The Association of Peripheral and Central Olfaction With Frailty in Older Adults

Abstract

Background Olfactory impairment is increasingly recognized as a biomarker of frailty, but the relationship between olfactory subdomains that describe peripheral or central dysfunction and frailty remains unexplored. Methods We examined 1,160 older adults from the National Social Life, Health, and Aging Project (NSHAP) Wave 3. Olfactory identification (OI): the ability to identify an odorant; and olfactory sensitivity (OS): the ability to detect the presence of an odorant, were assessed using 5 and 6-point measures respectively. Frailty was operationalized as both a 37-item Frailty Index (FI) and the 5-item Physical Frailty Phenotype (PFP). Mixed models were fit to examine the association between OI, OS, FI and PFP, while adjusting for demographic and clinical covariates. Results Subjects in the most-frail PFP category had lower OI and OS scores (OI: 3.88 vs 4.19, p= 0.016; OS: 3.15 vs 3.47, p= 0.031), whereas, subjects in the most-frail FI category exhibited lower OI scores but not OS scores when compared to non-frail subjects (OI: 3.72 vs 4.27, p= 0.014; OS: 3.19 vs 3.43, p= 0.476). Adjusted mixed models showed that a point increase in OI was associated with a lower PFP score (β= -0.107, p= 0.006) and FI score (β= -0.009, p= 0.010). A point increase in OS was associated with a lower PFP score (β= -0.058, p= 0.016), but not FI score (β= -0.004, p= 0.064). Conclusions Both OS and OI, predominantly peripheral and central measures of olfaction respectively, are associated with frailty implicating olfaction as a potential biomarker and risk factor for frailty.

Exploring Olfactory Dysfunction as a Marker of Frailty and Postoperative Outcomes in Head and Neck Cancer

“…For instance, the use of a shorter test, such as the Brief Smell Identification Test, which tracks well with the UPSIT, may offer similar accuracy . From a mechanistic perspective, olfactory subdomains may offer insight into the association between outcomes and peripheral vs central sensorineural function . Finally, it will be important to assess whether targeted olfactory interventions can make meaningful differences in clinical and oncologic outcomes.…”

Reimbursement for Olfactory Testing

“…We evaluated the volume of office visits, including the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Clinical Modification code R43* for “disturbances of smell and taste” from October 1, 2018, to June 30, 2022, finding that visits for smell and taste disturbances increased 4- to 6-fold during the peak of the pandemic in 2020 and 2021 and continued to be about 50% higher in 2022 than they were in 2018 (Figure). These data are noteworthy because OD has often been dismissed as an unimportant or unrecognized condition, but recent evidence suggests that it may be a harbinger of comorbid conditions . Additionally, OD also manifests with serious psychosocial implications of its own, and these new data on volume show greater numbers of individuals seeking care for changes in their smell.…”

“…More importantly, as newer therapies under active investigation such as olfactory cleft platelet–rich plasma injections, acupuncture, and stellate ganglion blocks come to fruition, it will be vital to ensure that physicians objectively collect and document OD. Furthermore, given the connection between olfaction (and possibly even predictive value) and cognition and pathological brain aging, it may be useful as a low-cost diagnostic measure for cognitive decline and frailty in older adults . A lack of proper reimbursement for olfactory testing makes these resource- and time-intensive assessments difficult for physicians to perform, especially in the setting of recent substantial Medicare payment cuts .…”

“…Furthermore, given the connection between olfaction (and possibly even predictive value) and cognition and pathological brain aging, 8 it may be useful as a low-cost diagnostic measure for cognitive decline and frailty in older adults. 9 A lack of proper reimbursement for olfactory testing makes these resource-and time-intensive assessments difficult for physicians to perform, especially in the setting of recent substantial Medicare payment cuts. 10 Adequate reimbursement for testing would lead to improved evidence-based interventions and reduce inequities in the diagnosis and treatment of OD (particularly if these ultimately become out-of-pocket expenses for patients).…”

Olfaction and Mobility in Older Adults

“…11 Recent findings suggest poor olfaction may have much broader implications for the health of older adults beyond its well-known connections to neurodegenerative diseases. [12][13][14][15][16] During the COVID-19 pandemic, olfactory dysfunction was quickly identified as one of the most common and differentiating symptoms of the SARS-CoV-2 infection and a post-COVID condition sequelae. 17 Such converging data make poor olfaction an emerging public health concern in older adults.…”