disease and enrolled in the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) study, Stockholm, Sweden. OD was defined as the inability to identify more than 10 out of 16 odors (free or cued identification) in a standardized odor identification task. OD prevalence was estimated, and associations with demographic, genetic, vascular, clinical, and behavioral factors, as well as their interactions were examined using multiple logistic regression analyses.Results:Overall prevalence of OD was 24.8% (CI: 23.1; 26.6). Self-reports were characterized by low sensitivity (35%), but high specificity (87%). Advancing age (OR = 15.50, CI = 9.40; 26.10 between the first and last age group), and history of coronary heart disease (OR = 1.35, 95% CI = 1.04; 1.75) were the principal factors associated with an increased probability of OD, whereas female gender (OR = 0.53, 95% CI = 0.43; 0.66) and more years of education (OR = 0.97, CI 0.94; 0.99) were linked to a lower probability. Exploratory interaction analyses indicated that prevalence of OD was particularly elevated among Apolipropotein E (APOE) ε4 allele carriers who were also obese, and that being physically active counteracted the negative impact of cerebrovascular disease on OD.Conclusion:Demographic and genetic factors, but also prior and current health insults, are linked to OD in old age. Modulatory effects of behavioral factors highlight their value as possible prevention targets.

Olfactory function in mild cognitive impairment and Alzheimer's disease: A meta‐analysis

“…Several studies have proposed that age might affect olfactory dysfunction in patient groups . In our study, a subgroup analysis of age revealed the unexpected observation that a smaller age difference (<2 years) between the two groups resulted in a greater olfactory deficit.…”

“…Several studies have proposed that age might affect olfactory dysfunction in patient groups. 26,27 In our study, a subgroup analysis of age revealed the unexpected observation that a smaller age difference (<2 years) between the two groups resulted in a greater olfactory deficit. These results indicated that the robust and confirmed difference in olfactory deficits found in our study was not merely due to a decrease in olfactory function due to old age, but rather was related to true deficits in olfaction related to AD pathology (see Supporting Figure 1A in the online version of this article).…”

The effectiveness of platelet‐rich plasma in an anosmia‐induced mice model

“…In addition to affecting quality of life, loss of sense of smell significantly impacts the inability to recognize harmful smells, such as those of rotten foods, gas, and smoke. The prevalence of smell disorders has been reported at between 1% to 25% in previous studies, whereas hyposmia, defined as a reduced ability to smell, is found in 16% of the general population. The prevalence of anosmia, or the loss of sense of smell, is 5% and that has been shown to vary .…”

Interaction Between Odor Identification Deficit and APOE4 Predicts 6-Year Cognitive Decline in Elderly Individuals

“…Participants were instructed to freely identify the odor; if they did not provide a response, or responded incorrectly, they were presented with four response alternatives (cued identification). In the present context, a correct response under either response format (free or cued) was considered correct (Seubert et al 2017). Test procedures have been described in more detail elsewhere (Larsson et al 2016).…”

“…Olfactory dysfunction is common among healthy old individuals, with prevalence ranging between 15 and 70% depending on sample characteristics and diagnostic criteria Handling Editor: Chandra A. Reynolds 1 3 (Seubert et al 2017;Murphy et al, 2002;Schubert et al, 2012). As olfactory impairments are common, a key challenge is to localize subgroups where such impairments may be especially informative with regard to future cognitive development.…”