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.