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. 2020 Feb;13(1):52-57.
doi: 10.21053/ceo.2018.01424. Epub 2019 Mar 1.

Does Improved Attention Induced by Caffeine Intake Affect Olfactory Function?

Kyujin Han  1 , Jiyeon Lee  1 , Bo Yoon Choi  1 , Hamin Jeong  1 , Jae Hoon Cho  1 , Jin Kook Kim  1
Affiliations

Does Improved Attention Induced by Caffeine Intake Affect Olfactory Function?

Kyujin Han et al. Clin Exp Otorhinolaryngol. 2020 Feb.

Abstract

Objectives: Past several studies have proven that caffeine facilitates attentional enhancement by acting as an adenosine antagonist once it is absorbed by the body, resulting in improved psycho-behavioral function. Modern clinical olfactory function tests are usually assessed by psychophysical tests but due to a paucity of data, the influence of enhanced attention by caffeine on olfactory function still remains unclear. The objective of this study was to compare results of cognitive function (attention) and olfactory function before and after caffeine administration in order to analyze effects of caffeine on olfactory function in normosmic subjects.

Methods: This study enrolled 49 participants of Konkuk University Hospital with a mean age of 27.7 years who had patent olfactory clefts and no olfactory dysfunction from May 2015 to February 2016. Subjects were restrained from caffeine 10 hours before the test. On day 1, participant's subjective olfactory function was evaluated before and after uptake of either caffeinated or decaffeinated coffee using visual analog scale (VAS) score, minimum cross-sectional area (MCA) measured by acoustic rhinometry, and the Korean version of Sniffin' Stick II (KVSS II). Evaluation of participant's attentional degree was measured by d2 test. On day 2, the same procedure was carried out with counterpart substance. The type of coffee initially administrated was randomly selected.

Results: After administration, caffeinated coffee resulted in significant attentional enhancement than decaffeinated coffee. Results of d2 test showed statistically significant differences in the parameters of total number of errors and omission errors. In both the caffeinated and decaffeinated groups, the patients showed slight increase in VAS score and nasal cavity area; however, the difference was not statistically significant. Also, caffeinated coffee intake compared to decaffeinated coffee intake showed no significant relevance to olfactory function.

Conclusion: Caffeine may significantly improve attentional congnitive function, while not have acute effects on olfactory function.

Keywords: Attention; Caffeine; Smell.

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Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1.
Fig. 1.
Comparison of the difference between the mean visual analog scale (VAS) score and minimum cross-sectional area (MCA) before and after caffeinated or decaffeinated coffee intake. Results showed no significant increase of VAS score or MCA (P>0.05). Rt, right; Lt, left.
Fig. 2.
Fig. 2.
Comparison of Korean version of Sniffin’ Stick II score before and after caffeinated or decaffeinated coffee intake. Subjects showed no significant improvement of olfactory function in threshold, discrimination and identification scores (P>0.05). Lines for the 95% confidence interval are shown. OFT, olfactory function test.
Fig. 3.
Fig. 3.
Comparison of d2 test before and after caffeinated or decaffeinated coffee intake. Values are difference of mean±standard deviation. *P<0.05, caffeinated vs. decaffeinated. Lines for the 95% confidence interval are shown.
See this image and copyright information in PMC

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