Higher Olfactory Sensitivity to Coffee Odour in Habitual Caffeine Users

The present two studies aimed to look at alternative methods of assaying the changes underpinning drug consumption and dependence. Here, we focus on whether olfactory differences exist in habitual consumers in the form of recognition and sensitivity tasks to a caffeine-related odor. In Experiment 1, high (n = 18), moderate (n = 23), and non-consumers (n = 21) of caffeine completed a threshold test for a coffee odor, followed by a recognition test for both a coffee and a neutral odor and, finally, a measure of caffeine craving. In Experiment 2, 16 consumers and 16 non-consumers completed threshold tests for two odors, coffee and control (n-butanol), followed by a caffeine-related implicit association test. In Experiment 1, recognition of the coffee odor was faster for caffeine consumers versus non-consumers. We also found that high-caffeine consumers had greater olfactory sensitivity for the coffee odor compared to the other groups, which was related to craving. In Experiment 2, we again found greater sensitivity for the coffee odor in consumers but no differences between groups for the control odor. Additionally, craving was greater in consumers who had just been exposed to the coffee odor. These findings provide evidence for the first time that regular consumers of coffee have enhanced sensitivity to an odor associated with caffeine. They further suggest that drug-associated odors could be a useful tool in furthering theory in drug dependence.