Olfactory Thresholds of the U.S. Population of Home-Dwelling Older Adults: Development and Validation of a Short, Reliable Measure

Abstract

Current methods of olfactory sensitivity testing are logistically challenging and therefore infeasible for use in in-home surveys and other field settings. We developed a fast, easy and reliable method of assessing olfactory thresholds, and used it in the first study of olfactory sensitivity in a nationally representative sample of U.S. home-dwelling older adults. We validated our method via computer simulation together with a model estimated from 590 normosmics. Simulated subjects were assigned n-butanol thresholds drawn from the estimated normosmic distribution and based on these and the model, we simulated administration of both the staircase and constant stimuli methods. Our results replicate both the correlation between the two methods and their reliability as previously reported by studies using human subjects. Further simulations evaluated the reliability of different constant stimuli protocols, varying both the range of dilutions and number of stimuli (6–16). Six appropriately chosen dilutions were sufficient for good reliability (0.67) in normosmic subjects. Finally, we applied our method to design a 5-minute, in-home assessment of older adults (National Social Life, Health and Aging Project, or NSHAP), which had comparable reliability (0.56), despite many subjects having estimated thresholds above the strongest dilution. Thus, testing with a fast, 6-item constant stimuli protocol is informative, and permits olfactory testing in previously inaccessible research settings.

Sleep and Olfaction among Older Adults

“…Actigraph estimates of sleep characteristics avoid potential biases of survey sleep questions and are practical to implement in the field [53]. Similarly, the OFFE includes a validated measure of odor identification [39] and a novel survey-modified measure of odor sensitivity [40], [54]. Although only a minority of NSHAP participants received both modularized measures, we did find several significant, and heretofore unobserved, associations.…”

“…Scores of 0-6 represent how many concentrations were correctly detected. This screening test is reliable and highly correlated (r = 0.92) with psychophysical olfactory sensitivity testing among older adults [40]. A detailed protocol of olfactory data collection, including interviewer training, has been described elsewhere [41].…”

Olfactory phenotypic expression unveils human aging

“…This represents the most important bias that is often ignored in olfactory psychophysiological testing. The reference material applied was that which is in widest use, n-butanol [ 8 , 9 , 14 ], and its dilutions (see Methods).…”

Relationship between odor intensity estimates and COVID-19 population prediction in a Swedish sample

“…However, the test-retest reliability of odor intensity measure, here estimated to .66, indicate that odor intensity function might not work as a reliable measure on the individual level. Indeed, other studies assessing test-retest of odor intensities have reached a near identical value (Kern et al, 2015). Hence, to achieve a high reliability at the individual level, a more general and advanced odor test than mere intensity ratings is probably needed to have the specificity needed.…”