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 < 10−13, ANOVA). When compared to the PDRBD− patients, the PDRBD+ and iRBD patients showed reduced mean MIBG heart:mediastinum ratios (P < 10−5, ANOVA) and colon 11C-donepezil standard uptake values (P = 0.008, ANOVA). The PDRBD+ group trended towards a reduced mean MRI locus coeruleus: pons ratio compared to PDRBD− (P = 0.07, t-test). In comparison to the other groups, the PDRBD+ group also had enlarged colon volumes (P < 0.001, ANOVA) and delayed colonic transit times (P = 0.01, Kruskal-Wallis). The combined iRBD and PDRBD+ patient data were compatible with a body-first trajectory, characterized by initial loss of cardiac MIBG signal and 11C-colonic donepezil signal followed by loss of putaminal FDOPA uptake. In contrast, the PDRBD− data were compatible with a brain-first trajectory, characterized by primary loss of putaminal FDOPA uptake followed by a secondary loss of cardiac MIBG signal and 11C-donepezil signal. These findings support the existence of brain-first and body-first subtypes of Parkinson’s disease.

We detected Lewy pathology in the gastrointestinal tract of patients up to 20 years prior to their Parkinson disease diagnosis. These findings are in accordance with a hypothesized prodromal disease phase spanning 10 to 20 years. Ann Neurol 2016;79:940-949.

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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-[(11)C]-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-[(11)C]-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 (11)C-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 (11)C-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 (11)C-donepezil binding may, therefore, represent a marker of parasympathetic denervation of internal organs, but further validation studies are needed.

IntroductionContinuous delivery of levodopa–carbidopa intestinal gel (LCIG) by percutaneous endoscopic gastrojejunostomy (PEG-J) in advanced Parkinson’s disease (PD) patients reduces variability in plasma levels, providing better control of motor fluctuations (“on” and “off” states). The MONOTREAT study assessed the effect of LCIG on activities of daily living, motor and non-motor symptoms, and quality of life in advanced PD patients.MethodsThis prospective, observational study included patients with advanced, levodopa-responsive PD with either 2–4 h of “off” time or 2 h of dyskinesia daily. Patients received LCIG via PEG-J for 16 h continuously. Effectiveness was assessed using Unified PD Rating Scale parts II and III, the Non-Motor Symptom Scale, and the PD Questionnaire-8.ResultsThe mean (SD) treatment duration was 275 (157) days. Patients experienced significant improvement from baseline in activities of daily living at final visit (p < 0.05) as well as at months 3 and 6 (p < 0.0001). Patients also experienced significant improvements from baseline in quality of life and non-motor symptoms at all time points (p < 0.001 for all). Specifically, patients manifested significant improvements in mean change from baseline at every study visit in five of nine non-motor symptom score domains: sleep/fatigue, mood/cognition, gastrointestinal tract, urinary, and miscellaneous. One-third of patients (32.8%) experienced an adverse event; 21.9% experienced a serious adverse event; 11.1% discontinued because of an adverse event.ConclusionThis study demonstrated significant and clinically relevant improvements in measures of activities of daily living, quality of life, and a specific subset of non-motor symptoms after treatment with LCIG.FundingAbbVie Inc.Electronic supplementary materialThe online version of this article (doi:10.1007/s12325-017-0571-2) contains supplementary material, which is available to authorized users.