Influence of aging on electrogustometry thresholds

The role of the soft palate dose regarding normal tissue toxicities in older adults with head and neck cancer undergoing definitive radiotherapy

PURPOSE

The number of older adults with head and neck squamous cell carcinoma (HNSCC) is continuously increasing. Older HNSCC patients may be more vulnerable to radiotherapy-related toxicities, so that extrapolation of available normal tissue complication probability (NTCP) models to this population may not be appropriate. Hence, we aimed to investigate the correlation between organ at risk (OAR) doses and chronic toxicities in older patients with HNSCC undergoing definitive radiotherapy.

METHODS

Patients treated with definitive radiotherapy, either alone or with concomitant systemic treatment, between 2009 and 2019 in a large tertiary cancer center were eligible for this analysis. OARs were contoured based on international consensus guidelines, and EQD2 doses using α/ß values of 3 Gy for late effects were calculated based on the radiation treatment plans. Treatment-related toxicities were graded according to Common Terminology Criteria for Adverse Events version 5.0. Logistic regression analyses were carried out, and NTCP models were developed and internally validated using the bootstrapping method.

RESULTS

A total of 180 patients with a median age of 73 years fulfilled the inclusion criteria and were analyzed. Seventy-three patients developed chronic moderate xerostomia (grade 2), 34 moderate dysgeusia (grade 2), and 59 moderate-to-severe (grade 2-3) dysphagia after definitive radiotherapy. The soft palate dose was significantly associated with all analyzed toxicities (xerostomia: OR = 1.028, dysgeusia: OR = 1.022, dysphagia: OR = 1.027) in the multivariable regression. The superior pharyngeal constrictor muscle was also significantly related to chronic dysphagia (OR = 1.030). Consecutively developed and internally validated NTCP models were predictive for the analyzed toxicities (optimism-corrected AUCs after bootstrapping: AUCxerostomia=0.64, AUCdysgeusia=0.60, AUCdysphagia=0.64).

CONCLUSIONS

Our data suggest that the dose to the soft palate is associated with chronic moderate xerostomia, moderate dysgeusia and moderate-to-severe dysphagia in older HNSCC patients undergoing definitive radiotherapy. If validated in external studies, efforts should be undertaken to reduce the soft palate dose in these patients.

Does presbygeusia really exist? An updated narrative review

This review critically assessed the existence of presbygeusia, i.e., the impairment in taste perception occurring in the elderly, as a natural part of the aging process and its potential clinical implications. Several factors might contribute to age-related taste alterations (TAs), including structural changes in taste buds, alterations in saliva composition, central nervous system changes, and oral microbiota dysbiosis. A comprehensive literature review was conducted to disentangle the effects of age from those of the several age-related diseases or conditions promoting TAs. Most of the included studies reported TAs in healthy elderly people, suggesting that presbygeusia is a relatively frequent condition associated with age-related changes in the absence of pathological conditions. However, the impact of TAs on dietary preferences and food choices among the elderly seems to be less relevant when compared to other factors, such as cultural, psychological, and social influences. In conclusion, presbygeusia exists even in the absence of comorbidities or drug side effects, but its impact on dietary choices in the elderly is likely modest.

Visualization of the relationship between electrogustometry and whole mouth test using multidimensional scaling

Interpreting the relationship between different taste function tests of different stimuli, such as chemical and electrical stimulation, is still poorly understood. This study aims to analyze visually as well as quantitatively how to interpret the relationship of results between taste function tests using different stimuli. Patients who underwent the whole mouth test and Electrogustometry (EGM) at a tertiary medical center between August 2018 and December 2018 were reviewed retrospectively with electronic medical records. Of the 110 patients, a total of 86 adults who self-reported that their taste function was normal through a questionnaire were enrolled. EGM measured the thresholds of the chorda tympani (CT) and glossopharyngeal nerve (GL) area of the tongue. The whole mouth test measured detection and recognition thresholds for sweet, salty, bitter, sour, and umami taste. Statistical analyses of Pearson's, Spearman's rank and polyserial correlation and multidimensional scaling (MDS) was performed. The EGM threshold for the average value of both CT regions and the recognition threshold of the whole mouth test were significantly correlated in sweet, salty, bitter, and sour taste (r = 0.244-0.398, P < 0.05), and the detection threshold was correlated only significant in sweet (r = 0.360, P = 0.007). In the MDS analysis results, the three-dimensional (D) solution was chosen over the 2-D solution because of the lower stress. Detection-, recognition threshold of whole mouth test and EGM thresholds of CT and GL area, those were standardized by Z-score, formed well-distinguished sections in the MDS analyses. The EGM threshold of the CT area was closer to the detection and recognition thresholds than the EGM threshold of the GL area. In general, the EGM threshold was closer to the recognition threshold than the detection threshold for each taste. Overall, visualization of the relationship of whole mouth test and EGM by MDS was in good agreement with quantitative analysis. EGM and whole mouth test seem to reflect different aspects of taste. However, when interpreting the EGM results, the EGM threshold of the CT area will show more similarity to the recognition threshold than the detection threshold for the whole mouth test.

The effect of mucosal dryness on the electrogustometric threshold

Electrogustometry (EGM) is one of the most useful diagnostic tools widely used to evaluate the taste function by measuring the perception threshold to electrogustatory stimuli on the tongue. However, the effects of oral environments on electrogustometric threshold (EGMT) remain to be established despite its simple applicability. Thus, this study aims to determine the effect of mucosal dryness on EGMT in 68 healthy subjects. The experiment was conducted in two different conditions. First, the baseline EGMT was measured when the dryness of the tongue surface was normal. Second, the EGMT was remeasured after the tongue was intentionally desiccated. The current study showed that the mean of the EGMT was significantly increased when the tongue was desiccated, possibly indicating the reduced sensitivity to electrogustatory stimuli. Such an alteration may be related to the disturbed EGM electrical circuit through the dried mucosa with enhanced impedance. Thus, these findings suggested that mucosal dryness should be considered for better evaluation of gustatory function using EGM.

Assessment of Taste Function

Taste disorders, impacting well-being and physical health, can be caused by many etiologies including the use of medication. Recently, taste disturbance is also considered as one of the predominant symptoms of COVID-19 although its pathogenesis requires further research. Localized taste disorders may be overlooked considering that whole-mouth taste perception is insured through several mechanisms. Individuals often fail to discern taste from flavor, and interviews/surveys are insufficient to properly assess taste function. Hence, various taste assessment methods have been developed. Among them, psychophysical methods are most widely applied in a clinical context. Less-biased electrophysiological, imaging, or morphological methods are used to a much lesser degree. Overall, more research is needed in the field of taste.

Electrogustometry: Normative data for stimulus duration, tongue site and age decline

OBJECTIVES

Our primary goal was to evaluate the effect of stimulus duration on electrogustometry (EGM) thresholds. Additionally, we sought to evaluate any sex-related influences and compare the above results to those of taste strips.

DESIGN

Electrogustometry thresholds of various stimulus durations (0.5, 1.0, 1.5 and 2.0 seconds) were measured in 212 non-smokers (age range: 10-80 years, divided into eight age-groups) without self-reported gustatory impairment. Furthermore, taste strips chemogustometry measurements in 132 participants were performed.

SETTING

Tertiary referral medical centre.

PARTICIPANTS

212 non-smokers, divided into eight age-groups participated in the study.

MAIN OUTCOME MEASURES

Electrogustometry thresholds and taste strips, duration of EGM stimuli.

RESULTS

Electrogustometry thresholds increased progressively with age and with stimulus duration from 0.5 to 2 seconds. This pattern was consistent in all six anatomic areas, irrespective of sex. In contrast, when using chemogustometry, no age- or sex-related differences were observed.

CONCLUSIONS

Electrogustometry-threshold values increase progressively with age and with stimulus duration. Therefore, we recommend documenting stimulus duration in the future EGM recordings as it may significantly affect EGM amplitude threshold values.

Mechanical tongue cleaning is a worthwhile procedure to improve the taste sensation

BACKGROUND

There are still only a few therapeutic strategies to improve taste sensation, which is part of oral health and quality of life.

OBJECTIVE

Therefore, here we aimed to investigate gustatory functions of healthy subjects performing mechanical tongue cleaning (MTC), an easy-to-perform oral hygiene procedure, to demonstrate taste changes and to describe possible negative side effects.

METHODS

Prior to and 14 days following MTC with an Orabrush^® , the following tests were conducted in 65 healthy participants including both non-smokers (n = 50, 76.9%) and smokers (n = 15, 23.1%): 'taste strips' test, the Winkel Tongue Coating Index (WTCI), and subjective self-assessment.

RESULTS

Among non-smokers, subjective self-assessments of gustatory function (P < .01), halitosis (P = .03) and tongue coating (P < .01) improved after 14 days of MTC; furthermore, they exhibited higher total taste (P < .01) and lower WTCI (P < .01) values. Their age and sex did not correlate with the differences between the pre- and post-MTC WTCI scores; however, differences between pre- and post-MTC total taste values were correlated with age. The total taste value improvements were greater in non-smokers aged 45-91 years than in those aged 20-44 years (P = .01). In smokers, total taste values (P < .01), as well as sweet (P = .03) and sour (P = .04) taste values, were significantly improved after 14 days of MTC.

CONCLUSION

Fourteen days of MTC using an Orabrush^® can improve gustatory functions in non-smokers and smokers. Therefore, MTC might be a useful, costless and easy option to improve taste and should be considered as a part of the daily oral care.

Relationships between subjective taste sensations and electrogustometry findings in patients with taste disorders

This study aimed to examine the relationships between subjective taste sensations and electrogustometry (EGM) findings in patients with taste disturbances according to the presence of burning mouth (BM) symptoms. Forty-six patients were included and asked to complete a questionnaire that contained questions on subjective taste sensations for the four basic taste qualities and the pattern of taste disorders such as ageusia, hypogeusia and dysgeusia. EGM was performed to measure detection thresholds. To examine the influence of BM symptoms, patients were divided into two groups: patients with and without BM symptoms. The patients consisted of 11 men and 35 women. The group without BM symptoms (n=26) had significantly lower degrees of subjective taste sensations for all taste qualities and higher correlation levels between subjective taste sensations and EGM thresholds than the group with BM symptoms (n=20). The patterns of taste disorders also showed more significant associations with the levels of subjective taste sensations in the patients without BM symptoms compared with those with BM symptoms. In conclusion, patients with taste disorders without BM symptoms had more severe taste disturbances than those with BM symptoms. The pathophysiology of taste disturbances differs according to the presence or absence of BM symptoms.

Psychophysical testing of smell and taste function

The senses of smell and taste are largely underappreciated by laypersons and medical professionals alike. Unlike vision, hearing, balance, and touch, they are rarely evaluated quantitatively in the clinic, even though hundreds of thousands of persons seek medical help annually for disorders of these senses. Chemosensory disorders impact quality of life, including the flavor of foods and beverages, and compromise the ability to detect such environmental hazards as fires, leaking natural gas, and spoiled foodstuffs. Moreover, olfactory dysfunction can be a harbinger for Alzheimer's and other neurodegenerative diseases, and is known to triple the likelihood of mortality in older persons over the course of 4 or 5 years. Without accurate testing, one cannot establish the veracity of a patient's complaint, the probability of malingering, the impact of treatments, and whether the degree of dysfunction is normal relative to a patient's age and sex. This chapter provides basic information as to how to measure both the senses of smell and taste, as well as normative data for several clinical smell and taste tests.

Measurement of chemosensory function

Although hundreds of thousands of patients seek medical help annually for disorders of taste and smell, relatively few medical practitioners quantitatively test their patients' chemosensory function, taking their complaints at face value. This is clearly not the approach paid to patients complaining of visual, hearing, or balance problems. Accurate chemosensory testing is essential to establish the nature, degree, and veracity of a patient's complaint, as well as to aid in counseling and in monitoring the effectiveness of treatment strategies and decisions. In many cases, patients perseverate on chemosensory loss that objective assessment demonstrates has resolved. In other cases, patients are malingering. Olfactory testing is critical for not only establishing the validity and degree of the chemosensory dysfunction, but for helping patients place their dysfunction into perspective relative to the function of their peer group. It is well established, for example, that olfactory dysfunction is the rule, rather than the exception, in members of the older population. Moreover, it is now apparent that such dysfunction can be an early sign of neurodegenerative diseases such as Alzheimer's and Parkinson's. Importantly, older anosmics are three times more likely to die over the course of an ensuring five-year period than their normosmic peers, a situation that may be averted in some cases by appropriate nutritional and safety counseling. This review provides the clinician, as well as the academic and industrial researcher, with an overview of the available means for accurately assessing smell and taste function, including up-to-date information and normative data for advances in this field.

Change of somatosensory function of the tongue caused by chorda tympani nerve disorder after stapes surgery

OBJECTIVES

Patients after middle ear surgery often complain of taste disturbance and a lingual numbness. The purpose of this study was to objectively assess changes in the somatosensation of the tongue and taste function in patients undergoing stapes surgery.

STUDY DESIGN

Prospective study.

METHODS

Symptoms of taste disturbance and tongue numbness after surgery were investigated before and after surgery in 41 patients (13 males, 28 females; mean age 41.8 years) who underwent stapes surgery. Twenty-eight patients (9 males, 19 females; mean age 43.1 years) underwent sensory and taste function tests before and after surgery. Sensory function of the tongue was measured at the operated side and the nonoperated side using the 2-point discrimination test and an electrostimulator test. Taste function was assessed with electrogustometry (EGM).

RESULTS

The chorda tympani nerve (CTN) was gently touched or stretched in all patients. Postoperative thresholds on the operated side were significantly higher than preoperative thresholds in all tests in the patients who underwent all three kinds of tests. Tongue somatosensory symptoms improved significantly earlier than the taste disturbance postoperatively, and the sensory thresholds returned to the baseline along with recovery of symptoms.

CONCLUSION

These findings suggest that dysfunction of the CTN occurred following surgery even when the CTN was preserved, and that the sensory nerve threshold of the tongue correlated with the symptom of lingual numbness. The CTN may play a role not only in taste function but also in the somatosensory function of the tongue.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:701-706, 2018.

Longitudinal study of factors affecting taste sense decline in old-old individuals

The sense of taste plays a pivotal role for personal assessment of the nutritional value, safety and quality of foods. Although it is commonly recognised that taste sensitivity decreases with age, alterations in that sensitivity over time in an old-old population have not been previously reported. Furthermore, no known studies utilised comprehensive variables regarding taste changes and related factors for assessments. Here, we report novel findings from a 3-year longitudinal study model aimed to elucidate taste sensitivity decline and its related factors in old-old individuals. We utilised 621 subjects aged 79-81 years who participated in the Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians Study for baseline assessments performed in 2011 and 2012, and then conducted follow-up assessments 3 years later in 328 of those. Assessment of general health, an oral examination and determination of taste sensitivity were performed for each. We also evaluated cognitive function using Montreal Cognitive Assessment findings, then excluded from analysis those with a score lower than 20 in order to secure the validity and reliability of the subjects' answers. Contributing variables were selected using univariate analysis, then analysed with multivariate logistic regression analysis. We found that males showed significantly greater declines in taste sensitivity for sweet and sour tastes than females. Additionally, subjects with lower cognitive scores showed a significantly greater taste decrease for salty in multivariate analysis. In conclusion, our longitudinal study revealed that gender and cognitive status are major factors affecting taste sensitivity in geriatric individuals.

Factors related to taste sensitivity in elderly: cross-sectional findings from SONIC study

The sense of taste is important, as it allows for assessment of nutritional value, as well as safety and quality of foods, with several factors suggested to be associated with taste sensitivity. However, comprehensive variables regarding taste and related factors have not been utilised in previous studies for assessments of sensitivity. In the present study, we performed cross-sectional analyses of taste sensitivity and related factors in geriatric individuals who participated in the SONIC Study. We analysed 2 groups divided by age, 69-71 years (young-old, n = 687) and 79-81 years (old-old, n = 621), and performed a general health assessment, an oral examination and determination of taste sensitivity. Contributing variables were selected by univariate analysis and then subjected to multivariate logistic regression analysis. In both groups, females showed significantly better sensitivity for bitter and sour tastes. Additionally, higher cognitive scores for subjects with a fine taste for salty were commonly seen in both groups, while smoking, drinking, hypertension, number of teeth, stimulated salivary flow salt intake and years of education were also shown to be associated with taste sensitivity. We found gender and cognitive status to be major factors affecting taste sensitivity in geriatric individuals.

Ageing and taste

Taste perception has been studied frequently in young and older adult groups. This paper systematically reviews these studies to determine the effect of ageing on taste perception and establish the reported extent of sensory decline. Five databases were searched from 1900 to April 2012. Articles relating to healthy ageing in human subjects were included, reviewed and rated (Downs and Black scoring system). Sixty-nine studies investigated the effect of ageing on taste perception; forty examined detection thresholds of which twenty-three provided sufficient data for meta-analysis, eighteen reported identification thresholds and twenty-five considered supra-threshold intensity perception. Researchers investigating detection thresholds considered between one and thirteen taste compounds per paper. Overall, the consensus was that taste detection thresholds increased with age (Hedges’ g = 0·91, P < 0·001), across all taste modalities. Identification thresholds were reported to be higher for older adults in seventeen out of eighteen studies. Sixteen out of twenty-five studies reported perception of taste intensity at supra-threshold levels to be significantly lower for older adults. However, six out of nine studies concerning sucrose found perceived intensity of sweet taste not to diminish with age. The findings of this systematic review suggest taste perception declines during the healthy ageing process, although the extent of decline varies between studies. Overall, the studies reviewed had low Downs and Black scores (mean 16 (SD 2)) highlighting the need for more robust large scale and longitudinal studies monitoring the impact of ageing on the sensory system, and how this influences the perception of foods and beverages.

The influence of sour taste on Dysphagia in brain injury: blind study

Objective

To verify the influence of sour taste on swallowing and the presence of reflex cough when sour material was swallowed in patients with dysphagia secondary to brain injury.

Method

Fifty dysphagic brain injury patients who underwent videofluoroscopic swallowing study (VFSS) were recruited. The patients who had shown severe aspiration at 2 ml of liquid were excluded. The dysphagic patients were given 5 ml each of a sour tasting liquid (SOUR) and a thin liquid barium (LIQUID) in random order. An expert analyzed the result of VFSS by reviewing recorded videotapes. Analysis components consisted of the Penetration-Aspiration-Scale (PAS) score, oral transit time (OTT), pharyngeal transit time (PTT), pharyngeal delay time (PDT) and the reflex cough presence.

Results

The PAS score for SOUR was significantly lower than the one for LIQUID (p=0.03). The mean OTT for SOUR was significantly shortened compared to that for LIQUID (p=0.03). The mean PTT and PDT were also shortened in SOUR, although the differences were not statistically significant (p=0.26 and p=0.32, respectively). There was no significant difference between SOUR and LIQUID regarding the presence of reflex cough (p=1.00).

Conclusion

The sour taste could enhance sensorimotor feedback in the oropharynx, thus lowering the chances of penetration-aspiration caused by shortening of the oropharyngeal passage times. There was no significant difference in the presence of reflex cough produced between LIQUID and SOUR.

Effect of lingual nerve block on burning mouth syndrome (stomatodynia): a randomized crossover trial

Burning mouth syndrome (stomatodynia) is associated with changes of a neuropathic nature the main location of which, peripheral or central, remains unknown. A randomised, double-blind crossover design was used to investigate the effects of lingual nerve block on spontaneous burning pain and a possible correlation with the effects of topical clonazepam, the patient's response to a psychological questionnaire, and the taste and heat thresholds. The spontaneous burning was measured with a visual analogue scale (VAS) just before and 15 min after injection. The decreases in VAS score after lidocaine or saline injection were not significantly different (2.7+/-3.9 and 2.0+/-2.6, respectively; n=20). However, two groups of patients could be identified: in a "peripheral group" (n=10) the VAS decrease due to lingual nerve injection was 4.3+/-3.1cm after lidocaine and 0.9+/-0.3 cm after saline (p=0.02). In a "central group" (n=7), there were an increase in pain intensity score (-0.8+/-2.6 cm) after lidocaine and a decrease (1.5+/-3.0 cm) after saline (p=0.15). An increase in the hospital anxiety and depression (HAD) score and a decreased taste sensitivity and heat pain threshold of painful oral area were seen in patients compared with age-and-sex-matched controls (p<0.05). Topical clonazepam treatment tended to be more effective (p=0.07) and HAD score lower (p<0.03) in the peripheral than in the central group. These results suggest that the neuropathic disorder associated with stomatodynia may be predominantly peripheral, central or mixed depending on the individual. Topical application of clonazepam and HAD may serve as indicators of which mechanism is dominating.

Evaluation of young smokers and non-smokers with Electrogustometry and Contact Endoscopy

Background

Smoking is the cause of inducing changes in taste functionality under conditions of chronic exposure. The objective of this study was to evaluate taste sensitivity in young smokers and non-smokers and identify any differences in the shape, density and vascularisation of the fungiform papillae (fPap) of their tongue.

Methods

Sixty-two male subjects who served in the Greek military forces were randomly chosen for this study. Thirty-four were non-smokers and 28 smokers. Smokers were chosen on the basis of their habit to hold the cigarette at the centre of their lips. Taste thresholds were measured with Electrogustometry (EGM). The morphology and density of the fungiform papillae (fPap) at the tip of the tongue were examined with Contact Endoscopy (CE).

Results

There was found statistically important difference (p < 0.05) between the taste thresholds of the two groups although not all smokers presented with elevated taste thresholds: Six of them (21%) had taste thresholds similar to those of non-smokers. Differences concerning the shape and the vessels of the fungiform papillae between the groups were also detected. Fewer and flatter fPap were found in 22 smokers (79%).

Conclusion

The majority of smokers shown elevated taste thresholds in comparison to non-smokers. Smoking is an important factor which can lead to decreased taste sensitivity. The combination of methods, such as EGM and CE, can provide useful information about the vascularisation of taste buds and their functional ability.

Normative values for the assessment of gustatory function using liquid tastants

CONCLUSION

The present study introduces normative data for the 'three-drop test' of gustatory function.

OBJECTIVES

Although in some instances liquid tastants appear to be preferable for the measurement of taste function, no such test has been established for the routine clinical testing. The aim of the present study was to provide normative data for a test system based on administration of taste solutions.

SUBJECTS AND METHODS

The investigation involved 230 participants (104 female, 126 male, mean age 39 years, age range 14-79 years). After establishing the concentration range of the taste solutions, recognition thresholds were obtained for the four basic tastes using a three-alternative forced choice paradigm (three-drop test).

RESULTS

The study confirmed previous observations on effects of age and sex on gustatory function, with younger subjects being more sensitive than older ones, and women being more sensitive than men.

Dietary zinc intake and sex differences in taste acuity in healthy young adults

BACKGROUND

Previous research suggests that adequate dietary zinc intake may be important in determining the sensory experience of food, appetite and consequently, dietary quality. The aim of this pilot study was to explore relationships between taste sensitivity and dietary zinc intake in healthy young adults (age 20-40 years: 24 male, mean age +/- SD = 27 +/- 4.86 years; 26 female, mean age +/- SD = 23 +/- 2.10).

METHOD

A signal detection method was used to assess taste acuity for the four basic tastes: sweet (glucose), sour (citric acid), salt (sodium chloride) and bitter (quinine). A 4-day food diary was used to determine dietary intakes of zinc (mg day(-1)) and salt.

RESULTS

Males reported a higher zinc intake than females (P=0.001). Higher dietary zinc intake was associated with better taste acuity for salt in females (P=0.017) but not in males. Acuity for bitter taste appeared to be related to zinc intake in males (P=0.007) but not females. Among those whose average daily zinc intake was below the RNI, males were less sensitive than females to sour (P=0.02) and bitter (P=0.014) taste.

CONCLUSION

These findings suggest that zinc is more important for taste acuity in males than females and indicate the importance of taking sex differences into account when studying taste acuity.

Taste deficits related to dental deafferentation: an electrogustometric study in humans

Dental treatments, the prevalence of which increases with age, can cause orofacial somatosensory deficits. In order to examine whether they may also affect taste sensitivity, electrogustometric thresholds were measured at 9 loci on the tongue surface in 391 healthy non-smoking, non-medicated subjects. Results showed that the greater the number of deafferented teeth, the higher the thresholds. Irrespective of age, subjects with more than 7 deafferented teeth exhibited significantly higher thresholds than subjects with fewer than 7 deafferented teeth. Conversely, across age groups, no statistical difference was observed among subjects with no, or few, deafferented teeth. Hence, a taste deficit, which was not correlated to aging, was observed. An association was noticed between the location of taste deficits and the location of deafferented teeth. Higher thresholds at anterior sites, with no possible traumatic injury relationship, suggested that neurophysiological convergence between dental somatosensory and taste pathways - possibly in the nucleus tractus solitarius - could be responsible for these relative decreases of taste sensitivity when dental afferences were lacking. Among trigeminal contributions, lingual nerve and inferior alveolar nerve may synergize taste.

Taste in dementing diseases and Parkinsonism

Like with many sensory abilities a reduction of taste and smell occurs during aging. Since there are hints to an additional reduction in dementing diseases, we assessed 52 patients, 26 women and 26 men, who were presented to a memory clinic, using the Sniffin' Sticks, Whole Mouth and Taste Strip Tests. While smoking, alcohol consumption, intake of drugs and sex exerted only minor impact, age and the severity of cognitive impairment were of major importance. There was a moderate but significant correlation between the severity of dementia, taste and smell, even if the age effect was partialled out. Notably, patients with Parkinson syndrome showed worse taste and smell abilities than those without. Here the differences were indeed marked enough to play a possible role in making the diagnosis. This exploratory study confirms a mild reduction of gustatory function in dementing diseases over and beyond that of normal aging which--in addition to a reduction of smell--seems to be especially marked in Parkinson syndromes.