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 odour. In experiment 1, High (n = 18), moderate (n = 23) and non-consumers (n = 21) of caffeine completed a threshold test for a coffee odour, followed by a recognition test for both a coffee and a neutral odour; finally a measure of caffeine craving. In experiment 2, (n=16 consumers/n=16 non-consumers) completed threshold tests for two odours: coffee; control (n-butanol), followed by a caffeine related Implicit Association Test. In exp 1, recognition to the coffee odour was faster for caffeine consumers versus non-consumers. We also found that high caffeine consumers had greater olfactory sensitivity for the coffee odour compared to the other groups, which was related to craving. In exp 2, again we found greater sensitivity for the coffee odour in consumers but no differences between groups for the control odour. Additionally, craving was greater in consumers who had just been exposed to the coffee odour. These findings provide evidence for the first time, that regular consumers of coffee have enhanced sensitivity to an odour associated to caffeine. They further suggest that drug associated odours could be a useful tool in furthering theory in drug dependence.