Faster olfactory adaptation in patients with olfactory deficits: an analysis of results from odor threshold testing.

BACKGROUND

Patients with olfactory deficits often report rapid and lasting olfactory adaptation compared to the time when they had normal olfactory function. However, this phenomenon receives little scientific attention. This retrospective study aimed to compare the patterns of olfactory adaptation in normosmic controls and patients with olfactory impairment by analyzing the trajectory of turning points in odor threshold tests based on the staircase technique.

METHODS

4120 subjects (1684 hyposmia, 1742 anosmia and 694 normosmic controls) were included in this study. Their odor threshold, odor discrimination and odor identification ability were assessed using the Sniffin’ Sticks. We analyzed the trajectory of turning points in the odor threshold test.

RESULTS

Current results suggested that patients with hyposmia needed significantly more trials to reach the final threshold scores than controls and anosmic group, and controls needed more trials than anosmic group. The difference between the first turning point and final threshold scores in the anosmic group was significantly larger than in the hyposmia group and in controls.

CONCLUSION

People with poor olfaction seem to adapt faster to olfactory stimuli. The trajectory of turning points in odor threshold test may serve as an indicator of olfactory adaptation and function of olfactory receptors. Olfactory adaptation may provide a new tool in the assessment of subtle olfactory loss.