Background: Cross-modal chemosensory dysfunction between olfaction and gustation is not well known.
Methodology: 180 participants were classified into three groups (60 with olfactory dysfunction, 60 with gustatory dysfunction and 60 healthy controls without chemosensory dysfunction). Olfactory functions were obtained with Sniffin Sticks; gustatory function was measured by suprathreshold gustatory stimuli (taste sprays) and a quasi-threshold measure of taste function (taste strips) for five taste qualities (sweet, salty, sour, bitter and umami). Electric taste threshold was measured using electrogustometry (EGM). In addition, group differences in dietary behaviors were investigated with a specifically designed questionnaire.
Results: Patients with olfactory dysfunction had increased electric taste thresholds and decreased scores for the umami taste strip test as compared to healthy controls. Overall there was no major difference between patients with chemosensory dysfunction and healthy controls regarding dietary behaviors, although some patients certainly exhibited dietary problems. Importantly, patients with taste loss, but not patients with smell loss, exhibited a higher degree of depression than controls.
Conclusion: Patients with olfactory dysfunction showed decreased taste sensitivity which suggested an interaction between the chemical senses taste, trigeminal function, and olfaction. This provides the basis for including both smell and taste psychophysical assessment in clinical practices. In addition, patients with taste loss appeared to suffer most from chemosensory dysfunction.