Valid across-group comparisons with labeled scales: the gLMS versus magnitude matching.

Labeled scales are commonly used for across-group comparisons. The labels consist of adjective/adverb intensity descriptors (e.g., "very strong"). The relative distances among descriptors are essentially constant but the absolute perceived intensities they denote vary with the domain to which they are applied (e.g., a "very strong" rose odor is weaker than a "very strong" headache), as if descriptors were printed on an elastic ruler that compresses or expands to fit the domain of interest. Variation in individual experience also causes the elastic ruler to compress or expand. Taste varies genetically: supertasters perceive the most intense tastes; nontasters, the weakest; and medium tasters, intermediate tastes. Taste intensity descriptors on conventional-labeled scales denote different absolute perceived intensities to the three groups making comparisons across the groups invalid. Magnitude matching provides valid comparisons by asking subjects to express tastes relative to a standard not related to taste (e.g., supertasters match tastes to louder sounds than do nontasters). Borrowing the logic of magnitude matching, we constructed a labeled scale using descriptors unrelated to taste. We reasoned that expressing tastes on a scale labeled in terms of all sensory experience might work. We generalized an existing scale, the Labeled Magnitude Scale (LMS), by placing the label "strongest imaginable sensation of any kind" at the top. One hundred subjects rated tastes and tones using the generalized LMS (gLMS) and magnitude matching. The two methods produced similar results suggesting that the gLMS is valid for taste comparisons across nontasters, medium tasters, and supertasters.

Comparison of the Green scale versus magnitude estimation for taste perception.

The Green scale is a new psychophysical method that is simple for subjects to use, but its relation with magnitude estimation has yet to be fully characterized. In comparing the consistency between the Green scale and magnitude estimation, we found that the former seems to provide a psychological oral sensation measurement that is different from the latter method. A simple correction formula can be derived.

Taste performance in Sjogren's syndrome.

Sjogren's Syndrome (SS) patients have impaired salivary gland function and an elevated frequency of oral complaints. The taste complaints are thought to be due to sensory deficits that arise in the absence of sufficient saliva to maintain taste receptors. We assessed the subjective complaints, salivary production and taste functioning of SS patients and unaffected individuals. We found the expected decreased salivary gland function and increased frequency of taste complaints. Our taste assessment with weak stimuli confirmed and expanded the previous report of decreased taste threshold sensitivity in SS. However, perception of stronger taste stimuli was not impaired. In contrast with previous reports, patient judgments of intensity were not significantly reduced for any of the four taste qualities. Although the salivary gland function of all patients was markedly impaired relative to that of controls, patients lacking measurable salivary flow were no more likely than patients with residual function to exhibit subjective complaints or taste impairments. Our observations are inconsistent with a simple causal chain running from salivary gland dysfunction to sensory loss to taste complaints.

Touch and taste in the mouth: presence and character of sapid solutions.

Complex dynamic properties of a bolus in the mouth are specified by touch. Cooperation between touch and taste may help to specify the character of the bolus. The role of touch in specifying the presence of the oral bolus, in contrast to it's characteristics, remains a theoretical and experimental challenge.

Taste intensity performance in patients irradiated to the head and neck.

Decrements in taste-detection thresholds during radiotherapy and subsequent recovery in the months after therapy are well documented. However, few studies have explored suprathreshold taste intensity perception in radiation patients. This cross-sectional study compared taste function in 15 men postradiation with a group of 23 healthy, nonirradiated male volunteers. A direct-scaling procedure was used to assess taste intensity perception of the four basic taste qualities. Patients performed nearly as well as control subjects on objective measures of suprathreshold functioning. Postradiation intensity judgments of salty (sodium chloride), sweet (sucrose), and bitter (quinine sulfate) solutions were not significantly reduced. Subtle, age-related taste impairments were identified for sour perception (citric acid) postradiotherapy. Younger patients judged citric acid to be more intense than did age-appropriate control subjects, whereas older patients judged it to be less intense. Moreover, younger patients were likely to be midly dysgeusic, whereas older patients appeared to be hypogeusic for citric acid. This study provides evidence for near normal suprathreshold taste intensity perception in patients who have received head and neck irradiation.

Age, gender, medical treatment, and medication effects on smell identification.

Olfactory function diminishes with increasing age, which may impact on the safety and quality of life of older persons. This study examined the influence of age, gender, medical treatment, and medications on smell identification in a group of generally healthy individuals. Males (n = 221) and females (n = 166) between the ages of 19 and 95 years, from the oral physiology component of the Baltimore Longitudinal Study of Aging, were administered the University of Pennsylvania Smell Identification Test [UPSIT; (1)]. Older subjects had lower UPSIT scores, were more likely to be anosmic, and more often complained about their sense of smell and taste compared to younger subjects. Females had higher UPSIT scores compared to males. Although these age and gender effects are comparable to previous findings, performance among all subjects was superior to other studies; this is attributable, in part, to the overall healthy status of the population. Subjects being treated for medical problems and taking prescription medications had slightly lower UPSIT scores and more smell and taste complaints compared to other subjects, but these findings did not achieve statistical significance. Results suggest that age-related declines in olfaction occur as a part of the normal physiological aging process.

Taste and smell.

Olfaction declines dramatically with age. Taste is relatively robust. A variety of causes other than aging are known to produce declines in olfaction and to a lesser extent in taste. Many chemosensory deficits in the elderly cannot be attributed to age but rather to pathologic conditions. In addition to deficits, individuals may experience taste or smell phantoms. In many cases, losses and phantoms are untreatable but their effects on the elderly may be mitigated by appropriate coping skills.

Oral sensory changes in aging.

Perception of oral sensory intensity was assessed in healthy, community-dwelling men (n = 46) and women (n = 41) between 25 and 93 years of age. Cross-modal matches of distance to perceived intensity were obtained for five types of oral stimuli (sugar water, salt water, heated or chilled water, water thickened with methylcellulose, and local pressure on the dorsal tongue). Differences among stimulus types were observed for measures of response size (mean, median, maximum, and range of response distance and rate of increase with stimulus strength), but not measures of judgment quality, repeatability (ICC), and conformity to a linear rise with stimulus strength (r2). Age had no significant effect on any of the response measures for any stimulus type except pressure. All measures of response to lingual pressure except median size declined significantly with age. We conclude that (a) the various oral stimulus types elicit perceptions that differ in intensity but were judged with similar accuracy, and that (b) aging brings a specific decline in the perception of localized lingual pressure while both size and accuracy of intensity judgments are maintained for the other oral sensitivities tested.

Assessment of chemosensory functioning in aging. Subjective and objective procedures.

Assessments of human sensory and perceptual functioning are meaningfully classified as either subjective or objective. Both subjective and objective measures have been employed in studies of age-related changes in chemosensory functioning. Subjective and objective assessments proceed from different philosophic assumptions, provide different types of information, and play different roles in understanding age-related change. Subjective assessment exploits each person's unique access to the functioning of his or her own sensory apparatus. It assumes that subjects can and will give an accurate account of their sensory experience and is distinguished by the attempt to directly communicate private experience. Objective assessment strategies circumvent the practical and philosophical problems of verifying and communicating private experience. Objective measures assume that sensory function is reflected in the subject's performance of tasks that require perception of the relevant sensory information. Subjective measures are primarily descriptive. They can be used to characterize chemosensory experience and may reveal the fullness and drama of age differences. Objective measures, while they may fail to capture the richness of perceptual experience, are directly relevant to the investigation of the underlying mechanisms. Thus, subjective measures serve to direct attention to the issues and phenomena of perceptual change in aging whereas objective measures are most useful for specifying and evaluating candidate mechanisms by which these changes might be generated.

Olfactory detection and identification performance are dissociated in early Alzheimer's disease.

Ten carefully screened men with very mild symptoms of Alzheimer's disease (AD) and ten healthy controls of similar age were compared on multiple chemosensory tasks: odor detection and identification, and taste detection. The patients scored significantly worse than controls on identification of odors and of a subset of airborne stimuli providing trigeminal stimulation. In contrast, the patients' olfactory detection thresholds as well as taste detection thresholds were not impaired relative to those of controls. The patients' scores on neuropsychological tests and the results 18F-2 deoxy-D-glucose PET studies did not correlate with any of the chemosensory measures. The isolated odor identification deficit suggests that the initial chemosensory impairment in AD is central rather than peripheral.

Taste and salivary function.

Human taste perception was remarkably unimpaired in eight individuals with severe, chronic failure of all major and minor salivary gland function. Subjective reports of taste experience and objective measures of suprathreshold sensitivity were within normal limits for the overwhelming majority of these individuals. Impairments of threshold sensitivity for at least one quality was common, but normal thresholds for all four qualities were observed in one individual. These data demonstrated that the functional integrity of the taste system is not dependent upon the presence of normal saliva in the mouth. Thus, the suggestion that a salivary factor is responsible for the maintenance of taste receptor end organs can be rejected and attention directed toward other mechanisms, not dependent on saliva, that might account for the unusual resistance of these cells to environmental insult.

Taste intensity perception in aging.

Men (n = 91) and women (n = 79) between the ages of 23 and 88 years made cross-modal matches of distance to the perceived intensity of aqueous solutions representing the four basic taste qualities. Traditional analysis, which characterizes age-group performance in terms of the slope of a group's psychophysical function, yielded results consistent with previous findings in that some flattening of slope was observed in the oldest group. Analyses based on the slope of the functions generated by individual participants demonstrated significant regression on age for some qualities. None of these findings were observed in the analogous analysis of variance (ANOVA). Significant age-related changes in Intraclass Correlation Coefficient (ICC) were demonstrated by both ANOVA and regression analysis. The ICC reflects the consistency of an individual's discriminative response over repeated stimulus presentations. Its variation with age was dependent upon taste quality.

Xerostomia: evaluation of a symptom with increasing significance.

Xerostomia is the subjective sensation of oral dryness. Although it is most commonly associated with salivary gland dysfunction, it may also occur with normal gland activity. Xerostomia may be an early symptom of several morbid systemic conditions with important implications for the medical and dental management of patients. Oral dryness also has negative effects on an individual's emotional well-being and quality of life. The complaint of xerostomia necessitates a complete evaluation of a patient's general health, salivary gland function, and oral motor and sensory abilities. The salivary gland assessment includes symptom review, analysis of glandular secretions, scintiscanning, and minor labial gland biopsy. No single component is sufficient to adequately diagnose the presence, extent, or cause of salivary dysfunction. Treatment of a dry mouth, to date, is mainly palliative in nature, with the intent of preserving oral structures and functions. Better therapies are essential in the management of xerostomia, whatever the cause. The importance of xerostomia as a symptom is increasingly recognized in medicine and dentistry. The dentist is commonly the first health professional to hear this complaint and may be critical in directing a full and appropriate evaluation.

Taste thresholds: quality specific variation with human aging.

Detection thresholds for each of the four basic taste qualities were obtained from 81 adults between 23 and 88 years of age. Sodium chloride thresholds show a small but significant increase with age, confirming the only previous observations derived from procedures that control for age-related changes in response criterion and salivary sodium. Quinine sulfate thresholds display a similar but weaker relation to age. Sucrose and citric acid thresholds are not significantly related to age. Citric acid alone shows a sex effect. Detection thresholds for the four taste qualities undergo different changes with age.

Quantitative assessment of oral tactile sensitivity in pre-term and term neonates, and comparison with adults.

The tongues of 34 infants between 31 and 40 weeks estimated gestational age were stimulated with filament esthesiometers. Stereotyped ipsilateral movements of the tongue were elicited in all infants. An assessment of tactile sensitivity based on this reflex is minimally affected by infant activity state and habituation to repeated stimulation. Small pre-term infants (31 to 35 weeks gestation) and infants born near term (37 to 40 weeks gestation) were more sensitive to tactile stimulation than an intermediate group (35 to 37 weeks gestation). In infants followed longitudinally, a transient decrement in sensitivity occurred at two weeks postnatal age. The tactile sensitivity in 12 adults (as measured by their correct reports of stimulus location) was far greater than the sensitivity of the infants.