Chemical Senses Advance Access originally published online on August 30, 2007
Chemical Senses 2008 33(1):17-21; doi:10.1093/chemse/bjm058
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Different Odor Tests Contribute Differently to the Evaluation of Olfactory Loss
1 Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Johann Wolfgang Goethe-University, Theodor Stern Kai 7, D-60590 Frankfurt am Main, Germany 2 Department of Neurology, University of Dresden Medical School, Fetscherstrasse 74, D-01307 Dresden, Germany 3 Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstrasse 74, D-01307 Dresden, Germany
Correspondence to be sent to: Thomas Hummel, Smell and Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School ("Technische Universität Dresden"), Fetscherstrasse 74, 01307 Dresden, Germany. e-mail: thummel{at}mail.zih.tu-dresden.de
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Abstract |
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In a clinical context, the importance of the sense of smell has increasingly been recognized, for example, in terms of the evaluation of neurodegenerative disorders. In this study, 2 strategies of olfactory testing, a simple one and a more complex one, were compared with respect to their suitability to assess olfactory dysfunction. Odor threshold (T), discrimination (D), and identification (I) were assessed in a control sample of 916 males and 1160 females, aged 6–90 years, and in 81 men and 21 women, aged 38–80 years, suffering from idiopathic Parkinson's disease (IPD). Sums of the 3 subtest results T, D, and I yielded threshold discrimination identification (TDI) scores reflecting olfactory function. Sensitivity of any of the 3 subtests to confirm the diagnosis established by the composite TDI score was assessed separately for each test. Principal component analyses were applied to determine any common source of variance among the 3 specific subtests. Sensitivities of the subtests to provide the diagnosis established by the composite TDI score were 64% (T), 56% (D), and 47% (I), respectively. In IPD patients, each of the subtests provided the correct diagnosis (sensitivity >90%), as olfaction was impaired in 99% of the patient group. Two principal components emerged in both controls and IPD patients, with eigenvalues >0.5. The first component received high loadings from all factors. The second component received high loadings from odor threshold, whereas loadings from odor discrimination and identification were much smaller. In conclusion, combined testing of several components of olfaction, especially including assessment of thresholds, provides the most significant approach to the diagnosis of smell loss.
Key words: olfaction, psychophysics, smell
Accepted 3 August 2007