Taste responses in patients with Parkinson's disease

Taste and smell function in Wilson's disease

OBJECTIVE

Wilson's disease (WD) is a metabolic disorder associated with abnormal copper metabolism that results in hepatic, psychiatric, and neurologic symptoms. No investigation of taste function has been made in patients with WD, although olfactory dysfunction has been evaluated.

METHODS

Quantitative taste and smell test scores of 29 WD patients were compared to those of 790 healthy controls. Taste was measured using the 53-item Waterless Empirical Taste Test (WETT®) and smell using the 40-item revised University of Pennsylvania Smell Identification Test (R-UPSIT®). Multiple linear regression analysis controlled for age and sex.

RESULTS

Average WETT® scores did not differ meaningfully between WD and control subjects (respective medians & IQRs = 32 [28-42] & 34 [27-41]); linear regression coefficient = 1.19, 95% CI [-0.81, 3.19], p = 0.242). In contrast, WD was associated with significantly reduced olfactory function [respective median (IQR) R-UPSIT® scores = 35 (33-37) vs. 37 (35-38); adjusted linear regression coefficient = -1.59, 95% CI [-2.34, -0.833]; p < 0.001)]. Neither olfaction nor taste were influenced by WD symptom subtype [23 (79.3%) were hepatic-predominant; 6 (20.7%) neurologic predominant]; R-UPSIT®, p = 0.774; WETT®, p = 0.912). No effects of primary medication or years since diagnosis (R-UPSIT®, p = 0.147; WETT®, p = 0.935) were found. Weak correlations were present between R-UPSIT® and WETT® scores for both control (r=0.187, p < 0.0001) and WD (r=0.237) subjects, although the latter correlation did not reach the 0.05 α level (p = 0.084).

CONCLUSION

Although WD negatively impacts smell function, taste is spared. Research is needed to understand the pathophysiologic mechanisms responsible for this divergence.

Gustatory dysfunction is related to Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Olfactory dysfunction has been reported to be involved in Parkinson's disease (PD) pathogenesis. However, gustatory dysfunction in PD has not been evaluated as in-depth as olfactory dysfunction. We reviewed the previously published studies regarding gustatory function in PD patients and suggested the possibility that gustatory dysfunction may also be associated with PD.

METHODS

MEDLINE, Cochrane Library, Embase, and PubMed databases were searched for studies evaluating gustatory function in PD patients. We used the standardized mean difference and a 95% confidence interval (CI) as the effect analysis index regarding the taste strip test. The relative risk and 95% CI were used as the effect analysis index for the questionnaires and propylthiouracil (PTU)/phenylthiocarbamide (PTC) perception test. Statistical heterogeneity was assessed using forest plots, Cochran's Q, and the I2 statistic; heterogeneity was considered high when I2 was over 75%. Publication bias was assessed by funnel plots and the Egger bias test.

RESULTS

We identified 19 articles that reported the results of gustatory function tests in PD patients and healthy controls. Most of these studies used various gustatory tests, including taste strips, questionnaires, taste solutions, PTU/PTC perception tests, and electrogustometry, and reported significantly lower gustatory function in PD patients than in the controls. However, several articles reported contradictory results.

CONCLUSIONS

Based on these studies, gustatory dysfunction is closely related to PD. However, the number of studies and enrolled subjects was small, and a unified gustatory function test was lacking. Therefore, further studies with larger populations and normalized gustatory function tests are needed.

Systematic review: Validity, reliability, and diagnostic accuracy of the electrogustometer

Objective

What are the electrogustometer's (EGM) validity, reliability, and diagnostic accuracy in assessing taste sensation in adults compared to other taste tests?

Data Sources

PubMed Medline, Elseviers's Embase, and the six databases of Cochrane Library.

Methods

We conducted a systematic search on December 20, 2022, consisting of synonyms for EGM. We considered randomized controlled trials and observational studies with original data for inclusion if they included adults who underwent electrogustometry. Articles were excluded if no analysis regarding validity, reliability, or diagnostic accuracy had been performed or if these analyses could not be performed with the published data.

Results

Nineteen articles discussing 18 studies were included for data extraction. The included studies carry a high risk of bias. Overall, the association between a variety of reference taste tests and EGM was moderate or weak with correlation coefficients ranging from -0.51 to 0.40 with one outlier of -0.74 found in one study correlating EGM and taste solutions. Test-retest reliability was good with reported correlation coefficients between 0.78 and 1.0. The sensitivity, specificity, PPV, and NPV of EGM in identifying abnormal taste function varied widely between the four studies on diagnostic accuracy.

Conclusion

The included studies in this review lack the required standards regarding study design to draw firm conclusions about the validity, reliability, and diagnostic accuracy of the EGM. Future research is needed to assess these measurement properties. Based on the reported results, we would not recommend using the EGM as a screening test for taste disturbance in clinical practice.

Level of Evidence

NA.

Sucrose Preference Test as a Measure of Anhedonic Behavior in a Chronic Unpredictable Mild Stress Model of Depression: Outstanding Issues

Despite numerous studies on the neurobiology of depression, the etiological and pathophysiological mechanisms of this disorder remain poorly understood. A large number of animal models and tests to evaluate depressive-like behavior have been developed. Chronic unpredictable mild stress (CUMS) is the most common and frequently used model of depression, and the sucrose preference test (SPT) is one of the most common tests for assessing anhedonia. However, not all laboratories can reproduce the main effects of CUMS, especially when this refers to a decrease in sucrose preference. It is also unknown how the state of anhedonia, assessed by the SPT, relates to the state of anhedonia in patients with depression. We analyzed the literature available in the PubMed database using keywords relevant to the topic of this narrative review. We hypothesize that the poor reproducibility of the CUMS model may be due to differences in sucrose consumption, which may be influenced by such factors as differences in sucrose preference concentration threshold, water and food deprivation, and differences in animals’ susceptibility to stress. We also believe that comparisons between animal and human states of anhedonia should be made with caution because there are many inconsistencies between the two, including in assessment methods. We also tried to offer some recommendations that should improve the reproducibility of the CUMS model and provide a framework for future research.

Taste Impairments in a Parkinson’s Disease Model Featuring Intranasal Rotenone Administration in Mice

Background: Taste impairments are often accompanied by olfactory impairments in the early stage of Parkinson’s disease (PD). The development of animal models is required to elucidate the mechanisms underlying taste impairments in PD. Objective: This study was conducted to clarify whether the intranasal administration of rotenone causes taste impairments prior to motor deficits in mice. Methods: Rotenone was administrated to the right nose of mice once a day for 1 or 4 week(s). In the 1-week group, taste, olfactory, and motor function was assessed before and after a 1-week recovery period following the rotenone administration. Motor function was also continuously examined in the 4-weeks group from 0 to 5 weeks. After a behavioral test, the number of catecholamine neurons (CA-Nos) was counted in the regions responsible for taste, olfactory, and motor function. Results: taste and olfactory impairments were simultaneously observed without locomotor impairments in the 1-week group. The CA-Nos was significantly reduced in the olfactory bulb and nucleus of the solitary tract. In the 4-week group, locomotor impairments were observed from the third week, and a significant reduction in the CA-Nos was observed in the substantia nigra (SN) and ventral tegmental area (VTA) at the fifth week along with the weight loss. Conclusion: The intranasal administration of rotenone caused chemosensory and motor impairments in an administration time-period dependent manner. Since chemosensory impairments were expressed prior to the locomotor impairments followed by SN/VTA CA neurons loss, this rotenone administration model may contribute to the clarification of the prodromal symptoms of PD.

Umami and Other Taste Perceptions in Patients With Parkinson's Disease

Objective

Studies of taste perceptions in Parkinson’s disease (PD) patients have been controversial, and none of these studies have assessed umami taste. This study aimed to assess umami, along with the other 4 taste functions in PD patients.

Methods

Participants were tested for gustation using the modified filter paper disc method and olfaction using the modified Sniffin’ Stick-16 (mSS-16) test (only 14 culturally suitable items were used). A questionnaire evaluated patients’ subjective olfactory and gustatory dysfunction, taste preference, appetite, and food habits.

Results

A total of 105 PD patients and 101 age- and sex-matched controls were included. The body mass index (BMI) of PD patients was lower than that of controls (PD = 22.62, controls = 23.86, p = 0.028). The mSS-16 score was 10.7 for controls and 6.4 for PD patients (p < 0.001) (normal ≥ 9). Taste recognition thresholds (RTs) for sweet, salty, sour, bitter and umami tastes were significantly higher in PD, indicating poorer gustation. All taste RTs correlated with each other, except for umami. Most patients were unaware of their dysfunction. Patients preferred sweet, salty and umami tastes more than the controls. Dysgeusia of different tastes in patients was differentially associated with poorer discrimination of tastes, an inability to identify the dish and adding extra seasoning to food. BMI and mSS-16 scores showed no correlation in either patients or controls.

Conclusion

PD patients have dysgeusia for all five tastes, including umami, which affects their appetite and diet. Patients preferred sweet, salty and umami tastes. This information can help adjust patients’ diets to improve their nutritional status.

Olfative and taste perception in Parkinson's disease

PURPOSE

To analyze the olfactory and gustatory perception and discrimination and self-perception of smell and taste in people with Parkinson's disease, comparing them with healthy nodes.

METHODS

Observational, analytical, cross-sectional, and quantitative study. Olfactory and gustatory perception and discrimination were verified following Parkinson's disease, compared to a control group, matched by sex and age, using the Olfactory Perception and Taste Strips Tests, respectively, after nasal cleaning and oral brushing. Self-perception was assessed by the Visual Analogue Scale before and after specific tests of perception and discrimination.

RESULTS

We included individuals of both sexes, 35 with Parkinson's Disease and 20 assigned to the control group, matched for mean age. The olfactory self-perception of the group with Parkinson's disease improved after the olfactory test. There was no difference in taste self-perception in the Parkinson's disease group before and after the taste test. In the olfactory perception assessment test, the Parkinson's disease group discriminated fewer essences than the control group. Both groups have similar generation and taste discrimination.

CONCLUSION

The olfactory perception of people with Parkinson's disease was lower, compared to the group of healthy desires, and the self-perception of olfactory efficacy improved after the test, in both groups. As for taste, there was no difference in perception and discrimination between groups, the sour taste was the most identified and there was an improvement in self-perception of taste efficiency in the group without Parkinson's disease after the test.

Neural Representation of Costs and Rewards in Decision Making

Decision making is crucial for animal survival because the choices they make based on their current situation could influence their future rewards and could have potential costs. This review summarises recent developments in decision making, discusses how rewards and costs could be encoded in the brain, and how different options are compared such that the most optimal one is chosen. The reward and cost are mainly encoded by the forebrain structures (e.g., anterior cingulate cortex, orbitofrontal cortex), and their value is updated through learning. The recent development on dopamine and the lateral habenula's role in reporting prediction errors and instructing learning will be emphasised. The importance of dopamine in powering the choice and accounting for the internal state will also be discussed. While the orbitofrontal cortex is the place where the state values are stored, the anterior cingulate cortex is more important when the environment is volatile. All of these structures compare different attributes of the task simultaneously, and the local competition of different neuronal networks allows for the selection of the most appropriate one. Therefore, the total value of the task is not encoded as a scalar quantity in the brain but, instead, as an emergent phenomenon, arising from the computation at different brain regions.

Molecular and Genetic Factors Involved in Olfactory and Gustatory Deficits and Associations with Microbiota in Parkinson's Disease

Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson’s disease (PD) that start very early and frequently precede the PD motor symptoms. The limited data available suggest that the basis of the olfactory and gustatory dysfunction related to PD are likely multifactorial and may include the same determinants responsible for other non-motor symptoms of PD. This review describes the most relevant molecular and genetic factors involved in the PD-related smell and taste impairments, and their associations with the microbiota, which also may represent risk factors associated with the disease.

How Does Adenotonsillectomy Affect the Olfactory Threshold in Children?

Adenotonsillectomy is one of the main operations on the head and neck surgery quality in children. This study aimed to compare the olfactory threshold changes in adenotonsillectomy patients. This comparative study was done on 152 children whom candidate for adenotonsillectomy before and 3 weeks after the operation referred to the Dr. Kermanshahi Hospital, Kermanshah, Iran during 2015-2016. The olfactory threshold was determined by olfactory test using phenyl butyl alcohol in propylene glycol. The orthonasal test was done by a strip and the lowest propylene glycol detection used as olfactory threshold. The mean age was 6.81 ± 3.83 of patients were boys and 69 of them were girls. The allergic rhinitis was detected in 83.6% of the patients before the adenotonsillectomy while it was only in 16.4% after adenotonsillectomy. Also, nocturia was higher before the adenotonsillectomy 104 (68.4%) compared to post-adenotonsillectomy 48 (31.6%). In 73 (48%) patients, the sleep quality score was 10 after the surgery while there was a patient with score 10 before the operation. The positive allergic rhinitis was higher in male 70 (84.3%) compared to female 57 (82.6%). Also, no significant difference detected on nocturia (P = 0.531). Also, significant difference detected between 2 groups in sleep quality score before and after the adenotonsillectomy (P = 0.001). The olfactory threshold significantly improved after surgery compared to previous (P = 0.034). These results suggest olfactory threshold improves after adenotonsillectomy in children.

Olfaction and taste in Parkinson's disease: the association with mild cognitive impairment and the single cognitive domain dysfunction

Mild cognitive impairment (MCI) and chemosensory dysfunction are non-motor symptoms of Parkinson's disease (PD), but their association is unclear. We explored if MCI and the involvement of single cognitive domains influence olfaction and taste in PD. The role of demographic, clinical and neuropsychiatric variables was tested. We recruited 50 PD patients without dementia, no other reasons for cognitive impairment, no condition that could influence evaluation of cognition, olfaction and taste. They underwent a full neuropsychological and chemosensory (i.e., olfaction and taste) test with the Sniffin' Sticks Extended test (SSET), Whole Mouth test (WMT) and Taste Strips test (TST). Fifty age- and sex-matched healthy subjects served as controls. Olfactory function and sweet identification were worse in PD than controls. MCI negatively influenced odor identification. Factors associated with poor olfactory function were age, overall cognition, apathy, and visuospatial dysfunction. Sour identification was affected by MCI and executive dysfunction, and salty identification by executive dysfunction. MCI, age and executive dysfunction worsened TST score. Awareness of olfactory dysfunction was impaired in PD with MCI. Education positively influenced SSET and TST scores. Our data confirmed that olfaction is abnormal in PD, while taste was only slightly impaired. Olfaction was worse in PD patients with visuospatial dysfunction, while sour and salty identification was worse in those with MCI and executive dysfunction, suggesting different underlying anatomical abnormalities. Future studies should incorporate neuroimaging and cerebrospinal fluid data to confirm this hypothesis. SSET odor identification and TST sour identification could be explored as quick screening tests for PD-MCI.

Neuroimaging of smell and taste

The senses of taste and smell developed early in evolution and are of high ecological and clinical relevance in humans. Chemosensory systems function, in large part, as hazard avoidance systems, thereby ensuring survival. Moreover, they play a critical role in nutrition and in determining the flavor of foods and beverages. Their dysfunction has been shown to be a key element of early stages of a number of diseases, including Alzheimer's and Parkinson's diseases. Advanced neuroimaging methods provide a unique means for understanding, in vivo, neural and psychological processing of smell, taste, and flavor, and how diseases can impact such processing. This chapter provides, from a neuroimaging perspective, a comprehensive overview of the anatomy and physiology involved in the odor and taste processing in the central nervous system. Some methodological challenges associated with chemosensory neuroimaging research are discussed. Multisensory integration, the mechanisms that enable holistic sensory experiences, is emphasized.

Chemosensory dysfunction in neurodegenerative diseases

A number of neurodegenerative diseases are accompanied by disordered smell function. The degree of dysfunction can vary among different diseases, such that olfactory testing can aid in differentiating, for example, Alzheimer's disease (AD) from major affective disorder and Parkinson's disease (PD) from progressive supranuclear palsy. Unfortunately, altered smell function often goes unrecognized by patients and physicians alike until formal testing is undertaken. Such testing uniquely probes brain regions not commonly examined in physical examinations and can identify, in some cases, patients who are already in the "preclinical" stage of disease. Awareness of this fact is one reason why the Quality Standards Committee of the American Academy of Neurology has designated smell dysfunction as one of the key diagnostic criteria for PD. The same recommendation has been made by the Movement Disorder Society for both the diagnosis of PD and identification of prodromal PD. Similar suggestions are proposed to include olfactory dysfunction as an additional research criterion for the diagnosis of AD. Although taste impairment, i.e., altered sweet, sour, bitter, salty, and umami perception, has also been demonstrated in some disorders, taste has received much less scientific attention than smell. In this review, we assess what is known about the smell and taste disorders of a wide range of neurodegenerative diseases and describe studies seeking to understand their pathologic underpinnings.

Evolving Concepts of Emotion and Motivation

This review takes a historical perspective on concepts in the psychology of motivation and emotion, and surveys recent developments, debates and applications. Old debates over emotion have recently risen again. For example, are emotions necessarily subjective feelings? Do animals have emotions? I review evidence that emotions exist as core psychological processes, which have objectively detectable features, and which can occur either with subjective feelings or without them. Evidence is offered also that studies of emotion in animals can give new insights into human emotions. Beyond emotion, motivation concepts have changed over decades too, and debates still continue. Motivation was once thought in terms of aversive drives, and reward was thought of in terms of drive reduction. Motivation-as-drive concepts were largely replaced by motivation-as-incentive concepts, yet aversive drive concepts still occasionally surface in reward neuroscience today. Among incentive concepts, incentive salience is a core motivation process, mediated by brain mesocorticolimbic systems (dopamine-related systems) and sometimes called 'wanting' (in quotation marks), to distinguish it from cognitive forms of desire (wanting without quotation marks). Incentive salience as 'wanting' is separable also from pleasure 'liking' for the same reward, which has important implications for several human clinical disorders. Ordinarily, incentive salience adds motivational urgency to cognitive desires, but 'wanting' and cognitive desires can dissociate in some conditions. Excessive incentive salience can cause addictions, in which excessive 'wanting' can diverge from cognitive desires. Conversely, lack of incentive salience may cause motivational forms of anhedonia in depression or schizophrenia, whereas a negatively-valenced form of 'fearful salience' may contribute to paranoia. Finally, negative 'fear' and 'disgust' have both partial overlap but also important neural differences.

Impaired Taste Associative Memory and Memory Enhancement by Feeding Omija in Parkinson's Disease Fly Model

Neurodegeneration can result in memory loss in the central nervous system (CNS) and impairment of taste and smell in the peripheral nervous system (PNS). The neurodegeneration seen in Parkinson's disease (PD) is characterized by functional loss of dopaminergic neurons. Recent studies have also found a role for dopaminergic neurons in regulating taste memory rewards in insects. To investigate how taste memories and sugar sensitivity can be affected in PD, we utilized the DJ-1β mutant fruit fly, DJ-1βex54 , as a PD model. We performed binary choice feeding assays, electrophysiology and taste-mediated memory tests to explore the function of the DJ-1β gene in terms of sugar sensitivity as well as associative taste memory. We found that PD flies exhibited an impaired ability to discriminate sucrose across a range of sugar concentrations, with normal responses at only very high concentrations of sugar. They also showed an impairment in associative taste memory. We highlight that the taste impairment and memory defect in DJ-1βex54 can be recovered by the expression of wild-type DJ-1β gene in the dopaminergic neurons. We also emphasized the role of dopaminergic neurons in restoring taste memory function. This impaired memory property of DJ-1βex54 flies also allows them to be used as a model system for finding supplementary dietary foods that can improve memory function. Here we provide evidence that the associative taste memory of both control and DJ-1βex54 flies can be enhanced with dietary supplementation of the medicinal plant, omija.

Music, dance, and other art forms: New insights into the links between hedonia (pleasure) and eudaimonia (well-being)

For Aristotle, the goal of human life was to live well, to flourish, and to ultimately have a good life. These goals can be conceptualized as "eudaimonia," a concept distinct from "hedonia" (pleasure). Many people would argue that the arts play a large role in their well-being and eudaimonia. Music in particular is a culturally ubiquitous phenomenon which brings joy and social bonding to listeners. Research has given insights into how the "sweet anticipation" of music and other art forms can lead to pleasure, but a full understanding of eudaimonia from the arts is still missing. What is clear is that anticipation and prediction are important for extracting meaning from our environment. In fleeting moments this may translate into pleasure, but over longer timescales, it can imbue life with meaning and purpose and lead to eudaimonia. Based on the existing evidence from neuroimaging, we hypothesize that a special network in the brain, the default-mode network, may play a central role in orchestrating eudaimonia, and propose future strategies for exploring these questions further.

6-n-propylthiouracil taste disruption and TAS2R38 nontasting form in Parkinson's disease

BACKGROUND

The few studies that evaluated taste function in Parkinson's disease (PD) showed inconsistent results. The inherited ability to taste the bitter compound of 6-n-propylthiouracil has been considered to be a paradigm of general taste perception. 6-n-propylthiouracil taste perception is mediated by the TAS2R38 receptor, and reduced 6-n-propylthiouracil sensitivity has been associated with several diseases not typically related to taste function.

OBJECTIVES

We evaluated the 6-n-propylthiouracil taste perception and the TAS2R38 gene as genetic risk factors for the development of idiopathic PD in PD patients and healthy controls (HC).

METHODS

The 6-n-propylthiouracil taste perception was assessed by testing the responsiveness, and the ability to recognize, 6-n-propylthiouracil and sodium chloride. The participants were classified for 6-n-propylthiouracil taster status and genotyped for the TAS2R38 gene.

RESULTS

A significant increase in the frequency of participants classified as 6-n-propylthiouracil nontasters and a reduced ability to recognize bitter taste quality of 6-n-propylthiouracil were found in PD patients when compared with healthy controls. The results also showed that only 5% of PD patients had the homozygous genotype for the dominant tasting variant of TAS2R38, whereas most of them carried the recessive nontaster form and a high number had a rare variant.

CONCLUSIONS

Our results show that 6-n-propylthiouracil taster status and TAS2R38 locus are associated with PD. The 6-n-propylthiouracil test may therefore represent a novel, simple way to identify increased vulnerability to PD. Moreover, the presence of the nontasting form of TAS2R38 in PD may further substantiate that disease-associated taste disruption may represent a risk factor associated with the disease. © 2018 International Parkinson and Movement Disorder Society.

Flavor perception and the risk of malnutrition in patients with Parkinson's disease

Flavor perception involves both olfactory and gustatory function. In patients with Parkinson’s disease (PD), hyposmia is a frequent finding, as well as an increased risk of malnutrition. We performed a pilot study to investigate the relationship between flavor perception and risk of malnutrition in PD patients. 63 PD patients participated to perform an olfactory (Sniffin’ Sticks) and gustatory (Taste Strips) task, and a questionnaire to establish nutritional risk (MUST), which includes BMI measurements. The relationship between olfactory and gustatory function and BMI was analyzed using partial correlations, corrected for disease duration, and regression analysis. Patients displayed a high prevalence of hyposmia (68.3%), and a low prevalence (6.3%) of hypogeusia. A small, but significant correlation was found between olfactory function and BMI (r = 0.261, p = 0.038), and not for gustatory function and BMI (r = 0.137, p = 0.284). Hyposmia, and not hypogeusia, may contribute to weight loss in Parkinson’s disease, and hence increase the risk of malnutrition.

Weight Loss and Malnutrition in Patients with Parkinson's Disease: Current Knowledge and Future Prospects

Parkinson's Disease (PD) is currently considered a systemic neurodegenerative disease manifested with not only motor but also non-motor symptoms. In particular, weight loss and malnutrition, a set of frequently neglected non-motor symptoms, are indeed negatively associated with the life quality of PD patients. Moreover, comorbidity of weight loss and malnutrition may impact disease progression, giving rise to dyskinesia, cognitive decline and orthostatic hypotension, and even resulting in disability and mortality. Nevertheless, the underlying mechanism of weight loss and malnutrition in PD remains obscure and possibly involving multitudinous, exogenous or endogenous, factors. What is more, there still does not exist any weight loss and malnutrition appraision standards and management strategies. Given this, here in this review, we elaborate the weight loss and malnutrition study status in PD and summarize potential determinants and mechanisms as well. In conclusion, we present current knowledge and future prospects of weight loss and malnutrition in the context of PD, aiming to appeal clinicians and researchers to pay a closer attention to this phenomena and enable better management and therapeutic strategies in future clinical practice.

Anosmia and Ageusia in Parkinson's Disease

Anosmia, the loss of sense of smell, is a common nonmotor feature of Parkinson's disease (PD). Ageusia, the loss of sense of taste, is additionally an underappreciated nonmotor feature of PD. The olfactory tract is involved early in PD as indicated by frequent occurrence of hyposmia or anosmia years or decades before motor symptoms and by autopsy studies showing early synuclein pathology in the olfactory tract and anterior olfactory nucleus even in the early stages of PD. Testing for olfaction consists of evaluation of olfactory thresholds, smell identification and discrimination, and olfactory memory. Testing for gustation involves evaluating thresholds and discrimination of five basic tastes (salty, sweet, bitter, sour, and umami). The presence of a specific pattern of loss in both olfaction and gustation in PD has been proposed, but this has not yet been confirmed. Within PD, olfactory loss is strongly tied with cognitive status though links to other features of PD or a particular PD phenotype is debated. Hyposmia is more often present and typically more severe in PD patients than other parkinsonian syndromes, making it a potentially useful biomarker for the disease.

Weight gain after STN-DBS: The role of reward sensitivity and impulsivity

Weight gain has been reported after deep brain stimulation of the subthalamic nucleus (STN-DBS), a widely used treatment for Parkinson's disease (PD). This nucleus has been repeatedly found to be linked both to reward and to inhibitory control, two key aspects in the control of food intake. In this study, we assessed whether weight gain experienced by patients with PD after STN-DBS, might be due to an alteration of reward and inhibitory functions. Eighteen patients with PD were compared to eighteen healthy controls and tested three times: before surgery, in ON medication and after surgery, respectively five days after the implantation in ON medication/OFF stimulation and at least three months after surgery in ON medication/ON stimulation. All participants were assessed for depression (Beck Depression Inventory), anhedonia (Snaith-Hamilton Pleasure Scale) and impulsiveness (Barratt Impulsiveness Scale). They performed a battery of tests assessing food reward sensitivity (Liking, Wanting and Preference) and a food go/no-go task. Results showed that body weight significantly increased after STN-DBS. A few days after surgery, patients were slower and more impulsive in the go/no-go task, showed a higher preference for high calorie (HC) foods and rated foods as less tasty. Months after subthalamic stimulation, the performance on the go/no-go task improved while no differences were observed in reward sensitivity. Interestingly, weight gain resulted greater in patients with higher levels of attentional impulsiveness pre-surgery, higher wanting for low calorie (LC) foods and impulsivity in the go/no-go task in ON medication/ON stimulation. However, only wanting and attentional impulsivity significantly predicted weight change. Furthermore, weight gain resulted associated with the reduction of l-Dopa after surgery and disease's duration. In conclusion, our findings are consistent with the view that weight gain in PD after STN-DBS has a multifactorial nature, which reflects the complex functional organization of the STN.

New test of odor pleasantness in Parkinson's disease

The New Test of Odor Pleasantness (NTOP) evaluates the hedonicity of olfactory stimulants. The aim of this study was to compare results of the NTOP, the Sniffin' Sticks test, and the Odorized Marker Test (OMT) in patients with Parkinson's disease (PD). The study sample comprised 30 PD patients (mean age 71±7.36 years) and the control group made up of 31 non-PD subjects (mean age 68±12.39 years). Sociodemographic data, medical history and tests of cognitive function were investigated. Olfaction was evaluated using the NTOP, Sniffin' Sticks test and OMT. The PD patients, compared with the control group, recorded significantly lower scores on all three tests: NTOP (p=0.00), Sniffin' Sticks (p=0.02), OMT (p=0.00). The NTOP was the test preferred by 55% of the subjects. This preference was more marked in the PD group. This study shows that the NTOP is a valuable method within the complex array of olfactory screening tools used in PD.

Deep Brain Stimulation for Obesity: From a Theoretical Framework to Practical Application

Obesity remains a pervasive global health problem. While there are a number of nonsurgical and surgical options for treatment, the incidence of obesity continues to increase at an alarming rate. The inability to curtail the growing rise of the obesity epidemic may be related to a combination of increased food availability and palatability. Research into feeding behavior has yielded a number of insights into the homeostatic and reward mechanisms that govern feeding. However, there remains a gap between laboratory investigations of feeding physiology in animals and translation into meaningful treatment options for humans. In addition, laboratory investigation may not be able to recapitulate all aspects of human food consumption. In a landmark pilot study of deep brain stimulation (DBS) of the lateral hypothalamic area for obesity, we found that there was an increase in resting metabolic rate as well as a decreased urge to eat. In this review, the authors will review some of the work relating to feeding physiology and research surrounding two nodes involved in feeding homeostasis, nucleus accumbens (NAc) and hypothalamus, and use this to provide a framework for future investigations of DBS as a viable therapeutic modality for obesity.

Pleasure systems in the brain

Pleasure is mediated by well-developed mesocorticolimbic circuitry and serves adaptive functions. In affective disorders, anhedonia (lack of pleasure) or dysphoria (negative affect) can result from breakdowns of that hedonic system. Human neuroimaging studies indicate that surprisingly similar circuitry is activated by quite diverse pleasures, suggesting a common neural currency shared by all. Wanting for reward is generated by a large and distributed brain system. Liking, or pleasure itself, is generated by a smaller set of hedonic hot spots within limbic circuitry. Those hot spots also can be embedded in broader anatomical patterns of valence organization, such as in a keyboard pattern of nucleus accumbens generators for desire versus dread. In contrast, some of the best known textbook candidates for pleasure generators, including classic pleasure electrodes and the mesolimbic dopamine system, may not generate pleasure after all. These emerging insights into brain pleasure mechanisms may eventually facilitate better treatments for affective disorders.

Reward processing in neurodegenerative disease

Representation of reward value involves a distributed network including cortical and subcortical structures. Because neurodegenerative illnesses target specific anatomic networks that partially overlap with the reward circuit, they would be predicted to have distinct impairments in reward processing. This review presents the existing evidence of reward processing changes in neurodegenerative diseases including mild cognitive impairment (MCI), Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis (ALS), Parkinson's disease, and Huntington's disease, as well as in healthy aging. Carefully distinguishing the different aspects of reward processing (primary rewards, secondary rewards, reward-based learning, and reward-based decision-making) and using tasks that differentiate the stages of processing reward will lead to improved understanding of this fundamental process and clarify a contributing cause of behavioral change in these illnesses.

Disorders of the oral cavity in Parkinson's disease and parkinsonian syndromes

Awareness of nonmotor symptoms of Parkinson's disease is growing during the last decade. Among these, oral cavity disorders are, although prevalent, often neglected by the patients, their caregivers, and physicians. Some of these disorders include increased prevalence of caries and periodontal disease, sialorrhea and drooling, xerostomia, orofacial pain, bruxism, and taste impairment. Though many of these disorders are not fully understood yet and relatively few controlled trials have been published regarding their treatment, physicians should be aware of the body of evidence that does exist on these topics. This paper reviews current knowledge regarding the epidemiology, pathophysiology, and treatment options of disorders of the oral cavity in Parkinson's disease patients.

Taste function in early stage treated and untreated Parkinson's disease

Since brain stem regions associated with early Parkinson's disease (PD) pathology encroach upon those involved in taste function, the ability to taste may be compromised in PD. However, studies on this point have been contradictory. We administered well-validated whole-mouth and regional taste tests that incorporated multiple concentrations of sucrose, citric acid, caffeine, and sodium chloride to 29 early stage PD patients and 29 age-, sex-, and race-matched controls. Electrogustometry was also performed on the anterior tongue. The PD cohort was tested both on and off dopamine-related medications in counterbalanced test sessions. While whole-mouth taste identification test scores for all stimuli were, on average, nominally lower for the PD patients than for the controls, a trend in the opposite direction was noted for the intensity ratings at the lower stimulus concentrations for all stimuli except caffeine. Moreover, regional testing found that PD subjects tended to rate the stimuli, relative to the controls, as more intense on the anterior tongue and less intense on the posterior tongue. No significant associations were evident between taste test scores and UPDRS scores, L-DOPA medication equivalency values, or [(99m)Tc]TRODAT-1 SPECT imaging of dopamine transporter uptake within the striatum and associated regions. Our findings suggest that suprathreshold measures of taste function are influenced by PD and that this disease differentially influences taste function on anterior (CN VII) and posterior (CN IX) tongue regions. Conceivably PD-related damage to CN IX releases central inhibition on CN VII at the level of the brainstem, resulting in enhanced taste intensity on the anterior tongue.

Body weight and food intake in Parkinson's disease. A review of the association to non-motor symptoms

Research on eating behaviours has extensively highlighted that cognitive systems interact with the metabolic system in driving food intake and in influencing body weight regulation. Parkinson's disease is a good model for studying these complex interactions since alterations in both body weight and cognitive domains have been frequently reported among these patients. Interestingly, even if different non-motor symptoms may characterize the course of the disease, their contribution to weight and food preference has been poorly investigated. This review describes body weight alterations and eating habits in patients with Parkinson's disease, including those who underwent deep brain stimulation surgery. In particular, the review considers the link between non-motor symptoms, affecting sensory perception, cognition, mood and motivation, and food intake and weight alterations. The take home message is twofold. First, we recommend a comprehensive approach in order to develop effective strategies in the management of patients' weight. Second, we also suggest that investigating this issue in patients with Parkinson's disease may provide some useful information about the mechanisms underlying food and weight regulation in healthy subjects.

Intensity and pleasantness of sucrose taste in patients with winter depression

OBJECTIVES

Increased consumption of carbohydrates and craving for sweets are considered core features of winter depression. Unfortunately, little is known about neural and behavioral correlates of these symptoms. The primary aim of the present study was to evaluate taste responses to sucrose solutions in depressed patients with seasonal affective disorder (SAD).

METHODS

Intensity and pleasantness ratings of sucrose solutions, electrogustometric thresholds, and taste identification abilities were assessed in depressed patients with SAD and non-seasonal affective disorder (non-SAD), and in non-depressed controls.

RESULTS

Electrogustometric thresholds and identification abilities did not differ between the study groups. There were no differences between the groups in intensity or pleasantness ratings of sucrose solutions (1-30%). The proportion of 'sweet likers', i.e. subjects rating the highest sucrose concentration as most pleasant, was similar in the controls, SAD, and non-SAD patients.

DISCUSSION

The present results suggest that: (i) winter depression is not associated with major alterations in gustatory function; and (ii) sweet craving and increased consumption of carbohydrates in patients with winter depression is not secondary to altered responses to sweet tastants. More studies are needed to characterize hedonic responses of patients with SAD to other sweet and non-sweet foods.

Sweet liking in patients with Parkinson's disease

Pleasant tastes and odors are considered phylogenetically old natural rewards and their hedonic evaluation is regarded as a good indicator of the reward system function. The primary aim of the present study was to compare pleasantness ratings of sucrose solutions (1-30%, w/w) and sweet liking/disliking status in 20 patients with Parkinson's disease (PD) and in 20 age-matched healthy controls. In addition, basic sensory aspects of gustatory (intensity ratings, electrogustometric thresholds) and olfactory function (identification abilities in the Sniffin' Stick test) were assessed in both groups. The number of odors rated as pleasant, unpleasant, and neutral was also compared. As expected, the PD patients showed a significant impairment in olfactory identification abilities. There were no differences between the PD patients and controls in electrogustometric thresholds. Rated intensity of higher sucrose concentrations did not differ between the groups. The PD patients tended to rate water taste as more intense in comparison with the controls. Pleasantness ratings of sucrose solutions, the proportion of subjects rating 30% sucrose as the most pleasant (sweet likers), and the number of odors rated as pleasant did not differ between the study groups. The present results suggest that PD does not lead to any obvious alterations in pleasantness ratings of chemosensory stimuli. The study requires replication in larger samples.

From prediction error to incentive salience: mesolimbic computation of reward motivation

Reward contains separable psychological components of learning, incentive motivation and pleasure. Most computational models have focused only on the learning component of reward, but the motivational component is equally important in reward circuitry, and even more directly controls behavior. Modeling the motivational component requires recognition of additional control factors besides learning. Here I discuss how mesocorticolimbic mechanisms generate the motivation component of incentive salience. Incentive salience takes Pavlovian learning and memory as one input and as an equally important input takes neurobiological state factors (e.g. drug states, appetite states, satiety states) that can vary independently of learning. Neurobiological state changes can produce unlearned fluctuations or even reversals in the ability of a previously learned reward cue to trigger motivation. Such fluctuations in cue-triggered motivation can dramatically depart from all previously learned values about the associated reward outcome. Thus, one consequence of the difference between incentive salience and learning can be to decouple cue-triggered motivation of the moment from previously learned values of how good the associated reward has been in the past. Another consequence can be to produce irrationally strong motivation urges that are not justified by any memories of previous reward values (and without distorting associative predictions of future reward value). Such irrationally strong motivation may be especially problematic in addiction. To understand these phenomena, future models of mesocorticolimbic reward function should address the neurobiological state factors that participate to control generation of incentive salience.

Revisão: metodologias para análise da sensibilidade gustativa ao sal

A avaliação da sensibilidade gustativa ao sal é utilizada na área da saúde, bem como em análise sensorial aplicada à Ciência e Tecnologia de Alimentos, para avaliar o paladar e identificar ageusia e hipoageusia de diversas origens; notavelmente, identifica os indivíduos que apresentam risco ou consumo excessivo de sal. A adoção de um método acurado e reprodutível para avaliação do limiar gustativo ao sal permite seu uso de forma ampliada. Esta revisão integrativa tem como objetivo descrever as metodologias empregadas para avaliar o limiar de detecção e reconhecimento do cloreto de sódio. Foram utilizadas as bases de dados CINAHAL, LILACS e MEDLINE, e as palavras-chave taste threshold, sodium chloride e salt. Foram localizados 27 artigos de 1985 a 2009 e, nestes, empregados 29 testes de análise do limiar. A maioria dos artigos utilizou o estímulo da boca toda (75,9%), seguida da aplicação tópica na língua (24,1%), aplicação da solução em partes da língua (10,3%), eletrogustometria (6,4%), disco impregnado (3,4%) e aplicação de vácuo (3,4%). Houve grande variação nos procedimentos metodológicos e, em alguns, ausência de informações importantes. Os artigos não apresentam cálculo do tamanho amostral e os critérios de seleção dos julgadores foram também variados. Assim, existe uma dificuldade para a reprodutibilidade e as comparações dos artigos. Avaliações comparativas entre os diferentes métodos de avaliação do limiar gustativo ao cloreto de sódio quanto à sua reprodutibilidade podem trazer subsídios importantes para a escolha do método mais adequado a ser empregado em pesquisa e na prática clínica.

Developing a Rational Approach to Tobacco Use Treatment in Pulmonary Practice: A Review of the Biological Basis of Nicotine Addiction

The toll of tobacco use on a pulmonary practice is severe. Physicians, patients, and their families experience frustration, hopelessness and even anger when confronted with a seemingly irrational decision to keep smoking despite morbid lung disease. This paper examines the biological basis of this behavior and seeks to integrate this insight into a rational approach to the problem in practice. Smoking is reexamined within the framework of an irrational compulsion to seek nicotine, despite a rational desire to stop. Control over the compulsion to smoke is established as an important clinical outcome, and the rationale for treating tobacco dependence as a chronic illness is examined. Finally, practical insights into managing ambivalence, including an aggressive pharmacotheapeutic approach based on the neurobiology, are presented.

Nutritional therapies in Parkinson's disease

Advise patients with Parkinson's disease (PD) to consume a balanced diet, with special attention to adequate intake of dietary fiber, fluids, and macro- and micronutrients. Regularly reassess patients' nutritional history and anthropomorphic measures (height and weight), particularly in patients with advanced disease. PD-related psychosocial as well as physical and cognitive limitations increase susceptibility to subacute and chronic malnutrition. Nutritional requirements may change with PD progression or after surgical therapy for PD. Patients and caregivers may benefit from counseling by a dietician who is knowledgeable about the nutritional risks and needs of PD. Regularly inquire about dysphagia symptoms, and consider speech therapy consultation for clinical and modified barium-swallowing evaluations and management recommendations. Although non-oral delivery options of dopaminergic therapy are increasing, severe dysphagia may warrant percutaneous endoscopic gastrostomy tube placement for nutritional support and more reliable PD medication dosing. Analyze vitamin B(12) and D concentrations at regular intervals. Both vitamins are frequently deficient in elderly persons but may not be routinely checked by primary care physicians. Record over-the-counter and nutritional supplement medications at each visit, and assist patients in periodically re-evaluating their potential benefits, side effects, drug interactions, and costs. To date, clinical trials of antioxidant vitamins and nutritional supplements have provided insufficient evidence to support routine use for PD in the clinic. Data from several clinical trials of antioxidant vitamins/nutritional supplements are expected in the near future. Consider altering medication dosing in relation to meals to help with mild to moderate motor fluctuations. Patients with severe motor fluctuations may benefit from adapting the 5:1 carbohydrate-to-protein ratio in their daily meals and snacks. Following a "protein redistribution" diet is logistically more difficult and less palatable, and therefore less frequently recommended. To ensure adequate protein intake, a registered dietician should supervise patients who follow either of these diets.

Appetitive motivational deficits in individuals with Parkinson's disease

Parkinson's disease is known for its effects on sensorimotor coordination caused by degeneration of the nigrostriatal dopamine pathway. Dopamine-innervated areas of the ventral striatum also become compromised in Parkinson's disease, and little is known about the potential impact of this pathology on motivational processes mediated by the mesolimbic dopamine system. The current study tested the hypothesis that patients with Parkinson's disease would show a deficit in appetitive motivational arousal. Patients with Parkinson's disease and age-matched healthy controls completed a visual discrimination task in which control and appetitive food images (incidental to the task) were presented in the background. Response rate changes indicated appetitive motivational arousal. The healthy controls showed an increase in response rate on the task when appetitive food cues were present compared with control stimuli. In contrast, the Parkinson's disease group showed an inverse pattern to the healthy controls. The reduction in appetitive motivation correlated with an individual's Parkinsonian symptomology. Patients with Parkinson's disease demonstrated an impairment in appetitive motivational arousal consistent with the progression of dopaminergic degeneration across the course of the disease. Dysfunction of this system affects quality of life in Parkinson's disease, and a blunting of the anticipatory motivation may contribute to the high prevalence of depression in Parkinson's disease.

Building a neuroscience of pleasure and well-being

BACKGROUND: How is happiness generated via brain function in lucky individuals who have the good fortune to be happy? Conceptually, well-being or happiness has long been viewed as requiring at least two crucial ingredients: positive affect or pleasure (hedonia) and a sense of meaningfulness or engagement in life (eudaimonia). Science has recently made progress in relating hedonic pleasure to brain function, and so here we survey new insights into how brains generate the hedonic ingredient of sustained or frequent pleasure. We also briefly discuss how brains might connect hedonia states of pleasure to eudaimonia assessments of meaningfulness, and so create balanced states of positive well-being. RESULTS: Notable progress has been made in understanding brain bases of hedonic processing, producing insights into that brain systems that cause and/or code sensory pleasures. Progress has been facilitated by the recognition that hedonic brain mechanisms are largely shared between humans and other mammals, allowing application of conclusions from animal studies to a better understanding of human pleasures. In the past few years, evidence has also grown to indicate that for humans, brain mechanisms of higher abstract pleasures strongly overlap with more basic sensory pleasures. This overlap may provide a window into underlying brain circuitry that generates all pleasures, including even the hedonic quality of pervasive well-being that detaches from any particular sensation to apply to daily life in a more sustained or frequent fashion. CONCLUSIONS: Hedonic insights are applied to understanding human well-being here. Our strategy combines new findings on brain mediators that generate the pleasure of sensations with evidence that human brains use many of the same hedonic circuits from sensory pleasures to create the higher pleasures. This in turn may be linked to how hedonic systems interact with other brain systems relevant to self-understanding and the meaning components of eudaimonic happiness. Finally, we speculate a bit about how brains that generate hedonia states might link to eudaimonia assessments to create properly balanced states of positive well-being that approach true happiness.

Frequency and characteristics of taste impairment in patients with Parkinson's disease: results of a clinical interview

OBJECTIVE

Patients with Parkinson's disease (PD) frequently complain of a diminished sense of smell. Less frequently, they may complain of taste impairment. In the present study, we investigated the symptoms, frequency, and severity of taste impairment as well as smell impairment in PD patients and compared the results with those of age- and sex-matched healthy controls.

PATIENTS AND METHODS

We interviewed 285 PD patients (120 men, 165 women) without dementia or nasal problems. Control subjects comprised 61 (20 men, 41 women) healthy spouses of the PD patients. Alteration of smell and taste sense lasting more than 3 months was defined as abnormal.

RESULTS

One hundred and sixteen patients with PD complained of smell impairment and 26 complained of taste impairment. Only 5 controls complained of smell impairment, and no control subjects reported taste impairment. Taste impairment was more marked in patients with smell impairment. Impaired taste included diminished taste perception in 21 patients, altered sense of taste in 4 patients and burning mouth in 1 patient.

CONCLUSION

Taste as well as smell perception is impaired in patients with PD. The frequency of smell and taste impairments tended to increase with disease progression.

Taste function in patients with Parkinson disease

Despite the important role of taste function in nutrition and health, little is known about changes in taste function caused by Parkinson disease (PD). The taste function of 31 PD patients and 29 healthy controls was assessed quantitatively using filter paper taste strip tests (TSTs) impregnated with four basic taste qualities at four different concentrations. The mean TST score was significantly lower in PD patients, as a consequence of taste impairment in the female PD patients (it did not differ significantly in males), which was likely to be attributable to the lower Mini-Mental State Examination score in patients with PD than in controls in women. TST scores in PD patients were not correlated with patient age, duration, or severity of their PD, or olfactory function. The findings of our study suggest that taste dysfunction should be included in the list of nonmotor symptoms of PD.

A basic smell test is as sensitive as a dopamine transporter scan: comparison of olfaction, taste and DaTSCAN in the diagnosis of Parkinson's disease

AIM

To evaluate relationship between odour identification, taste threshold, dopamine transporter scan (DaTSCAN) and motor function in early Parkinson's disease (PD) and their diagnostic accuracy.

METHODS

Seventy-three patients with early parkinsonism were evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS), DaTSCAN, electrogustometry (EGM) threshold and University of Pennsylvania Smell Identification Test (UPSIT). Olfactory Event-Related potentials (OERP) were performed on 49 patients. At follow-up (mean 15.3 months), patients were diagnosed as 'PD' or 'non-PD'. DaTSCAN images were assessed visually and semi-quantitatively by QuantiSPECT.

RESULTS

The sensitivity of UPSIT (86%) was not significantly different from that of the DaTSCAN (92%). UPSIT correlated moderately with DaTSCAN uptake (r = 0.44; P < 0.005) and UPDRS score (r = 0.43; P < 0.05) and weakly with symptom duration (r = 0.25; P < 0.05). In the PD group, OERP showed increased latency but no change in amplitude and no correlation with DaTSCAN. EGM thresholds were impaired in 22% of the PD group but they did not correlate with any other test parameters. DaTSCAN-UPSIT discordance was found in nine patients with PD, but neither was diagnostically superior.

CONCLUSION

Our patients with early PD have a frequent and severe olfactory deficit that correlates with disease severity, symptom duration and DaTSCAN but not EGM. The sensitivities of UPSIT and DaTSCAN are high at 86% and 92%, respectively. Although DaTSCAN is superior for 'localization', UPSIT is considerably 'cheaper', and neither is disease specific. EGM threshold impairment in PD is independent of the smell deficit, and probably signifies advanced disease.

Retronasal olfactory function in Parkinson's disease

OBJECTIVES/HYPOTHESIS

Orthonasal olfaction is severely altered in PD patients. Retronasal olfactory function has been shown to be preserved under certain conditions even in the absence of orthonasal function. This study was undertaken to investigate retronasal versus orthonasal olfactory function in Parkinson's disease (PD).

STUDY DESIGN

Prospective study.

METHODS

A total of 45 PD patients (mean age, 61 years; range 26-82 years) underwent orthonasal olfactory testing with a standardized olfactory test (Sniffin' Sticks) and retronasal olfactory testing with a 10-item identification kit based on aromatized powders.

RESULTS

Regarding orthonasal tests, all PD patients scored within the range of hyposmia and functional anosmia. The mean correct orthonasal identification score for PD patients was 56% +/- 2.6%, and the mean retronasal identification rate was 60% +/- 3%. There was no significant difference between ortho- and retronasal odor identification (P = .15).

CONCLUSIONS

The present study shows that retronasal and orthonasal olfactory function are severely impaired in PD patients, and this impairment is of similar magnitude for both functions. The contribution of this finding to the food-intake behavior of PD patients is discussed.

Parkinson disease: systemic and orofacial manifestations, medical and dental management

BACKGROUND

More than 1.5 million Americans have Parkinson disease (PD), and this figure is expected to rise as the population ages. However, the dental literature offers little information about the illness.

TYPES OF STUDIES REVIEWED

The authors conducted a MEDLINE search using the key terms "Parkinson's disease," "medical management" and "dentistry." They selected contemporaneous articles published in peer-reviewed journals and gave preference to articles reporting randomized controlled trials.

RESULTS

PD is a progressive neurodegenerative disorder caused by loss of dopaminergic and nondopaminergic neurons in the brain. These deficits result in tremor, slowness of movement, rigidity, postural instability and autonomic and behavioral dysfunction. Treatment consists of administering medications that replace dopamine, stimulate dopamine receptors and modulate other neurotransmitter systems.

CLINICAL IMPLICATIONS

Oral health may decline because of tremors, muscle rigidity and cognitive deficits. The dentist should consult with the patient's physician to establish the patient's competence to provide informed consent and to determine the presence of comorbid illnesses. Scheduling short morning appointments that begin 90 minutes after administration of PD medication enhances the patient's ability to cooperate with care. Inclination of the dental chair at 45 degrees, placement of a bite prop, use of a rubber dam and high-volume oral evacuation enhance airway protection. To avoid adverse drug interactions with levodopa and entacapone, the dentist should limit administration of local anesthetic agents to three cartridges of 2 percent lidocaine with 1:100,000 epinephrine per half hour, and patients receiving selegiline should not be given agents containing epinephrine or levonordefrin. The dentist should instruct the patient and the caregiver in good oral hygiene techniques.

Gustatory and olfactory function in patients with unipolar and bipolar depression

Although the crucial distinction between unipolar depressive disorder and bipolar disorder is the presence of mania (or hypomania) in the course of the latter, significant differences between unipolar and bipolar depression have also been found in clinical studies. The primary aim of the present investigation was to assess pleasantness/unpleasantness ratings of chemosensory stimuli in depressed patients, including subjects with unipolar and bipolar depression. Sensory aspects (thresholds and identification abilities) of gustatory and olfactory function were also assessed. There were no major differences between a depression group, as a whole, and healthy controls in terms of gustatory and olfactory thresholds and identification abilities. Similarly, pleasantness ratings of various gustatory and olfactory stimuli did not differ between the control and depression group. Gustatory and olfactory thresholds and identification abilities did not differ between individuals with unipolar and bipolar depression. Bipolar patients tended to rate less gustatory stimuli as unpleasant and more olfactory stimuli as pleasant compared to unipolar patients. The present results suggest that: i) depression is not associated with any major deficit in sensory aspects of gustatory and olfactory function or altered hedonic ratings of chemosensory stimuli; ii) hedonic responses to chemosensory stimuli tend to be increased in bipolar as compared to unipolar depressed patients.

Chocolate consumption is increased in Parkinson's disease. Results from a self-questionnaire study

Clinical observations in Parkinson's disease (PD) patients suggested an increased chocolate consumption. Chocolate contains high contents of various biogenic amines potentially influencing brain monoamine metabolism. 498 PD patients and their partners were evaluated by a structured self-questionnaire asking for consumption of chocolate and non-chocolate sweets, changes in chocolate consumption during the disease course, and depressive symptoms. Questionnaires from 274 patients (55 %) and 234 controls were eligible for further analysis. Consumption of chocolate was significantly higher in PD patients compared to controls, while consumption of non-chocolate sweets was similar in both groups. Our study suggests that chocolate consumption is increased in PD independent of concomitant depressive symptoms measured by BDI-1. Although reasons for increased chocolate consumption in PD remain elusive, it may hypothetically be a consequence of the high content of various biogenic amines and/or caffeine analogues with potential antiparkinsonian effects.