Does Ability to Identify Odours Differ Among Clinical Subtypes of Parkinson’s Disease?

Abstract

We read with great interest the article by Ozcan et al. (1) The general findings are correct and overlap with the previous studies. However, we would like to discuss some issues within the study. First, this study uses the University of Pennsylvania Smell Identification Test-40 (UPSIT-40) to test olfactory function. This test may not be proper for Turkish patients because the UPSIT-40 has been created for American subjects. It contains some odors which are not familiar to Turkish people (dill pickle, wintergreen, licorice, whiskey, lime, pineapple, skunk, chili etc.). Though culture-specific tests have been developed into European, Brazilian, Chinese and Arabic versions, no applicable version for Turkey exist yet. Yucepur et al. concluded in their study that UPSIT is insufficient to evaluate olfactory functions in Turkish population. (2) To compensate for this deficiency, Dr. Tekeli and Dr. Doty have developed a Turkish version of UPSIT to be released by this year. Secondly, the smoking habits of the patients should be questioned in the study methodology. In a recent study Schriever et al. showed that olfactory bulb volumes were smaller in smokers than in non-smokers, indicating that smoking had a negative effect on the olfactory system (3) Lastly, the number of the patients in the subgroups is too small to make generalizations, and the authors of the paper express this same thought in the discussion section.