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BACKGROUND: We have hypothesized that Parkinson's disease (PD) comprises two subtypes. Brain-first, where pathogenic α-synuclein initially forms unilaterally in one hemisphere leading to asymmetric nigrostriatal degeneration, and body-first with initial enteric pathology, which spreads through overlapping vagal innervation leading to more symmetric brainstem involvement and hence more symmetric nigrostriatal degeneration. Isolated REM sleep behaviour disorder has been identified as a strong marker of the body-first type.OBJECTIVE: To analyse striatal asymmetry in [18F]FDOPA PET and [123I]FP-CIT DaT SPECT data from iRBD patients, de novo PD patients with RBD (PD +RBD) and de novo PD patients without RBD (PD - RBD). These groups were defined as prodromal body-first, de novo body-first, and de novo brain-first, respectively.METHODS: We included [18F]FDOPA PET scans from 21 iRBD patients, 11 de novo PD +RBD, 22 de novo PD - RBD, and 18 controls subjects. Also, [123I]FP-CIT DaT SPECT data from iRBD and de novo PD patients with unknown RBD status from the PPPMI dataset was analysed. Lowest putamen specific binding ratio and putamen asymmetry index (AI) was defined.RESULTS: Nigrostriatal degeneration was significantly more symmetric in patients with RBD versus patients without RBD or with unknown RBD status in both FDOPA (p = 0.001) and DaT SPECT (p = 0.001) datasets.CONCLUSION: iRBD subjects and de novo PD +RBD patients present with significantly more symmetric nigrostriatal dopaminergic degeneration compared to de novo PD - RBD patients. The results support the hypothesis that body-first PD is characterized by more symmetric distribution most likely due to more symmetric propagation of pathogenic α-synuclein compared to brain-first PD.

Background and purpose Cholinergic dysfunction appears to play a role in the cognitive impairment observed in Parkinson's disease and dementia with Lewy bodies. The occurrence of cholinergic dysfunction in the early stages of these conditions, however, has not been investigated. The objective of this study was to investigate cholinergic function in patients with idiopathic rapid eye movement sleep behaviour disorder (iRBD), a disorder recognized to be an early stage of both Parkinson's disease and dementia with Lewy bodies. Methods A total of 21 patients with polysomnography-confirmed iRBD with no evidence of parkinsonism and cognitive impairment and 10 controls underwent positron emission tomography (PET) to assess brain acetylcholinesterase levels (11 C-donepezil PET) and nigrostriatal dopaminergic function (18 F-DOPA PET). Clinical examination included the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III, Mini Mental State Examination and Montreal Cognitive Assessment. Results The 11 C-donepezil PET was successfully performed in 17 patients with iRBD and nine controls. Compared with controls, patients with iRBD showed a mean 7.65% reduction in neocortical 11 C-donepezil levels (P = 0.005). Bilateral superior temporal cortex, occipital cortex, cingulate cortex and dorsolateral prefrontal cortex showed the most significant reductions at voxel level. Conclusion Reduced neocortical 11 C-donepezil binding in our patients indicates cholinergic denervation and suggests that the projections from the nucleus basalis of Meynert, which supplies cholinergic innervation to the neocortex, are dysfunctional in iRBD. Longitudinal studies will clarify if these changes are predictive of future cognitive impairment in these patients.

Background: Vagal parasympathetic neurons are prone to degeneration in Parkinson's disease (PD). High-resolution ultrasound can precisely estimate the cross-sectional (CSA) area of peripheral nerves. Here, we tested the hypothesis that vagus CSA is reduced in PD.Methods: We included 56 healthy controls (HCs) and 63 patients with PD. Using a high-end ultrasound system equipped with a high-frequency transducer, five images were obtained of each nerve. The hypoechoic neuronal tissue was delineated offline with dedicated software and the CSA extracted.Results: In the initial PD vs. HC comparison, no statistically significant differences were observed in mean left vagus CSA (HC: 1.97 mm2, PD: 1.89 mm2, P = 0.36) nor in mean right vagus CSA (HC: 2.37 mm2, PD: 2.23 mm2, P = 0.17). The right vagus CSA was significantly larger than the left vagus CSA in both groups (P < 0.0001). Females were overrepresented in the HC group and presented with generally smaller vagus CSAs. Consequently, sex-adjusted CSA was significantly smaller for the right vagus nerve of the PD group (P = 0.041), but not for the left.Conclusion: A small but significant reduction in sex-adjusted right vagus CSA was observed in patients with PD. The left vagus CSA was not significantly reduced in patients with PD. Ultrasound may not be a suitable method to detecting vagal axonal loss in individual patients.

Previous studies have reported substantial involvement of the noradrenergic system in Parkinson’s disease. Neuromelanin-sensitive MRI sequences and PET tracers have become available to visualize the cell bodies in the locus coeruleus and the density of noradrenergic terminal transporters. Combining these methods, we investigated the relationship of neurodegeneration in these distinct compartments in Parkinson’s disease. We examined 93 subjects (40 healthy controls and 53 Parkinson’s disease patients) with neuromelanin-sensitive turbo spin-echo MRI and calculated locus coeruleus-to-pons signal contrasts. Voxels with the highest intensities were extracted from published locus coeruleus coordinates transformed to individual MRI. To also investigate a potential spatial pattern of locus coeruleus degeneration, we extracted the highest signal intensities from the rostral, middle, and caudal third of the locus coeruleus. Additionally, a study-specific probabilistic map of the locus coeruleus was created and used to extract mean MRI contrast from the entire locus coeruleus and each rostro-caudal subdivision. Locus coeruleus volumes were measured using manual segmentations. A subset of 73 subjects had 11C-MeNER PET to determine noradrenaline transporter density, and distribution volume ratios of noradrenaline transporter-rich regions were computed. Patients with Parkinson’s disease showed reduced locus coeruleus MRI contrast independently of the selected method (voxel approaches: P The data shed first light on the interaction between the axonal and cell body compartments and their differential susceptibility to neurodegeneration in Parkinson’s disease, which may eventually direct research towards potential novel treatment approaches.

Study Objectives Parkinson’s disease (PD) commonly involves degeneration of sleep-wake regulating brainstem nuclei; likewise, sleep-wake disturbances are highly prevalent in PD patients. As polysomnography macroparameters typically show only minor changes in PD, we investigated sleep microstructure, particularly cyclic alternating pattern (CAP), and its relation to alterations of the noradrenergic system in these patients. Methods We analyzed 27 PD patients and 13 healthy control (HC) subjects who underwent overnight polysomnography and 11C-MeNER positron emission tomography for evaluation of noradrenaline transporter density. Sleep macroparameters, as well as CAP metrics, were evaluated according to the consensus statement from 2001. Statistical analysis comprised group comparisons and correlation analysis of CAP metrics with clinical characteristics of PD patients as well as noradrenaline transporter density. Results PD patients and HC subjects were comparable in demographic characteristics (age, sex, body mass index) and polysomnography macroparameters. CAP rate as well as A index differed significantly between groups, with PD patients having a lower CAP rate (46.7 ± 6.6% versus 38.0 ± 11.6%, p = 0.015) and lower A index (49.0 ± 8.7/hour versus 40.1 ± 15.4/hour, p = 0.042). In PD patients, both CAP metrics correlated significantly with diminished noradrenaline transporter density in arousal prompting brainstem nuclei (locus coeruleus, raphe nuclei) as well as arousal propagating brain structures like thalamus and bitemporal cortex. Conclusions Sleep microstructure is more severely altered than sleep macrostructure in PD patients and is associated with widespread dysfunction of the noradrenergic arousal system.

Parkinson’s disease is characterized by the presence of abnormal, intraneuronal α-synuclein aggregates, which may propagate from cell-to-cell in a prion-like manner. However, it remains uncertain where the initial α-synuclein aggregates originate. We have hypothesized that Parkinson’s disease comprises two subtypes. A brain-first (top-down) type, where α-synuclein pathology initially arises in the brain with secondary spreading to the peripheral autonomic nervous system; and a body-first (bottom-up) type, where the pathology originates in the enteric or peripheral autonomic nervous system and then spreads to the brain. We also hypothesized that isolated REM sleep behaviour disorder (iRBD) is a prodromal phenotype for the body-first type. Using multimodal imaging, we tested the hypothesis by quantifying neuronal dysfunction in structures corresponding to Braak stages I, II and III involvement in three distinct patient groups. We included 37 consecutive de novo patients with Parkinson’s disease into this case-control PET study. Patients with Parkinson’s disease were divided into 24 RBD-negative (PDRBD−) and 13 RBD-positive cases (PDRBD+) and a comparator group of 22 iRBD patients. We used 11C-donepezil PET/CT to assess cholinergic (parasympathetic) innervation, 123I-metaiodobenzylguanidine (MIBG) scintigraphy to measure cardiac sympathetic innervation, neuromelanin-sensitive MRI to measure the integrity of locus coeruleus pigmented neurons, and 18F-dihydroxyphenylalanine (FDOPA) PET to assess putaminal dopamine storage capacity. Colon volume and transit times were assessed with CT scans and radiopaque markers. Imaging data from the three groups were interrogated with ANOVA and Kruskal-Wallis tests corrected for multiple comparisons. The PDRBD− and PDRBD+ groups showed similar marked reductions in putaminal FDOPA-specific uptake, whereas two-thirds of iRBD patients had normal scans (P

Isolated REM sleep behaviour disorder (iRBD) is a predictive marker of prodromal Lewy body disease. iRBD prevalence in the general population is around 1%, but it remains under-diagnosed, even though symptoms are alleviated by medication. We developed a population screening strategy and identified 16 iRBD patients by conducting telephone interviews and polysomnography examinations. We compared our population-screened cohort with sleep-center referred patients and found higher MoCA scores and lower MDS-UPDRS-III scores in our patients. In conclusion, screening can be used to identify iRBD patients in a cost-effective manner with the benefit of identifying patients at a very early disease stage.

Noradrenergic neurotransmission may play an important role in tremor modulation through its innervation of key structures of the central tremor circuits. Here, Parkinson's disease (PD) patients with (PDT+) or without (PDT-) rest tremor had 11C-methylreboxetine(11C-MeNER) positron emission tomography (PET) to test the hypothesis that noradrenaline terminal function was relatively preserved in PDT+ compared to PDT-. Methods Sixty-five PD patients and 28 healthy controls (HC) were scanned with 11C-MeNER PET. Patients were categorized as PDT+ if subscores in UPDRS-III item 3 or MDS-UPDRS-III item 17 was ≥2; remaining were categorized as PDT-. Simplified reference tissue model 2 distribution volume ratios (DVR) for 11C-MeNER were calculated for thalamus, dorsal and median raphe, locus coeruleus (LC) and red nucleus using time activity curves (TACs) obtained from volumes of interest (VOI). Data were statistically interrogated with a general linear mixed model using ‘region’, and ‘group’ as factors and the interaction of ‘region x group’ was examined. Results Tremor positive PD patients had a significantly higher mean 11C-MeNER DVR compared to PDT- in LC and thalamus. The PDT+ mean LC DVR was similar to that of HC. PDT+ mean 11C-MeNER DVRs were significantly lower than HC in the dorsal raphe while the PDT- group showed significantly lower mean 11C-MeNER DVR across all regions compared to HC. Conclusion While both PD T+ and PD T- groups showed a significant loss of noradrenaline terminal function compared to controls, noradrenergic neurons were relatively preserved in PDT+ in LC and thalamus. The greater loss of noradrenergic transporters in PDT- in LC and thalamus compared with PDT+ is in line with earlier in-vitro studies and could potentially contribute to their tremor negative phenotype.

Introduction: Noradrenergic denervation is thought to aggravate motor dysfunction in Parkinson's disease (PD). In a previous PET study with the norepinephrine transporter (NART) ligand C-11-MeNER, we detected reduced NART binding in primary sensorimotor cortex (M1S1) of PD patients. Idiopathic rapid-eye-movement sleep behaviour disorder (iRBD) is a phenotype of prodromal PD. Using C-11-MeNER PET, we investigated whether iRBD patients showed similar NART binding reductions in M1S1 cortex as PD patients. Additionally, we investigated whether C-11-MeNER binding and loss of nigrostriatal dopamine storage capacity measured with F-18-DOPA PET were correlated.Methods: 17 iRBD patients, 16 PD patients with (PDRBD+) and 14 without RBD (PDRBD-), and 25 control subjects underwent C-11-MeNER PET. iRBD patients also had F-18-DOPA PET. Volume-of-interest analyses and voxel-level statistical parametric mapping were performed.Results: Partial-volume corrected C-11-MeNER binding potential (BPND) values in M1S1 differed across the groups (P = 0.022) with the iRBD and PDRBD+ groups showing significant reductions (controls vs. iRBD P = 0.007; control vs. PDRBD+ P = 0.008). Voxel-wise comparisons confirmed reductions of M1S1 C-11-MeNER binding in PD and iRBD patients. Significant correlation was seen between putaminal F-18-DOPA uptake and thalamic C-11-MeNER binding in iRBD patients (r(2) = 0.343, P = 0.013).Conclusions: This study found altered noradrenergic neurotransmission in the M1S1 cortex of iRBD patients. The observed reduction of M1S1 C-11-MeNER binding in iRBD may represent noradrenergic terminal degeneration or physiological down-regulation of NARTs in this prodromal phenotype of PD. The correlation between thalamic C-11-MeNER binding and putaminal F-18-DOPA binding suggests that these neurotransmitter systems degenerate in parallel in the iRBD phenotype of prodromal PD.

Reduced noradrenaline levels have been reported to occur in the motor cortices of PD patients postmortem. Imaging techniques have recently become available to specifically study noradrenergic terminal function in vivo using PET. The objective of this study was to evaluate cortical 11 C-MeNER binding in PD patients. Thirty PD patients and 12 healthy control subjects comparable in age, sex, and cognitive performance underwent PET imaging with 11 C-MeNER, a specific ligand of the noradrenaline transporter. Cortical noradrenaline transporter binding was compared at a voxel level using Statistical Parametric Mapping, whereas cortical thickness was assessed using FreeSurfer software with MRI. PD patients showed reduced 11 C-MeNER binding in the primary motor cortex unrelated to cortical thickness; other cortical regions did not differ between groups. In a subgroup analysis, patients with higher Hoehn & Yahr stage exhibited more pronounced 11 C-MeNER binding reductions. Loss of cortical noradrenergic projections to the primary motor cortex occurs in PD associated with disease stage. © 2018 International Parkinson and Movement Disorder Society.

Background: Alzheimer's disease copathology is common in PD at autopsy. In non-PD subjects with mild cognitive impairment, tau depositions can be detected using 18F-AV-1451 PET. We hypothesized that 18F-AV-1451 PET would show tau aggregation in PD with mild cognitive impairment and correlate with cognitive dysfunction. Objectives: To describe tau aggregation in PD patients. Methods: Twenty-six PD patients and 23 controls had 18F-AV-1451 PET and neuropsychological assessment to detect mild cognitive impairment. Results: Nine PD patients (35%) were identified with mild cognitive impairment. Regional analyses showed no significant differences between groups. Voxel-wise analyses showed no correlation with cognitive domain z-scores within patients. One patient with mild cognitive impairment was estimated Braak tau stage 5; all other patients were stage 0. Conclusion: Our results indicate that tau pathology, as detected by 18F-AV-1451, is uncommon in PD with mild cognitive impairment and shows no significant correlation with cognitive dysfunction at this stage. © 2017 International Parkinson and Movement Disorder Society

BACKGROUND: 11 C-Donepezil positron emission tomography (PET) allows non-invasive assessment of cholinergic innervation of visceral organs. We aimed to compare cholinergic innervation in the gut in patients with diabetes mellitus (DM) and in healthy controls (HC).METHODS: 11 C-Donepezil PET and computed tomography (CT) were performed in 19 patients with type 1 DM and gastrointestinal symptoms and in 19 age- and sex-matched HC in a cross-sectional design.KEY RESULTS: All patients had severe gastrointestinal symptoms when assessed by standard questionnaires. DM patients had significantly increased volume of the small intestinal wall (DM: median 557 cm3 [interquartile range [IQR] 446-697] vs HC median: 448 cm3 [IQR; 341-518; P < .01]), and the 11 C Donepezil PET uptake was reduced in patients (DM: median 7.08 standardized uptake value [SUV] [IQR; 5.94-8.43] vs HC: median 9.18 SUV [IQR; 8.57-10.11; P < .01]). A similar pattern was found in colon (DM: median volume 1064 cm3 [IQR; 882-1312] vs HC: median 939 cm3 [IQR; 785-1081; P = .13] and DM: median 1.22 SUV (IQR; 1.08-1.36) vs HC: median 1.42 SUV (IQR; 1.32-1.53; P = .03). Furthermore, patients had significantly reduced pancreatic volume (DM: median 53 cm3 [IQR; 41-69] vs HC: median 98 cm3 [IQR;82-110; P < .01]) and reduced PET uptake of the pancreas (DM: median 13.14 SUV [IQR;9.58-15.82] vs HC: median 21.46 SUV [IQR;18.97-24.06; P < .01]) as well as the adrenal gland (DM: median 7.62 SUV [IQR;7.61;15.82] vs HC: median 15.51 SUV [IQR;12.22;19.49; P = .03]).CONCLUSION AND INFERENCES: Assessed with 11 C-Donepezil PET/CT, patients with DM and severe bowel symptoms have reduced cholinergic innervation of the gut indicative of parasympathetic denervation.

Background Parasympathetic neuropathy is a key feature in many common disorders, including diabetes, neurological disorders, and cancers, but few objective methods exist for assessing damage to the parasympathetic nervous system, particularly in the gastrointestinal system. This study aimed to validate the use of C-11-donepezil positron emission tomography (PET) to assess parasympathetic integrity in a group of vagotomized patients.Methods Sixteen healthy controls and 12 patients, vagotomized due to esophagectomy, underwent C-11-donepezil PET, measurement of colonic transit time, quantification of plasma pancreatic polypeptide (PP), and assessment of subjective long-term symptoms.Key Results Vagotomized patients had significantly decreased PET signal in the small intestine and colon compared with healthy controls (5.7 [4.4-7.9] vs 7.4 [4.5-11.3], P = .01 and 1.4 [1.1-2.1] vs 1.6 [1.4-2.4], P Conclusions and Inferences We found significantly decreased C-11-donepezil signal in the intestine of vagotomized patients, supporting that C-11-donepezil PET is a valid measure of intestinal parasympathetic denervation.

Background:Donepezil may have cardioprotective properties, but the mechanism is unclear. Using positron-emission tomography (PET), we explored 11C-donepezil uptake in the heart of humans in relatio...

The tau tangle ligand (18)F-AV-1451 ((18)F-T807) binds to neuromelanin in the midbrain, and may therefore be a measure of the pigmented dopaminergic neuronal count in the substantia nigra. Parkinson's disease is characterized by progressive loss of dopaminergic neurons. Extrapolation of post-mortem data predicts that a ∼30% decline of nigral dopamine neurons is necessary to cause motor symptoms in Parkinson's disease. Putamen dopamine terminal loss at disease onset most likely exceeds that of the nigral cell bodies and has been estimated to be of the order of 50-70%. We investigated the utility of (18)F-AV-1451 positron emission tomography to visualize the concentration of nigral neuromelanin in Parkinson's disease and correlated the findings to dopamine transporter density, measured by (123)I-FP-CIT single photon emission computed tomography. A total of 17 patients with idiopathic Parkinson's disease and 16 age- and sex-matched control subjects had (18)F-AV-1451 positron emission tomography using a Siemens high-resolution research tomograph. Twelve patients with Parkinson's disease also received a standardized (123)I-FP-CIT single photon emission computed tomography scan at our imaging facility. Many of the patients with Parkinson's disease displayed visually apparent decreased (18)F-AV-1451 signal in the midbrain. On quantitation, patients showed a 30% mean decrease in total nigral (18)F-AV-1451 volume of distribution compared with controls (P = 0.004), but there was an overlap of the individual ranges. We saw no significant correlation between symptom dominant side and contralateral nigral volume of distribution. There was no correlation between nigral (18)F-AV-1451 volume of distribution and age or time since diagnosis. In the subset of 12 patients, who also had a (123)I-FP-CIT scan, the mean total striatal dopamine transporter signal was decreased by 45% and the mean total (18)F-AV-1451 substantia nigra volume of distribution was decreased by 33% after median disease duration of 4.7 years (0.5-12.4 years). (18)F-AV-1451 positron emission tomography may be the first radiotracer to reflect the loss of pigmented neurons in the substantia nigra of parkinsonian patients. The magnitude of the nigral signal loss was smaller than the decrease in striatal dopamine transporter signal measured by dopamine transporter single photon emission computed tomography. These findings suggest a more severe loss of striatal nerve terminal function compared with neuronal cell bodies, in accordance with the post-mortem literature.

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; p0·99), 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 (pINTERPRETATION: 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.

BACKGROUND: Parkinson's disease is characterized by pathological α-synuclein accumulation and cell death, which has been hypothesized to originate in peripheral nerve terminals and subsequently spread via autonomic nerves. Supporting this, most Parkinson's disease patients experience autonomic non-motor symptoms such as constipation, often years prior to diagnosis.OBJECTIVE: We aimed to study gastrointestinal transit time, colonic volume, and peristaltic movements in idiopathic REM Sleep Behavior Disorder patients, a prodromal marker of Parkinson's disease or Dementia with Lewy bodies.METHODS: Twenty-two patients were included and compared to previously published data from Parkinson's disease patients and controls. Gastrointestinal transit time, computed tomography-based volume estimation, and colonic motility were performed as markers of gastrointestinal function and autonomic involvement. Subjective constipation symptoms were evaluated with two different questionnaires.RESULTS: Gastrointestinal transit time was increased in 33% (p = 0.039) and colonic volume in 48% (p = 0.0049) of patients. Colonic transit time measured by the 3D-Transit system was increased in 70% (p = 0.0326) and the number of fast peristaltic colonic movements was reduced (p = 0.015). Mean small intestinal transit time was comparable to Parkinson's disease patients, although not significantly different compared to controls (p = 0.18). Subjective constipation symptoms were present in 18 or 41%, depending on type of questionnaire.CONCLUSIONS: Total gastrointestinal transit time, colonic volume, and 3D-Transit colonic transit time were significantly increased compared to controls, although not to the extent seen in medicated Parkinson's patients. Limited correlation was seen between subjective constipation and objective markers. The findings support that marked GI dysfunction is present in the early prodromal PD phase.

Pathological involvement of the noradrenergic locus coeruleus occurs early in Parkinson's disease, and widespread noradrenaline reductions are found at post-mortem. Rapid eye movement sleep behaviour disorder (RBD) accompanies Parkinson's disease and its presence predicts an unfavourable disease course with a higher propensity to cognitive impairment and orthostatic hypotension. MRI can detect neuromelanin in the locus coeruleus while 11C-MeNER PET is a marker of noradrenaline transporter availability. Here, we use both imaging modalities to study the association of RBD, cognition and autonomic dysfunction in Parkinson's disease with loss of noradrenergic function. Thirty non-demented Parkinson's disease patients [16 patients with RBD and 14 without RBD, comparable across age (66.6 ± 6.7 years), sex (22 males), and disease stage (Hoehn and Yahr, 2.3 ± 0.5)], had imaging of the locus coeruleus with neuromelanin sensitive MRI and brain noradrenaline transporter availability with 11C-MeNER PET. RBD was confirmed with polysomnography; cognitive function was assessed with a neuropsychological test battery, and blood pressure changes on tilting were documented; results were compared to 12 matched control subjects. We found that Parkinson's disease patients with RBD showed decreased locus coeruleus neuromelanin signal on MRI (P < 0.001) and widespread reduced binding of 11C-MeNER (P < 0.001), which correlated with amount of REM sleep without atonia. Parkinson's disease with RBD was also associated with a higher incidence of cognitive impairment, slowed EEG activity, and orthostatic hypotension. Reduced 11C-MeNER binding correlated with EEG slowing, cognitive performance, and orthostatic hypotension. In conclusion, reduced noradrenergic function in Parkinson's disease was linked to the presence of RBD and associated with cognitive deterioration and orthostatic hypotension. Noradrenergic impairment may contribute to the high prevalence of these non-motor symptoms in Parkinson's disease, and may be of relevance when treating these conditions in Parkinson's disease.

OBJECTIVES: Rapid eye movement (REM) sleep behavior disorder (RBD) is defined by dream enactment due to a failure of normal muscle atonia. Visual assessment of this muscle activity is time consuming and rater-dependent.METHODS: An EMG computer algorithm for scoring 'tonic', 'phasic' and 'any' submental muscle activity during REM sleep was evaluated compared with human visual ratings. Subsequently, 52 subjects were analyzed with the algorithm. Duration and maximal amplitude of muscle activity, and self-awareness of RBD symptoms were assessed.RESULTS: The computer algorithm showed high congruency with human ratings and all subjects with RBD were correctly identified by excess of submental muscle activity, when artifacts were removed before analysis. Subjects with RBD exhibited prolonged bouts of 'phasic' muscle activity with high amplitude. Self-awareness of RBD symptoms correlated with amount of REM sleep without atonia.CONCLUSIONS: Our proposed algorithm was able to detect and rate REM sleep without atonia allowing identification of RBD. Increased duration and amplitude of muscle activity bouts were characteristics of RBD. Quantification of REM sleep without atonia represents a marker of RBD severity.SIGNIFICANCE: Our EMG computer algorithm can support a diagnosis of RBD while the quantification of altered muscle activity provides a measure of its severity.

BACKGROUND: Symptoms from the gastrointestinal tract are highly prevalent in Parkinson's disease (PD), but knowledge of the underlying pathology is incomplete and valid objective markers on regional gastrointestinal function are limited.OBJECTIVE: The aims were to evaluate gastrointestinal transit time and motility in PD patients and controls.METHODS: Twenty-two PD patients and 15 controls were included. Gastric-, small intestinal-, and caecum-ascending colonic transit times as well as colonic motility, defined as mass- and fast movements, were performed using the ambulatory 3D-Transit system. Gastrointestinal transit time with radio opaque markers, gastric emptying scintigraphy, and subjective non-motor symptoms were also evaluated.RESULTS: Using the 3D-Transit system, the patient group displayed significantly longer small intestinal- and caecum-ascending transit times (p = 0.030 and p = 0.0063). No between-group difference was seen in gastric transit time (p = 0.91). Time to first mass- and fast colonic movement were significantly increased in PD (p = 0.023 and p = 0.006). Radio opaque marker gastrointestinal transit time was significantly increased in the patient group (p CONCLUSIONS: Significantly increased small intestinal- and caecum-ascending 3D-Transit times were detected in PD patients. Also, time to first propagating colonic movement was increased. Radio opaque marker gastrointestinal transit time was significantly delayed, but no difference was seen in gastric transit time and gastric emptying time. The present findings highlight widespread intestinal involvement in PD increasing throughout the gastrointestinal tract.

Parkinson’s disease is a systemic disorder with widespread and early α-synuclein pathology in the autonomic and enteric nervous systems, which is present throughout the gastrointestinal canal prior to diagnosis. Gastrointestinal and genitourinary autonomic symptoms often predate clinical diagnosis by several years. It has been hypothesized that progressive α-synuclein aggregation is initiated in hyperbranched, non-myelinated neuron terminals, and may subsequently spread via retrograde axonal transport. This would explain why autonomic nerves are so prone to formation of α-synuclein pathology. However, the hypothesis remains unproven and in vivo imaging methods of peripheral organs may be essential to study this important research field. The loss of sympathetic and parasympathetic nerve terminal function in Parkinson’s disease has been demonstrated using radiotracers such as 123I-meta-iodobenzylguanidin, 18F-dopamine, and 11C-donepezil. Other radiotracer and radiological imaging methods have shown highly prevalent dysfunction of pharyngeal and esophageal motility, gastric emptying, colonic transit time, and anorectal function. Here, we summarize the methodology and main findings of radio-isotope and radiological modalities for imaging peripheral pathology in Parkinson’s disease.

Objective:To investigate systemic levels of acetylcholinesterase in early Parkinson disease (PD) with 11C-donepezil PET, a potential marker of parasympathetic innervation.Methods:This was a cross-sectional study with 19 patients with early-stage PD (disease duration 1.5 ± 0.6 years) and 16 age-matched controls who had clinical assessments, olfaction tests, and 11C-donepezil PET to measure acetylcholinesterase density in peripheral organs.Results:The patients with PD showed significantly reduced 11C-donepezil uptake in the small intestine (−14%, p = 0.018), colon (−22%, p < 0.001), and kidneys (−14%, p = 0.028). No difference in myocardial or pancreatic acetylcholinesterase levels was seen.Conclusion:We found significantly decreased 11C-donepezil signal in the intestine and kidneys of patients with early PD, suggesting that parasympathetic denervation is present early in the disease course.

BACKGROUND: Gastrointestinal function has received increased interest in the context of Parkinson's disease (PD). Constipation is among the most frequent non-motor symptoms, but our understanding of the underlying pathology is limited. Subjective constipation correlates poorly with objective markers.OBJECTIVE: The aims were to evaluate colonic transit time and volume in PD and to correlate these measures with subjective symptoms and gastric emptying.METHODS: Thirty-two PD patients and 26 controls were included. Colonic transit time, computed tomography-based volume estimation, and gastric emptying were performed as objective markers of gastrointestinal function. Subjective gastrointestinal symptoms were evaluated by three different questionnaires.RESULTS: Seventy-nine percent of PD patients displayed prolonged colonic transit time (p CONCLUSIONS: Significantly delayed colonic transit time and increased volume were frequent findings in PD patients, and objective dysfunction was considerably more prevalent than subjective constipation symptoms. Also, the prevalence of subjective constipation varied widely depending upon which questionnaire was employed. These findings highlight the need for more research on how to define constipation in PD and also the need for improved understanding of the relationship between subjective symptoms and objective dysfunction.

Parkinson's disease is associated with early parasympathetic dysfunction leading to constipation and gastroparesis. It has been suggested that pathological α-synuclein aggregations originate in the gut and ascend to the brainstem via the vagus. Our understanding of the pathogenesis and time course of parasympathetic denervation in Parkinson's disease is limited and would benefit from a validated imaging technique to visualize the integrity of parasympathetic function. The positron emission tomography tracer 5-[11C]-methoxy-donepezil was recently validated for imaging acetylcholinesterase density in the brain and peripheral organs. Donepezil is a high-affinity ligand for acetylcholinesterase—the enzyme that catabolizes acetylcholine in cholinergic synapses. Acetylcholinesterase histology has been used for many years for visualizing cholinergic neurons. Using 5-[11C]-methoxy-donepezil positron emission tomography, we studied 12 patients with early-to-moderate Parkinson's disease (three female; age 64 ± 9 years) and 12 age-matched control subjects (three female; age 62 ± 8 years). We collected clinical information about motor severity, constipation, gastroparesis, and other parameters. Heart rate variability measurements and gastric emptying scintigraphies were performed in all subjects to obtain objective measures of parasympathetic function. We detected significantly decreased 11C-donepezil binding in the small intestine (−35%; P = 0.003) and pancreas (−22%; P = 0.001) of the patients. No correlations were found between the 11C-donepezil signal and disease duration, severity of constipation, gastric emptying time, and heart rate variability. In Parkinson's disease, the dorsal motor nucleus of the vagus undergoes severe degeneration and pathological α-synuclein aggregations are also seen in nerve fibres innervating the gastro-intestinal tract. In contrast, the enteric nervous system displays little or no loss of cholinergic neurons. Decreases in 11C-donepezil binding may, therefore, represent a marker of parasympathetic denervation of internal organs, but further validation studies are needed. * Abbreviations : AChE : acetylcholinesterase DMV : dorsal motor nucleus of the vagus RR : distance in ms between consecutive normal R waves in QRS complexes SUV : standardized uptake value

BACKGROUND AND OBJECTIVES: Parkinson's disease (PD) patients experience several non-motor symptoms from the gastrointestinal tract that may partly be caused by parasympathetic deficiency. The pancreas is densely innervated by the vagus nerve, which mediates early meal-induced secretion of pancreatic polypeptide (PP). Early secretion after sham feeding has been validated as a marker of vagal integrity. Thus, the aim was to evaluate the ratio of increased PP plasma levels after sham feeding in PD and correlate findings with gastrointestinal transit time (GITT).METHODS: Twenty-five PD patients and 17 controls were included. PP, insulin, and blood glucose levels were measured before, during, and after sham feeding with white bread and chocolate spread. GITT was measured using radiopaque markers. Furthermore, faeces samples were analyzed for pancreatic elastase enzyme as a marker of exocrine pancreatic function.RESULTS: PD patients showed significantly lower PP ratio levels after sham feeding, which was most pronounced at 10 minutes. No significant association was seen between attenuated PP response and GITT in PD patients. No between-group differences were seen in glucose or insulin levels over time, but PD patients showed generally lower insulin levels compared to controls. No difference was found in faeces pancreatic elastase.CONCLUSIONS: Early-to-moderate stage PD patients demonstrated significantly decreased PP response after sham feeding suggestive of vagal denervation.

Objectives REM sleep without atonia (RSWA) is a key feature of REM sleep behavior disorder (RBD). However, detailed visual scoring of EMG on 30 and 3 s intervals is highly time demanding. A computer program with automated scoring algorithm would thus be a valuable asset for sleep professionals scoring RBD. Methods Criteria’s for tonic (2xRMS baseline for >15 s per 30 s epoch), phasic (max amplitude >4 × RMS baseline (or 2 × Tonic), 3 s epochs) and any (tonic and/or phasic) chin EMG activity were implemented in a software algorithm. Sleep stages, respiratory-, arousal- and artifact events were visually scored and imported into the software. Visual scoring of EMG activity done by a blinded board-certified sleep professional was compared to the software algorithm by regression analysis and Kappa statistics. A total of 31989 3 s epochs in 19 patients with Parkinson’s disease (PD) were evaluated (mean age 65.2 ± 9.7, 10 RBD+, 9 RBD−). Results Total percentages of tonic, phasic and any muscle activity correlated strongly between the software algorithm and visual scoring ( R 2 > 0.97 for all activities). Cohen’s Kappa indicated very high agreement on individual events (0.73 for tonic, 0.80 for phasic, 0.83 for any activity). A cut-off value of 10% of any activity separated both groups correctly. Bouts of phasic activity were longer in patients with RBD compared non-RBD (375.4 ± 61.1 versus 478.3 ± 88.9, p = 0.014). Conclusion/significance Our software reliably detects altered chin muscle activity in PD patients when excluding artifact corrupted epochs, providing a fast tool for detecting RBD patients and metrics for correlation analysis with clinical variables.

Introduction. Decreased salivary flow and xerostomia are frequent findings in Parkinson’s disease (PD), possibly caused by alterations in the parasympathetic tonus. Here we explore salivary acetylcholinesterase (AChE) activity as a potential biomarker in PD.Methods. We measured salivary flow, AChE activity, and total protein concentration in 30 PD patients and 49 healthy controls. We also performed exploratory correlation analyses with disease duration, motor symptom severity, autonomic complaints, and other nonmotor symptoms.Results. PD patients displayed significantly decreased salivary flow rate, significantly increased salivary AChE activity, and total protein concentration. Importantly, the AChE activity/total protein ratio was significantly increased in PD patients, suggesting that increased AChE activity cannot be explained solely by upconcentration of saliva. The Unified PD Rating Scale (UPDRS) score displayed significant correlation with total salivary protein (P=0.002) and near-significant correlation with salivary flow (P=0.07). Color vision test scores were also significantly correlated with AChE activity (P=0.04) and total protein levels (P=0.002).Conclusion. Salivary AChE activity is increased in PD patients compared to healthy controls. Future studies are needed to elucidate whether this parameter reflects the extent of neuronal damage and parasympathetic denervation in the salivary glands of PD patients.