Cardiac sympathetic degeneration correlates with olfactory function in Parkinson's disease

Correlation of olfactory function factors with cardiac sympathetic denervation in Parkinson's disease

BACKGROUND

Hyposmia is a common nonmotor symptom of Parkinson's disease (PD) and reportedly associated with dysautonomia in PD. The smell identification test for measuring olfactory function consists of multiple items to discriminate specific scents. In the present study, factor analysis of the smell identification test was performed, and the correlation of extracted factors with cardiac sympathetic denervation (CSD) in patients with PD was investigated.

METHODS

The present study included 183 early PD patients who underwent the Cross-Cultural Smell Identification Test (CC-SIT) and 123I-meta-iodobenzylguanidine (123I-MIBG) myocardial scintigraphy. Factor analysis of 12 items on the CC-SIT was performed using the computed correlation matrix for the binary items, and five smell factors were extracted. Multiple linear regression was performed to determine the correlation of olfactory function with late heart-to-mediastinum (H/M) ratio of 123I-MIBG uptake.

RESULTS

The mean CC-SIT score was 6.1 ± 2.6, and 133 patients (72.7%) had CSD. The CC-SIT score and five smell factors were not associated with dopamine transporter uptake or cognitive functions. However, the CC-SIT score significantly correlated with age (P < 0.001) and late H/M ratio (P < 0.001). Factors 1 and 5 showed an increasing trend with larger H/M ratio, although it was not statistically significant (β = 0.203, P = 0.085 and β = 0.230, P = 0.085, respectively). Factor 5 significantly correlated with the H/M ratio in PD patients with CSD (β = 0.676, P = 0.036).

DISCUSSION

The results showed olfactory dysfunction to be selectively associated with cardiac sympathetic burden in PD. The correlation of certain factors with CSD indicates the possibility of selective hyposmia in PD patients.

Vagus Nerve Ultrasonography Helps Distinguish Multiple System Atrophy from Other Parkinsonian Syndromes

Background

Distinguishing multiple system atrophy from other parkinsonian syndromes is challenging.

Objectives

To evaluate vagus nerve ultrasonography for differentiating parkinsonian syndromes.

Methods

A single-center, cross-sectional, observational study assessed 85 consecutive adult patients with de novo parkinsonism between June 2020 and December 2022, using 12 MHz ultrasonography of the vagus nerve cross-sectional area.

Results

Bilateral vagus nerves were smaller in multiple system atrophy than in other parkinsonian syndromes. The area under the receiver operating characteristic curve for differentiating multiple system atrophy was 0.79 on the right side and 0.74 on the left. The cut-off values to diagnose multiple system atrophy were 0.71 and 0.86 mm2 on the right and left sides, respectively, with sensitivities of 82.6% and 87.0%, specificities of 74.2% and 64.5%, positive predictive values of 54% and 47.6%, and negative predictive values of 92.0% and 93.0%.

Conclusions

Vagus nerve ultrasonography may differentiate multiple system atrophy from other parkinsonian syndromes.

Reduced 123I-MIBG uptake in the parotid and submandibular glands in patients with Parkinson's disease identified using a quantitative semi-automatic method

OBJECTIVES

To analyze 123I-metaiodobenzylguanidine (MIBG) uptake in the parotid and submandibular glands in patients with Parkinson's disease (PD) in comparison with controls, and to compare MIBG uptake between those glands and the myocardium. Furthermore, we aimed to identify the relationships between clinical features and MIBG uptake.

METHODS

We recruited 77 patients with PD and 21 age-matched controls. We assessed MIBG scintigraphy in the major salivary glands and myocardium. We calculated the MIBG uptake ratio in the parotid glands/mediastinum (P/M), submandibular glands/mediastinum (S/M), and heart/mediastinum (H/M) using a quantitative semi-automatic method. We investigated the correlations between MIBG uptake and clinical features.

RESULTS

The P/M and H/M ratios in the early and delayed phases were significantly reduced in PD patients compared to controls, while the delayed phase S/M ratio was reduced in PD patients compared to controls. The P/M ratio correlated with the S/M ratio, while neither the P/M nor S/M ratio correlated with the H/M ratio. Between PD patients and controls, sensitivity and specificity were 54.8% and 59.1% for the delayed phase P/M ratio, while sensitivity and specificity were 59.5% and 61.0% for the delayed phase S/M ratio, respectively. Furthermore, sensitivity and specificity for the delayed phase H/M ratio were 85.7% and 79.2, respectively.

CONCLUSION

MIBG uptake in the parotid and submandibular glands was reduced in patients with PD. Furthermore, sympathetic denervation in the major salivary glands and myocardium might progress independently. Our findings suggest a new aspect of the pathological distribution of PD.

A new systematic collection and classification of odour words by using a product review dataset

The odours encountered on a daily basis are dependent on an individual's society and culture. Therefore, when conducting olfactory tests, the odour stimuli utilized must be appropriate for the individual's environment. In this study, we gathered and classified the odours experienced by Japanese individuals in their daily lives through a large dataset of product reviews encompassing food and household items. Specifically, we performed morphological analysis on product review sentences in Japanese that contained odour descriptions, and we compiled the nouns used to describe odours. A total of 617,208 sentences that reviewed odour experiences and their corresponding nouns were collected. The top 100 frequently used odour nouns were classified into 15 clusters according to the context in which they were used. The methodology employed in collecting and classifying odour nouns as presented in this study can be utilized in other situations. It can assist in selecting appropriate odour stimuli for the olfactory test based on the society, culture, and time period.

Sleep-related hypoventilation and hypercapnia in multiple system atrophy detected by polysomnography with transcutaneous carbon dioxide monitoring

PURPOSE

We aimed to evaluate sleep-related hypoventilation in multiple system atrophy (MSA) using polysomnography (PSG) with transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring.

METHODS

This prospective study included 34 patients with MSA. Motor and autonomic function, neuropsychological tests, PSG with PtcCO2 monitoring, and pulmonary function tests were performed. Sleep-related hypoventilation disorder (SRHD) was defined according to the International Classification of Sleep Disorders, third edition.

RESULTS

Nine (27%) of the 34 patients met the diagnostic criteria of SRHD. Twenty-nine (85%) patients had sleep-related breathing disorders based on an Apnea-Hypopnea Index of ≥ 5/h. The patients with MSA and SRHD had a higher arousal index (p = 0.017) and obstructive apnea index (p = 0.041) than those without SRHD. There was no difference in the daytime partial pressure of carbon dioxide in arterial blood or respiratory function between MSA patients with and without SRHD.

CONCLUSION

Sleep-related hypoventilation may occur in patients with MSA even with a normal daytime partial pressure of carbon dioxide. This can be noninvasively detected by PSG with PtcCO2 monitoring. SRBD and sleep-related hypoventilation are common among patients with MSA, and clinicians should take this into consideration while evaluating and treating this population.

Smell tests can discriminate Parkinson's disease patients from healthy individuals: A meta-analysis

BACKGROUND

Olfactory impairment is common in Parkinson's disease (PD). The authors aimed to identify the clinical tests used to assess olfactory function and examine their ability to distinguish PD with different disease duration from healthy individuals with physiological aging.

METHODS

Cross-sectional studies published until May 2020 that assessed the olfaction of individuals with PD using search terms related to PD, olfactory function, and assessment were searched on PubMed, PsycInfo, Cinahl, and Web of Science databases.

RESULTS

Twelve smell tests were identified from the reviewed studies (n = 125) that assessed 8776 individuals with PD. Data of 6593 individuals with PD and 8731 healthy individuals were included in the meta-analyses. Individuals with PD presented worse performance than healthy individuals, regardless of the smell test used. The University of Pennsylvania Smell Identification Test (UPSIT) was used by most studies (n = 2310 individuals with PD) and presented smaller heterogeneity. When the studies were subclassified according to the years of PD duration, there were no significant differences.

CONCLUSION

All smell tests were able to discriminate the olfactory function of PD from that of healthy individuals, although the UPSIT was widely used. The abnormal olfaction was not related to the disease duration. Systematic review protocol registration (PROSPERO/2020-CRD42020160878).

Rapid Eye Movement Sleep Behavior Disorder: Abnormal Cardiac Image and Progressive Abnormal Metabolic Brain Pattern

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (iRBD) is prodromal for α-synucleinopathies.

OBJECTIVE

The aim of this study was to determine whether pathological cardiac [¹²³ I]meta-iodobenzylguanidine scintigraphy ([¹²³ I]MIBG) is associated with progression of [¹⁸ F]fluorodeoxyglucose-positron emission tomography-based Parkinson's disease (PD)-related brain pattern (PDRP) expression in iRBD.

METHODS

Seventeen subjects with iRBD underwent [¹⁸ F]fluorodeoxyglucose-positron emission tomography brain imaging twice ~3.6 years apart. In addition, [¹²³ I]MIBG and [¹²³ I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single-photon emission computed tomography ([¹²³ I]FP-CIT-SPECT) at baseline were performed. Olfactory, cognitive, and motor functions were tested annually.

RESULTS

Twelve of 17 subjects had pathological [¹²³ I]MIBG. At baseline, 6 of 12 of these expressed the PDRP (suprathreshold PDRP z score). At follow-up, 12 of 17 subjects had suprathreshold PDRP z scores, associated with pathological [¹²³ I]MIBG in 92% and with pathological [¹²³ I]FP-CIT-SPECT in 75%. Subjects with pathological [¹²³ I]MIBG had higher PDRP z score change per year (P = 0.027). Three subjects phenoconverted to PD; all had pathological [¹²³ I]MIBG and [¹²³ I]FP-CIT-SPECT, suprathreshold baseline PDRP z scores, and hyposmia.

CONCLUSIONS

Pathological [¹²³ I]MIBG was associated with progressive and suprathreshold PDRP z scores at follow-up. Abnormal [¹²³ I]MIBG likely identifies iRBD as prodromal PD earlier than pathological [¹²³ I]FP-CIT-SPECT. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Electrogastrography for diagnosis of early-stage Parkinson's disease

INTRODUCTION

Patients with Parkinson's disease (PD) often present with gastric symptoms. Electrogastrography (EGG) can noninvasively assess gastric electric activity and may be useful for early PD diagnosis. The present study aimed to compare the efficacy of EGG in early PD diagnosis with those of ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy and odor stick identification test -Japanese version (OSIT-J).

METHODS

Thirty-seven untreated PD patients (mean age ± SD, 66 ± 8years; disease duration < 3 years) and 20 healthy control subjects (68 ± 6.9 years) were recruited. EGG and OSIT-J were performed in both groups, and MIBG scintigraphy in the PD group. EGG parameters were assessed in the preprandial and early and late postprandial segments using power spectrum analysis.

RESULTS

Irregular EGG waves were observed in PD patients. The preprandial instability coefficient of dominant frequency (ICDF), an index of EGG irregularity, in PD patients (9.5% [6.3%]) was higher than that in controls (3.9% [3.9%], p = 0.00005). The OSIT-J score was also lower in PD patients (4.6 [3.3]) than in controls (7.7 [3.3], p = 0.006). In receiver operating characteristics analyses, the areas under the curves of preprandial ICDF and OSIT-J were 0.83 and 0.72, respectively. The sensitivities of preprandial ICDF and MIBG (delayed-phase) scintigraphy were 73% and 70%, respectively.

CONCLUSIONS

Early and untreated PD patients showed irregular EGG waves and high ICDF. EGG showed better accuracy than the olfactory test for early PD diagnosis and similar sensitivity to MIBG scintigraphy.

Is 123I-MIBG Scintigraphy Beneficial or Excessive for the Diagnosis of Parkinson's Disease in the Early Phase?

INTRODUCTION/OBJECTIVE

In most cases, abnormal cardiac 123I-meta-iodobenzylguanidine (MIBG) scintigraphy increases the probability of a diagnosis of Parkinson's disease (PD) in patients with parkinsonian features. In our study, we validated the additional value of 123I-MIBG scintigraphy beyond providing information on neurological findings and response to dopaminergic therapy for the diagnosis of PDin the early phase.

METHODS

We investigated 77 cases of PD (Hoehn and Yahr Stages I-III) and 73 cases of atypical parkinsonian disorder (APD), including 35 patients with multiple system atrophy, 19 with corticobasal syndrome, and 19 with progressive supranuclear palsy. Two multiple logistic regression models were developed to predict the probability of PD based on APD. Common covariates were resting tremor, vertical supranuclear palsy, apraxia, cerebellar symptoms, and response to dopaminergic therapy with MIBG scintigraphy (reference model) or without it (MIBG-added model). The net reclassification index (NRI) was examined and net benefit using decision curve analysis was performed to examine the additional clinical value of MIBG scintigraphy. Finally, we estimated the cost-effectiveness of MIBG scintigraphy.

RESULTS

The MIBG-added model significantly improved the ability to classify PD or APD compared with the reference model (NRI index 1.390, p < 0.001). However, the decision curve of the reference model ranked equally with the MIBG-added model up to a risk threshold of 0.8. In addition, MIBG scintigraphy was not cost-effective.

CONCLUSIONS

Although MIBG scintigraphy has statistical usefulness for PD diagnosis, there may be little additional benefit in the early phase of PD beyond the neurological findings and response to dopaminergic therapy regarding clinical effectiveness and cost-effectiveness. It may be of greatest value when neurological findings that do not match PD are observed during the clinical course.

Association between autonomic dysfunction and olfactory dysfunction in Parkinson's disease in southern Chinese

BACKGROUND

The aim was to investigate the autonomic dysfunction between Parkinson's disease (PD) patients with olfactory dysfunction and PD patients without olfactory dysfunction in southern Chinese population.

METHODS

Fifty-six PD patients with olfactory dysfunction and 44 patients without olfactory dysfunction were included. All patients were evaluated by Sniffin' sticks (SS-16), scales for outcomes in Parkinson's disease-autonomic questionnaire, Hamilton anxiety rating scale and Hamilton depression rating scale RESULTS: The score of subpart of gastrointestinal symptoms and subpart of urinary symptoms were different in two groups (gastrointestinal symptoms: p value: 0.024; urinary symptoms: p value: 0.008). As for each question items, questions 2, 8, 10, 11, 13, 14 were correlated with SS-16 scores (Question 2: p value: 0.013; question 6: p value: 0.006; question 8: p value: 0.025; question 10: p value: 0.005; question 11: p value: 0.022; question 13: p value: < 0.001; question 14: p value: 0.038). Question 10 and 14 were associated with olfactory dysfunction after adjusting disease duration and gender (Question 10: p value: 0.011, OR: 3.91; Question 14: p value: 0.027, OR: 3.27).

CONCLUSIONS

Gastrointestinal, urinary and a part of cardiovascular symptoms of SCOPA-AUT were associated with olfactory dysfunction in PD patients.

A refined concept: α-synuclein dysregulation disease

α-synuclein (αSyn) still remains a mysterious protein even two decades after SNCA encoding it was identified as the first causative gene of familial Parkinson's disease (PD). Accumulation of αSyn causes α-synucleinopathies including PD, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Recent advances in therapeutic approaches offer new antibody-, vaccine-, antisense-oligonucleotide- and small molecule-based options to reduce αSyn protein levels and aggregates in patient's brain. Gathering research information of other neurological disease particularly Alzheimer's disease, recent disappointment of an experimental amyloid plaques busting antibody in clinical trials underscores the difficulty of treating people who show even mild dementia as damage in their brain may already be too extensive. Prodromal intervention to inhibit the accumulation of pathogenic protein may advantageously provide a better outcome. However, treatment prior to onset is not ethically justified as standard practice at present. In this review, we initiate a refined concept to define early pathogenic state of αSyn accumulation before occurrence of brain damage as a disease criterion for αSyn dysregulation disease.

Neuropathology of Nonmotor Symptoms of Parkinson's Disease

Parkinson's disease (PD), a multiorgan neurodegenerative disorder associated with α-synuclein deposits throughout the nervous system and many organs, is clinically characterized by motor and nonmotor features, many of the latter antedating motor dysfunctions by 20 or more years. The causes of the nonmotor manifestations such as olfactory, autonomic, sensory, neuropsychiatric, visuospatial, sleep, and other disorders are unlikely to be related to single lesions. They are mediated by the involvement of both dopaminergic and nondopaminergic systems, and diverse structures outside the nigrostriatal system that is mainly responsible for the motor features of PD. The nonmotor alterations appear in early/prodromal stages of the disease and its further progression, suggesting a topographical and chronological spread of the lesions. This lends further support for the notion that PD is a multiorgan proteinopathy, although the exact relationship between presymptomatic and later developing nonmotor features of PD and neuropathology awaits further elucidation.

Usefulness of Cardiac MIBG Scintigraphy, Olfactory Testing and Substantia Nigra Hyperechogenicity as Additional Diagnostic Markers for Distinguishing between Parkinson's Disease and Atypical Parkinsonian Syndromes

Background

We aimed to evaluate the utility of the combined use of cardiac ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy, olfactory testing, and substantia nigra (SN) hyperechogenicity on transcranial sonography (TCS) in differentiating Parkinson’s disease (PD) from atypical parkinsonian syndromes (APSs), such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP).

Methods

Cardiac MIBG scintigraphy, card-type odor identification testing (Open Essence (OE), Wako, Japan), and TCS were performed with 101 patients with PD and 38 patients with APSs (MSA and PSP). Receiver operating characteristic (ROC) curve analysis was used to assess the sensitivity and specificity of these batteries for diagnosing PD from APSs. The diagnostic accuracy of the three tests was also assessed among patients at the early disease stage (drug-naïve patients with a disease duration of 3 years or less).

Results

In differentiating PD from APSs, the area under the ROC curve was 0.74 (95% CI, 0.65–0.83), 0.8 (95% CI, 0.73–0.87), and 0.75 (95% CI, 0.67–0.82) for TCS, cardiac MIBG scintigraphy, and olfactory testing, respectively. The diagnostic sensitivity and specificity were 53.1% and 91.7%, respectively, for TCS, 70.3% and 86.8%, respectively, for cardiac MIBG scintigraphy, 58.4% and 76.3%, respectively, for OE. Among early-stage patients, sensitivity and specificity were 50.0% and 93.8%, respectively, for TCS, 57.1% and 87.5%, respectively, for cardiac MIBG scintigraphy, and 54.8% and 79.2%, respectively, for OE. At least one positive result from 3 tests improved sensitivity (86.1%) but decreased specificity (63.2%). In contrast, at least 2 positive results from 3 tests had good discrimination for both early-stage patients (50.0% sensitivity and 93.8% specificity) and patients overall (57.8% sensitivity and 95.8% specificity). Positive results for all 3 tests yielded 100% specificity but low sensitivity (25%).

Conclusions

At least 2 positive results from among TCS, cardiac MIBG scintigraphy, and olfactory testing can support clinical diagnosis in distinguishing PD from APSs.

(123)I-meta-iodobenzylguanidine (MIBG) cardiac scintigraphy in α-synucleinopathies

Cardiac meta-iodobenzylguanidine (MIBG) uptake on (123)I-MIBG cardiac scintigraphy is reduced in patients with Lewy body disease such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and pure autonomic failure, and has been reported to be useful for differentiating PD from other parkinsonian syndromes, as well as DLB from Alzheimer disease (AD). Postmortem studies have shown that the number of tyrosine hydroxylase (TH)-immunoreactive nerve fibers of the heart was decreased in pathologically-confirmed Lewy body disease, supporting the findings of reduced cardiac MIBG uptake in Lewy body diseases. Now, reduced cardiac MIBG uptake can be a potential biomarker for the presence of Lewy bodies in the nervous system. (123)I-MIBG cardiac scintigraphy can allow us to determine the presence of Lewy bodies.

Neuropathobiology of non-motor symptoms in Parkinson disease

Parkinson disease (PD) is a multisystem disorder associated with α-synuclein aggregates throughout the central, autonomic, and peripheral nervous system, clinically characterized by motor and non-motor (NM) symptoms. The NMS in PD, many of which antedating motor dysfunction and representing a preclinical phase spanning 20 or more years, are linked to widespread distribution of α-synuclein pathology not restricted to the dopaminergic nigrostriatal system that is responsible for core motor features of PD. The pathologic substrate of NM manifestations such as olfactory, autonomic (gastrointestinal, urogenital, cardia, respiratory), sensory, skin, sleep, visual, neuropsychiatric dysfunctions (cognitive, mood, dementia), and others are critically reviewed. In addition to non-nigral brainstem nuclei, α-synuclein pathology involves sympathetic and parasympathetic, enteric, cardiac and pelvic plexuses, and many other organs indicating a topographical and chronological spread, particularly in the prodromal stages of the disease. Few animal models recapitulate NMS in PD. The relationship between regional α-synuclein/Lewy pathology, neurodegeneration and the corresponding clinical deficits awaits further elucidation. Controlled clinicopathologic studies will refine the correlations between presymptomatic and late-developing NM features of PD and neuropathology, and new premotor biomarkers will facilitate early diagnosis of PD as a basis for more effective preventive and therapeutic options of this devastating disease.

Relationship and factor structure in multisystem neurodegeneration in Parkinson's disease

OBJECTIVES

Parkinson's disease (PD) is a multisystem neurodegenerative disease. We aimed to identify the relationship and factor structure among its different features.

MATERIALS & METHODS

Motor, olfactory and cognitive function, and cardiac sympathetic denervation were evaluated in 125 patients with PD using the Unified Parkinson's Disease Rating Scale (UPDRS) part III score, odor stick identification test for the Japanese (OSIT-J), Mini-Mental State Examination (MMSE), and [(123) I] meta-iodobenzylguanidine (MIBG) cardiac scintigraphy (heart-to-mediastinum (H/M) ratio). Pearson's correlation and multiple regression analysis were used to evaluate the association among the four measures with age, gender, and disease duration as the covariates. Exploratory factor analysis was used to identify the underlying factor structure among the measures and covariates.

RESULTS

Pearson's correlation and multiple regression analysis showed correlations between OSIT-J score and MIBG H/M ratio, OSIT-J and MMSE scores, UPDRS part III score and MIBG H/M ratio, UPDRS part III score and disease duration, and MMSE score and age. Factor analysis identified three factors: (i) age and MMSE score; (ii) MIBG H/M ratio and OSIT-J score; and (iii) UPDRS part III score and disease duration.

CONCLUSIONS

Our results suggest that aging, PD-related pathogenesis, and disease duration underlie the multisystem neurodegeneration present in PD. Moreover, age and disease duration are the major risk factors for cognitive impairment and motor symptoms, respectively. Olfactory impairment and cardiac sympathetic denervation are strongly associated in PD.

[A case report of Parkinson's disease presenting with olfactory disturbance as a primary symptom in the early stage]

We report herein on a 71 year-old male who presented with olfactory disturbance at the early stage of Parkinson's disease (PD). Due to a persistent olfactory disturbance for 5 years, the patient visited our clinic and showed disorientation between the olfactory detection threshold and recognition in T&T olfactometry and scored 3 out of 12 points in OE. During the follow-up period, the typical symptoms of PD, including mask-like face and motor disturbance emerged, which led to the diagnosis of PD by the neurologist. Since it is generally accepted that olfactory disturbance precedes the appearance of motor disturbance in the early stage of PD, otolaryngologists should be aware of the necessity of olfactory tests for the patients with reported persistent olfactory disturbance, especially in elderly patients. In those cases where the patients present positive findings in olfactory tests without any particular cause, referral to neurologists is recommended.

Olfactory bulb involvement in neurodegenerative diseases

Olfactory dysfunction is a common and early symptom of many neurodegenerative diseases, particularly of Parkinson's disease and other synucleinopathies, Alzheimer's disease (AD), and mild cognitive impairment heralding its progression to dementia. The neuropathologic changes of olfactory dysfunction in neurodegenerative diseases may involve the olfactory epithelium, olfactory bulb/tract, primary olfactory cortices, and their secondary targets. Olfactory dysfunction is related to deposition of pathological proteins, α-synuclein, hyperphosphorylated tau protein, and neurofilament protein in these areas, featured by neurofibrillary tangles, Lewy bodies and neurites inducing a complex cascade of molecular processes including oxidative damage, neuroinflammation, and cytosolic disruption of cellular processes leading to cell death. Damage to cholinergic, serotonergic, and noradrenergic systems is likely involved, since such damage is most marked in those diseases with severe anosmia. Recent studies of olfactory dysfunction have focused its potential as an early biomarker for the diagnosis of neurodegenerative disorders and their disease progression. Here, we summarize the current knowledge on neuropathological and pathophysiological changes of the olfactory system in the most frequent neurodegenerative diseases, in particular AD and synucleinopathies. We also present neuropathological findings in the olfactory bulb and tract in a large autopsy cohort (n = 536, 57.8 % female, mean age 81.3 years). The severity of olfactory bulb HPτ, Aβ, and αSyn pathology correlated and increased significantly (P < 0.001) with increasing neuritic Braak stages, Thal Aβ phases, and cerebral Lewy body pathology, respectively. Hence, further studies are warranted to investigate the potential role of olfactory biopsies (possibly restricted to the olfactory epithelium) in the diagnostic process of neurodegenerative diseases in particular in clinical drug trials to identify subjects showing early, preclinical stages of neurodegeneration and to stratify clinically impaired cohorts according to the underlying cerebral neuropathology.

Hyposmia and cardiovascular dysautonomia correlatively appear in early-stage Parkinson's disease

OBJECTIVE

Olfactory dysfunction is considered to precede motor symptoms and early markers of Parkinson's disease (PD), while the relative time at which cardiovascular dysautonomia appears in PD is not well understood. To assess the appearance of cardiovascular dysautonomia in PD, we evaluated its relation to olfactory dysfunction in early-stage PD patients.

METHODS

Twenty-three non-demented PD patients within 2 years from the onset of motor symptoms were enrolled. We evaluated olfactory dysfunction by the Odor Stick Identification Test for Japanese (OSIT-J) and analyzed its relationship to the results of other cardiovascular autonomic tests and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphy.

RESULTS

There was a correlation between olfactory scores and increased blood pressure in both the norepinephrine (r = 0.75, p < 0.0001, n = 21) and dobutamine (r = 0.57, p = 0.0087, n = 20) infusion tests and cardiac MIBG uptake (r = 0.42, p = 0.049, n = 23). The fall in orthostatic blood pressure during the head-up tilt test was not correlated with the olfactory scores, but the Valsalva maneuver revealed that OSIT-J scores correlated with the pressure recovery time from phase III to the return of blood pressure to baseline (r = 0.54, p = 0.037, n = 15) and with the magnitude of blood pressure overshoot during phase IV (r = 0.67, p = 0.0016, n = 20).

CONCLUSION

Our results demonstrate that extensive components of the cardiovascular sympathetic system as well as the olfactory system are correlatively impaired in the early stage of PD, suggesting that degeneration of broad aspects of the cardiovascular sympathetic system occurs concurrently with olfactory system degeneration during the premotor phase of PD.

EFNS/MDS-ES/ENS [corrected] recommendations for the diagnosis of Parkinson's disease

BACKGROUND

A Task Force was convened by the EFNS/MDS-ES Scientist Panel on Parkinson's disease (PD) and other movement disorders to systemically review relevant publications on the diagnosis of PD.

METHODS

Following the EFNS instruction for the preparation of neurological diagnostic guidelines, recommendation levels have been generated for diagnostic criteria and investigations.

RESULTS

For the clinical diagnosis, we recommend the use of the Queen Square Brain Bank criteria (Level B). Genetic testing for specific mutations is recommended on an individual basis (Level B), taking into account specific features (i.e. family history and age of onset). We recommend olfactory testing to differentiate PD from other parkinsonian disorders including recessive forms (Level A). Screening for pre-motor PD with olfactory testing requires additional tests due to limited specificity. Drug challenge tests are not recommended for the diagnosis in de novo parkinsonian patients. There is an insufficient evidence to support their role in the differential diagnosis between PD and other parkinsonian syndromes. We recommend an assessment of cognition and a screening for REM sleep behaviour disorder, psychotic manifestations and severe depression in the initial evaluation of suspected PD cases (Level A). Transcranial sonography is recommended for the differentiation of PD from atypical and secondary parkinsonian disorders (Level A), for the early diagnosis of PD and in the detection of subjects at risk for PD (Level A), although the technique is so far not universally used and requires some expertise. Because specificity of TCS for the development of PD is limited, TCS should be used in conjunction with other screening tests. Conventional magnetic resonance imaging and diffusion-weighted imaging at 1.5 T are recommended as neuroimaging tools that can support a diagnosis of multiple system atrophy (MSA) or progressive supranuclear palsy versus PD on the basis of regional atrophy and signal change as well as diffusivity patterns (Level A). DaTscan SPECT is registered in Europe and the United States for the differential diagnosis between degenerative parkinsonisms and essential tremor (Level A). More specifically, DaTscan is indicated in the presence of significant diagnostic uncertainty such as parkinsonism associated with neuroleptic exposure and atypical tremor manifestations such as isolated unilateral postural tremor. Studies of [(123) I]MIBG/SPECT cardiac uptake may be used to identify patients with PD versus controls and MSA patients (Level A). All other SPECT imaging studies do not fulfil registration standards and cannot be recommended for routine clinical use. At the moment, no conclusion can be drawn as to diagnostic efficacy of autonomic function tests, neurophysiological tests and positron emission tomography imaging in PD.

CONCLUSIONS

The diagnosis of PD is still largely based on the correct identification of its clinical features. Selected investigations (genetic, olfactory, and neuroimaging studies) have an ancillary role in confirming the diagnosis, and some of them could be possibly used in the near future to identify subjects in a pre-symptomatic phase of the disease.

Olfactory dysfunction and parasympathetic dysautonomia in Parkinson's disease

OBJECTIVE

Olfactory impairment occurs early in Parkinson’s disease (PD), as may dysautonomia. We investigated the relationship between olfaction and dysautonomia as well as other non-motor manifestations of PD.

METHODS

Olfaction [University of Pennsylvania Smell Identification Test (UPSIT)], autonomic function in the pupillary (constriction and redilation velocity) and cardiac systems (resting low- and high-frequency heart rate variability (LF and HF HRV), positional changes in systolic blood pressure), neuropsychiatric function [Mini-mental Status Exam (MMSE)], Hamilton Depression Scale, activities of daily living [(ADLs), Schwab and England ADLs scale], quality of life [Short Form-36 health survey, PD Questionnaire 39 (PDQ-39)], and other non-motor symptoms [Non-motor Symptoms Scale (NMSS)] were simultaneously assessed in 33 participants (15 PD, 18 controls). Group comparisons, Spearman’s coefficients and non-parametric rank-based regression were employed to characterize relationships between olfaction and non-motor features.

RESULTS

Smell scores were lower in the PD group and correlated positively with pupil constriction velocity and HF HRV. Smell scores were correlated negatively with PDQ-39 and gastrointestinal items of the NMSS and positively with MMSE and Schwab and England ADLs. These correlated measures were not significant terms in regression models of smell scores in which age and PD diagnosis were significant and accounted for over half of the variability (R-squared 0.52–0.58).

INTERPRETATION

This study suggests olfactory involvement occurs with parasympathetic dysautonomia in the pupillary and cardiovascular systems, involving both age-related and PD-related processes. Other non-motor features are concurrently involved, supporting the notion that aging and PD have widespread effects involving discrete portions of the autonomic and olfactory systems.

Olfactory loss as a supporting feature in the diagnosis of Parkinson's disease: a pragmatic approach

There is ample evidence from a large number of clinical and pathological studies of an early involvement of olfactory bulbs and cortex in the Lewy body pathology in idiopathic Parkinson's disease (iPD), the olfactory system being one of the first targets of degeneration in this condition. The olfactory dysfunction may be measurably present at the time of initial presentation and progresses in a proportion of patients as the disease advances. Patients with iPD have a more severe olfactory loss as compared to multisystem atrophy whereas the syndromes of corticobasal degeneration and progressive supranuclear palsy have no olfactory loss. A proportion of drug induced parkinsonism may have olfactory loss indicative of primary pathology of dopaminergic degeneration in these patients. Unlike single photon emission tomography, formal measurement of olfaction would provide a supportive role in diagnosing or excluding iPD depending on the duration of an individual patient's parkinsonian symptoms. Whilst olfaction may be only minimally impaired in early stages and may thus not help to differentiate from other syndromes, an intact olfaction in patients with parkinsonism of few years' duration would indicate a non-iPD pathology. Olfactory measurement is easy, cheap and now easily available in a number of tests, and olfactory assessment at different stages of parkinsonism should be used as a diagnostic aid for idiopathic PD and would enhance the diagnostic accuracy of iPD when used in conjunction with the UK Parkinson's disease society Brain Bank supportive criteria for diagnosis of idiopathic Parkinson's disease.

Identifying prodromal Parkinson's disease: pre-motor disorders in Parkinson's disease

Increasing recognition that Parkinson's disease (PD) may start outside of the substantia nigra has led to a rapidly expanding effort to define prodromal stages of PD, before motor signs permit classical diagnosis. Many of these efforts center around the identification of clinical non-motor symptoms and signs of disease. There is now direct evidence that olfaction, rapid eye movement (REM) sleep behavior disorder (RBD), constipation, and depression can be present in prodromal PD. In addition, there is suggestive evidence that visual changes, other autonomic symptoms, and subtle cognitive changes may also be present at prodromal stages. A critical issue in utility of these prodromal markers will be assessment of sensitivity, specificity, and positive and negative predictive values. Although these have yet to be fully defined, olfactory deficits, some visual changes, and autonomic symptoms occur in the majority of PD patients at diagnosis, suggesting good potential sensitivity. However, with the exception of RBD and perhaps some specific autonomic measures, specificity, and positive predictive value of these markers may be insufficient to be used alone as identifiers of prodromal disease. The evidence for the utility of olfaction, RBD, autonomic markers, visual changes, mood disorders, and cognitive loss as markers of prodromal PD and the potential sensitivity and specificity of these markers are summarized.

The odor stick identification test for Japanese differentiates Parkinson's disease from multiple system atrophy and progressive supra nuclear palsy

Background

Progressive supranuclear palsy (PSP) and parkinsonian variant of multiple system atrophy (MSA-P) are clinically difficult to differentiate from idiopathic Parkinson's disease (PD), particularly in the early stages of the disease. Previous reports indicated that the olfactory function is relatively intact or slightly reduced in patients with PSP and MSA-P, suggesting that the odor stick identification test for Japanese (OSIT-J), which is a short and simple noninvasive test that is potentially useful clinically for detecting early-stage PD in Japan, may be useful in the differential diagnosis of early-stage PD from MSA-P and PSP. There is no information on the sensitivity and specificity of OSIT-J in the diagnosis of parkinsonian syndromes such as PSP and MSA-P.

Methods

We assessed the olfactory function using the OSIT-J test in 94 Japanese patients with idiopathic PD, 15 with MSA-P, 7 with PSP, and 29 age-matched control subjects.

Results

The mean ± SD score of OSIT-J in patients with PD (4.4 ± 2.9) was significantly lower than in patients with MSA-P (8.7 ± 2.2, P < 0.0001), PSP (7.6 ± 2.2, P < 0.0057), and control subjects (10.5 ± 1.3, P < 0.0001). The area under the curve (AUC) of receiver operating characteristic (ROC) to discriminate PD from normal control using OSIT-J scores was 0.97 (95% confidence interval, 0.95-1.00), from MSA-P 0.87 (0.80-0.95), and from PSP 0.81 (0.66-0.96).

Conclusion

The OSIT-J is a potentially useful clinical test not only for detection of olfactory deficit in PD but also for differentiating PD from MSA-P and PSP.

Biomarkers of Parkinson's disease and Dementia with Lewy bodies

Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are progressive and disabling neurodegenerative disorders, in which signs and symptoms overlap with each other and with other neurodegenerative conditions. Currently, diagnosis, measurement of progression, and response to therapeutic intervention rely upon clinical observation. However, there remains a critical need for validated biomarkers in each of these areas. A definitive diagnostic test would improve clinical management and enrollment into clinical trials. An objective measure of progression is vitally important in identifying neuroprotective interventions. Biomarkers may also provide insight into pathogenesis, and might therefore suggest possible novel targets for therapeutic intervention. In addition, certain biomarkers might be of use in monitoring the biochemical and physiological effects of therapeutic interventions. Development of diagnostic biomarkers has focused until recently upon imaging techniques based upon measuring loss of dopamine neurons. Additionally, advances in understanding the genetic contribution to neurodegenerative disorders, in particular in PD, have identified multiple causative genes and risk factors that in some cases may help estimate PD risk. However, recent availability of increasingly sophisticated bioinformatics technology has rendered development of fluid biomarkers feasible, opening the possibility of generally accessible blood or cerebrospinal fluid (CSF) tests that could impact upon diagnosis, management, and research in PD, PDD, and DLB.

Differences in odor identification among clinical subtypes of Parkinson's disease

OBJECTIVE

Olfactory dysfunction is a non-motor symptom in idiopathic Parkinson's disease (PD). We investigated whether this dysfunction differs among clinical subtypes of PD.

METHODS

Participants comprised of 90 patients with idiopathic PD and without dementia. Olfactory function was evaluated using the odor stick identification test for Japanese, which evaluated the detection of 12 odorants familiar to Japanese participants. Patients were divided into tremor-dominant type (TDT), akinetic-rigid type (ART), and mixed type (MXT) PD subgroups using part III of the Unified Parkinson's Disease Rating Scale.

RESULTS

Fifty-five patients were classified as ART, 21 as MXT, and 14 as TDT. There were no differences in age, sex, or duration of illness among the subtypes. Subjective symptoms of impaired sense of smell were significantly higher (P<0.05) in the ART than in the TDT. Mean odor identification score was 4.3 in the ART, 5.2 in MXT, and 6.6 in TDT. It was significantly lower in the ART than in the TDT (P<0.01).

CONCLUSION

Olfactory dysfunction differed among the clinical subtypes of PD. This suggests that olfactory function might relate to prognosis of patients with PD.

Olfactory dysfunction is associated with neuropsychiatric manifestations in Parkinson's disease

Hyposmia, psychiatric disorders, and cognitive problems are common nonmotor manifestations in Parkinson's disease, but how they are related remains unclear. We investigated the relationship between olfactory dysfunction and neuropsychiatric manifestations and performed a cross-sectional study of 248 patients at two movement disorders clinics at academic medical centers. Psychiatric measures were the Geriatric Depression Scale-15, Inventory of Depressive Symptomatology, State Anxiety Inventory, Apathy Scale, and Parkinson's Psychosis Rating Scale. Cognitive measures were the Mini-Mental State Examination, Hopkins Verbal Learning Test-Revised, Digit Span, Tower of London-Drexel, and the Stroop Color Word Test. Olfaction was tested with the University of Pennsylvania Smell Identification Test. There was no significant association between olfaction and mood measures, but psychotic symptoms were more common in patients with olfaction scores below the median (30% vs. 12%; P < 0.001). Worse olfaction was associated with poorer memory (Hopkins Verbal Learning Test-Revised delayed recall items: mean [standard deviation], 6.2 [3.2] vs. 8.4 [2.8]; P < 0.001) and executive performance (Tower of London total moves, 52 [38] vs. 34 [21]; P < 0.001). Odor-identification score was a significant predictor of abnormal performance on these cognitive tests after adjustment for age, sex, and disease characteristics in logistic regression models. The relationship between hyposmia, psychosis, and specific cognitive impairments may reflect the anatomic distribution of Lewy pathology and suggests that olfactory dysfunction could be a biomarker of additional extranigral disease. Future prospective studies are warranted to assess whether hyposmia, a very early feature of Parkinson's disease, might be used to predict the appearance of other common nonmotor symptoms.

Idiopathic REM Sleep Behavior Disorder: Implications for the Pathogenesis of Lewy Body Diseases

Objectives. Both results of the odor identification and cardiac (123)I-metaiodobenzylguanidine accumulation have been investigated for their potential to enhance the detection of pathogenesis resembling that of Lewy body-related α-synucleinopathies in patients clinically diagnosed as having idiopathic REM sleep behavior disorder. Methods. We performed both the Odor Stick Identification Test for Japanese and (123)I-metaiodobenzylguanidine scintigraphy in 30 patients with idiopathic REM sleep behavior disorder, 38 patients with Parkinson's disease, and 20 control subjects. Results. In idiopathic REM sleep behavior disorder, reduced odor identification score and an early or delayed heart to mediastinum ratio on (123)I-metaiodobenzylguanidine were almost as severe as in Parkinson's disease patients. Delayed cardiac (123)I-metaiodobenzylguanidine uptake was even more severe in the idiopathic REM sleep behavior disorder group than in the Parkinson's disease group. Conclusions. Reduced cardiac (123)I-metaiodobenzylguanidine uptake, which is independent of parkinsonism, may be more closely associated with idiopathic REM sleep behavior disorder than olfactory impairment.

123I-MIBG cardiac uptake and smell identification in parkinsonian patients with LRRK2 mutations

Reduced uptake of (123)I- metaiodobenzylguanidine (MIBG) on cardiac gammagraphy and impaired odor identification are markers of neurodegenerative diseases with Lewy bodies (LB) as a pathological hallmark, such as idiopathic Parkinson's disease (IPD). LRRK2 patients present with a clinical syndrome indistinguishable from IPD, but LB have not been found in some cases. Patients with such mutations could behave differently than patients with IPD with respect to MIBG cardiac uptake and olfaction. We studied 14 LRRK2 patients, 14 IPD patients matched by age, gender, disease duration and severity, and 13 age and gender matched control subjects. Olfaction was analyzed through the University of Pennsylvania Smell Identification Test (UPSIT). MIBG cardiac uptake was evaluated through the H/M ratio. The late H/M was 1.44 ± 0.31 for LRRK2 patients, 1.19 ± 0.15 for PD patients, and 1.67 ± 0.16 for control subjects. LRRK2 patients presented lower but not statistically significant MIBG cardiac uptake than controls (p = 0.08) and significant higher uptake than PD patients (p = 0.04). UPSIT mean scores were 21.5 ± 7.3 for LRRK2 patients, 18.7 ± 6.2 for IPD patients and 29.7 ± 5.7 for control subjects. UPSIT score was lower in both LRRK2 and PD than in controls. In LRRK2 patients a positive correlation was found between myocardial MIBG uptake and UPSIT scores, (R = 0.801, p < 0.001). In LRRK2 patients, MIBG cardiac uptake was less impaired than in PD; a positive correlation between MIBG cardiac uptake and UPSIT scores was observed. As MIBG cardiac reduced uptake and impaired odor identification are markers of LB pathology, this findings may represent neuropathological heterogeneity among LRRK2 patients.