Richard L. Doty

Handbook of olfaction and gustation

Part 1 Olfaction: Anatomy, Biochemistry and Physiology - Olfactory Mucosa: Composition, Enzymatic Localization and Metabolism, Anatomy of the Human Nasal Passages, Anatomy and Ultrastructure of the Human Olfactory Neuroepithelium, Functional Anatomy, Central Connections, and Neurochemistry of the Mammalian Olfactory Bulb, The Molecular Mechanisms of Olfactory Signal Transduction, Developmental Anatomy of the Olfactory System Human Psychophysics and Measurement of Odor-Induced Responses - Current Trends In the Measurement of Olfactory Function, Modern Approaches to Air Dilution Olfactometry, Olfactory Adaptation, Perception of Odor Mixtures, Olfaction and Development of Social Preferences in Neonatal Organisms, The Genetics of Olfactory Perception Clinical Applications and Perspectives - Clinical Disorders of Olfaction - A Review, Viruses and the Olfactory System, Evaluation of Olfactory Deficits by Medical Imaging, Rhinological Considerations and Upper Airway Physical Examination of Patients with Olfactory Disorders, Distorted Olfactory Perception, Deprivation and the Olfactory System, Nasal Airway Dynamics and Olfactory Function. Part 2 Gustation: Anatomy, Biochemistry, Development, Genetics, and Physiology - Saliva: Its Function and Disorders, Anatomy of the Peripheral Taste System, Central Taste Anatomy and Neurophysiology, Receptor Mechanisms in Gustation, Transduction of Taste Stimuli by Receptor Cells in the Gustatory System Human Psychophysics and Measurement of Testant-Induced Responses - Current Trends in Measuring Taste, Perception of Taste Mixtures, Ontogeny of Human Taste Perception clinical Applications and Perspectives - nutritional implications of Taste and Smell Disorders, Conditioned Flavour Aversions, Head Injury and Taste, Iatrogenic Causes of Taste Disturbances: Radiation Therapy, Surgery, Medication Other Chemosensory Systems. (Part Contents).

Intranasal trigeminal stimulation from odorous volatiles: Psychometric responses from anosmic and normal humans ☆

Abstract Psychometric ratings of the perceived intensity, pleasantness, coolness, warmth, and presumptive safety of high concentrations of 47 nasally-inhaled chemicals commonly used in olfactory research were established for three groups of human observers (n = 15/group): (1) anosmics lacking olfactory (CN I), but not trigeminal (CN V), nerve function; (2) normals asked to rate only intranasal trigeminal (CN V) sensations (trigeminal focus group); and (3) normals asked to rate the overall odor experience in the traditional fashion. Forty-five of the 47 compounds were detected by at least some proportion of the anosmics in a forced-chice test. Although differences in the rated intensities of the stimuli were present between the three experimental groups, the relative rankings of the intensity responses were quite similar (rs ranging from 0.92 to 0.97). The pleasantness and presumed safety of the chemicals varied inversely with the perceived intensity in all three groups. The use of 11 to 13 readily-available and computer-derived molecular descriptors in linear learning machine pattern recognition analyses separated the 47 stimuli correctly into four discrete intensity classes. A multiple linear regression equation based upon such molecular descriptors (multiple R = .88) proved successful in predicting the perceived trigeminal intensities of 12 chemical stimuli similar in general structure to members of the original stimulus set (r = .80 between predicted and observed intensities). These results emphasize the importance of trigeminal input in human nasal chemoreception and support the notion that the perceived intensities of nasally-inhaled stimulants can be mathematically predicted from relatively simple physicochemical and molecular structural parameters.

Development of the 12‐Item Cross‐Cultural Smell Identification Test(CC‐SIT)

The development of the 12‐item Cross‐Cultural Smell Identification Test(CC‐SIT), based upon items from the University of Pen.sylvania Smell Identification Test (UPSIT), is described. In developing this test, the authors initially selected UPSIT items that are familiar to most persons from North American, European, South American, and Asian cultures. The CC‐SIT was then administered to 198 people ranging in age from 5 to 96 years, and the test scores were compared to analogous items from UPSITs administered to 198 age‐, sex‐, race‐, and smoking‐habit‐matched control subjects. Since the pattern of test scores did not differ for the two groups, the authors developed normative data for the 12‐item test using equivalent UPSIT items sampled from a database containing UPSIT scores for 3760 subjects. Norms are provided for determining the percentile ranks of a given patients score as a function of age and gender. The CC‐SIT provides, for the first time, a self‐administered means for reliably assessing olfactory function in less than 5 minutes.

Presence of both odor identification and detection deficits in alzheimer's disease

Recent studies of Alzheimers disease patients have demonstrated (a) marked structural and biochemical alterations in brain regions associated with olfactory function (including the olfactory bulb and entorhinal cortex) and (b) decrements in the ability to identify odorants. In light of such findings, we administered the University of Pennsylvania Smell Identification Test (UPSIT) and a forced-choice phenyl ethyl alcohol odor detection threshold test to a relatively large number of patients diagnosed, on the basis of stringent criteria, as having mild to moderately severe Alzheimers disease. Compared to age-, gender-, and race-matched normal controls, these individuals evidenced consistent and marked decrements on both types of olfactory tests (ps less than 0.001). Surprisingly few of the patients were aware of their disorder, despite its appearance early in the disease process. These findings indicate that both odor identification and odor detection problems are present in dementia of the Alzheimers type, and raise the possibility that the odor identification problem may be secondary to the odor detection problem.

Bilateral olfactory dysfunction in early stage treated and untreated idiopathic Parkinson's disease.

Decreased olfactory function is among the first signs of idiopathic Parkinsons disease (PD). Whether such dysfunction is present to the same degree on both sides of the nose, however, is unknown. Furthermore, whether the deficit results from or is influenced by anti-Parkinsonian medications has not been definitely established. Odour identification ability was evaluated on the left and right sides of the nose in 20 early-stage untreated PD patients, 20 early-stage treated PD patients, and 20 controls. In all cases, the PD related olfactory dysfunction was bilateral and no difference was observed between the test scores of patients taking or not taking drugs for PD. Although asymmetries of unsystematic direction were present in the test scores of some PD patients, similar asymmetries were observed in the controls and the asymmetries were not related to the side of the major motor dysfunction. As in earlier work, no relation was present between the olfactory test scores and the degree of tremor, rigidity, bradykinesia, or gait disturbance at the time of testing. These findings indicate that the olfactory dysfunction of early stage PD is robust, typically of the same general magnitude on both sides of the nose, and uninfluenced by anti-Parkinsonian medications.

Sex differences in odor identification ability: a cross-cultural analysis.

To ascertain the generality of a sex difference noted in odor identification ability, the University of Pennsylvania Smell Identification Test (UPSIT) was administered to four groups of subjects: Black Americans (n = 438), White Americans (n = 1559), Korean Americans (n = 106), and Native Japanese (n = 308). The women of all four groups outperformed the men to the same relative degree. The Korean American group performed better than the Black and White American groups, which, in turn, outperformed the Native Japanese. Analyses of the proportions of subjects correctly answering each of the test items revealed considerable similarity of relative item difficulty among the subject groups. Taken together, these data suggest that sex differences in odor identification ability are probably not due to ethnic or cultural factors, per se.

Olfactory Dysfunction in Schizophrenia: A Qualitative and Quantitative Review

Olfactory dysfunction in patients with schizophrenia has been a topic of increasing interest, with deficits in odor identification, detection threshold sensitivity, discrimination, and memory being reported. Despite increasing knowledge, controversy has existed about possible differential deficits among olfactory tests as well as the influences of gender, smoking, and medication status on olfactory measures. To help elucidate some of this controversy, we conducted a qualitative and quantitative (meta-analytic) review of the English language literature on olfaction in schizophrenia. Moderator variables such as gender, medication status, and smoking history were also examined. Results indicated that substantial olfactory deficits, across all domains, are observed in patients with schizophrenia. No differential deficits were observed across domains of odor identification, detection threshold sensitivity, discrimination, and memory. The influences of gender, medication status, and smoking on effect sizes were not significant across studies. This supports the hypothesis of primary dysfunction in the olfactory system that is regulated by brain regions where structural and functional abnormalities have also been reported in neuroimaging studies.

Olfactory dysfunction in Parkinson disease

Olfactory dysfunction is among the earliest nonmotor features of Parkinson disease (PD). Such dysfunction is present in approximately 90% of early-stage PD cases and can precede the onset of motor symptoms by years. The mechanisms responsible for olfactory dysfunction are currently unknown. As equivalent deficits are observed in Alzheimer disease, Down syndrome, and the Parkinson–dementia complex of Guam, a common pathological substrate may be involved. Given that olfactory loss occurs to a lesser extent or is absent in disorders such as multiple system atrophy, corticobasal degeneration, and progressive supranuclear palsy, olfactory testing can be useful in differential diagnosis. The olfactory dysfunction in PD and a number of related diseases with smell loss correlates with decreased numbers of neurons in structures such as the locus coeruleus, the raphe nuclei, and the nucleus basalis of Meynart. These neuroanatomical findings, together with evidence for involvement of the autonomic nervous system in numerous PD-related symptoms, suggest that deficits in cholinergic, noradrenergic and serotonergic function may contribute to the olfactory loss. This Review discusses the current understanding of olfactory dysfunction in PD, including factors that may be related to its cause.

Combining early markers strongly predicts conversion from mild cognitive impairment to Alzheimer's disease.

BACKGROUND The utility of combining early markers to predict conversion from mild cognitive impairment (MCI) to Alzheimers Disease (AD) remains uncertain. METHODS Included in the study were 148 outpatients with MCI, broadly defined, followed at 6-month intervals. Hypothesized baseline predictors for follow-up conversion to AD (entire sample: 39/148 converters) were cognitive test performance, informant report of functional impairment, apolipoprotein E genotype, olfactory identification deficit, and magnetic resonance imaging (MRI) hippocampal and entorhinal cortex volumes. RESULTS In the 3-year follow-up patient sample (33/126 converters), five of eight hypothesized predictors were selected by backward and stepwise logistic regression: Pfeffer Functional Activities Questionnaire (FAQ; informant report of functioning), University of Pennsylvania Smell Identification Test (UPSIT; olfactory identification), Selective Reminding Test (SRT) immediate recall (verbal memory), MRI hippocampal volume, and MRI entorhinal cortex volume. For 10% false positives (90% specificity), this five-predictor combination showed 85.2% sensitivity, combining age and Mini-Mental State Examination (MMSE) showed 39.4% sensitivity; combining age, MMSE, and the three clinical predictors (SRT immediate recall, FAQ, and UPSIT) showed 81.3% sensitivity. Area under ROC curve was greater for the five-predictor combination (.948) than age plus MMSE (.821; p = .0009) and remained high in subsamples with MMSE > or = 27/30 and amnestic MCI. CONCLUSIONS The five-predictor combination strongly predicted conversion to AD and was markedly superior to combining age and MMSE. Combining the clinically administered measures also led to strong predictive accuracy. If independently replicated, the findings have potential utility for early detection of AD.

Sex differences and reproductive hormone influences on human odor perception.

The question of whether men and women differ in their ability to smell has been the topic of scientific investigation for over a hundred years. Although conflicting findings abound, most studies suggest that, for at least some odorants, women outperform men on tests of odor detection, identification, discrimination, and memory. Most functional imaging and electrophysiological studies similarly imply that, when sex differences are present, they favor women. In this review we examine what is known about sex-related alterations in human smell function, including influences of the menstrual cycle, pregnancy, gonadectomy, and hormone replacement therapy on a range of olfactory measures. We conclude that the relationship between reproductive hormones and human olfactory function is complex and that simple associations between circulating levels of gonadal hormones and measures of olfactory function are rarely present.