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Randomized Controlled Trial
. 2020 Dec;237(12):3511-3517.
doi: 10.1007/s00213-020-05695-6. Epub 2020 Oct 29.

The effects of caffeine on olfactory function and mood: an exploratory study

Lorenzo D Stafford  1 , Kaylee Orgill  2
Affiliations
Randomized Controlled Trial

The effects of caffeine on olfactory function and mood: an exploratory study

Lorenzo D Stafford et al. Psychopharmacology (Berl). 2020 Dec.

Abstract

Caffeine has been demonstrated to enhance olfactory function in rodents, but to date, the sparse research in humans has not shown any equivalent effects. However, due to the methodological nature of those human studies, a number of questions remain unanswered, which the present study aimed to investigate. Using a double-blind experimental design, participants (n = 40) completed baseline mood measures, standardised threshold and identification tests and were then randomly allocated to receive a capsule containing either 100 mg of caffeine or placebo, followed by the same olfactory tests and mood measures. Results revealed that despite a trend toward elevated arousal following caffeine for habitual caffeine consumers, there were no changes in odour function. In contrast, for non-caffeine consumers, caffeine acted to enhance odour (threshold) sensitivity but reduce odour identification. Overall, these findings demonstrate a complex profile of effects of caffeine on odour function and, given the evidence from the wider caffeine literature, it is proposed that the effects of caffeine might be limited to older populations.

Keywords: Adenosine; Coffee; Odour identification; Odour threshold; Smell; Tea.

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Conflict of interest statement

The authors declare that they have no conflicts of interest.

Figures

Fig. 1
Fig. 1
Mean odour threshold by condition (Caffeine/Placebo) and Group (Consumer/Non-consumer)
Fig. 2
Fig. 2
Mean odour identification by Condition (Caffeine/Placebo) and Group (Consumer/Non-consumer)
See this image and copyright information in PMC

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