Orthostatic hypotension and cardiac sympathetic denervation in Parkinson disease patients with REM sleep behavioral disorder

Cardiovascular dysautonomia and cognitive impairment in Parkinson's disease (Review)

Cognitive impairment is a prevalent non-motor symptom of Parkinson's disease (PD), which can result in significant disability and distress for patients and caregivers. There is a marked variation in the timing, characteristics and rate at which cognitive decline occurs in patients with PD. This decline can vary from normal cognition to mild cognitive impairment and dementia. Cognitive impairment is associated with several pathophysiological mechanisms, including the accumulation of β-amyloid and tau in the brain, oxidative stress and neuroinflammation. Cardiovascular autonomic dysfunctions are commonly observed in patients with PD. These dysfunctions play a role in the progression of cognitive impairment, the incidents of falls and even in mortality. The majority of symptoms of dysautonomia arise from changes in the peripheral autonomic nervous system, including both the sympathetic and parasympathetic nervous systems. Cardiovascular changes, including orthostatic hypotension, supine hypertension and abnormal nocturnal blood pressure (BP), can occur in both the early and advanced stages of PD. These changes tend to increase as the disease advances. The present review aimed to describe the cognitive changes in the setting of cardiovascular dysautonomia and to discuss strategies through which these changes can be modified and managed. It is a multifactorial process usually involving decreased blood flow to the brain, resulting in the development of cerebral ischemic lesions, an increased presence of abnormal white matter signals in the brain, and a potential influence on the process of neurodegeneration in PD. Another possible explanation is this association being independent observations of PD progression. Patients with clinical symptoms of dysautonomia should undergo 24-h ambulatory BP monitoring, as they are frequently subtle and underdiagnosed.

Orthostatic Hypotension: a clinical marker for the body-first subtype of patients with Parkinson's Disease

Our study aimed to investigate the clinical characteristics of PD patients stratified by OH status before and after levodopa challenge to explore the hypothesis that OH might serve as a clinical marker for the body-first subtype of PD. Supine and standing blood pressure were measured in a large cross-sectional cohort of PD patients at the OFF status before and after levodopa challenge test (LCT). Based on OH status, patients were divided into three groups: spontaneous OH (SOH), only levodopa-induced OH (LOH) and non-OH (NOH). Clinical characteristics and associated factors were compared among the groups. A total of 928 patients with a mean age of 62.4 years and average disease duration of 7.9 years were included. There were 224 (24.1%) patients with SOH, 321 (34.6%) with LOH, and 383 (41.3%) with NOH. Compared to NOH, both SOH and LOH were associated with older age, motor fluctuations, and probable rapid eye movement sleep behavior disorder (pRBD). In addition, OH was more associated with cardiovascular and digestive dysfunction, disease severity and worse quality of life. Results of the current study suggest that PD patients developed OH which is more likely to comorbid with RBD, severe autonomic dysfunction and motor fluctuations, consistent with the body-first subtype of PD.

A pathophysiological biomarker combination separates Lewy body from non-Lewy body neurogenic orthostatic hypotension ​

PURPOSE

Neurogenic orthostatic hypotension (nOH) results from deficient reflexive delivery of norepinephrine to cardiovascular receptors in response to decreased cardiac venous return. Lewy body (LB) forms of nOH are characterized by low 18F-dopamine-derived radioactivity (a measure of cardiac noradrenergic deficiency), olfactory dysfunction by the University of Pennsylvania Smell Identification Test (UPSIT), and increased deposition of alpha-synuclein (α-syn) in dermal sympathetic noradrenergic nerves by the α-syn-tyrosine hydroxylase (TH) colocalization index. This observational, cross-sectional study explored whether combinations of these biomarkers specifically identify LB forms of nOH.

METHODS

Clinical laboratory data were reviewed from patients referred for evaluation at the National Institutes of Health for chronic autonomic failure between 2011 and 2023. The cutoff value for low myocardial 18F-dopamine-derived radioactivity was 6000 nCi-kg/cc-mCi, for olfactory dysfunction an UPSIT score ≤ 28, and for an increased α-syn-TH colocalization index ≥ 1.57.

RESULTS

A total of 44 patients (31 LB, 13 non-LB nOH) had data for all three biomarkers. Compared to the non-LB group, the LB nOH group had low myocardial 18F-dopamine-derived radioactivity, low UPSIT scores, and high α-syn-TH colocalization indexes (p < 0.0001 each). Combining the three biomarkers completely separated the groups. Cluster analysis identified two distinct groups (p < 0.0001) independently of the clinical diagnosis, with one cluster corresponding exactly to LB nOH.

CONCLUSION

LB forms of nOH feature cardiac noradrenergic deficiency, olfactory dysfunction, and increased α-syn-TH colocalization in skin biopsies. Combining the data for these variables efficiently separates LB from non-LB nOH. Independently of the clinical diagnosis, this biomarker triad identifies a pathophysiologically distinct cluster of nOH patients.

Cardiac noradrenergic deficiency revealed by 18F-dopamine positron emission tomography identifies preclinical central Lewy body diseases

BACKGROUND

In Lewy body diseases (LBDs) Parkinson disease (PD), and dementia with Lewy bodies (DLB), by the time parkinsonism or cognitive dysfunction manifests clinically, substantial neurodegeneration has already occurred. Biomarkers are needed to identify central LBDs in a preclinical phase, when neurorescue strategies might forestall symptomatic disease. This phase may involve catecholamine deficiency in the autonomic nervous system. We analyzed data from the prospective, observational, long-term PDRisk study to assess the predictive value of low versus normal cardiac 18F-dopamine positron emission tomography (PET), an index of myocardial content of the sympathetic neurotransmitter norepinephrine, in at-risk individuals.

METHODS

Participants self-reported risk factor information (genetics, olfactory dysfunction, dream enactment behavior, and orthostatic intolerance or hypotension) at a protocol-specific website. Thirty-four with 3 or more confirmed risk factors underwent serial cardiac 18F-dopamine PET at 1.5-year intervals for up to 7.5 years or until PD was diagnosed.

RESULTS

Nine participants had low initial myocardial 18F-dopamine-derived radioactivity (<6,000 nCi-kg/cc-mCi) and 25 had normal radioactivity. At 7 years of follow-up, 8 of 9 with low initial radioactivity and 1 of 11 with normal radioactivity were diagnosed with a central LBD (LBD+) (P = 0.0009 by Fisher's exact test). Conversely, all 9 LBD+ participants had low 18F-dopamine-derived radioactivity before or at the time of diagnosis of a central LBD, whereas among 25 participants without a central LBD only 1 (4%) had persistently low radioactivity (P < 0.0001 by Fisher's exact test).

CONCLUSION

Cardiac 18F-dopamine PET highly efficiently distinguishes at-risk individuals who are diagnosed subsequently with a central LBD from those who are not.

TRIAL REGISTRATION

CLINICALTRIALS

gov NCT00775853.

FUNDING

Division of Intramural Research, NIH, NINDS.

Is there any correlation between alpha-synuclein levels in tears and retinal layer thickness in Parkinson's disease?

PURPOSE

To determine the total alpha-synuclein (αSyn) reflex tears and its association with retinal layers thickness in Parkinson's disease (PD).

METHODS

Fifty-two eyes of 26 PD subjects and 52 eyes of age-and sex-matched healthy controls were included. Total αSyn in reflex tears was quantified using a human total αSyn enzyme-linked immunosorbent assay (ELISA) kit. The retinal thickness was evaluated with spectral-domain optical coherence tomography. The Movement Disorder Society-Unified Parkinsońs Disease Rating Scale (MDS-UPDRS), Non-Motor Symptoms Scale (NMSS), and Montreal Cognitive Assessment (MoCA) were used to assess motor, non-motor, and cognition.

RESULTS

In PD, total αSyn levels were increased compared to control subjects [1.76pg/mL (IQR 1.74-1.80) vs 1.73pg/mL (IQR 1.70-1.77), p < 0.004]. The nerve fiber layer, ganglion cell layer, internal plexiform layer, inner nuclear layer, and outer nuclear layer were thinner in PD in comparison with controls (p < 0.05). The outer plexiform layer and retinal pigment epithelium were thicker in PD (p < 0.05). The total αSyn levels positively correlated with the central volume of the inner nuclear layer (r = 0.357, p = 0.009).

CONCLUSION

Total αSyn reflex tear levels were increased in subjects with PD compared to controls. PD patients showed significant thinning of the inner retinal layers and thickening of outer retinal layers in comparison with controls. Total αSyn levels positively correlate with the central volume of the inner nuclear layer in PD. The combination of these biomarkers might have a possible role as a diagnostic tool in PD subjects.

The Increasing Prevalence of REM Sleep Behavior Disorder with Parkinson's Disease Progression: A Polysomnography-Supported Study

Objectives

Rapid eye movement (REM) sleep behavior disorder (RBD) is proposed as an early diagnostic marker in Parkinson's disease (PD). We investigated the frequency of RBD during the progression of PD in the advanced stages and identified potential risk factors for developing RBD earlier or later.

Patients and Methods

We performed a retrospective analysis and determined the frequency of RBD in all PD in-patients (Hoehn and Yahr stages ≥3) with motor fluctuations who had undergone video-polysomnography (vPSG) for a sleep complaint or daytime sleepiness. To correct for selection bias, we analyzed the prevalence of RBD in PD patients from the DeNoPa cohort. PD patients with RBD were compared with PD without RBD. To identify potential risk factors, we performed multiple regression modeling.

Results

A total of 504 PD patients had vPSG. 37 were excluded due to missing REM or artifacts during REM. RBD was present in 406/467 (86.9%) PD patients. PD + RBD patients were older than PDnonRBD (69 ± 7.7 vs. 64 ± 9.2 years, P < 0.01), were more likely to have postural instability [234 (59.1%) vs. 19 (33.9%), P < 0.01], and were treated more often with antidepressants (other than SSRIs) [141 (34.7%) vs. 7 (13%), P < 0.01]. Multiple regression modeling identified predictors of RBD with an AUC of 0.78.

Conclusion

The prevalence of RBD in patients with advanced PD is high and increases with disease severity, motor deficits, postural instability, orthostatic symptoms, and age. This suggests RBD is a progression marker of PD in patients with sleep complaints.

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.

The noradrenergic subtype of Parkinson disease: from animal models to clinical practice

Many advances in understanding the pathophysiology of Parkinson disease (PD) have been based on research addressing its motor symptoms and phenotypes. Various data-driven clinical phenotyping studies supported by neuropathological and in vivo neuroimaging data suggest the existence of distinct non-motor endophenotypes of PD even at diagnosis, a concept further strengthened by the predominantly non-motor spectrum of symptoms in prodromal PD. Preclinical and clinical studies support early dysfunction of noradrenergic transmission in both the CNS and peripheral nervous system circuits in patients with PD that results in a specific cluster of non-motor symptoms, including rapid eye movement sleep behaviour disorder, pain, anxiety and dysautonomia (particularly orthostatic hypotension and urinary dysfunction). Cluster analyses of large independent cohorts of patients with PD and phenotype-focused studies have confirmed the existence of a noradrenergic subtype of PD, which had been previously postulated but not fully characterized. This Review discusses the translational work that unravelled the clinical and neuropathological processes underpinning the noradrenergic PD subtype. Although some overlap with other PD subtypes is inevitable as the disease progresses, recognition of noradrenergic PD as a distinct early disease subtype represents an important advance towards the delivery of personalized medicine for patients with PD.

Baroreflex-sympathoneural dysfunction characterizes at-risk individuals with preclinical central Lewy body diseases

PURPOSE

In central Lewy body diseases (LBDs) such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB), by the time parkinsonism or cognitive dysfunction becomes manifest, substantial central neurodegeneration has already occurred. Cardiovascular autonomic biomarkers might detect preclinical central LBDs in at-risk individuals, enabling possibly effective disease-modifying treatment.

METHODS

In the prospective, longitudinal PDRisk study, 59 participants provided information about family history of PD, olfactory dysfunction, dream enactment behavior, and orthostatic intolerance or hypotension at a protocol-specific website and were screened as outpatients. Thirty-four had three or more confirmed risk factors and were followed until PD was diagnosed or up to 7.5 years. Dependent measures included assessments of baroreflex-sympathoneural function, via the blood pressure recovery time (PRT) after release of the Valsalva maneuver and baroreflex areas; and baroreflex-cardiovagal function, via heart rate variability in the time and frequency domains and Valsalva baroslopes. Data were compared from groups with or without a subsequent diagnosis of a central LBD (LBD+, N = 9; LBD-, N = 25) and PDRisk participants with fewer than three confirmed risk factors (PDRisk-, N = 25).

RESULTS

The LBD+ group had larger orthostatic falls in systolic blood pressure than did the LBD- and PDRisk- groups (p < 0.0001 each). The LBD+ group had increased PRTs (p = 0.0114 versus LBD-, p = 0.0094 versus PDRisk-) and baroreflex areas after the Valsalva maneuver (p = 0.0225 versus LBD-, p = 0.0028 versus PDRisk-), whereas the groups did not differ in indices of baroreflex-cardiovagal function.

CONCLUSION

Orthostatic hypotension and baroreflex-sympathoneural dysfunction characterize at-risk individuals who go on to be diagnosed with a central LBD during longitudinal follow-up.

Sleep and Autonomic Manifestations in Parkinson’s Disease Complicated With Probable Rapid Eye Movement Sleep Behavior Disorder

Patients with Parkinson’s disease (PD) complicated with rapid eye movement sleep behavior disorder (RBD) present with distinct clinical features. The purpose of this study was to determine the clinical features of sleep and autonomic symptoms in PD patients with probable RBD (pRBD). The study included 126 patients with PD. pRBD was defined as having a history of dream-enacting behavior with a total score of 5 or greater on the Japanese version of the RBD Screening Questionnaire (RBDSQ-J). The Parkinson’s Disease Sleep Scale-2 (PDSS-2) was used to evaluate sleep disturbances. Scales for Outcomes in Parkinson’s Disease-Autonomic dysfunction (SCOPA-AUT) were used to evaluate autonomic symptoms. Clinical assessments included disease severity, motor symptoms, olfaction, depression, cognitive function, levodopa equivalent dose (LED), and cardiac metaiodobenzylguanidine (MIBG) scintigraphy. Correlations between RBDSQ-J total scores and clinical variables were analyzed. Compared to PD patients without pRBD, PD patients with pRBD showed severe hyposmia, severe sleep-related symptoms, severe dysautonomia, and more reduced cardiac MIBG scintigraphy. Within the PDSS-2, the “PD symptoms at night” domain was significantly more severe in PD patients with pRBD. Within the SCOPA-AUT, the “urinary” and “cardiovascular” domains were significantly higher in PD patients with pRBD. In correlation analyses, RBDSQ-J total scores were positively correlated with PDSS-2 total scores, “PD symptoms at night” and “disturbed sleep” domains, Epworth Sleepiness Scale scores, SCOPA-AUT total scores, “urinary,” “cardiovascular,” and “thermo” domain scores, and LED. RBDSQ-J total scores were negatively correlated with cardiac MIBG scintigraphy uptake. Binary logistic regression analysis showed that PDSS-2 subitem 7 (distressing hallucinations) and SCOPA-AUT subitem 11 (weak stream of urine) were significant determinants for pRBD. Our study showed that PD patients with pRBD had characteristic sleep and autonomic symptoms.

REM sleep behavioral disorder may be an independent risk factor for orthostatic hypotension in Parkinson's disease

PURPOSE

The purpose of this study was to evaluate the association between clinically possible rapid eye movement (REM) sleep behavioral disorder (pRBD) and orthostatic hypotension (OH) in PD patients, as well as to explore the mechanisms underlying the association.

METHODS

PD patients (n = 116) were assigned to a group with OH (PD-OH) or without OH (PD-NOH). General demographic and clinical data were collected. A series of scales were used to assess the clinical symptoms in the two groups.

RESULTS

A total of 27 patients (23.3%) had OH. The PD-OH group showed significantly higher H-Y staging score and significantly higher frequencies of pRBD, anxiety, depression, and cognitive impairment than the PD-NOH group. Binary logistic regression analysis identified the following factors as independently associated with PD-OH: H-Y staging [odds ratio (OR) 2.565, 95% confidence interval (CI) 1.160-5.673; P = 0.020], RBD (OR 7.680, 95% CI 1.944-30.346; P = 0.004), UPDRS II (OR 1.021, 95% CI 0.980-1.063; P = 0.020), depression (OR 7.601, 95% CI 1.492-38.718; P = 0.015), and cognitive impairment (OR 0.824, 95% CI 0.696-0.976; P = 0.025).

CONCLUSIONS

Our results suggest that pRBD is an independent risk factor for OH in patients with PD. We speculate that there may be a close relationship between RBD and OH, which requires attention. Early diagnosis of RBD may help predict the appearance of OH in PD patients.

Dynamic planar scintigraphy for the rapid kinetic measurement of myocardial 123I-MIBG turnover can identify Lewy body disease

BACKGROUND

Using two static scans for ¹²³I-meta-iodobenzyl-guanidine (¹²³I-MIBG) myocardial scintigraphy ignores the dynamic response from vesicular trapping in nerve terminals. Moreover, the long pause between scans is impractical for patients with Lewy body diseases (LBDs). Here, we optimized indices that capture norepinephrine kinetics, tested their diagnostic performance, and determined the differences in ¹²³I-MIBG performance among disease groups.

METHODS

We developed a new 30-min protocol for ¹²³I-MIBG dynamic planar imaging for suspected LBD patients. Pharmacokinetic modelling of time-activity curves (TACs) was used to calculate three new indices: unidirectional uptake of ¹²³I-MIBG to vesicular trapping (iUp), rate of myocardial ¹²³I-MIBG loss (iLoss), and non-specific fractional distribution of ¹²³I-MIBG in the interstitial space. We compared the performance of the new and existing indices with regard to discrimination of patients with or without LBDs. Subgroup analysis was performed to examine differences in ¹²³I-MIBG turnover between patients in a dementia with Lewy bodies (DLB) group and two Parkinson's disease (PD) groups, one with and the other without REM sleep behaviour disorder (RBD).

RESULTS

iLoss was highly discriminative, particularly for patients with low myocardial ¹²³I-MIBG trapping, and the new indices outperformed existing ones. ROC analysis revealed that the AUC of iLoss (0.903) was significantly higher than that of early HMR (0.863), while comparable to that of delayed HMR (0.892). The RBD-positive PD group and the DLB group had higher turnover rates than the RBD-negative PD group, indicating a potential association between prognosis and iLoss.

CONCLUSION

¹²³I-MIBG turnover can be quantified in 30 min using a three-parameter model based on ¹²³I-MIBG TACs. The discriminatory performance of the new model-based indices might help explain the neurotoxicity or neurodegeneration that occurs in LBD patients.

Cardiac Autonomic Dysfunction Is Associated with Severity of REM Sleep without Atonia in Isolated REM Sleep Behavior Disorder

123I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy was performed to assess cardiac autonomic dysfunction and demonstrate its correlation with clinical and polysomnographic characteristics in patients with isolated rapid eye movement (REM) sleep behavior disorder. All subjects including 39 patients with isolated REM sleep behavior disorder and 17 healthy controls underwent MIBG cardiac scintigraphy for cardiac autonomic dysfunction assessment. The isolated REM sleep behavior disorder was confirmed by in-lab overnight polysomnography. A receiver operating curve was constructed to determine the cut-off value of the early and delayed heart-to-mediastinum ratio in patients with isolated REM sleep behavior disorder. Based on each cut-off value, a comparison analysis of REM sleep without atonia was performed by dividing isolated REM sleep behavior disorder patients into two groups. MIBG uptake below the cut-off value was associated with higher REM sleep without atonia. The lower heart-to-mediastinum ratio had significantly higher REM sleep without atonia (%), both with cut-off values of early (11.0 ± 5.6 vs. 29.3 ± 23.2%, p = 0.018) and delayed heart-to-mediastinum ratio (9.1 ± 4.3 vs. 30.0 ± 22.9%, p = 0.011). These findings indicate that reduced MIBG uptake is associated with higher REM sleep without atonia in isolated REM sleep behavior disorder.

Preoperative REM Sleep Behavior Disorder and Subthalamic Nucleus Deep Brain Stimulation Outcome in Parkinson Disease 1 Year After Surgery

BACKGROUND AND OBJECTIVES

To determine whether patients with Parkinson disease (PD) eligible for subthalamic nucleus deep brain stimulation (STN-DBS) with probable REM sleep behavior disorder (RBD) preoperatively could be more at risk of poorer motor, nonmotor, and quality of life outcomes 12 months after surgery compared to those without RBD.

METHODS

We analyzed the preoperative clinical profile of 448 patients with PD from a French multicentric prospective study (PREDISTIM) according to the presence or absence of probable RBD based on the RBD Single Question and RBD Screening Questionnaire. Among the 215 patients with PD with 12 months of follow-up after STN-DBS, we compared motor, cognitive, psycho-behavioral profile, and quality of life outcomes in patients with (pre-opRBD+) or without (pre-opRBD-) probable RBD preoperatively.

RESULTS

At preoperative evaluation, pre-opRBD+ patients were older (61 ± 7.2 vs 59.5 ± 7.7 years; p = 0.02), had less motor impairment (Movement Disorder Society-sponsored version of the Unified Parkinson's Disease Rating Scale [MDS-UPDRS] III "off": 38.7 ± 16.2 vs 43.4 ± 7.1; p = 0.03) but more nonmotor symptoms on daily living activities (MDS-UPDRS I: 12.6 ± 5.5 vs 10.7 ± 5.3; p < 0.001), had more psychobehavioral manifestations (Ardouin Scale of Behavior in Parkinson's Disease total: 7.7 ± 5.1 vs 5.1 ± 0.4; p = 0.003), and had worse quality of life (Parkinson's Disease Questionnaire-39: 33 ± 12 vs 29 ± 12; p = 0.03), as compared to pre-opRBD- patients. Both pre-opRBD+ and pre-opRBD- patients had significant MDS-UPDRS IV score decrease (-37% and -33%, respectively), MDS-UPDRS III "med 'off'/stim 'on'" score decrease (-52% and -54%), and dopaminergic treatment decrease (-52% and -49%) after surgery, with no between-group difference. There was no between-group difference for cognitive and global quality of life outcomes.

CONCLUSIONS

In patients with PD eligible for STN-DBS, the presence of probable RBD preoperatively is not associated with a different clinical outcome 1 year after neurosurgery.

TRIAL REGISTRATION INFORMATION

NCT02360683.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with PD eligible for STN-DBS, the presence of probable RBD preoperatively is not associated with poorer outcomes 1 year post surgery.

Plasma neurofilament light chain level and orthostatic hypotension in early Parkinson's disease

To delineate the impact of non-motor markers (REM sleep behavior disorder (RBD), orthostatic hypotension (OH), cardiac sympathetic denervation, hyposmia) on neuronal injury in early-stage Parkinson's disease (PD), we measured the plasma neurofilament light chain (NFL) level of PD patients and evaluated its relationship with these markers. The study population comprised a cohort of 77 patients with PD and 54 controls. OH was assessed using 5-min head-up tilt-table test. Other clinical parameters such as RBD, Unified Parkinson's Disease Rating Scale (UPDRS), cognition, Cross-Cultural Smell Identification Test (CCSIT), white matter hyperintensity (WMH), cardiac metaiodobenzylguanidine (MIBG) and striatal dopamine transporter (DAT) uptake were assessed. Plasma NFL levels were measured using Simoa platform. During mean 24.8 months of follow-up, 70 patients remained PD, 5 patients converted to Parkinson-plus syndrome (P + converter), and 2 were lost to follow-up. NFL level did not differ between PD and control groups (age-adjusted means 10.40 pg/mL vs 9.51 pg/mL, p = 0.151), but PD patients with OH (median 15.31 pg/mL) had higher levels compared with those without OH (median 9.2 pg/mL, p = 0.008), as well as the control group (median 9.7 pg/mL, p = 0.002). P + converter group had the highest plasma NFL level (38.17 pg/mL, p < 0.001). In a multiple regression analysis, OH, age, and disease duration independently correlated with plasma NFL level. This finding adds biomarker-based evidence for poor clinical outcomes associated with OH in patients with PD.

Cardiac sympathetic burden reflects Parkinson disease burden, regardless of high or low orthostatic blood pressure changes

Reduced uptake of ¹²³I-meta-iodobenzylguanidine (¹²³I-MIBG) and orthostatic hypotension (OH) are independently associated with worse clinical outcomes of Parkinson's disease (PD). However, their interactive influence on PD has not been studied. The role of ¹²³I-MIBG myocardial uptake, as a biomarker of PD severity, was investigated, conditional on the mediating effects of OH. A total of 227 PD patients were enrolled. Their motor and nonmotor aspects were assessed with standardized tools. Global disease burden was estimated by averaging the scaled z-scores of the assessment tools. Every patient went through ¹²³I-MIBG scan, and OH was evaluated with the head-up tilt-test. The mediating role of orthostatic blood pressure changes (ΔBP) on the association between cardiac sympathetic denervation and disease burden was investigated. Low heart-to-mediastinum (H/M) ratio with less than 1.78 was seen in 69.6% of the patient population, and 22.9% of patients had OH. Low H/M ratio was associated with OH, and these patients had worse disease burden than subjects with normal ¹²³I-MIBG uptake (global composite z-score: normal ¹²³I-MIBG vs. abnormal ¹²³I-MIBG; -0.3 ± 0.5 vs. 0.1 ± 0.7; p < 0.001). The mediation models, controlled for age and disease duration, revealed that the delayed H/M ratio and global composite score were negatively associated, irrespective of orthostatic ΔBP. Adverse relationship between cardiac sympathetic denervation and disease burden was shown without any interference from orthostatic blood pressure fluctuations. This result suggested that extracranial cardiac markers might reflect disease burden, regardless of labile blood pressure influence.

Impact of rapid eye movement sleep behavior disorder and autonomic disorders on Parkinson's disease: a review

Parkinson's disease (PD) has heterogeneous clinical manifestations and prognoses. It is accompanied by a group of motor and non-motor symptoms ranging from independence to total disability, limiting work and personal care activities. Currently, disease subtype markers for informing prognosis remain elusive. However, some studies have reported an association between rapid eye movement (REM) sleep behavior disorder (RBD) and faster motor and non-motor symptom progression, including autonomic dysfunction and cognitive decline. Moreover, since autonomic dysfunction has been described in idiopathic forms of RBD, and they share some central regulatory pathways, it remains unclear whether they have a primary association or if they are more severe in patients with PD and RBD, and thus are a disease subtype marker. This article aimed at critically reviewing the literature on the controversies about the prevalence of RBD in PD, the higher incidence of PD non-motor symptoms associated with RBD, the evidence of faster motor worsening in parkinsonian patients with this parasomnia, and the main pathophysiological hypotheses that support these findings.

Parkinson-like early autonomic dysfunction induced by vagal application of DOPAL in rats

AIM

To understand why autonomic failures, a common non-motor symptom of Parkinson's disease (PD), occur earlier than typical motor disorders.

METHODS

Vagal application of DOPAL (3,4-dihydroxyphenylacetaldehyde) to simulate PD-like autonomic dysfunction and understand the connection between PD and cardiovascular dysfunction. Molecular and morphological approaches were employed to test the time-dependent alternation of α-synuclein aggregation and the ultrastructure changes in the heart and nodose (NG)/nucleus tractus solitarius (NTS).

RESULTS

Blood pressure (BP) and baroreflex sensitivity of DOPAL-treated rats were significantly reduced accompanied with a time-dependent change in orthostatic BP, consistent with altered echocardiography and cardiomyocyte mitochondrial ultrastructure. Notably, time-dependent and collaborated changes in Mon-/Tri-α-synuclein were paralleled with morphological alternation in the NG and NTS.

CONCLUSION

These all demonstrate that early autonomic dysfunction mediated by vagal application of DOPAL highly suggests the plausible etiology of PD initiated from peripheral, rather than central site. It will provide a scientific basis for the prevention and early diagnosis of PD.

Lower Urinary Tract and Gastrointestinal Dysfunction Are Common in Early Parkinson's Disease

Purpose

Autonomic dysfunction is a common nonmotor feature and early manifestation of Parkinsons disease (PD). Autonomic dysfunction in PD is associated with a worse prognosis. We sought to characterize autonomic dysfunction and identify associated factors in patients with early PD.

Methods

An observational, cross-sectional, descriptive, and analytical study was conducted to evaluate patients with early PD from the Parkinsons Progression Markers Initiative. We utilized the Scales for Outcomes in Parkinsons Disease-Autonomic dysfunction questionnaire to determine the prevalence and frequencies of autonomic symptomatology. The cohort was grouped into high and low dysautonomic scores. A regression model identified variables that independently explained dysautonomic scores in our early PD cohort.

Results

414 PD patients had a mean age of 61.1 (SD 9.7) years at diagnosis and mean disease duration of 6.7 (SD 6.6) months. Among all patients, 43.7% (181/414) had high dysautonomic scores. Urinary and gastrointestinal symptoms were the most prevalent and frequently reported dysautonomic symptoms. Patients with fatigue (beta = 4.28, p < 0.001), probable rapid eye movement sleep behavior disorder (beta = 2.71, p < 0.001), excessive daytime sleepiness (beta = 1.88,p=0.039), impulsivity and compulsivity (beta = 2.42, p < 0.001), and increasing age (beta = 1.05, p < 0.001) were more likely to have high dysautonomic scores.

Conclusion

Lower urinary tract and gastrointestinal symptoms are prevalent and frequent in early PD patients. Fatigue, sleep disorders, impulsivity and compulsivity, and age are predictors of autonomic dysfunction. Autonomic symptoms predominated in this group of early PD patients in the disease course and were associated with more severe disease.

Non-motor symptoms are associated with REM sleep behavior disorder in Parkinson's disease: a systematic review and meta-analysis

OBJECTIVE

Parkinson's disease (PD) is usually accompanied by rapid eye movement sleep behavior disorder (RBD). A systematic review has concluded that motor manifestations are associated with RBD in PD patients, but whether the same is true of non-motor symptoms is unclear.

METHODS

A systematic review and meta-analysis was conducted by searching studies related to PD and RBD in PubMed, Web of Science, Embase, and Cochrane databases. Data were pooled where appropriate and used to calculate odds ratios (ORs), mean differences (MDs), or standardized mean differences (SMDs) with 95% confidence intervals (CI). Heterogeneity was assessed using the I² statistic.

RESULTS

PD patients with RBD were more likely to be male (OR 1.26, 95% CI 1.14-1.40) and older (MD 1.70 years, 95% CI 1.24-2.16) than those of patients without RBD. Patients with RBD were at a higher risk of non-motor symptoms such as constipation (OR 1.94, 95% CI 1.57-2.38), hallucination (OR 2.62, 95% CI 2.01-3.41), depression (SMD 0.39, 95% CI 0.25-0.53), and cognitive impairment (SMD - 0.29, 95% CI - 0.42 to - 0.17) based on standardized questionnaire scores. Similarly, PD patients with RBD suffered more severe motor symptoms and required higher doses of levodopa therapy.

CONCLUSIONS

The available evidence suggests that PD patients with RBD suffer severer non-motor and motor symptoms than those without RBD. A potential explanation is that PD patients with RBD present more diffuse neurodegeneration.

Differences in correlations of depression and anhedonia with cardiovascular sympathetic functions during a head-up tilt test in drug-naïve Parkinson's disease patients

BACKGROUND

Depression is a symptom of Parkinson's disease (PD) and may be correlated with cardiovascular sympathetic function. Anhedonia is an element of depression, but these symptoms can emerge independently in PD. A correlation of anhedonia with cardiovascular sympathetic function has rarely been examined.

OBJECTIVE

To compare correlations of depression and anhedonia with cardiovascular sympathetic function in drug-naive PD patients.

METHODS

Assessments of depression (Self-rating Depression Scale; SDS), anhedonia (Snaith-Hamilton Pleasure Scale; SHAPS), myocardial ¹²³I-MIBG (¹²³I-meta-iodobenzylguanidine) scintigraphy (heart to mediastinum (H/M) ratios in early and delayed images), and head-up tilt test (HUT) up to 60° for 10 min were performed in 45 drug-naïve PD patients. During the HUT, blood pressure was measured every minute and the maximum decrease in systolic blood pressure (SBP) was determined. Plasma noradrenaline (NA) and arginine vasopressin (AVP) levels were examined at baseline and 10 min after tilt, with subsequent calculation of increases in plasma NA and AVP levels in this 10 min. Correlation coefficients were calculated among these assessment parameters.

RESULTS

SDS significantly correlated with % maximum decrease in SBP (r = 0.344, p = 0.02), but not with H/M ratios in both images and increases in plasma NA and AVP levels. SHAPS did not correlate with the change in SBP, H/M ratios in both images, or plasma NA and AVP levels.

CONCLUSION

Depression was correlated with the % maximum decrease in SBP during a 10-min HUT, but anhedonia did not show this relationship. This suggests that depression and anhedonia may have different pathophysiological backgrounds in drug-naïve PD patients.

Blood pressure lability is associated with subcortical atrophy in early Parkinson's disease

OBJECTIVE

Increased cerebral white matter intensities associated with blood pressure (BP) lability were reported in patients with Parkinson's disease. However, this type of cardiovascular dysautonomia has seldom been associated with disruptions in deep gray matter structures in Parkinson's disease. In the present study, the associations between BP lability and subcortical deep gray matter structures in early Parkinson's disease were evaluated.

METHODS

The present study included 98 early nondemented Parkinson's disease patients. Supine and orthostatic BPs were measured using head-up tilt tests. BP variabilities, measured as standard deviations of 24-h daytime and nighttime BPs, were assessed using 24-h ambulatory BP monitoring. Every patient underwent brain MRI and measurement of deep gray matter volumes. The associations between BP lability and deep gray matter structures were analyzed.

RESULTS

Parkinson's disease patients with orthostatic hypotension had smaller volumes of striatum, particularly caudate, than patients without OH after adjusting for covariates of age, sex, disease duration, and Mini-Mental Status Examination score. Nocturnal BP variability was inversely associated with thalamus, hippocampus, and globus pallidus volumes.

CONCLUSION

The results from the present study showed that BP lability was adversely associated with structural changes in early Parkinson's disease. Different forms of BP fluctuations influenced distinct deep gray matter structures.

Biofluid Markers for Prodromal Parkinson's Disease: Evidence From a Catecholaminergic Perspective

Parkinson's disease (PD) is the most frequent of all Lewy body diseases, a family of progressive neurodegenerative disorders characterized by intra-neuronal cytoplasmic inclusions of α-synuclein. Its most defining features are bradykinesia, tremor, rigidity and postural instability. By the time PD manifests with motor signs, 70% of dopaminergic midbrain neurons are lost, and the disease is already in the middle or late stage. However, there are various non-motor symptoms occurring up to 20 years before the actual parkinsonism that are closely associated with profound deficiency of myocardial noradrenaline content and peripheral sympathetic denervation, as evidenced by neuroimaging experiments in recent years. Additionally, there is an inherent autotoxicity of catecholamines in the neuronal cells in which they are produced, forming toxic catecholaldehyde intermediates that make α-synuclein prone to aggregation, initiating a cascade of events that ultimately leads to neuronal death. The etiopathogenesis of PD and related synucleinopathies thus may well be a prototypical example of a catecholamine-regulated neurodegeneration, given that the synucleinopathy in PD spreads in synergy with central and peripheral catecholaminergic dysfunction from the earliest phases onward. That is why catecholamines and their metabolites, precursors, or derivatives in cerebrospinal fluid or plasma could be of particular interest as biomarkers for prodromal and de novo PD. Because there is great demand for such markers, this mini-review summarizes all catecholamine-related studies to date, in addition to providing profound neurochemical evidence on a systemic and cellular level to further emphasize this hypothesis and with emphasis on extracellular vesicles as a novel diagnostic and therapeutic incentive.

Dysautonomia Is Linked to Striatal Dopamine Deficits and Regional Cerebral Perfusion in Early Parkinson Disease

PURPOSE

The aim of this study was to investigate the association between autonomic dysfunction and striatal dopamine depletion or metabolic changes in de novo Parkinson disease (PD).

METHODS

Based on the Composite Autonomic Severity Score (CASS), patients with de novo PD were classified into PD with (PD-AUT+) and without autonomic dysfunction (PD-AUT-) groups. We compared the dopamine transporter (DAT) availability in the striatum by quantitatively measuring F-FP-CIT PET between both groups. We also assessed the association between DAT availability and the CASS. In addition, we compared regional uptake in early-phase images of F-FP-CIT PET as well as cortical thickness between the PD-AUT+ and PD-AUT- groups.

RESULTS

The PD-AUT+ group had significantly lower DAT availability in all striatal subregions than did the PD-AUT- group. The total CASS was significantly correlated with DAT availability in all striatal subregions. In addition, the subscores of the adrenergic component were correlated with DAT availability in all striatal subregions. The subscores of the cardiovagal component were negatively correlated with DAT availability in the caudate and ventral striatum. In early-phase F-FP-CIT PET, the PD-AUT+ group exhibited decreased regional perfusion in the parieto-occipital areas and increased regional perfusion in the pallidothalamic, pontocerebellar, inferior frontal, and primary motor areas compared with the PD-AUT- group. There were no regions of different cortical thickness between the PD groups.

CONCLUSIONS

The present study revealed that autonomic dysfunction is closely linked to striatal dopamine depletion and prominent PD-related perfusion patterns in de novo PD, suggesting a greater pathological burden in patients with dysautonomia.

Molecular Mechanisms and Clinical Manifestations of Catecholamine Dysfunction in the Eye in Parkinson's Disease As a Basis for Developing Early Diagnosis

This review provides information on the non-motor peripheral manifestations of Parkinson's disease (PD) associated with a pathology of the visual analyzer and the auxiliary apparatus of the eye. The relationship between neurodegenerative processes that take place in the brain and in the eye opens new prospects to use preventive ophthalmologic examination to diagnose PD long before the characteristic motor symptoms appear. This will encourage the use of neuroprotective therapy, which stops, or at least slows down, neuronal death, instead of the current replacement therapy with dopamine agonists. An important result of an eye examination of patients with PD may be a non-invasive identification of new peripheral biomarkers manifesting themselves as changes in the composition of the lacrimal fluid.

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.

Computational modeling reveals multiple abnormalities of myocardial noradrenergic function in Lewy body diseases

BACKGROUND

Lewy body diseases, a family of aging-related neurodegenerative disorders, entail loss of the catecholamine dopamine in the nigrostriatal system and equally severe deficiency of the closely related catecholamine norepinephrine in the heart. The myocardial noradrenergic lesion is associated with major non-motor symptoms and decreased survival. Numerous mechanisms determine norepinephrine stores, and which of these are altered in Lewy body diseases has not been examined in an integrated way. We used a computational modeling approach to assess comprehensively pathways of cardiac norepinephrine synthesis, storage, release, reuptake, and metabolism in Lewy body diseases. Application of a novel kinetic model identified a pattern of dysfunctional steps contributing to norepinephrine deficiency. We then tested predictions from the model in a new cohort of Parkinson disease patients.

METHODS

Rate constants were calculated for 17 reactions determining intra-neuronal norepinephrine stores. Model predictions were tested by measuring post-mortem apical ventricular concentrations and concentration ratios of catechols in controls and patients with Parkinson disease.

RESULTS

The model identified low rate constants for three types of processes in the Lewy body group-catecholamine biosynthesis via tyrosine hydroxylase and L-aromatic-amino-acid decarboxylase, vesicular storage of dopamine and norepinephrine, and neuronal norepinephrine reuptake via the cell membrane norepinephrine transporter. Post-mortem catechols and catechol ratios confirmed this triad of model-predicted functional abnormalities.

CONCLUSION

Denervation-independent impairments of neurotransmitter biosynthesis, vesicular sequestration, and norepinephrine recycling contribute to the myocardial norepinephrine deficiency attending Lewy body diseases. A proportion of cardiac sympathetic nerves are "sick but not dead," suggesting targeted disease-modification strategies might retard clinical progression.

TRIAL REGISTRATION

This study was not a clinical trial.

FUNDING

The research reported here was supported by the Division of Intramural Research, NINDS.

Orthostatic hypotension following deep brain stimulation in parkinson's disease: a systematic review

Background: Deep brain stimulation (DBS) is a treatment that may be suitable for patients with Parkinson's disease (PD) with severe motor fluctuations and/or dyskinesias despite optimised medical therapy. DBS has been associated with side effects including deterioration in cognition, verbal fluency and mood. Studies assessing the effect of DBS on orthostatic hypotension (OH) have produced variable results.Objectives: The aim is to summarise peer-reviewed studies that have assessed the effect of DBS on systolic or diastolic BP in PD patients.Methods: The databases PubMed, EMBASE, Medline and Scopus were searched using the terms (Deep brain stimulation OR DBS) AND (hypotension OR hypertension OR blood pressure) on 13 April 2017.Results: Fourteen studies fulfilled the inclusion criteria. Ten studies involved subthalamic nucleus (STN) DBS, three studies globus pallidus interna (GPi) DBS and one study involved DBS of the pedunculopontine nuclei and motor thalamus. The majority of the studies found results indicating that DBS in PD does not worsen OH in PD.Conclusions: Small sample sizes and lack of blinding of outcome assessors means this result should be approached cautiously. Future research may further investigate the effect of GPi DBS on OH and should aim to address these methodological issues.

Roles of cardiac sympathetic neuroimaging in autonomic medicine

Sympathetic neuroimaging is based on the injection of compounds that either radiolabel sites of the cell membrane norepinephrine transporter (NET) or that are taken up into sympathetic nerves via the NET and radiolabel intra-neuronal catecholamine storage sites. Detection of the radioactivity is by planar or tomographic radionuclide imaging. The heart stands out among body organs in terms of the intensity of radiolabeling of sympathetic nerves, and virtually all of sympathetic neuroimaging focuses on the left ventricular myocardium. The most common cardiac sympathetic neuroimaging method worldwide is ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) scanning. ¹²³I-MIBG scanning is used routinely in Europe and East Asia in the diagnostic evaluation of neurogenic orthostatic hypotension (nOH), to distinguish Lewy body diseases (e.g., Parkinson disease with orthostatic hypotension (OH), pure autonomic failure) from non-Lewy body diseases (e.g., multiple system atrophy) and to distinguish dementia with Lewy bodies from Alzheimer's disease. In the USA, ¹²³I-MIBG scanning has been approved by the Food and Drug Administration for the evaluation of pheochromocytoma and some forms of heart failure-but not for the above-mentioned differential diagnoses. Positron emission tomographic methods based on imaging agents such as ¹⁸F-dopamine are categorized as research tools, despite more than a quarter century of clinical experience with these modalities. Considering that ¹²³I-MIBG scanning is available at most academic medical centers in the USA, cardiac sympathetic neuroimaging by this methodology merits consideration as an autonomic test, especially in patients with nOH.

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.

REM sleep behavior disorder is related to enteric neuropathology in Parkinson disease

OBJECTIVE

To determine whether REM sleep behavior disorder (RBD) in Parkinson disease (PD) is associated with lesions and dysfunctions of the autonomic nervous system by evaluating enteric phosphorylated α-synuclein histopathology (PASH) and permeability.

METHODS

A total of 45 patients with PD were included in this cross-sectional study. RBD was diagnosed on the basis of a standardized clinical interview and confirmed by polysomnography. For each patient, 5 biopsies were taken at the junction between the sigmoid and descending colon during the course of a rectosigmoidoscopy. For the detection of enteric PASH, 2 colonic biopsies were analyzed by immunohistochemistry with antibodies against phosphorylated α-synuclein and PGP9.5 in 43 patients (2 patients were excluded because only 1 biopsy was available). The paracellular permeability and transcellular permeability were evaluated by measuring sulfonic acid and horseradish peroxidase flux, respectively, in the 3 remaining biopsies mounted in Ussing chambers.

RESULTS

Enteric PASH was more frequent in the subgroup of patients with PD with RBD compared to patients without RBD (18 of 28, 64.3%, vs 2 of 15, 13.3%, respectively, p < 0.01). No differences were observed in intestinal permeability between patients with PD with and without RBD.

CONCLUSIONS

Patients with PD and RBD have a greater frequency of synuclein pathology in the enteric nervous system, suggesting that RBD is associated with widespread synuclein neuropathology.

Clinical Significance of REM Sleep Behavior Disorders and Other Non-motor Symptoms of Parkinsonism

Rapid eye movement sleep behavior disorder (RBD) is one of the most common non-motor symptoms of parkinsonism, and it may serve as a prodromal marker of neurodegenerative disease. The mechanism underlying RBD is unclear. Several prospective studies have reported that specific non-motor symptoms predict a conversion risk of developing a neurodegenerative disease, including olfactory dysfunction, abnormal color vision, autonomic dysfunction, excessive daytime sleepiness, depression, and cognitive impairment. Parkinson's disease (PD) with RBD exhibits clinical heterogeneity with respect to motor and non-motor symptoms compared with PD without RBD. In this review, we describe the main clinical and pathogenic features of RBD, focusing on its association with other non-motor symptoms of parkinsonism.

Nonmotor Subtyping in Parkinson's Disease

Nonmotor symptoms are integral to Parkinson's disease. Several subtypes dominated by specific nonmotor symptoms have emerged. In this chapter, the rationale behind nonmotor subtyping and currently proposed nonmotor subgroups within Parkinson's disease based on data-driven cluster analysis and clinical observations will be summarized. Furthermore, the concept of seven clinical nonmotor subtypes will be discussed in detail including the clinical presentation, potential biomarkers, and the clinical relevance. In future, nonmotor subtypes will possibly play a major role within the aim to achieve personalized medicine.

Sleep Dysfunction in Parkinson's Disease

The spectrum of sleep problems in Parkinson's disease (PD) is broad. These symptoms are recognized as being clinically relevant by the PD patients and may seriously affect their quality of life. Some studies reveal the occurrence of sleep disorders in more than half of the PD patients. The etiology is multifactorial and it mainly involves the degeneration of the sleep-regulating structures. Sleep disorders in PD can be classified into: disturbances of sleep and disturbances of wakefulness. Generic and specific scales were designed to help the screening and evaluation of sleep dysfunction. Further assessment can be done using sleep recording techniques, like actigraphy or polysomnography. All types of sleep disturbances may be encountered in PD: insomnia, excessive daytime sleepiness, rapid eye movement sleep behavior disorders, and restless legs syndrome. This chapter will focus on reviewing the main characteristics, pathophysiology, assessment, and management of the most frequent sleep disturbances encountered in PD.

Neuropathology of Nonmotor Symptoms of Parkinson's Disease

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

Cardiovascular Autonomic Dysfunction in Patients with Drug-Induced Parkinsonism

BACKGROUND AND PURPOSE

Recent studies have shown that several nonmotor symptoms differ between Parkinson's disease (PD) and drug-induced parkinsonism (DIP). However, there have been no reports on cardiovascular autonomic function in DIP, and so this study investigated whether cardiovascular autonomic function differs between PD and DIP patients.

METHODS

This study consecutively enrolled 20 DIP patients, 99 drug-naïve PD patients, and 25 age-matched healthy controls who underwent head-up tilt-table testing and 24-h ambulatory blood pressure monitoring.

RESULTS

Orthostatic hypotension was more frequent in patients with PD or DIP than in healthy controls. In DIP, orthostatic hypotension was associated with the underlying psychiatric diseases and neuroleptics use, whereas prokinetics were not related to orthostatic hypotension. The supine blood pressure, nighttime blood pressure, and nocturnal blood pressure dipping did not differ significantly between the DIP and control groups. Supine hypertension and nocturnal hypertension were more frequent in PD patients than in controls.

CONCLUSIONS

The included DIP patients frequently exhibited orthostatic hypotension that was associated with the underlying diseases as well as the nature of and exposure time to the offending drugs. Clinicians should individualize the manifestations of DIP according to underlying diseases as well as the action mechanism of and exposure time to each offending drug.