Chemosensory interaction: acquired olfactory impairment is associated with decreased taste function

Post-traumatic taste disorders: a case series

Since 1800s there are reports of post-traumatic anosmia, but few studies investigated post-traumatic gustatory deficit and adopted validated evaluation tests. Peripheral and/or central mechanisms may be involved in the genesis of post-traumatic gustatory dysfunction. Beyond a reduction/loss (hypogeusia/ageusia) of gustatory function following a trauma, qualitative taste changes (dysgeusia) may occur. Especially when persistent, taste deficits might be particularly relevant for patient's quality of life and activities of daily life, but knowledge on this topic is limited. Fifty-three consecutive patients with previous head trauma were recruited. Every patient underwent a careful history taking and thorough olfactory and gustatory chemosensory testing by Sniffin'Sticks Extended test, Whole Mouth Test and Taste Strips Test. All patients had olfactory abnormalities (hyposmia: n = 10, functional anosmia: n = 43), while 10 of them (19%) showed taste deficits (dysgeusia: n = 3, dysgeusia with hypogeusia: n = 1, hypogeusia: n = 5, ageusia: n = 1). Here, we report clinical and neuroimaging data and detailed description of four meaningful cases representing central and peripheral injury patterns. Chemosensory evaluation might be useful to explore taste disorder, a still neglected and underestimated sequela of head trauma.

Differences in the Density of Fungiform Papillae and Composition of Saliva in Patients With Taste Disorders Compared to Healthy Controls

This study investigated the relation of the fungiform taste papillae density and saliva composition with the taste perception of patients suffering from diagnosed taste disorders. For this purpose, 81 patients and 40 healthy subjects were included. Taste was measured by means of regional and whole mouth chemosensory tests, and electrogustometry. Olfaction was assessed using the Sniffin Sticks. Fungiform papillae were quantified using the "Denver Papillae Protocol for Objective Analysis of Fungiform Papillae". In addition, salivary parameters [flow rate, total proteins, catalase, total anti-oxidative capacity (TAC), carbonic anhydrase VI (caVI), and pH] were determined and the Beck Depression Inventory was administered. Patients showed less taste papillae compared to healthy subjects. The number of papillae correlated with total taste strip score and salivary flow rate. Regarding salivary parameters, the flow rate, protein concentration, and TAC of patients were higher compared to controls. In addition, salivary flow rate, protease, caVI, and catalase values correlated with the summed taste strip score. Regarding various taste disorders, salty-dysgeusia patients showed the lowest taste test scores compared to those with bitter or metal-dysgeusia. Olfactory function of patients was significantly worse compared to healthy controls. This difference was most pronounced for ageusia patients. Compared to controls, patients also exhibited higher depressive symptoms. The density of fungiform papillae seemed to be positively associated with taste perception. Furthermore, patients exhibited changes in saliva composition (higher salivary flow rate, increased protein concentration, proteolysis, and TAC) compared to controls indicating that assessment of saliva may be critical for the diagnostic procedure in taste disorders.

Unlocking the Complex Flavors of Dysgeusia after Hematopoietic Cell Transplantation

Dysgeusia is a frequently occurring symptom after hematopoietic cell transplantation (HCT) that has important long-term effects on physical, nutritional, and immunologic recovery, as well as on quality of life. Despite the relevance of this symptom, the study of dysgeusia in patients undergoing HCT has been limited, owing in part to its complexity. In this article, we review normal taste function and its clinical evaluation, discuss how dysgeusia uniquely affects patients undergoing HCT, and examine distinct, transplantation-related contributors to dysgeusia that may help elucidate strategies to ultimately reduce this symptom burden after transplantation.

Chemosensory function before and after multimodal treatment in chronic rhinosinusitis patients

OBJECTIVES/HYPOTHESIS

Olfactory dysfunction is common among the general population, with chronic rhinosinusitis (CRS) as one of the leading causes. Patients affected by CRS often report changes in taste sensations; however, quantitative measurements have not been performed to date. Therefore, the present study aimed to investigate gustatory and olfactory function in CRS patients prior to and after multimodal treatment.

STUDY DESIGN

Prospective cohort study.

METHODS

Twenty-one patients suffering from CRS with nasal polyps (14 male, seven female) with a mean age of 48 ± 15 years were included in the study. Chemosensory function was assessed prior to and approximately 190 days after multimodal treatment, which included endoscopic sinus surgery, oral antibiotics for 5 days, oral steroids for 12 days, and at least 6 weeks of topical nasal steroids. Olfactory function was tested with the Sniffin' Sticks test battery, whereas gustatory function was measured with taste strips. A clinically relevant change in olfactory function was defined as a change of ≥5 points in the threshold, discrimination, and identification scores.

RESULTS

Compared to normative data, patients baseline gustatory and olfactory function was impaired. After multimodal treatment, improvements were seen in olfactory function for eight patients (42%), remained stable in 10 patients (53%), and deteriorated in one patient (5%). Taste function remained unchanged following sinus surgery.

CONCLUSIONS

Patients suffering from CRS with polyps exhibit olfactory and taste dysfunctions. Multimodal treatment leads to an improvement in olfactory, but not gustatory functionality.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:E86-E90, 2018.

Occlusal, chewing, and tasting characteristics associated with orofacial dysfunctions in children with unilateral cleft lip and palate: a case-control study

OBJECTIVE

The objective of this study is to assess the associations between orofacial dysfunctions with malocclusion, masticatory performance, and taste in children with and without unilateral cleft lip and palate (UCLP).

MATERIAL AND METHODS

A patient-based, matched, case-control study was conducted involving 108 8- to 10-year-old children divided in UCLP and control groups. Orofacial dysfunctions were evaluated using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need was evaluated using the Goslon Yardstick Index (GYI) and the Index of Orthodontic Treatment Need (IOTN) of patients and controls, respectively. Masticatory performance was assessed using a chewable test material to determine median particle size (X ₅₀) and distribution of particles in different sieves (b value). Taste perception was evaluated using four solutions (sweet, salty, bitter, or acid) in three different concentrations.

RESULTS

More than half of the patients needed orthodontic surgery. UCLP group presented higher median particle size and needed more chewing cycles to comminute the artificial test into particles smaller than the median than those of controls. UCLP group had less perception of salty flavor than controls. There was a positive correlation between b value and NOT-S examination score for patients. In regression analysis, a significant interrelationship was observed between NOT-S examination score and b value.

CONCLUSIONS

In the UCLP patients, masticatory performance was compromised probably as a result of facial asymmetry and speech disturbance; whereas, taste was less perceived only for salty flavor.

CLINICAL RELEVANCE

These findings provide preliminary evidence that mastication and taste are altered in children with UCLP, so these factors must be followed up to ensure oral and general health in growing individuals.

The Gut and Nonmotor Symptoms in Parkinson's Disease

Gastrointestinal (GI) symptoms are one of the most common nonmotor symptoms (NMS) in patients with Parkinson's disease (PD) involving the whole GI tract (GIT) and being evident throughout the whole course of the disease. Furthermore, constipation serves as a risk factor for PD as well as an early prodromal NMS of PD. The gut as gateway to the environment with its enteric nervous system (ENS) plays a crucial role in the neurodegenerative process that leads to PD. Alpha-synucleinopathy as the pathological hallmark of PD could be found within the whole GIT in a rostrocaudal gradient interacting with the ENS, the gut microbiome, and enteric glial cells. Bidirectional interactions between the ENS and the central nervous system (CNS) via a brain-gut-enteric microbiota axis have been reported. As well as there is evidence out of animal, autopsy, and epidemiological studies that α-synuclein spreads via rostrocranial transmission by transsynaptic cell-to-cell transfer via the sympathetic and parasympathetic nervous system to the CNS causing the typical neuropathological changes of PD. Recognition of GI NMS as prodromal markers of PD as well as a better understanding of the brain-gut connection offers new insights in the pathophysiology of PD and might provide the opportunity of PD diagnosis before CNS involvement. Hereby the opportunity for development of neuroprotective and disease-modifying therapeutics, respectively, seem to be promising. This chapter covers the variety of GI NMS and its consequences in PD as well as the important role of the gut as part of the pathological process in PD.

Smell and Taste Impairment After Total Laryngectomy

Objective:

Aim of this observational study is the evaluation of olfactory and gustatory impairments in laryngectomized long-term survivors compared to control subjects. Correlation between smell and taste alterations, age, and previous adjuvant treatments in laryngectomees was investigated.

Methods:

Fifty control subjects and 50 patients who underwent total laryngectomy for advanced laryngeal carcinoma were evaluated. All subjects underwent symptoms evaluation, oropharyngeal exam, endoscopic fiberoptic nasal examination, and Taste Strips and Sniffin’ Sticks tests.

Results:

Hyposmia was reported by all laryngectomees and hypogeusia by 54% of patients. Sniffin’ Sticks and Taste Strips tests demonstrated a statistically significant difference between controls and laryngectomees regarding olfactory threshold, odor discrimination and identification, Threshold Discrimination Identification (TDI) score, and sour, salty, and gustatory Total Taste score ( P < .05). Multivariate analysis for Total Taste score in laryngectomees showed a statistically significant correlation with aging, having an odds ratio of 0.127 for age ≥65 years, but not with TDI score, radiotherapy, and follow-up time, whereas multivariate analysis for TDI score demonstrated no correlation with radiotherapy, age, and follow-up time.

Conclusions:

Total laryngectomy determines olfactory and gustatory impairments that should be taken into account in clinical practice. Relationships between sensorial alterations, aging, follow-up period, and adjuvant treatments should be further evaluated in prospective studies.

Olfactory Loss and Regain: Lessons for Neuroplasticity

For the visual and auditory senses, an array of studies has reported on neuronal reorganization processes after sensory loss. In contrast to this, neuroplasticity has been investigated only scarcely after loss of the olfactory sense. The present review focuses on the current extent of literature on structural and functional neuroplasticity effects after loss, with a focus on magnetic resonance imaging-based studies. We also include findings on the regain of the olfactory sense, for example after successful olfactory training. Existing studies indicate that widespread structural changes beyond the level of the olfactory bulb occur in the brain after loss of the olfactory sense. Moreover, on a functional level, loss of olfactory input not only entails changes in olfaction-related brain regions but also in the trigeminal system. Existing evidence should be strengthened by future longitudinal studies, a more thorough investigation of the neuronal consequences of congenital anosmia, and the application of state-of-the-art neuroimaging methods, such as connectivity analyses and joint analyses of brain structure and function.

Evaluation of olfactory function in Behçet's disease

OBJECTIVE

Behçet's disease (BD) is a chronic, relapsing type of vasculitis of unknown etiology and is characterized by oral and urogenital ulcers and ocular inflammation with cutaneous, musculoskeletal, vascular, and nervous system manifestations. Few cases involving the nasal mucosa have been reported in the literature, and the true prevalence of BD remains unknown. Neurological involvement associated with BD might play a more important role in causing olfactory dysfunction than mucosal involvement, but sufficient clinical data are not available on the effect of BD on olfaction in adults. We therefore evaluated the olfactory function of patients diagnosed with BD.

MATERIAL AND METHODS

Patients were chosen from among a consecutive patient group population who visited the internal medicine rheumatology polyclinic and otolaryngology departments of Ondokuz Mayıs University Hospital. A total of 50 patients (both males and females) aged 18 to 60 years with a diagnosis of BD and 46 healthy controls (matched to the study group in terms of age and gender) were included. BD was diagnosed based on the criteria defined by the International Study Group for BD. A complete clinical history was taken for and a physical examination was performed in all participants. Patients with other rheumatic diseases; obstructive nasal pathologies leading to conductive-type olfactory dysfunction (e.g., septum deviation or nasal polyp); advanced systemic disease (e.g., hypertension or malignancy); a history of antithyroid, antihistamine, antidepressant, or steroid medication use within the past month; or who were current smokers, had an active upper respiratory infection, or had a history of otolaryngologic operations were excluded. The results of the "Sniffin' Sticks" (SS) olfactory test were compared between the two groups.

RESULTS

The mean age of the 50 BD patients was 35.3±10 years; that of the 46 health controls was 36.9±11 years. There was no significant group difference in age or gender distribution (p>0.05). Odor identification and overall scores were significantly lower in the BD group than in the control group. There were no significant differences in odor discrimination scores between the BD and control groups (p>0.05).

CONCLUSION

To our knowledge, this is the first study to evaluate olfactory function in patients diagnosed with BD using the SS test. Odor identification was more impaired in BD patients than in healthy controls, but there was no group difference in odor discrimination. BD patients should also be assessed for the involvement of olfactory function and may require treatment due to a malfunction of the olfactory system that affects the quality of life.

Taste detection and recognition thresholds in Japanese patients with Alzheimer-type dementia

OBJECTIVE

Alzheimer-type dementia (AD) is pathologically characterized by massive neuronal loss in the brain, and the taste cortex is thought to be affected. However, there are only a few reports regarding the gustatory function of AD patients, and the conclusions of this research are inconsistent.

METHODS

This prospective study enrolled 22 consecutive patients with mild to moderately severe Alzheimer-type dementia (AD) with mean age of 84.0 years, and 49 elderly volunteers without dementia with mean age of 71.0 years as control subjects. The control subjects were divided into two groups according to age: a younger group (N=28, mean age: 68.5) and an older group (N=21, mean age: 83.0). The gustatory function was investigated using the filter paper disc method (FPD) and electrogustometry (EGM).

RESULTS

The gustatory function as measured by the FPD was significantly impaired in patients with AD as compared with age-matched control subjects; no such difference was found between the younger and the older control groups. On the other hand, as for the EGM thresholds, there were no differences between the AD patient group and the age-matched controls.

CONCLUSION

The FPD method demonstrated decreased gustatory function in AD patients beyond that of aging. On the other hand, EGM thresholds did not differ between the AD patient group and the age-matched controls. These results suggest that failure of taste processing in the brain, but not taste transmission in the peripheral taste system, occurs in patients with AD.

Relationship of Phenylthiocarbamide (PTC) Taster Status to Olfactory and Gustatory Function in Patients with Chemosensory Disturbances

Poor sensitivity to the bitter taste of phenylthiocarbamide (PTC) and related substances has been associated with a number of diseases. We determined, in patients with chemosensory dysfunction from multiple etiologies, whether PTC "tasters" (n = 511) exhibit less smell and taste dysfunction than their non-PTC-tasting counterparts (n = 432) on a comprehensive battery of olfactory and gustatory tests. The proportion of tasters (54%) in our study population was much lower than that calculated from 11 North American population studies (76.5%; P < 0.0001). This taster/nontaster ratio was maintained across a range of etiologic categories. More women (60.7%) than men (45.5%) were PTC tasters (P < 0.0001). Although PTC tasting status was unrelated to scores on the olfactory tests (which included tests of odor identification, detection threshold, and odor memory/discrimination), tasters significantly outperformed nontasters on suprathreshold identification and intensity taste tests employing both bitter (caffeine) and nonbitter (sucrose, citric acid, sodium chloride) tasting stimuli. Regardless of PTC taster status, women outperformed men on the taste tests. Our findings suggest the possibility that the T2R38 gene may protect against significant olfactory dysfunction, but once such dysfunction becomes manifest at a level where professional help is sought, such protection is not evident. However, other hypotheses for this phenomenon are possible. This study demonstrates that patients with chemosensory disturbances who are PTC tasters outperform their non-PTC taster counterparts in both identifying and perceiving the intensity of a range of suprathreshold tastants, including ones that do not taste bitter.

Olfactory drug effects approached from human-derived data

The complexity of the sense of smell makes adverse olfactory effects of drugs highly likely, which can impact a patient's quality of life. Here, we present a bioinformatics approach that identifies drugs with potential olfactory effects by connecting drug target expression patterns in human olfactory tissue with drug-related information and the underlying molecular drug targets taken from publically available databases. We identified 71 drugs with listed olfactory effects and 147 different targets. Taking the target-based approach further, we found additional drugs with potential olfactory effects, including 152 different substances interacting with genes expressed in the human olfactory bulb. Our proposed bioinformatics approach provides plausible hypotheses about mechanistic drug effects for drug discovery and repurposing and, thus, would be appropriate for use during drug development.

Neural correlates of taste perception in congenital olfactory impairment

Olfaction and gustation contribute both to the appreciation of food flavours. Although acquired loss of smell has profound consequences on the pleasure of eating, food habits and body weight, less is known about the impact of congenital olfactory impairment on gustatory processing. Here we examined taste identification accuracy and its neural correlates using functional magnetic resonance imaging (fMRI) in 12 congenitally olfactory impaired individuals and 8 normosmic controls. Results showed that taste identification was worse in congenitally olfactory impaired compared to control subjects. The fMRI results demonstrated that olfactory impaired individuals had reduced activation in medial orbitofrontal cortex (mOFC) relative to normosmic subjects while tasting. In addition, olfactory performance as measured with the Sniffin' Sticks correlated positively with taste-induced blood-oxygen-level dependent (BOLD) signal increases in bilateral mOFC and anterior insula. Our data provide a neurological underpinning for the reduced taste perception in congenitally olfactory impaired individuals.

Impaired taste and increased mortality in acutely hospitalized older people

Taste ability is known to be impaired in elderly and even more so in acutely hospitalized elderly people. To our knowledge, no study has investigated the association between taste impairment and mortality. Our aim was to examine this association in acutely hospitalized older people. In a prospective study, 200 acutely hospitalized elderly people ≥70 years of age were included between November 2009 and October 2010 at the Oslo University Hospital, Norway. Exclusion criteria were cognitive impairment, nursing home residency, and terminal diseases. Comorbidity was registered with the Cumulative Illness Rating Scale, in addition to recording of age, gender, smoking, education, and number of medications. Taste ability was assessed quantitatively with the "taste strips method" in 174 patients (mean age: 84 years). Mortality until 1 January 2012 was obtained from hospital records. Fifty-six patients died during the observation period. The relative risk of death in total taste score quartile 4 compared with total taste score quartile 1 was 0.31 (95% confidence interval [95% CI]: 0.14-0.69, P = 0.004), after adjusting for age, gender, smoking, education, and Cumulative Illness Rating Scale. Adjusted 1-year mortality decreased from 30% in total taste score quartile 1 to 9% in total taste score quartile 4. Thus, impaired taste appears to be strongly associated with mortality in acutely hospitalized elderly people.

Olfactory function and nasal manifestations of Behçet's disease

OBJECTIVE

To investigate the effect of Behçet's disease on olfactory function, the nasal mucosa, and nasal symptoms.

METHODS

A total of 30 patients with Behçet's disease and 30 healthy individuals volunteered to enroll in the study. Any condition leading to olfactory dysfunction was a criterion for exclusion. Nasal endoscopy was carried out individually, and nasal symptoms were assessed. An olfactory function assessment test defined by the Connecticut Chemosensory Clinical Research Center (CCCRC) was carried out. n-Butanol odor threshold and odor identification tests were performed, and the CCCRC test score (0: worst score; 7: best score) was calculated. The relationship between nasal findings, nasal symptoms, and olfactory function was evaluated.

RESULTS

The mean age of each group was the late 1930s, and demographic differences were not significant. n-Butanol threshold test scores were 5.57 ± 1.0 and 6.47 ± 0.7 out of 7 for subjects with Behçet's disease and the healthy control group, respectively. Identification test scores were 4.93 ± 1.3 and 6.15 ± 0.8 out of 7 and the mean CCCRC scores were 5.25 ± 1.0 and 6.31 ± 0.6, respectively, with significant differences (p<0.001). Some nasal symptoms were significantly more common in patients with nasal findings, but no correlation was found between nasal findings and olfactory function.

CONCLUSION

Although Behçet's disease has been shown to involve the nasal cavity, its effects on olfactory function are unknown. The significant difference in CCCRC scores suggests, for the first time, that olfactory dysfunction is associated with Behçet's disease. Nasal symptoms are associated with the presence of nasal lesions, but there is no correlation between nasal findings and olfactory function.

Clinical features of olfactory disorders in patients seeking medical consultation

Background

Olfactory disorders are common complaints in ENT clinics. We investigated causes and relevant features of olfactory disorders and the need for gustatory testing in patients with olfactory dysfunction.

Material/Methods

A total of 140 patients seeking medical consultations were enrolled. All patients were asked about their olfactory disorders in a structured interview of medical history and underwent thorough otolaryngologic examinations and imaging of the head.

Results

Causes of olfactory disorders were classified as: upper respiratory tract infection (URTI), sinonasal diseases (NSD), head trauma, idiopathic, endoscopic sinus surgery, congenital anosmia, and other causes. Each of the various causes of olfactory dysfunction had its own distinct clinical features. Nineteen of 54 patients whose gustation was assessed had gustatory disorders.

Conclusions

The leading causes of olfactory dysfunction were URTI, NSD, head trauma, and idiopathic causes. Gustatory disorders were fairly common in patients with olfactory dysfunction. High priority should be given to complaints of olfactory disorders.

Taste intensity in the Beaver Dam Offspring Study

OBJECTIVES/HYPOTHESIS

To determine the distribution of the perceived intensity of salt, sweet, sour, and bitter in a large population and to investigate factors associated with perceived taste intensity.

STUDY DESIGN

Cross-sectional population.

METHODS

Subjects (n = 2,374; mean age, 48.8 years) were participants in the Beaver Dam Offspring Study examined during 2005 to 2008. Perceived taste intensity was measured using paper disks and a general labeled magnitude scale. Multiple linear regression was performed.

RESULTS

Mean intensity ratings were: salt = 27.2 (standard deviation [SD] = 18.5), sweet = 20.4 (SD = 15.0), sour = 35.7 (SD = 21.4), and bitter = 49.6 (SD = 23.3). Females and those with less than a college degree education rated tastes stronger. With adjustment for age, sex, and education, stronger perceived sour and bitter intensities were related to current smoking (sour: B = 2.8, 95% confidence interval [CI], 0.4 to 5.2; bitter: B = 2.8, 95% CI, 0.3 to 5.4) and lipid-lowering medications (sour: B = 5.1, 95% CI, 2.5 to 7.6; bitter: B = 3.2, 95% CI, 0.6 to 5.8). Alcohol consumption in the past year was related to weaker salt (B = -2.8, 95% CI, -5.3 to -0.3) and sweet intensity ratings (B = -2.3, 95% CI, -4.3 to -0.3), whereas olfactory impairment was associated with higher sweet ratings (B = 4.7, 95% CI, 1.4 to 7.9).

CONCLUSIONS

Perceived intensities were strongest for bitter and weakest for sweet. Sex and education were associated with each taste, whereas age did not demonstrate a consistent relationship. Associations with other factors differed by tastants, with current smoking and alcohol consumption being related to some tastes.

Nasal drug delivery devices: characteristics and performance in a clinical perspective-a review

Nasal delivery is the logical choice for topical treatment of local diseases in the nose and paranasal sinuses such as allergic and non-allergic rhinitis and sinusitis. The nose is also considered an attractive route for needle-free vaccination and for systemic drug delivery, especially when rapid absorption and effect are desired. In addition, nasal delivery may help address issues related to poor bioavailability, slow absorption, drug degradation, and adverse events in the gastrointestinal tract and avoids the first-pass metabolism in the liver. However, when considering nasal delivery devices and mechanisms, it is important to keep in mind that the prime purpose of the nasal airway is to protect the delicate lungs from hazardous exposures, not to serve as a delivery route for drugs and vaccines. The narrow nasal valve and the complex convoluted nasal geometry with its dynamic cyclic physiological changes provide efficient filtration and conditioning of the inspired air, enhance olfaction, and optimize gas exchange and fluid retention during exhalation. However, the potential hurdles these functional features impose on efficient nasal drug delivery are often ignored. With this background, the advantages and limitations of existing and emerging nasal delivery devices and dispersion technologies are reviewed with focus on their clinical performance. The role and limitations of the in vitro testing in the FDA guidance for nasal spray pumps and pressurized aerosols (pressurized metered-dose inhalers) with local action are discussed. Moreover, the predictive value and clinical utility of nasal cast studies and computer simulations of nasal airflow and deposition with computer fluid dynamics software are briefly discussed. New and emerging delivery technologies and devices with emphasis on Bi-Directional™ delivery, a novel concept for nasal delivery that can be adapted to a variety of dispersion technologies, are described in more depth.

Physiological and psychosocial age-related changes associated with reduced food intake in older persons

Dietary intake changes during the course of aging. Normally an increase in food intake is observed around 55 years of age, which is followed by a reduction in food intake in individuals over 65 years of age. This reduction in dietary intake results in lowered levels of body fat and body weight, a phenomenon known as anorexia of aging. Anorexia of aging has a variety of consequences, including a decline in functional status, impaired muscle function, decreased bone mass, micronutrient deficiencies, reduced cognitive functions, increased hospital admission and even premature death. Several changes during lifetime have been implicated to play a role in the reduction in food intake and the development of anorexia of aging. These changes are both physiological, involving peripheral hormones, senses and central brain regulation and non-physiological, with differences in psychological and social factors. In the present review, we will focus on age-related changes in physiological and especially non-physiological factors, that play a role in the age-related changes in food intake and in the etiology of anorexia of aging. At the end we conclude with suggestions for future nutritional research to gain greater understanding of the development of anorexia of aging which could lead to earlier detection and better prevention.

Implicit olfactory abilities in traumatic brain injured patients

To investigate implicit olfactory abilities in a group of anosmic traumatic brain injured (TBI) patients, an olfactomotor priming paradigm was administered. A group of matched normosmic/mildly microsmic TBI patients and a group of neurologically healthy participants served as controls. For all the groups, an interference effect was evident on the peak velocity of grip aperture when participants grasped a large target preceded by a "small" odor. The present results suggest that some form of implicit olfactory processing is preserved in TBI patients even when diagnosed as anosmic on the basis of explicit olfactory testing.

Examination of chemosensory functions in patients with dysosmia

Background

To examine changes of chemical sensory functions in patients with dysosmia.

Material/Methods

The 272 study subjects included 98 healthy volunteers, 86 subjects with hyposmia and 88 subjects with functional anosmia. Their chemical sensory functions were examined using olfactory event-related potentials (oERPs), trigeminal event-related potentials (tERPs), T&T olfactometer and triple drop method, respectively.

Results

The T&T results showed that the difference between patients and healthy subjects had statistical significance. The oERPs and tERPs results showed that patients with functional anosmia had N1 and P2 waves of prolonged latency and reduced amplitude when compared to healthy subjects with the difference of statistical significance. When compared to healthy subjects, patients with functional anosmia had clear hypogeusia and the difference had statistical significance. For the younger group there was significant difference between healthy subjects and patients in T&T, oERPs and tERPs results.

Conclusions

It is suggested by the apparently concomitant trigeminal nerve dysfunction and hypogeusia in patients with functional anosmia in this study that olfactory and nasal trigeminal function in young patients was clearly decreased. Our study suggests the possible application of oERPs, tERPs and three drops method in clinical diagnosis in Chinese populations and provides scientific evidence for treatment.

Smell and taste disorders

Smell and taste disorders can markedly affect the quality of life. In recent years we have become much better in the assessment of the ability to smell and taste. In addition, information is now available to say something about the prognosis of individual patients. With regard to therapy there also seems to be low but steady progress. Of special importance for the treatment is the ability of the olfactory epithelium to regenerate.

The role of TNF-α in inflammatory olfactory loss

BACKGROUND

Despite the significant health impact of olfactory loss in chronic rhinosinusitis (CRS), the underlying pathophysiology is incompletely understood. A transgenic mouse model of olfactory inflammation induced by tumor necrosis factor-alpha (TNF-α) has provided new insights into the cellular and molecular basis of inflammatory olfactory loss. Here, we utilize systemic corticosteroids to suppress downstream cytokine expression, in order to study the direct role of TNF-α in CRS-associated olfactory dysfunction.

METHODS

Transgenic mice were induced to express TNF-α in the olfactory epithelium for 6 weeks. In a subset of mice, 1 mg/kg prednisolone was administered concurrently to inhibit downstream inflammatory responses. The olfactory epithelium (OE) was analyzed by histology and electro-olfactogram (EOG) recordings.

RESULTS

Treatment with prednisolone successfully prevented inflammatory infiltration over significant regions of the OE. In areas where significant subepithelial inflammation was present, a corresponding loss of olfactory neurons was observed. In contrast, areas without major inflammatory changes had normal olfactory neuron layers, despite chronic local expression of TNF-α. Prednisolone partially reversed the complete loss of olfaction in the mouse model, preserving odorant responses that were significantly diminished compared to controls, but not absent.

CONCLUSIONS

The addition of prednisolone to the transgenic model of olfactory inflammation isolates the direct effects of induced TNF-α expression on the OE. The finding that prednisolone treatment prevents neuronal loss in some regions of the OE suggests that TNF-α does not directly cause neuronal apoptosis--rather, that subepithelial inflammation or other downstream mediators may be responsible. At the same time, EOG results imply that TNF-α directly causes physiologic dysfunction of olfactory neurons, independent of the inflammatory state. An understanding of the role of TNF-α and other inflammatory cytokines may suggest novel therapeutic strategies for CRS-associated olfactory loss.

Age-associated variation in sensory perception of iron in drinking water and the potential for overexposure in the human population

Humans interact with their environment through the five senses, but little is known about population variability in the ability to assess contaminants. Sensory thresholds and biochemical indicators of metallic flavor perception in humans were evaluated for ferrous (Fe(2+)) iron in drinking water; subjects aged 19-84 years participated. Metallic flavor thresholds for individuals and subpopulations based on age were determined. Oral lipid oxidation and oral pH were measured in saliva as potential biochemical indicators. Individual thresholds were 0.007-14.14 mg/L Fe(2+) and the overall population threshold was 0.17 mg/L Fe(2+) in reagent water. Average thresholds for individuals younger and older than 50 years of age (grouped by the daily recommended nutritional guidelines for iron intake) were significantly different (p = 0.013); the population thresholds for each group were 0.045 mg/L Fe(2+) and 0.498 mg/L Fe(2+), respectively. Many subjects >50 and a few subjects <50 years were insensitive to metallic flavor. There was no correlation between age, oral lipid oxidation, and oral pH. Standardized olfactory assessment found poor sensitivity for Fe(2+) corresponded with conditions of mild, moderate, and total anosmia. The findings demonstrate an age-dependent sensitivity to iron indicating as people age they are less sensitive to metallic perception.

Evaluation of smell and taste in patients with Wegener's granulomatosis

Although a reduced olfactory/gustatory function affects patients in all parts of life, this problem has not received much attention in Wegener's granulomatosis (WG). The aim of this study was to assess the smell/taste function of WG patients. Demographic data of 16 WG patients (9 males, 7 females) were obtained. They all subjectively assessed their taste/smell function on visual analogue scale. Olfactory/gustatory functions of the patients were tested with 'Sniffin' Sticks and 'Taste' strips, respectively. The results were then compared with those from sex and age-matched control group (n = 16) and normative data. WG patients subjectively assessed their olfactory (p = 0.03) and gustatory (p = 0.02) function to be lower than control group. All the olfactory scores (odour identification, odour discrimination and threshold) in both genders were significantly below the scores in the control group. WG patients were hyposmic. For taste (total taste score, as well as scores for the qualities sweet, sour, salty and bitter), WG patients did not significantly differ from controls and were normogeusic. However, the gustatory scores showed the tendency of reduction as compared to the control group. In conclusion, WG patients truly suffer from olfactory/taste dysfunction, but this is worse with olfaction. It is, therefore, imperative that physicians should make their patients to be aware of these sensory dysfunctions and educate them on methods to cope with it for better quality of life.

Crossmodal plasticity in sensory loss

In this review, we describe crossmodal plasticity following sensory loss in three parts, with each section focusing on one sensory system. We summarize a wide range of studies showing that sensory loss may lead, depending of the affected sensory system, to functional changes in other, primarily not affected senses, which range from heightened to lowered abilities. In the first part, the effects of blindness on mainly audition and touch are described. The latest findings on brain reorganization in blindness are reported, with a particular emphasis on imaging studies illustrating how nonvisual inputs recruit the visually deafferented occipital cortex. The second part covers crossmodal processing in deafness, with a special focus on the effects of deafness on visual processing. In the last portion of this review, we present the effects that the loss of a chemical sense have on the sensitivity of the other chemical senses, that is, smell, taste, and trigeminal chemosensation. We outline how the convergence of the chemical senses to the same central processing areas may lead to the observed reduction in sensitivity of the primarily not affected senses. Altogether, the studies reviewed herein illustrate the fascinating plasticity of the brain when coping with sensory deprivation.