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The Influence of Odorant Intensity on Odor Identification in Older Adults

Bailie, Jason M.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250010194

Abstract Details

2009, PhD, University of Cincinnati, Arts and Sciences : Psychology.
Although it is well established that olfactory functioning diminishes with normal aging, the basis for this effect is not well understood. Research investigating age-related hyposmia has typically found that measures of odor identification and odor threshold (the two most common psychophysical methods of olfactory assessment) are only moderately correlated. Though this finding provides evidence that the tests are assessing a common source of variance, it also suggests confounding factors are influencing performance on these tests and thereby obscuring the basis for age-related loss of olfactory abilities. The present study investigated the impact of three factors on the relationship between measures of odor identification and threshold in older adults: the poor reliability of threshold tests, the influence of cognitive deficits on olfactory performance, and the lack of standardization of the intensity of odor identification tests. The study attempted to control for the influence of poor odor threshold reliability through incorporation of a four-test composite threshold estimate. The influence of odor intensity was investigated by developing an odor identification test that employed multiple intensity levels. Finally, performance was assessed on a broad battery of neuropsychological measures to control for the effects of cognitive impairments. It was predicted that the relationship between odor threshold and identification would be substantially improved as a result of a more accurate threshold measurement. Specifically, a composite threshold would be a better predictor of odor identification than an estimate based on a single test. Further, it was hypothesized that in addition to odor sensitivity (threshold), both odor intensity and cognitive functioning would be significant predictors of identification ability in an older adult sample. This would not be the case for a sample of young adults who were included as a control group. The study included 45 older adults and 40 young adults. The results of a generalized linear model revealed that odor threshold level, odor intensity, and cognitive functioning were all significant predictors of odor identification ability. Further, a predicted interaction was observed between threshold and odor intensity in which the ability of threshold to predict odor identification was strongest for low intensity odors. However, despite efforts to control confounding sources of variance, threshold at best accounted for only 27% of the variance in odor identification performance. The results suggest that diminished olfactory sensitivity is just one factor that explains older adults’ performance on odor identification tests. This study suggests their performance is also impacted by the intensity of the odorants used in the identification test, an effect that needs to be taken into account when odor identification tests are employed to characterize age-related hyposmia or when performance on such a test is compared to other measures of olfaction. This study also brings to focus some methodological issues that need to be addressed in future research on age-related hyposmia, especially with regard to the use of computer technology in olfactory assessment.
Robert Frank, PhD (Committee Chair)
Paula Shear, PhD (Committee Member)
Steven Howe, PhD (Committee Member)
66 p.
Behaviorial Sciences; Gerontology; Psychology
Olfaction; Hyposmia; Older Adults; Aging; Odor Identification; Odor Intensity

Recommended Citations

Citations

  • Bailie, J. M. (2009). The Influence of Odorant Intensity on Odor Identification in Older Adults [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250010194

    APA Style (7th edition)

  • Bailie, Jason. The Influence of Odorant Intensity on Odor Identification in Older Adults. 2009. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250010194.

    MLA Style (8th edition)

  • Bailie, Jason. "The Influence of Odorant Intensity on Odor Identification in Older Adults." Doctoral dissertation, University of Cincinnati, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250010194

    Chicago Manual of Style (17th edition)

ucin1250010194
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© 2009, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.