1. Introduction
Loss of chemosensory function is associated with various conditions, such as natural aging, underlying chronic medical diseases, and neurocognitive disorders.1 It has been reported that 10.6% of American adults have reported an olfactory dysfunction within the past year, and 23% have had a lifetime of olfactory dysfunction.2,3 Compared to olfactory dysfunction, the prevalence of gustatory dysfunction is relatively low. Self-reported gustatory dysfunction in the past year has been reported to occur in only 5.3% of American adults, with a lifetime loss of around 18.7%.4
Self-reports tend to underestimate the actual prevalence of chemosensory dysfunction.3,5 It has been reported that the vast majority of patients complaining of gustatory dysfunction have no deficit in the gustatory function test, and the sensitivity of the questionnaire responses in detecting whole-mouth test-based gustatory dysfunction was less than 0.76.6,7 Furthermore, data regarding the prevalence of gustatory dysfunction show great dissimilarities between studies, the reported rates of generalized ageusia range from 0.84 to below 4% in patients complaining of gustatory dysfunction and up to almost 20% in the healthy population.8-11 These heterogeneous reports may be due to the lack of standardized gustatory function tests and the substantial effort and expense of preparing the different concentrations of taste stimuli. These limit the clinical application of the test-based gustatory function test and interfere with the early and proper diagnosis of gustatory dysfunction.
It has been reported that gustatory and olfactory functions are intermingled and affect each other. A patient’s olfactory function somehow alters the results of their gustatory function test and perhaps reflects confusion between loss of taste and decreased flavor perception secondary to loss of smell.7 To increase the efficiency and accuracy of diagnosing gustatory dysfunction, understanding the clinical characteristics, other than the subjective recognition of the symptoms associated with the objectively diagnosed gustatory is necessary.12
This study sought to identify the clinical characteristics associated with objective gustatory dysfunction, and suggest the meaningful factors clinicians should recognize in diagnosing and managing patients who are potential candidates for a gustatory function test.