Relationship between 123I-MIBG scintigrams and REM sleep behavior disorder in Parkinson’s disease

Urodynamic study and its correlation with cardiac meta-iodobenzylguanidine (MIBG) in body-first and brain-first subtypes of Parkinson's disease

BACKGROUND AND PURPOSE

Lower urinary tract symptoms (LUTS) are frequently observed in patients with Parkinson's disease (PD), but the underlying mechanism remains elusive. The concept of "body-first" and "brain-first" subtypes in PD has been proposed, but the correlation of PD subtype with LUTS remains unclear. We aimed to investigate the disparities in urological dysfunctions between body-first and brain-first subtypes of PD using urodynamic studies (UDS).

METHODS

We reviewed patients with PD (disease duration <3 years) who had undergone UDS and completed urological questionnaires (Overactive Bladder Symptom Score [OABSS] and International Prostate Symptom Score [IPSS]) and a voiding diary. Patients were categorized as having body-first or brain-first PD based on cardiac sympathetic denervation (CSD) using cardiac meta-iodobenzylguanidine (MIBG) uptake and the presence of rapid eye movement sleep behavior disorder (RBD), assessed using a questionnaire (PD with CSD and RBD indicating the body-first subtype).

RESULTS

A total of 55 patients with PD were categorized into body-first PD (n = 37) and brain-first PD (n = 18) groups. The body-first PD group exhibited smaller voiding volume and first desire volume (FDV) than the brain-first PD group (p < 0.05 in both). Also, the body-first PD group had higher OABSS and IPSS scores, and higher prevalence of overactive bladder diagnosed by OABSS, compared to the brain-first PD group. In multiple linear regression, cardiac MIBG uptake was positively correlated with FDV and voiding volume and negatively correlated with OABSS and IPSS (p < 0.05 in all).

CONCLUSIONS

Patients with the body-first PD subtype exhibited more pronounced overactive bladder symptoms and impaired storage function in the early stage of disease. Additionally, cardiac MIBG was significantly associated with urological dysfunction.

Research Progress on the Relationship between Parkinson's Disease and REM Sleep Behavior Disorder

An individual's quality of life is greatly affected by Parkinson's disease (PD), a prevalent neurological degenerative condition. Rapid eye movement (REM) sleep behavior disorder (RBD) is a prominent non-motor symptom commonly associated with PD. Previous studies have shown a close relationship between PD and RBD. In addition to being a prodromal symptom of PD, RBD has a major negative impact on the prognosis of PD patients. This intrinsic connection indicates that there is a bidirectional relationship between PD and RBD. This paper provides a comprehensive review of the pathological mechanism related to PD and RBD, including the α-synuclein pathological deposition, abnormal iron metabolism, neuroinflammation, glymphatic system dysfunction and dysbiosis of the gut microbiota. Increasing evidence has shown that RBD patients have the same pathogenic mechanisms that underlie PD, but relatively little research has been done on how RBD contributes to PD progression. Therefore, a more thorough investigation is warranted to characterise how RBD affects the course of PD, in order to prepare for future therapeutic trials.

Cholinergic changes in Lewy body disease: implications for presentation, progression and subtypes

Cholinergic degeneration is significant in Lewy body disease, including Parkinson's disease, dementia with Lewy bodies, and isolated REM sleep behaviour disorder. Extensive research has demonstrated cholinergic alterations in the CNS of these disorders. More recently, studies have revealed cholinergic denervation in organs that receive parasympathetic denervation. This enables a comprehensive review of cholinergic changes in Lewy body disease, encompassing both central and peripheral regions, various disease stages and diagnostic categories. Across studies, brain regions affected in Lewy body dementia show equal or greater levels of cholinergic impairment compared to the brain regions affected in Lewy body disease without dementia. This observation suggests a continuum of cholinergic alterations between these disorders. Patients without dementia exhibit relative sparing of limbic regions, whereas occipital and superior temporal regions appear to be affected to a similar extent in patients with and without dementia. This implies that posterior cholinergic cell groups in the basal forebrain are affected in the early stages of Lewy body disorders, while more anterior regions are typically affected later in the disease progression. The topographical changes observed in patients affected by comorbid Alzheimer pathology may reflect a combination of changes seen in pure forms of Lewy body disease and those seen in Alzheimer's disease. This suggests that Alzheimer co-pathology is important to understand cholinergic degeneration in Lewy body disease. Thalamic cholinergic innervation is more affected in Lewy body patients with dementia compared to those without dementia, and this may contribute to the distinct clinical presentations observed in these groups. In patients with Alzheimer's disease, the thalamus is variably affected, suggesting a different sequential involvement of cholinergic cell groups in Alzheimer's disease compared to Lewy body disease. Patients with isolated REM sleep behaviour disorder demonstrate cholinergic denervation in abdominal organs that receive parasympathetic innervation from the dorsal motor nucleus of the vagus, similar to patients who experienced this sleep disorder in their prodrome. This implies that REM sleep behaviour disorder is important for understanding peripheral cholinergic changes in both prodromal and manifest phases of Lewy body disease. In conclusion, cholinergic changes in Lewy body disease carry implications for understanding phenotypes and the influence of Alzheimer co-pathology, delineating subtypes and pathological spreading routes, and for developing tailored treatments targeting the cholinergic system.

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Cardiac sympathetic denervation could be associated with dysphagia in Parkinson's disease

Background

Dysphagia is an important non-motor symptom that is closely associated with quality of living and mortality in Parkinson's disease (PD). However, the pathophysiology of dysphagia in PD remains inconclusive. We tried to confirm whether the occurrence of dysphagia could be related to sympathetic degeneration using cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphy.

Methods

We prospectively recruited 27 PD patients and classified them into two groups (PD with dysphagia vs. PD without dysphagia) by Swallowing Disturbance Questionnaire (SDQ) score and compared the clinical characteristics, videofluoroscopic swallowing study (VFSS) findings and parameters from cardiac MIBG scintigraphy.

Results

The mean early and late H/M ratios were significantly lower in the PD with dysphagia group than those in the PD without dysphagia group (1.39 ± 0.21 vs. 1.86 ± 0.21, p &lt; 0.01; 1.26 ± 0.18 vs. 1.82 ± 0.29, p &lt; 0.01). In the correlation analysis, both the early and late H/M ratios were negatively correlated with the SDQ score and total VDS score (r = −0.65, p &lt; 0.01; r = −0.53, p &lt; 0.01; r = −0.65, p &lt; 0.01, r = −0.58, p &lt; 0.01).

Conclusion

We confirmed that cardiac sympathetic denervation might be associated with the presence and severity of dysphagia. This finding indicates that dysphagia in PD could be associated with a nondopaminergic mechanism.

Progressive Olfactory Impairment and Cardiac Sympathetic Denervation in REM Sleep Behavior Disorder

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (iRBD) is prodromal for Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

OBJECTIVE

We investigated the use of cardiac [123I]meta-iodo-benzyl-guanidine scintigraphy ([123I]MIBG) and olfactory testing- in comparison to [123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single photon emission computed tomography ([123I]FP-CIT-SPECT)- for identifying iRBD patients as prodromal phenotype of PD/DLB.

METHODS

37 RBD subjects underwent cardiac [123I]MIBG and brain [123I]FP-CIT-SPECT at baseline. Olfactory (Sniffin' Sticks), cognitive and motor functions were tested annually for ∼4 years.

RESULTS

29/37 (78.4%) subjects had a pathological [123I]MIBG, of whom 86.2% (25/29) presented at least a moderate hyposmia at baseline (threshold/discrimination/identification-(TDI-)score ≤25). 20/37 (54.1%) subjects had a pathological [123I]FP-CIT-SPECT, always combined with a pathological [123I]MIBG. In subjects with pathological [123I]MIBG, olfactory function worsened (mainly due to threshold and discrimination subscores) from baseline to follow-up (p = 0.005). Olfaction was more impaired in subjects with pathological [123I]MIBG compared to those with normal [123I]MIBG at baseline (p = 0.001) and follow-up (p < 0.001). UPDRS-III scores increased in subjects with both pathological [123I]MIBG and [123I]FP-CIT-SPECT. In this group, seven subjects phenoconverted to PD, all- except for one- presented with at least moderate hyposmia at baseline.

CONCLUSION

A combination of the biomarkers "pathological [123I]MIBG" and "hyposmia" likely identifies iRBD patients in an early prodromal stage of PD/DLB, i.e., before nigrostriatal degeneration is visualized. One-third of the subjects with pathological [123I]MIBG had a normal [123I]FP-CIT-SPECT. Noteworthy, in iRBD subjects with pathological [123I]MIBG, olfactory impairment is progressive independent of the [123I]FP-CIT-SPECT status.

Recent Progress in Non-motor Features of Parkinson's Disease with a Focus on Circadian Rhythm Dysregulation

Parkinson's disease (PD) is the second most common neurodegenerative disease, which manifests with both motor and non-motor symptoms. Circadian rhythm dysregulation, as one of the most challenging non-motor features of PD, usually appears long before obvious motor symptoms. Moreover, the dysregulated circadian rhythm has recently been reported to play pivotal roles in PD pathogenesis, and it has emerged as a hot topic in PD research. In this review, we briefly introduce the circadian rhythm and circadian rhythm-related genes, and then summarize recent research progress on the altered circadian rhythm in PD, ranging from clinical features to the possible causes of PD-related circadian disorders. We believe that future comprehensive studies on the topic may not only help us to explore the mechanisms of PD, but also shed light on the better management of PD.

Early diagnosis of prodromal dementia with Lewy bodies using clinical history of probable REM sleep behaviour disorder and cardiac 123 I-MIBG scintigraphy in memory clinics

BACKGROUND

Rapid eye movement sleep behaviour disorder (RBD) is associated with reduced cardiac ¹²³ I-metaiodobenzylguanidine (MIBG) uptake and often precedes the onset of Lewy body (LB) disorders. We investigated the role of cardiac ¹²³ I-MIBG scintigraphy in relation to probable RBD for the clinical diagnosis of prodromal dementia with Lewy bodies (DLB) in memory clinics.

METHODS

We reviewed clinical profiles of 60 consecutive patients who underwent cardiac ¹²³ I-MIBG scintigraphy in our memory clinics. The diagnostic threshold of 2.20 was used as the cut-off for the heart-to-mediastinum ratio at the delayed phase.

RESULTS

Cardiac ¹²³ I-MIBG abnormality was identified in 28 patients at baseline; six were cognitively unimpaired, six had mild cognitive impairment (MCI)-LB, and 16 had probable DLB based on the National Institute on Aging and Alzheimer's Association Research Framework. Although the number of core features increased in accordance with the progression of three cognitive categories, there were no differences in the prevalence of probable RBD and the cardiac MIBG scintigraphy indices among them. During the observation period, two cognitively unimpaired patients with probable RBD progressed to MCI-LB, and three MCI-LB patients with probable RBD developed DLB. The prevalence of final diagnosis of probable MCI-LB or DLB was significantly higher in these patients (85%) than the remaining 32 patients without (9%). Of 25 patients with probable RBD, 22 (88%) had a cardiac ¹²³ I-MIBG abnormality regardless of cognitive conditions. Only one patient consulted a sleep centre for the abnormal sleep behaviour before visiting our memory clinics. Regarding the gender differences, male predominance was not identified and sleep-related injury more frequently occurred in men (7/12, 58%) than in women (1/10, 10%).

CONCLUSIONS

Proactive detection of probable RBD plus cardiac ¹²³ I-MIBG abnormality provides the opportunity for an early diagnosis of prodromal DLB in memory clinics. This approach warrants further follow-up studies with polysomnographic and pathological verification.

Association Between REM Sleep Behavior Disorder and Cognitive Dysfunctions in Parkinson's Disease: A Systematic Review and Meta-Analysis of Observational Studies

Background: Rapid eye movement sleep behavior disorder (RBD) is thought to be a prodromal symptom of Parkinson's disease (PD). RBD is also thought to be involved in cognitive decline and dementia in PD. In PD, although the relationship between RBD and cognitive dysfunctions was confirmed by considerable studies, whether RBD was associated with distinct types of cognitive defects is worth of study. Objectives: This systematic review summarizes the evidence relating to cognitive dysfunction in PD patients with RBD (PD-RBD) and those without and explores their specificity to cognitive domains. Methods: A meta-analysis using a random-effects model was performed for 16 different cognitive domains, including global cognitive function, memory (long-term verbal recall, long-term verbal recognition, long-term visual recall, short-term spatial recall, and short-term verbal recall), executive function (general, fluid reasoning, generativity, shifting, inhibition, and updating), language, processing speed/complex attention/working memory, visuospatial/constructional ability, and psychomotor ability. The cognitive difference between the groups of patients was measured as a standardized mean difference (SMD, Cohen's d). PD-RBD patients were classified into Confirmed-RBD (definite diagnosis with polysomnography, PSG) and Probable-RBD (without PSG re-confirmation). In some domains, RBD patients could not be analyzed separately due to the exiguity of primary studies; this analysis refers to such RBD patients as "Mixed-RBD." Results: Thirty-nine studies with 6,695 PD subjects were finally included. Confirmed-RBD patients showed worse performance than those without in global cognitive function, long-term verbal recall, long-term verbal recognition, generativity, inhibition, shifting, language, and visuospatial/constructional ability; Probable-RBD, in global cognitive function and shifting; and Mixed-RBD, in long-term visual recall, short-term spatial recall, general executive function, and processing speed/complex attention/working memory. Conclusion: This meta-analysis strongly suggests a relationship between RBD, Confirmed-RBD in particular, and cognitive dysfunctions in PD patients. Early and routine screening by sensitive and targeted cognitive tasks is necessary for all PD-RBD patients because it may offer the therapeutic time window before they evolve to irreversible dementia.

Olfactory function deteriorates in patients with Parkinson's disease complicated with REM sleep behavior disorder

INTRODUCTION

It is not concluded whether the association between olfactory dysfunction and REM sleep behavior disorder (RBD) were worsen cognitive function in patients with Parkinson's disease (PD). We sought to evaluate the impact of these symptoms in PD.

METHODS

We examined 62 patients with PD using an olfactory test (Odor Stick Identification Test for Japanese: OSIT-J) and polysomnography (PSG). We divided the patients into 3 groups: PD with clinical RBD (n = 32), PD with subclinical RBD (n = 11), and PD with normal REM sleep (n = 19). We compared their clinical backgrounds, results of OSIT-J, autonomic functions, and cognitive functions such as Montreal cognitive assessment Japanese version (MoCA-J). Some factors associated with RBD were analyzed by multiple regression.

RESULTS

There were significant differences in the results of OSIT-J, and autonomic and cognitive functions between the 3 groups. There were significant differences in the total OSIT-J score between the 3 groups (PD with clinical RBD: 3.3 ± 2.2, PD with subclinical RBD: 4.0 ± 2.6, PD with normal REM sleep: 6.7 ± 3.0, p < 0.001). Patients in the group with PD with clinical RBD had a significantly lower score than those with normal REM sleep (p < 0.001). Logistic regression analysis showed that OSIT-J score was significantly associated with RBD. The PD group with clinical RBD had more patients with mild cognitive impairment than the group with normal REM sleep. Multiple regression analysis revealed that olfactory dysfunction was correlated with MoCA-J.

CONCLUSIONS

Olfactory dysfunction is associated with RBD. Especially, it is important to screen olfactory function in RBD complicated patients with PD in view of cognitive impairment.

Orthostatic hypotension and REM sleep behaviour disorder: impact on clinical outcomes in α-synucleinopathies

OBJECTIVE

Review the effect of orthostatic hypotension (OH) and rapid-eye-movement sleep behavioural disorder (RBD) on survival, cognitive impairment and postural stability, and discuss pathogenic mechanisms involved in the association of these two common non-motor features with relevant clinical outcomes in α-synucleinopathies.

METHODS

We searched PubMed (January 2007-February 2019) for human studies of OH and RBD evaluating cognitive impairment, postural instability, and survival in Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA) and pure autonomic failure (PAF). Included studies were analysed for design, key results and limitations as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

OH and RBD showed a positive association with cognitive impairment in PD and DLB, conflicting association in PAF, and no association in MSA. OH was correlated with incident falls and postural instability in PD and DLB but not in MSA. The association between RBD and postural instability was inconclusive; positive in five studies, negative in seven. OH, but not RBD, correlated with reduced survival in PD, DLB and MSA. The combination of OH and RBD was associated with cognitive impairment and more rapid progression of postural instability.

CONCLUSIONS

OH and RBD yielded individual and combined negative effects on disability in α-synucleinopathies, reflecting a 'malignant' phenotype of PD with early cognitive impairment and postural instability. Underlying mechanisms may include involvement of selected brainstem cholinergic and noradrenergic nuclei.

The Gut and Parkinson's Disease: Hype or Hope?

In the last two decades it has become clear that Parkinson’s disease (PD) is associated with a plethora of gastrointestinal symptoms originating from functional and structural changes in the gut and its associated neural structures. This is of particular interest not only because such symptoms have a major impact on the quality of life of PD patients, but also since accumulating evidence suggests that in at least a subgroup of patients, these disturbances precede the motor symptoms and diagnosis of PD by years and may thus give important insights into the origin and pathogenesis of the disease. In this mini-review we attempt to concisely summarize the current knowledge after two decades of research on the gut-brain axis in PD. We focus on alpha-synuclein pathology, biomarkers, and the gut microbiota and envision the development and impact of these research areas for the two decades to come.

Ultrasonication-based rapid amplification of α-synuclein aggregates in cerebrospinal fluid

α-Synuclein aggregates, a key hallmark of the pathogenesis of Parkinson’s disease, can be amplified by using their seeding activity, and the evaluation of the seeding activity of cerebrospinal fluid (CSF) is reportedly useful for diagnosis. However, conventional shaking-based assays are time-consuming procedures, and the clinical significance of the diversity of seeding activity among patients remains to be clarified. Previously, we reported a high-throughput ultrasonication-induced amyloid fibrillation assay. Here, we adapted this assay to amplify and detect α-synuclein aggregates from CSF, and investigated the correlation between seeding activity and clinical indicators. We confirmed that this assay could detect α-synuclein aggregates prepared in vitro and also aggregates released from cultured cells. The seeding activity of CSF correlated with the levels of α-synuclein oligomers measured by an enzyme-linked immunosorbent assay. Moreover, the seeding activity of CSF from patients with Parkinson’s disease was higher than that of control patients. Notably, the lag time of patients with Parkinson’s disease was significantly correlated with the MIBG heart-to-mediastinum ratio. These findings showed that our ultrasonication-based assay can rapidly amplify misfolded α-synuclein and can evaluate the seeding activity of CSF.

Imaging the Autonomic Nervous System in Parkinson's Disease

PURPOSE OF REVIEW

Patients with Parkinson's disease (PD) often display gastrointestinal and genitourinary autonomic symptoms years or even decades prior to diagnosis. These symptoms are thought to be caused in part by pathological α-synuclein inclusions in the peripheral autonomic and enteric nervous systems. It has been proposed that the initial α-synuclein aggregation may in some PD patients originate in peripheral nerve terminals and then spread centripetally to the spinal cord and brainstem. In vivo imaging methods can directly quantify the degeneration of the autonomic nervous system as well as the functional consequences such as perturbed motility. Here, we review the methodological principles of these imaging techniques and the major findings in patients with PD and atypical parkinsonism.

RECENT FINDINGS

Loss of sympathetic and parasympathetic nerve terminals in PD can be visualized using radiotracer imaging, including ¹²³I-MIBG scintigraphy, and ¹⁸F-dopamine and ¹¹C-donepezil PET. Recently, ultrasonographical studies disclosed reduced diameter of the vagal nerves in PD patients. Radiological and radioisotope techniques have demonstrated dysmotility and prolonged transit time throughout all subdivisions of the gastrointestinal tract in PD. The prevalence of objective dysfunction as measured with these imaging methods is often considerably higher compared to the prevalence of subjective symptoms experienced by the patients. Degeneration of the autonomic nervous system may play a key role in the pathogenesis of PD. In vivo imaging techniques provide powerful and noninvasive tools to quantify the degree and extent of this degeneration and its functional consequences.

Early diagnosis of Lewy body disease in patients with late-onset psychiatric disorders using clinical history of rapid eye movement sleep behavior disorder and [123 I]-metaiodobenzylguanidine cardiac scintigraphy

AIM

Rapid eye movement sleep behavior disorder (RBD) and psychiatric symptoms often antedate the clinical diagnosis of Parkinson's disease or dementia with Lewy bodies. The purpose of this study was to investigate RBD and its relevance to Lewy body disease (LBD) in patients with late-onset psychiatric disorders.

METHODS

Study subjects included 19 patients with late-onset psychiatric disorders who exhibited REM sleep without atonia (RWA), which is a hallmark of RBD on polysomnography, at our psychiatric ward. Clinical profiles and radiological findings by cardiac [¹²³ I]-metaiodobenzylguanidine ([¹²³ I]-MIBG) scintigraphy and imaging for the dopamine transporter (DAT) were compared between patients with and without RBD symptoms. The correlations between the percentage of RWA in the total rapid eye movement sleep (%RWA) and radiological findings were also investigated.

RESULTS

Nine patients reported RBD symptoms only on specific questioning, but clinical profiles, including the prevalence of antipsychotropic usage, did not differ when compared to the remaining 10 patients without RBD (incidental RWA group). The median %RWA was significantly higher in the definite RBD group than in the incidental RWA group. Although the cardiac [¹²³ I]-MIBG uptake was significantly lower in the definite RBD group than in the incidental RWA group, there was overlap in the specific binding ratio on DAT scan.

CONCLUSION

The severity of %RWA was highly correlated with the value of cardiac [¹²³ I]-MIBG uptake, but not with specific binding ratio on DAT scan. Clinical history of RBD and cardiac [¹²³ I]-MIBG scintigraphy are helpful for an early differential diagnosis of LBD from late-onset psychiatric disorders, even before parkinsonism or dementia appears.

In-vivo staging of pathology in REM sleep behaviour disorder: a multimodality imaging case-control study

BACKGROUND

Accumulating evidence suggests that α-synuclein aggregates-a defining pathology of Parkinson's disease-display cell-to-cell transmission. α-synuclein aggregation is hypothesised to start in autonomic nerve terminals years before the appearance of motor symptoms, and subsequently spread via autonomic nerves to the spinal cord and brainstem. To assess this hypothesis, we investigated sympathetic, parasympathetic, noradrenergic, and dopaminergic innervation in patients with idiopathic rapid eye movement (REM) sleep behaviour disorder, a prodromal phenotype of Parkinson's disease.

METHODS

In this prospective, case-control study, we recruited patients with idiopathic REM sleep behaviour disorder, confirmed by polysomnography, without clinical signs of parkinsonism or dementia, via advertisement and through sleep clinics in Denmark. We used ¹¹C-donepezil PET and CT to assess cholinergic (parasympathetic) gut innervation, ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy to measure cardiac sympathetic innervation, neuromelanin-sensitive MRI to measure integrity of pigmented neurons of the locus coeruleus, ¹¹C-methylreboxetine (MeNER) PET to assess noradrenergic nerve terminals originating in the locus coeruleus, and ¹⁸F-dihydroxyphenylalanine (DOPA) PET to assess nigrostriatal dopamine storage capacity. For each imaging modality, we compared patients with idiopathic REM sleep behaviour disorder with previously published reference data of controls without neurological disorders or cognitive impairment and with symptomatic patients with Parkinson's disease. We assessed imaging data using one-way ANOVA corrected for multiple comparisons.

FINDINGS

Between June 3, 2016, and Dec 19, 2017, we recruited 22 consecutive patients with idiopathic REM sleep behaviour disorder to the study. Compared with controls, patients with idiopathic REM sleep behaviour disorder had decreased colonic ¹¹C-donepezil uptake (-0·322, 95% CI -0·112 to -0·531; p=0·0020), ¹²³I-MIBG heart:mediastinum ratio (-0·508, -0·353 to -0·664; p<0·0001), neuromelanin-sensitive MRI locus coeruleus:pons ratio (-0·059, -0·019 to -0·099; p=0·0028), and putaminal ¹⁸F-DOPA uptake (Ki; -0·0023, -0·0009 to -0·0037; p=0·0013). No between-group differences were detected between idiopathic REM sleep behaviour disorder and Parkinson's disease groups with respect to ¹¹C-donepezil (p=0·39), ¹²³I-MIBG (p>0·99), neuromelanin-sensitive MRI (p=0·96), and ¹¹C-MeNER (p=0·56). By contrast, 15 (71%) of 21 patients with idiopathic REM sleep behaviour disorder had ¹⁸F-DOPA Ki values within normal limits, whereas all patients with Parkinson's disease had significantly decreased ¹⁸F-DOPA Ki values when compared with patients with idiopathic REM sleep behaviour disorder (p<0·0001).

INTERPRETATION

Patients with idiopathic REM sleep behaviour disorder had fully developed pathology in the peripheral autonomic nervous system and the locus coeruleus, equal to that in diagnosed Parkinson's disease. These patients also showed noradrenergic thalamic denervation, but most had normal putaminal dopaminergic storage capacity. This caudorostral gradient of dysfunction supports the hypothesis that α-synuclein pathology in Parkinson's disease initially targets peripheral autonomic nerves and then spreads rostrally to the brainstem.

FUNDING

Lundbeck Foundation, Jascha Foundation, and the Swiss National Foundation.

Accuracy of Rating Scales and Clinical Measures for Screening of Rapid Eye Movement Sleep Behavior Disorder and for Predicting Conversion to Parkinson's Disease and Other Synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by repeated episodes of REM sleep-related vocalizations and/or complex motor behaviors. Definite diagnosis of RBD is based on history and polysomnography, both of which are less accessible due to the lack of trained specialists and high cost. While RBD may be associated with disorders like narcolepsy, focal brain lesions, and encephalitis, idiopathic RBD (iRBD) may convert to Parkinson's disease (PD) and other synucleinopathies in more than 80% of patients and it is to date the most specific clinical prodromal marker of PD. Identification of individuals at high risk for development of PD is becoming one of the most important topics for current PD-related research as well as for future treatment trials targeting prodromal PD. Furthermore, concomitant clinical symptoms, such as subtle motor impairment, hyposmia, autonomic dysfunction, or cognitive difficulties, in subjects with iRBD may herald its phenoconversion to clinically manifest parkinsonism. The assessment of these motor and non-motor symptoms in iRBD may increase the sensitivity and specificity in identifying prodromal PD subjects. This review evaluates the diagnostic accuracy of individual rating scales and validated single items for screening of RBD and the role and accuracy of available clinical, electrophysiological, imaging, and tissue biomarkers in predicting the phenoconversion from iRBD to clinically manifest synucleinopathies.

Cardiac Sympathetic Activity differentiates Idiopathic and Symptomatic Rapid Eye Movement Sleep Behaviour Disorder

The pathophysiology of rapid eye movement sleep behavior disorder (RBD) associated with narcolepsy type 1 (NT1) is still poorly understood, potentially distinct from idiopathic RBD (iRBD), but may share affected common pathways. We investigated whether MIBG cardiac uptake differs between iRBD and NT1 comorbid with RBD. Thirty-four patients with NT1-RBD and 15 patients with iRBD underwent MIBG cardiac scintigraphy. MIBG uptake was measured by calculating the early and delayed heart to mediastinum (H/M) ratios. A delayed H/M ratio lower than 1.46 was considered abnormal based on a population of 78 subjects without neurological or cardiac diseases. Patients with iRBD were older, had an older RBD onset age and higher REM sleep phasic and tonic muscular activities than NT1-RBD. Lower delayed and early H/M ratios were associated with iRBD, but not with NT1-RBD, in crude and adjusted associations. The delayed H/M ratio differed between iRBD and controls, after adjustment, but not between patients with NT1-RBD and controls. In conclusion, the MIBG cardiac uptake difference between NT1-RBD and iRBD supports the hypothesis of different processes involved in RBD pathogenesis, providing for the first time a cardiac biomarker to differentiate those disorders.

Optimizing Parkinson's disease diagnosis: the role of a dual nuclear imaging algorithm

The diagnosis of Parkinson's disease (PD) currently relies almost exclusively on the clinical judgment of an experienced neurologist, ideally a specialist in movement disorders. However, such clinical diagnosis is often incorrect in a large percentage of patients, particularly in the early stages of the disease. A commercially available, objective and quantitative marker of nigrostriatal neurodegeneration was recently provided by 123-iodine ¹²³I-ioflupane SPECT imaging, which is however unable to differentiate PD from a variety of other parkinsonian syndromes associated with striatal dopamine deficiency. There is evidence to support an algorithm utilizing a dual neuroimaging strategy combining ¹²³I-ioflupane SPECT and the noradrenergic receptor ligand ¹²³I-metaiodobenzylguanidine (MIBG), which assesses the post-ganglion peripheral autonomic nervous system. Evolving concepts regarding the synucleinopathy affecting the central and peripheral autonomic nervous systems as part of a multisystem disease are reviewed to sustain such strategy. Data are presented to show how MIBG deficits are a common feature of multisystem Lewy body disease and can be used as a unique feature to distinguish PD from atypical parkinsonisms. We propose that the combination of cardiac (MIBG) and cerebral ¹²³I-ioflupane SPECT could satisfy one of the most significant unmet needs of current PD diagnosis and management, namely the early and accurate diagnosis of patients with typical Lewy body PD. Exemplary case scenarios will be described, highlighting how dual neuroimaging strategy can maximize diagnostic accuracy for patient care, clinical trials, pre-symptomatic PD screening, and special cases provided by specific genetic mutations associated with PD.

Prevalence and Clinical Characteristics of Probable REM Behavior Disorder in Thai Parkinson's Disease Patients

Background

Previous studies have shown that Parkinson's disease (PD) patients who have REM behavior disorder (PD with RBD) might be a PD subtype since they have different symptom clusters and disease trajectories from PD without RBD.

Objective

To study the prevalence of PD with pRBD and to compare the clinical characteristics with PD without pRBD. The feasibility of clinical interview of items adopted from the Mayo Sleep Questionnaire was also to be determined.

Methods

A total of 140 Parkinson's patients visiting neurological clinics during January to December 2016 were enrolled in this study. “Probable RBD (pRBD)” was defined as present when the patient answered “yes” to a question adapted from the first Mayo Sleep Questionnaire (MSQ). The demographic data, motor symptoms, and nonmotor symptoms were obtained.

Results

The prevalence of pRBD among this study's PD patients was 48.5% (68 out of the total of 140). The median onset of RBD before PD diagnosis was 5 years (range: 0–11 years). By comparison of PD with pRBD and PD without pRBD, this study showed significant difference in the levodopa equivalent dose (742 mg/day versus 566 mg/day; p < 0.01), prevalence of symptomatic orthostatic hypotension (35.3% versus 8.3%; p < 0.01). The multivariable analysis found that pRBD is independently associated with orthostatic hypotension (OR = 5.02, p < 0.01). Conclusion. The findings regarding prevalence and main clinical features of PD with pRBD in this study were similar to those of a previous study of PD with polysomnogram- (PSG-) proven RBD. This study hypothesized that interviewing by adopted MSQ may be a cost-effective tool for screening RBD. Further studies with direct comparison are needed.

Constipation is not associated with dopamine transporter pathology in early drug-naïve patients with Parkinson's disease

BACKGROUND AND PURPOSE

Constipation is a common non-motor symptom of Parkinson's disease (PD). Deposition of α-synuclein inclusions that spread from the gut to the substantia nigra through the vagus nerve has recently been speculated to be a pre-motor and early stage of PD. The aim of the study was to investigate whether constipation is associated with dopaminergic pathology on dopamine transporter (DAT) single-photon emission computed tomography in early drug-naïve patients with PD. Our hypothesis was that constipation is associated with other signs of pre-motor PD and is independent of DAT pathology. We then investigated for associations with motor and non-motor symptoms, and with cerebrospinal fluid biomarkers of PD pathology.

METHODS

Using the Parkinson's Progression Markers Initiative database, we investigated the prevalence of constipation and the association between constipation and clinical features, striatal [¹²³ I]Ioflupane uptake and non-imaging (cerebrospinal fluid and serum) biomarkers. Constipation was evaluated using Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part I item 1.11.

RESULTS

One third (132/398) of de-novo patients with PD had constipation. Higher severity of constipation correlated with older age (r = 0.728, P < 0.001), higher MDS-UPDRS total score (r = 0.285, P < 0.001), worse postural instability (r = 0.190, P = 0.012), rapid eye movement sleep behaviour disorder (r = 0.228, P < 0.0001) and depression (r = 0.187, P = 0.024). No correlation was found with cerebrospinal fluid, serum and imaging markers of PD pathology.

CONCLUSIONS

Constipation was not associated with DAT pathology but with rapid eye movement sleep behaviour disorder and depression, which are speculated to be pre-motor symptoms of PD. This confirms the hypothesis that constipation may be a pre-motor sign of PD due to an impairment of non-dopaminergic pathways.

A systematic review of the literature on disorders of sleep and wakefulness in Parkinson's disease from 2005 to 2015

Sleep disorders are among the most common non-motor manifestations in Parkinson's disease (PD) and have a significant negative impact on quality of life. While sleep disorders in PD share most characteristics with those that occur in the general population, there are several considerations specific to this patient population regarding diagnosis, management, and implications. The available research on these disorders is expanding rapidly, but many questions remain unanswered. We thus conducted a systematic review of the literature published from 2005 to 2015 on the following disorders of sleep and wakefulness in PD: REM sleep behavior disorder, insomnia, nocturia, restless legs syndrome and periodic limb movements, sleep disordered breathing, excessive daytime sleepiness, and circadian rhythm disorders. We discuss the epidemiology, etiology, clinical implications, associated features, evaluation measures, and management of these disorders. The influence on sleep of medications used in the treatment of motor and non-motor symptoms of PD is detailed. Additionally, we suggest areas in need of further research.

Differences in clinical characteristics when REM sleep behavior disorder precedes or comes after the onset of Parkinson's disease

OBJECTIVE

Rapid eye movement (REM) sleep behavior disorder (RBD) is important not only as a preclinical symptom of Parkinson's disease (PD), but also as an aggravating symptom of PD. However, it is not known whether the onset of RBD in relation to PD affects the clinical characteristics of PD. A cross-sectional study comparing clinical characteristics of PD between patients with RBD occurring before and after the onset of PD was conducted.

METHODS

Interviews regarding RBD symptoms were conducted and polysomnography was performed on 136 patients with PD. Patients with PD were divided into a group with RBD and a group without RBD. Moreover, the group with RBD was subdivided into those with RBD before the onset of PD (RBD→PD) and those with RBD after the onset of PD (PD→RBD). Clinical characteristics of the patients with and without RBD, and PD with RBD→PD and PD→RBD were compared.

RESULTS

Patients with RBD (47 PD patients) had more severe parkinsonian symptoms, autonomic dysfunction, and cognitive impairment than those without RBD (89 PD patients). Moreover, 38 PD patients with PD→RBD had greater cognitive impairment including Mini-metal examination than 9 with RBD→PD in spite of similar motor and autonomic dysfunction with similar dopaminergic agents.

CONCLUSION

The occurrence of RBD after the onset of PD might be an important factor aggravating cognitive function.

A community-based study of risk factors for probable rapid eye movement sleep behavior disorder

OBJECTIVES

To cross-sectionally explore the potential risk factors for rapid eye movement (REM) sleep behavior disorder (RBD) in a community cohort in Shanghai.

METHODS

Based on the validated RBD screening questionnaire (RBDSQ), we identified individuals with probable RBD (pRBD) in 3635 community-dwelling residents (≥50 years old) from an urban community of Shanghai. Potential risk factors of pRBD, including age, sex, smoking, socioeconomic status, obesity, consumption of tea (surrogate for caffeine intake) and alcohol, medications and chronic disease status, were assessed via questionnaire. We used logistic regression to investigate the associations between these studied factors and pRBD after adjusting for age, sex and other studied factors.

RESULTS

Based on the RBDSQ score ≥5, 2.70% (3.28% in men and 2.41% in women) participants were considered as pRBD. We found that lower education, presence of head injury, atrial fibrillation, hyperlipidemia, constipation, olfactory disturbance, and imbalance, use of alcoholic beverage, selective serotonin reuptake inhibitor, and benzodiazepine were associated with higher likelihood of having pRBD (P < 0.05 for all). In contrast, male sex, use of coffee or tea, smoking and other factors were not significantly association with altered risk of having pRBD. We did not find significant interaction between sex, age and these factors, in relation to pRBD risk.

CONCLUSIONS

In this community-based study of older adults, we identified several potential risk factors for concurrent pRBD, including environmental factors and vascular risk factors.

Parkinson's disease and sleep/wake disturbances

Sleep disturbances are a common non-motor feature in patients with Parkinson's disease (PD). Early diagnosis and appropriate management are imperative for enhancing patient quality of life. Sleep disturbances can be caused by multiple factors in addition to age-related changes in sleep, such as nocturnal motor symptoms (rigidity, resting tremor, akinesia, tardive dyskinesia, and the "wearing off" phenomenon), non-motor symptoms (pain, hallucination, and psychosis), nocturia, and medication. Disease-related pathology involving the brainstem and changes in the neurotransmitter systems (norepinephrine, serotonin, and acetylcholine) responsible for regulating sleep structure and the sleep/wake cycle play a role in emerging excessive daytime sleepiness and sleep disturbances. Additionally, screening for sleep apnea syndrome, rapid eye movement sleep behavior disorder, and restless legs syndrome is clinically important. Questionnaire-based assessment utilizing the PD Sleep Scale-2 is useful for screening PD-related nocturnal symptoms. In this review, we focus on the current understanding and management of sleep disturbances in PD.

Imaging the aetiology of sleep disorders in dementia and Parkinson's disease

Sleep disorders are commonly observed in patients with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease and often represent an early manifestation of the underlying degenerative process. The pathophysiology of sleep dysfunction in these conditions is complex and incompletely understood. However, in recent years, functional imaging in vivo with SPECT and PET has significantly improved our understanding of the possible molecular mechanisms. These include dysfunction of both dopaminergic and non-dopaminergic pathways involved in sleep/wakefulness control. This paper summarizes the main findings of the imaging studies performed to elucidate the aetiology of sleep disorders in Alzheimer's disease and Parkinson's disease.

Parkinson's disease and REM sleep behavior disorder result in increased non-motor symptoms

OBJECTIVE

Rapid eye movement (REM)-sleep behavior disorder (RBD) is often comorbid with Parkinson's disease (PD). The current study aimed to provide a detailed understanding of the impact of having RBD on multiple non-motor symptoms (NMS) in patients with PD.

METHODS

A total of 86 participants were evaluated for RBD and assessed for multiple NMS of PD. Principal component analysis was utilized to model multiple measures of NMS in PD, and a multivariate analysis of variance was used to assess the relationship between RBD and the multiple NMS measures. Seven NMS measures were assessed: cognition, quality of life, fatigue, sleepiness, overall sleep, mood, and overall NMS of PD.

RESULTS

Among the PD patients, 36 were classified as having RBD (objective polysomnography and subjective findings), 26 as not having RBD (neither objective nor subjective findings), and 24 as probably having RBD (either subjective or objective findings). RBD was a significant predictor of increased NMS in PD while controlling for dopaminergic therapy and age (p=0.01). The RBD group reported more NMS of depression (p=0.012), fatigue (p=0.036), overall sleep (p=0.018), and overall NMS (p=0.002).

CONCLUSION

In PD, RBD is associated with more NMS, particularly increased depressive symptoms, sleep disturbances, and fatigue. More research is needed to assess whether PD patients with RBD represent a subtype of PD with different disease progression and phenomenological presentation.

Clinical significance of REM sleep behavior disorder in Parkinson's disease

OBJECTIVE

Rapid eye movement (REM) sleep behavior disorder (RBD) may be a risk factor for dementia development in patients with Parkinson's disease (PD); however, the role of subclinical RBD remains unknown. Patients with PD and clinical RBD, subclinical RBD, or with normal REM sleep were examined in a cross sectional study and a longitudinal follow-up.

METHODS

Interviews regarding RBD symptoms and polysomnographies were performed on 82 PD patients divided into RBD subcategories based on the presence/absence of REM sleep without atonia (RWA) and/or RBD symptoms. Descriptive variables were compared and patients were followed-up longitudinally for 21.4±10.8months.

RESULTS

The existence of RBD, but not subclinical RBD, was associated with orthostatic hypotension and levodopa dose equivalents (LDEs) in patients with PD. Kaplan-Myer curves indicated that the occurrence of dementia in the PD group with clinical RBD was significantly faster than in the PD group with normal REM sleep (p=0.013). A Cox hazard regression analysis revealed that development to PD with dementia was only significantly associated with the presence of clinical RBD (hazard ratio: 14.1, p=0.017).

CONCLUSION

Clinical RBD symptoms, but not subclinical RBD, were associated with the development of dementia in PD.

Premotor symptoms and early diagnosis of Parkinson's disease

Parkinson's disease is a disorder characterized by the motor findings of bradykinesia, rest tremor, cogwheel rigidity, and postural instability. As the disease progresses, most patients develop numerous nonmotor signs and symptoms, many of which play a major role in reducing quality of life. What is becoming increasingly clear is that nonmotor findings, including hyposmia, sleep disorders, autonomic abnormalities, cognitive changes, and neurobehavioral changes, often precede the motor findings.

Rapid eye movement sleep behavior disorder and subtypes of Parkinson's disease

Numerous studies have explored the potential relationship between rapid eye movement sleep behavior disorder (RBD) and manifestations of PD. Our aim was to perform an expanded extensive assessment of motor and nonmotor manifestations in PD to identify whether RBD was associated with differences in the nature and severity of these manifestations. PD patients underwent polysomnography (PSG) to diagnose the presence of RBD. Participants then underwent an extensive evaluation by a movement disorders specialist blinded to PSG results. Measures of disease severity, quantitative motor indices, motor subtypes, therapy complications, and autonomic, psychiatric, visual, and olfactory dysfunction were assessed and compared using regression analysis, adjusting for disease duration, age, and sex. Of 98 included patients, 54 had RBD and 44 did not. PD patients with RBD were older (P = 0.034) and were more likely to be male (P < 0.001). On regression analysis, the most consistent links between RBD and PD were a higher systolic blood pressure (BP) change while standing (-23.9 ± 13.9 versus -3.5 ± 10.9; P < 0.001), a higher orthostatic symptom score (0.89 ± 0.82 versus 0.44 ± 0.66; P = 0.003), and a higher frequency of freezing (43% versus 14%; P = 0.011). A systolic BP drop >10 could identify PD patients with RBD with 81% sensitivity and 86% specificity. In addition, there was a probable relationship between RBD and nontremor predominant subtype of PD (P = 0.04), increased frequency of falls (P = 0.009), and depression (P = 0.009). Our results support previous findings that RBD is a multifaceted phenomenon in PD. Patients with PD who have RBD tend to have specific motor and nonmotor manifestations, especially orthostatic hypotension.

Rapid eye movement sleep behavior disorder and risk of dementia in Parkinson's disease: a prospective study

One of the most devastating nonmotor manifestations of PD is dementia. There are few established predictors of dementia in PD. In numerous cross-sectional studies, patients with rapid eye movement (REM) sleep behavior disorder (RBD) have increased cognitive impairment on neuropsychological testing, but no prospective studies have assessed whether RBD can predict Parkinson's dementia. PD patients who were free of dementia were enrolled in a prospective follow-up of a previously published cross-sectional study. All patients had a polysomnogram at baseline. Over a mean 4-year follow-up, the incidence of dementia was assessed in those with or without RBD at baseline using regression analysis, adjusting for age, sex, disease duration, and follow-up duration. Of 61 eligible patients, 45 (74%) were assessed and 42 were included in a full analysis. Twenty-seven patients had baseline RBD, and 15 did not. Four years after the initial evaluation, 48% with RBD developed dementia, compared to 0% of those without (P-adjusted = 0.014). All 13 patients who developed dementia had mild cognitive impairment on baseline examination. Baseline REM sleep atonia loss predicted development of dementia (% tonic REM = 73.2 ± 26.7 with dementia, 40.8 ± 34.5 without; P = 0.029). RBD at baseline also predicted the new development of hallucinations and cognitive fluctuations. In this prospective study, RBD was associated with increased risk of dementia. This indicates that RBD may be a marker of a relatively diffuse, complex subtype of PD.

Diagnostic tools for REM sleep behavior disorder

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by loss of muscle atonia during REM sleep that results in motor behaviors. Diagnosis of RBD involves a clinical interview in which history of dream enactment behaviors is elicited and a subsequent overnight polysomnography (PSG) evaluation to assess for REM sleep without atonia (RWA) and/or observe motor behaviors during REM sleep. Therefore, the nature of RBD diagnosis involves both subjective and objective measurements that attempt to qualify and quantify the different diagnostic sub-criteria.

OBJECTIVES

The primary aim of the current study was to identify and summarize the available clinical measurements that have been used for RBD assessment.

METHODS

Two major online databases (MEDLINE and PsycInfo) were searched for articles developing, validating, or evaluating psychometric properties of the RBD diagnostic criteria or methods used for diagnosis. Studies of adult subjects (18 years or more) that included sufficient psychometric data for validation were included.

RESULTS

Fifty-eight studies were found to meet review criteria. The objective measurements for assessment of RBD reviewed included visual electromyographic (EMG) scoring methods, computerized EMG scoring methods, cardiac (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy, actigraphy, behavioral classification and video analysis. Subjective measurements of RBD included interviews and questionnaires.

CONCLUSION

Sleep history may be sufficient for diagnosis of RBD in some populations. However, PSG is necessary for a definitive diagnosis. EMG scoring methods vary in definition used and there is no single accepted approach to scoring muscle activity. Additional validation studies are required for establishing cutoff scores for the different methods. Questionnaires were shown to be appropriate screening tools, yet further validation in different populations is necessary.