[Smell of fish slightly increases the heart rate and only one parameter of variability in adults]

Cardiac olfactory stimulus reactions could expand the range of objectifying test methods for testing olfactory function. In a pilot study, it was investigated whether and how pleasant and unpleasant odors change the heart rate (HR) and its variability.

32 healthy people with normal smell function inhaled nasally for seven minutes the smell of four Sniffin' Sticks (banana, fish, garlic and rose) alternating with blanks. At the same time, the ECG was recorded and offline the NN intervals (distance of the R-waves) and six parameters of the heart rate variability were determined and compared with the values of a blank irritation using generalized estimation equations (GEE). In addition, the values of the subjective assessment of intensity and hedonic valence of the four odors were correlated with the heart rate.

The unpleasant odor fish smell increased the heart rate slightly but significantly in the first stimulus minute. The fish smell increased a single heart rate variability parameter (LF/HF) during the continuous stimulation, too, and showed a significant moderate correlation between HR and the scaling of intensity and hedonics in the first stimulus minute. The pleasant and the garlic odors did not affect the analyzed cardiac parameters.

Olfactory evoked changes in HR should be further investigated as an indicator of the integrity of olfactory function. The most promising and time- and cost-effective is probably an 1-minute irritation with the unpleasant fishy smell from the identification set of the Sniffin' Sticks during the ECG recording.