Droxidopa and Reduced Falls in a Trial of Parkinson Disease Patients With Neurogenic Orthostatic Hypotension

Levodopa: From Biological Significance to Continuous Monitoring

A continuous levodopa sensor can improve the quality of life for patients suffering with Parkinson's disease by enhancing levodopa titration and treatment effectiveness; however, its development is currently hindered by the absence of a specific levodopa molecular recognition element and limited insights into how real-time monitoring might affect clinical outcomes. This gap in research contributes to clinician uncertainty regarding the practical value of continuous levodopa monitoring data. This paper examines the current state of levodopa sensing and the inherent limitations in today's methods. Further, these challenges are described, including aspects such as interference from the metabolic pathway and adjunct medications, temporal resolution, and clinical questions, with a specific focus on a comprehensive selection of molecules, such as adjunct medications and structural isomers, as an interferent panel designed to assess and validate future levodopa sensors. We review insights and lessons from previously reported levodopa sensors and present a comparative analysis of potential molecular recognition elements, discussing their advantages and drawbacks.

The impact of cardiovascular diagnostics and treatments on fall risk in older adults: a scoping review and evidence map

BACKGROUND

We aimed to summarize the published evidence on the fall risk reducing potential of cardiovascular diagnostics and treatments in older adults.

METHODS

Design: scoping review and evidence map.

DATA SOURCES

Medline and Embase.

ELIGIBILITY CRITERIA

all available published evidence; Key search concepts: "older adults," "cardiovascular evaluation," "cardiovascular intervention," and "falls." Studies reporting on fall risk reducing effect of the diagnostic/treatment were included in the evidence map. Studies that investigated cardiovascular diagnostics or treatments within the context of falls, but without reporting a fall-related outcome, were included in the scoping review for qualitative synthesis.

RESULTS

Two articles on cardiovascular diagnostics and eight articles on cardiovascular treatments were included in the evidence map. Six out of ten studies concerned pacemaker intervention of which one meta-analyses that included randomized controlled trials with contradictory results. A combined cardiovascular assessment/evaluation (one study) and pharmacotherapy in orthostatic hypotension (one study) showed fall reducing potential. The scoping review contained 40 articles on cardiovascular diagnostics and one on cardiovascular treatments. It provides an extensive overview of several diagnostics (e.g., orthostatic blood pressure measurements, heart rhythm assessment) useful in fall prevention. Also, diagnostics were identified, that could potentially provide added value in fall prevention (e.g., blood pressure variability and head turning).

CONCLUSION

Although the majority of studies showed a reduction in falls after the intervention, the total amount of evidence regarding the effect of cardiovascular diagnostics/treatments on falls is small. Our findings can be used to optimize fall prevention strategies and develop an evidence-based fall prevention care pathway. Adhering to the World guidelines on fall prevention recommendations, it is crucial to undertake a standardized assessment of cardiovascular risk factors, followed by supplementary testing and corresponding interventions, as effective components of fall prevention strategies. In addition, accompanying diagnostics such as blood pressure variability and head turning can be of added value.

Setting the clinical context to non-motor symptoms reflected by Park-pain, Park-sleep, and Park-autonomic subtypes of Parkinson's disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) are well described in both clinical practice and the literature, enabling their management and enhancing our understanding of PD. NMS can dominate the clinical pictures and NMS subtypes have recently been proposed, initially based on clinical observations, and later confirmed in data driven analyses of large datasets and in biomarker-based studies. In this chapter, we provide an update on what is known about three common subtypes of NMS in PD. The pain (Park-pain), sleep dysfunction (Park-sleep), and autonomic dysfunction (Park-autonomic), providing an overview of their individual classification, clinical manifestation, pathophysiology, diagnosis, and potential treatments.

Ampreloxetine Versus Droxidopa in Neurogenic Orthostatic Hypotension: A Comparative Review

Neurogenic orthostatic hypotension (nOH) is a disabling problem of autonomic dysfunction in patients with Parkinson's disease, which is associated with poor quality of life and higher mortality rates. The purpose of this literature review was to explore and compare the efficacy and safety of droxidopa (an existing treatment) and ampreloxetine (a newer medication) in the treatment of nOH. We used a mixed-method literature review that addresses the epidemiology, pathophysiology, and pharmacological and non-pharmacological management of nOH in Parkinson's disease in a general way, with a more exploratory approach to droxidopa- and ampreloxetine-controlled trial studies. We included a total of 10 studies of randomized controlled trials with eight studies focused on droxidopa and two studies focused on ampreloxetine. These two drugs were analyzed and compared based on the collected individual study results. Treatment of nOH in Parkinson's disease patients with droxidopa or ampreloxetine showed clinically meaningful and statistically significant improvements relative to placebo on the components of the OHSA (Orthostatic Hypotension Symptom Assessment) composite score and OHDAS (Orthostatic Hypotension Daily Activity Scale composite scores) composite score. Droxidopa had an improved effect on daily activities, with an associated increase in standing systolic blood pressure (BP), but the long-term efficacy of droxidopa has not been documented. Standing systolic BP was maintained by ampreloxetine and worsened after the withdrawal phase. This highlights the importance of conducting further research which will help us to improve the therapeutic approach for patients with nOH and Parkinson's disease.

Translational molecular imaging and drug development in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects elderly people and constitutes a major source of disability worldwide. Notably, the neuropathological hallmarks of PD include nigrostriatal loss and the formation of intracellular inclusion bodies containing misfolded α-synuclein protein aggregates. Cardinal motor symptoms, which include tremor, rigidity and bradykinesia, can effectively be managed with dopaminergic therapy for years following symptom onset. Nonetheless, patients ultimately develop symptoms that no longer fully respond to dopaminergic treatment. Attempts to discover disease-modifying agents have increasingly been supported by translational molecular imaging concepts, targeting the most prominent pathological hallmark of PD, α-synuclein accumulation, as well as other molecular pathways that contribute to the pathophysiology of PD. Indeed, molecular imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) can be leveraged to study parkinsonism not only in animal models but also in living patients. For instance, mitochondrial dysfunction can be assessed with probes that target the mitochondrial complex I (MC-I), while nigrostriatal degeneration is typically evaluated with probes designed to non-invasively quantify dopaminergic nerve loss. In addition to dopaminergic imaging, serotonin transporter and N-methyl-D-aspartate (NMDA) receptor probes are increasingly used as research tools to better understand the complexity of neurotransmitter dysregulation in PD. Non-invasive quantification of neuroinflammatory processes is mainly conducted by targeting the translocator protein 18 kDa (TSPO) on activated microglia using established imaging agents. Despite the overwhelming involvement of the brain and brainstem, the pathophysiology of PD is not restricted to the central nervous system (CNS). In fact, PD also affects various peripheral organs such as the heart and gastrointestinal tract - primarily via autonomic dysfunction. As such, research into peripheral biomarkers has taken advantage of cardiac autonomic denervation in PD, allowing the differential diagnosis between PD and multiple system atrophy with probes that visualize sympathetic nerve terminals in the myocardium. Further, α-synuclein has recently gained attention as a potential peripheral biomarker in PD. This review discusses breakthrough discoveries that have led to the contemporary molecular concepts of PD pathophysiology and how they can be harnessed to develop effective imaging probes and therapeutic agents. Further, we will shed light on potential future trends, thereby focusing on potential novel diagnostic tracers and disease-modifying therapeutic interventions.

An Update on Nondopaminergic Treatments for Motor and Non-motor Symptoms of Parkinson's Disease

Nondopaminergic neurotransmitters such as adenosine, norepinephrine, serotonin, glutamate, and acetylcholine are all involved in Parkinson's disease (PD) and promote its symptoms. Therefore, nondopaminergic receptors are key targets for developing novel preparations for the management of motor and non-motor symptoms in PD, without the potential adverse events of dopamine replacement therapy. We reviewed English-written articles and ongoing clinical trials of nondopaminergic treatments for PD patients till 2014 to summarize the recent findings on nondopaminergic preparations for the treatment of PD patients. The most promising research area of nondopaminergic targets is to reduce motor complications caused by traditional dopamine replacement therapy, including motor fluctuations and levodopa-induced dyskinesia. Istradefylline, Safinamide, and Zonisamide were licensed for the management of motor fluctuations in PD patients, while novel serotonergic and glutamatergic agents to improve motor fluctuations are still under research. Sustained- release agents of Amantadine were approved for treating levodopa induced dyskinesia (LID), and serotonin 5HT1B receptor agonist also showed clinical benefits to LID. Nondopaminergic targets were also being explored for the treatment of non-motor symptoms of PD. Pimavanserin was approved globally for the management of hallucinations and delusions related to PD psychosis. Istradefylline revealed beneficial effect on daytime sleepiness, apathy, depression, and lower urinary tract symptoms in PD subjects. Droxidopa may benefit orthostatic hypotension in PD patients. Safinamide and Zonisamide also showed clinical efficacy on certain non-motor symptoms of PD patients. Nondopaminergic drugs are not expected to replace dopaminergic strategies, but further development of these drugs may lead to new approaches with positive clinical implications.

Interventions for preventing falls in Parkinson's disease

BACKGROUND

Most people with Parkinson's disease (PD) experience at least one fall during the course of their disease. Several interventions designed to reduce falls have been studied. An up-to-date synthesis of evidence for interventions to reduce falls in people with PD will assist with informed decisions regarding fall-prevention interventions for people with PD.

OBJECTIVES

To assess the effects of interventions designed to reduce falls in people with PD.

SEARCH METHODS

CENTRAL, MEDLINE, Embase, four other databases and two trials registers were searched on 16 July 2020, together with reference checking, citation searching and contact with study authors to identify additional studies. We also conducted a top-up search on 13 October 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of interventions that aimed to reduce falls in people with PD and reported the effect on falls. We excluded interventions that aimed to reduce falls due to syncope.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Review procedures. Primary outcomes were rate of falls and number of people who fell at least once. Secondary outcomes were the number of people sustaining one or more fall-related fractures, quality of life, adverse events and economic outcomes. The certainty of the evidence was assessed using GRADE.

MAIN RESULTS

This review includes 32 studies with 3370 participants randomised. We included 25 studies of exercise interventions (2700 participants), three studies of medication interventions (242 participants), one study of fall-prevention education (53 participants) and three studies of exercise plus education (375 participants). Overall, participants in the exercise trials and the exercise plus education trials had mild to moderate PD, while participants in the medication trials included those with more advanced disease. All studies had a high or unclear risk of bias in one or more items. Illustrative risks demonstrating the absolute impact of each intervention are presented in the summary of findings tables. Twelve studies compared exercise (all types) with a control intervention (an intervention not thought to reduce falls, such as usual care or sham exercise) in people with mild to moderate PD. Exercise probably reduces the rate of falls by 26% (rate ratio (RaR) 0.74, 95% confidence interval (CI) 0.63 to 0.87; 1456 participants, 12 studies; moderate-certainty evidence). Exercise probably slightly reduces the number of people experiencing one or more falls by 10% (risk ratio (RR) 0.90, 95% CI 0.80 to 1.00; 932 participants, 9 studies; moderate-certainty evidence).  We are uncertain whether exercise makes little or no difference to the number of people experiencing one or more fall-related fractures (RR 0.57, 95% CI 0.28 to 1.17; 989 participants, 5 studies; very low-certainty evidence). Exercise may slightly improve health-related quality of life immediately following the intervention (standardised mean difference (SMD) -0.17, 95% CI -0.36 to 0.01; 951 participants, 5 studies; low-certainty evidence). We are uncertain whether exercise has an effect on adverse events or whether exercise is a cost-effective intervention for fall prevention. Three studies trialled a cholinesterase inhibitor (rivastigmine or donepezil). Cholinesterase inhibitors may reduce the rate of falls by 50% (RaR 0.50, 95% CI 0.44 to 0.58; 229 participants, 3 studies; low-certainty evidence). However, we are uncertain if this medication makes little or no difference to the number of people experiencing one or more falls (RR 1.01, 95% CI 0.90 to 1.14230 participants, 3 studies) and to health-related quality of life (EQ5D Thermometer mean difference (MD) 3.00, 95% CI -3.06 to 9.06; very low-certainty evidence). Cholinesterase inhibitors may increase the rate of non fall-related adverse events by 60% (RaR 1.60, 95% CI 1.28 to 2.01; 175 participants, 2 studies; low-certainty evidence). Most adverse events were mild and transient in nature.  No data was available regarding the cost-effectiveness of medication for fall prevention. We are uncertain of the effect of education compared to a control intervention on the number of people who fell at least once (RR 10.89, 95% CI 1.26 to 94.03; 53 participants, 1 study; very low-certainty evidence), and no data were available for the other outcomes of interest for this comparisonWe are also uncertain (very low-certainty evidence) whether exercise combined with education makes little or no difference to the number of falls (RaR 0.46, 95% CI 0.12 to 1.85; 320 participants, 2 studies), the number of people sustaining fall-related fractures (RR 1.45, 95% CI 0.40 to 5.32,320 participants, 2 studies), or health-related quality of life (PDQ39 MD 0.05, 95% CI -3.12 to 3.23, 305 participants, 2 studies). Exercise plus education may make little or no difference to the number of people experiencing one or more falls (RR 0.89, 95% CI 0.75 to 1.07; 352 participants, 3 studies; low-certainty evidence). We are uncertain whether exercise combined with education has an effect on adverse events or is a cost-effective intervention for fall prevention.  AUTHORS' CONCLUSIONS: Exercise interventions probably reduce the rate of falls, and probably slightly reduce the number of people falling in people with mild to moderate PD.  Cholinesterase inhibitors may reduce the rate of falls, but we are uncertain if they have an effect on the number of people falling. The decision to use these medications needs to be balanced against the risk of non fall-related adverse events, though these adverse events were predominantly mild or transient in nature. Further research in the form of large, high-quality RCTs are required to determine the relative impact of different types of exercise and different levels of supervision on falls, and how this could be influenced by disease severity. Further work is also needed to increase the certainty of the effects of medication and further explore falls prevention education interventions both delivered alone and in combination with exercise.

Droxidopa reduces postural sway in Parkinson disease patients with orthostatic hypotension

We evaluate the effect of droxidopa on gait and balance measures in nine patients with Parkinson's disease and neurogenic orthostatic hypotension. Computerized gait/balance analysis showed a significant effect of droxidopa in reducing postural sway. Future studies may determine if such effect translates into improvement in postural reflexes and falls.

The Pathogenesis and Treatment of Cardiovascular Autonomic Dysfunction in Parkinson's Disease: What We Know and Where to Go

Cardiovascular autonomic dysfunctions (CAD) are prevalent in Parkinson’s disease (PD). It contributes to the development of cognitive dysfunction, falls and even mortality. Significant progress has been achieved in the last decade. However, the underlying mechanisms and effective treatments for CAD have not been established yet. This review aims to help clinicians to better understand the pathogenesis and therapeutic strategies. The literatures about CAD in patients with PD were reviewed. References for this review were identified by searches of PubMed between 1972 and March 2021, with the search term “cardiovascular autonomic dysfunctions, postural hypotension, orthostatic hypotension (OH), supine hypertension (SH), postprandial hypotension, and nondipping”. The pathogenesis, including the neurogenic and non-neurogenic mechanisms, and the current pharmaceutical and non-pharmaceutical treatment for CAD, were analyzed. CAD mainly includes four aspects, which are OH, SH, postprandial hypotension and nondipping, among them, OH is the main component. Both non-neurogenic and neurogenic mechanisms are involved in CAD. Failure of the baroreflex circulate, which includes the lesions at the afferent, efferent or central components, is an important pathogenesis of CAD. Both non-pharmacological and pharmacological treatment alleviate CAD-related symptoms by acting on the baroreflex reflex circulate. However, pharmacological strategy has the limitation of failing to enhance baroreflex sensitivity and life quality. Novel OH treatment drugs, such as pyridostigmine and atomoxetine, can effectively improve OH-related symptoms via enhancing residual sympathetic tone, without adverse reactions of supine hypertension. Baroreflex impairment is a crucial pathological mechanism associated with CAD in PD. Currently, non-pharmacological strategy was the preferred option for its advantage of enhancing baroreflex sensitivity. Pharmacological treatment is a second-line option. Therefore, to find drugs that can enhance baroreflex sensitivity, especially via acting on its central components, is urgently needed in the scientific research and clinical practice.

Peculiarities of promiscuous L-threonine transaldolases for enantioselective synthesis of β-hydroxy-α-amino acids

The introduction of β-hydroxy-α-amino acids (βHAAs) into organic molecules has received considerable attention as these molecules have often found widespread applications in bioorganic chemistry, medicinal chemistry and biomaterial science. Despite innovation of asymmetric synthesis of βHAAs, stereoselective synthesis to control the two chiral centres at C_α and C_β positions is still challenging, with poor atomic economy and multi protection and deprotection steps. These syntheses are often operated under harsh conditions. Therefore, a biotransformation approach using biocatalysts is needed to selectively introduce these two chiral centres into structurally diverse molecules. Yet, there are few ways that enable one-step synthesis of βHAAs. One is to extend the substrate scope of the existing enzyme inventory. Threonine aldolases have been explored to produce βHAAs. However, the enzymes have poor controlled installation at C_β position, often resulting in a mixture of diastereoisomers which are difficult to be separated. In this respect, L-threonine transaldolases (LTTAs) offer an excellent potential as the enzymes often provide controlled stereochemistry at C_α and C_β positions. Another is to mine LTTA homologues and engineer the enzymes using directed evolution with the aim of finding engineered biocatalysts to accept broad substrates with enhanced conversion and stereoselectivity. Here, we review the development of LTTAs that incorporate various aldehyde acceptors to generate structurally diverse βHAAs and highlight areas for future developments. KEY POINTS: • The general mechanism of the transaldolation reaction catalysed by LTTAs • Recent advances in LTTAs from different biosynthetic pathways • Applications of LTTAs as biocatalysts for production of βHAAs.

[Options for the symptomatic treatment of chronic neurological gait disorders]

Gait and mobility impairments are common and relevant in patients with chronic neurological disorders. It reduces the health-related quality of life and induces falls with morbidity. Symptomatic treatment options are therefore necessary in order to improve the health status of patients with neurological disorders.By means of a selective literature research focusing on studies with specific gait-related outcome measures. We discuss the differential treatment options for (1) hypokinetic gait disorders (Parkinson´s disease, Normal pressure hydrocephalus, vascular encephalopathy), (2) gait unsteadiness with ataxia (sensory and cerebellar ataxia), and (3) gait with spasticity and paresis (due to multiple sclerosis). Therapeutical options for the symptomatic treatment of gait disorders comprise non-pharmacological and pharmacological approaches. Both address the functional domains of "locomotion", "postural control", "modulation" and "adaptability" of gait.Pharmacological options are orientated to pathophysiology of the underlying diseases. Supportive physiotherapeutic interventions offer broader and unspecific options for treatment. Clinical conditions that specifically disturb the execution of locomotion or gait can also be addressed by the provision of physical therapy or supportive devices.Effective options for the symptomatic treatment of patients with neurological gait disorders are available. Applications of options addressing the pathophysiology of the underlying disease, a functional domain-based exercise and physiotherapy program, and the provision of walking aides for specific symptoms that further worsen gait performance can be recommended.

The absence of orthostatic heart rate increase is associated with cognitive impairment in Parkinson's disease

Orthostatic hypotension (OH) frequently accompanies autonomic dysfunction and is an important risk factor for cognitive impairment in Parkinson’s disease (PD). While OH is usually diagnosed based on an orthostatic blood pressure drop, the association between the heart rate response and cognitive impairment remains unclear. We retrospectively analyzed 143 cases of clinically diagnosed PD to determine the association between the absence of a heart rate response and cognitive impairment in PD with OH. Among the patients with OH, neurogenic OH was diagnosed in cases without a heart rate increase, while all other patients were diagnosed with non-neurogenic OH. Dementia was found in 23 of 143 PD cases (16.1%) in this cohort. The presence of OH was an independent risk factor for dementia in PD in addition to the disease severity, years of education and beta-blockers use. Neurogenic OH was significantly associated with dementia compared to the no OH group (hazard ratio [HR] 7.3, 95% confidence interval [CI] 2.2–24.6, P<0.01), an association that was preserved after adjusting for age, gender and other covariant factors. However, no such association was observed for non-neurogenic OH (HR 2.9, 95%CI 0.8–10.9, P = 0.12). While the cognitive impairment was significantly worse in the neurogenic OH group than the no-OH group, the groups were otherwise similar. The blood pressure decrease was significantly lower in both OH groups than in the no-OH group, despite no significant differences between the OH groups. Our finding showed that OH without a heart rate response was an important predictor of cognitive impairment in PD.

Clinical Trials for Neurogenic Orthostatic Hypotension: A Comprehensive Review of Endpoints, Pitfalls, and Challenges

Neurogenic orthostatic hypotension (nOH) is among the most debilitating nonmotor features of patients with Parkinson's disease (PD) and other synucleinopathies. Patients with PD and nOH generate more hospitalizations, make more emergency room visits, create more telephone calls/mails to doctors, and have earlier mortality than those with PD but without nOH. Overall, the health-related cost in patients with PD and OH is 2.5-fold higher compared with patients with PD without OH. Hence, developing effective therapies for nOH should be a research priority. In the last few decades, improved understanding of the pathophysiology of nOH has led to the identification of therapeutic targets and the development and approval of two drugs, midodrine and droxidopa. More effective and safer therapies, however, are still needed, particularly agents that could selectively increase blood pressure only in the standing position because supine hypertension is the main limitation of available drugs. Here we review the design and conduct of nOH clinical trials in patients with PD and other synucleinopathies, summarize the results of the most recently completed and ongoing trials, and discuss challenges, bottlenecks, and potential remedies.

Morbidity and mortality in orthostatic hypotension

This review summarizes the current literature on the epidemiology of orthostatic hypotension (OH) in the elderly and in patients with autonomic impairment also known as neurogenic OH (nOH); these two conditions have distinct pathophysiologies and affect different patient populations. The prevalence of OH in the elderly varies depending on the study population. In community dwellers, OH prevalence is estimated at 16%, whereas in institutionalized patients, it may be as high as 60%. The prevalence of OH increases exponentially with age, particularly in those 75 years and older. Multiple epidemiological studies have identified OH as a risk factor for all-cause mortality and cardiovascular disease including heart failure and stroke. Real-world data from administrative databases found polypharmacy, multiple co-morbid conditions, and high health-care utilization as common characteristics in OH patients. A comprehensive evaluation of medications associated with OH is discussed with particular emphasis on the use of anti-hypertensive therapy from two large clinical trials on high-intensive versus standard blood pressure management. Finally, we also review the epidemiology of nOH based on the underlying neurodegenerative disorder (either Parkinson's disease or multiple system atrophy), and the presence of co-morbid conditions such as hypertension and cognitive impairment.

Predicting falls in people with Parkinson's disease: impact of methodological approaches on predictors identified

BACKGROUND

Previous investigations of falls predictors in people with Parkinson's disease (PD) have used various statistical methods and categorization of falls outcomes. The impact of methodological differences on falls predictors has not been investigated.

OBJECTIVES

To describe similarities and differences in predictors modelled for fall rates [negative binomial (NB), Poisson Inverse Gaussian (PIG) and quantile regression] and previously-reported predictors of time to second fall (Cox regression), i.e. past falls, motor fluctuations, disability, levodopa dose and balance impairment. To investigate whether predictors from quantile regression vary across subsets of fallers based on fall frequency.

METHODS

Participants with PD (n = 229) were followed-up for 12 months. NB and PIG regression were used to determine predictors of fall rates, with the best fitting model reported. Quantile regression was used to determine predictors at higher (62nd, 70th, 80th) percentiles of the falls distribution. Univariate and multivariate analyses were performed.

RESULTS

Predictors of fall rates were the same in NB and PIG multivariate models, with the PIG model fitting our data better. Past falls, disability and levodopa dose were associated with fall rates from PIG and quantile regression. Freezing of gait was associated with fall rates from PIG regression. Disease severity predicted less (70th percentile, approximately 2-4) and more (80th percentile, approximately ≥ 5) frequent falls, and anteroposterior stability also predicted less frequent falls (p < 0.05), from quantile regression.

CONCLUSIONS

Not all predictors of time to second fall were predictors of fall rates. Quantile regression revealed some divergent predictors depending on the percentile of fall frequency examined.

Parkinson Disease and Orthostatic Hypotension in the Elderly: Recognition and Management of Risk Factors for Falls

Parkinson disease (PD) is often associated with postural instability and gait dysfunction that can increase the risk for falls and associated consequences, including injuries, increased burden on healthcare resources, and reduced quality of life. Patients with PD have nearly twice the risk for falls and associated bone fractures compared with their general population counterparts of similar age. Although the cause of falls in patients with PD may be multifactorial, an often under-recognized factor is neurogenic orthostatic hypotension (nOH). nOH is a sustained decrease in blood pressure upon standing whose symptomology can include dizziness/lightheadedness, weakness, fatigue, and syncope. nOH is due to dysfunction of the autonomic nervous system compensatory response to standing and is a consequence of the neurodegenerative processes of PD. The symptoms associated with orthostatic hypotension (OH)/nOH can increase the risk of falls, and healthcare professionals may not be aware of the real-world clinical effect of nOH, the need for routine screening, or the value of early diagnosis of nOH when treating elderly patients with PD. nOH is easily missed and, importantly, healthcare providers may not realize that there are effective treatments for nOH symptoms that could help lessen the fall risk resulting from the condition. This review discusses the burden of, and key risk factors for, falls among patients with PD, with a focus on practical approaches for the recognition, assessment, and successful management of OH/nOH. In addition, insights are provided as to how fall patterns can suggest fall etiology, thereby influencing the choice of intervention.

Neurogenic Orthostatic Hypotension in Parkinson Disease: A Primer

Parkinson disease (PD) is associated with a variety of motor and non-motor clinical manifestations, including cardiovascular autonomic dysfunction. Neurogenic orthostatic hypotension (nOH) is a potentially serious manifestation of cardiovascular sympathetic failure that occurs in approximately 30% of patients with PD. Here we review the pathophysiology and effects of the condition as well as treatment considerations for patients with PD and nOH. Screening for nOH using orthostatic symptom questionnaires, orthostatic blood pressure measurements, and specialized autonomic testing is beneficial for the identification of symptomatic and asymptomatic cases because cardiac sympathetic denervation and nOH can occur even at early (premotor) stages of PD. Symptoms of nOH, such as orthostatic lightheadedness, in patients with PD, have been shown to adversely affect patient safety (with increased risk of falls) and quality of life and should prompt treatment with non-pharmacologic and, occasionally, pharmacologic measures. Patients with nOH are also at increased risk of supine hypertension, which requires balancing various management strategies. FUNDING: Lundbeck (Deerfield, IL).

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.

Falls in Synucleinopathies

Parkinson's disease (PD) and other synucleinopathies, namely dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), are common degenerative neurological disorders that share synuclein pathology. Although certain cardinal features of parkinsonism, including bradykinesia and rigidity, respond well to levodopa, axial features, such as gait and balance impairment, are less reliably responsive to dopaminergic therapy and surgical interventions. Consequently, falls are common in PD and other synucleinopathies and are a major contributor toward injury and loss of independence. This underscores the need for appropriate fall risk assessment and implementation of preventative measures in all patients with parkinsonism. The aim of this review is therefore to explore modifiable and non-modifiable risk factors for falls in synucleinopathies. We next review and evaluate the evidence for pharmacological, nonpharmacological, and surgical approaches for fall prevention, and emphasize individualized and multifaceted approaches.

Treatment options for postural instability and gait difficulties in Parkinson's disease

Introduction: Gait and balance disorders in Parkinson's disease (PD) represent a major therapeutic challenge as frequent falls and freezing of gait impair quality of life and predict mortality. Limited dopaminergic therapy responses implicate non-dopaminergic mechanisms calling for alternative therapies.Areas covered: The authors provide a review that encompasses pathophysiological changes involved in axial motor impairments in PD, pharmacological approaches, exercise, and physical therapy, improving physical activity levels, invasive and non-invasive neurostimulation, cueing interventions and wearable technology, and cognitive interventions.Expert opinion: There are many promising therapies available that, to a variable degree, affect gait and balance disorders in PD. However, not one therapy is the 'silver bullet' that provides full relief and ultimately meaningfully improves the patient's quality of life. Sedentariness, apathy, and emergence of frailty in advancing PD, especially in the setting of medical comorbidities, are perhaps the biggest threats to experience sustained benefits with any of the available therapeutic options and therefore need to be aggressively treated as early as possible. Multimodal or combination therapies may provide complementary benefits to manage axial motor features in PD, but selection of treatment modalities should be tailored to the individual patient's needs.

Falls When Standing, Falls When Walking: Different Mechanisms, Different Outcomes in Parkinson Disease

Our retrospective study of falls and resultant trauma in consecutive Parkinson disease (PD) patients seen in one year at the Muhammad Ali Parkinson Clinic found that multiple-fallers could be divided into patients who fell mainly when walking or those who fell mainly when standing. Patients who fell when walking were more likely to visit an emergency room or be admitted to a hospital. Of 455 consecutive patients who were evaluated over a one-year period, 51 were excluded because they had atypical Parkinson disorders, had multiple risk factors for falling, or were demented. Unified Parkinson Disease Rating Scales and Zeno Walkway results were compared among non-fallers, single-fallers, and multiple-fallers. Among multiple-fallers, comparisons were made between patients who fell mainly when standing and those who fell mainly when walking. Most patients (197, 49%) did not fall, 142 (35%) fell once, and 65 (16%) fell more than once. Multiple-fallers differed significantly from single-fallers and non-fallers: they had PD significantly longer (p<0.001), were more severely affected (p<0.001), and took shorter steps (p<0.001). Of 65 multiple-fallers, 26 (40%) fell mainly when standing, 28 (43%) fell mainly when walking, and 11 (17%) fell equally often when standing or walking. Falls when walking resulted in more severe injuries. Patients who fell mainly when standing did not realize they could fall when standing; engaged in inappropriate weight shifting, bending, reaching, and multitasking; and failed to use their assistive devices. Such patients would benefit from being counseled about falling when standing. Patients who fell mainly when walking were aware they could fall, despite using an assisted device, and were more likely to have freezing of gait (FOG). They were more likely to sustain a severe injury, and were more likely to be admitted to an emergency room or hospital. Such patients would benefit from reducing, if possible, FOG.

Role of nurses and nurse practitioners in the recognition, diagnosis, and management of neurogenic orthostatic hypotension: a narrative review

Neurogenic orthostatic hypotension (nOH) is a sustained reduction in blood pressure (BP) upon standing that is caused by autonomic dysfunction and is common among patients with a variety of neurodegenerative disorders (eg, Parkinson's disease, multiple system atrophy, pure autonomic failure). A systolic BP drop of ≥20 mmHg (or ≥10 mmHg diastolic) upon standing with little or no compensatory increase in heart rate is consistent with nOH. Symptoms of nOH include light-headedness, dizziness, presyncope, and syncope; these symptoms can severely impact patients' activities of daily living and increase the likelihood of potentially dangerous falls. Because of their patient contact, nurses and nurse practitioners can play a key role in identifying and evaluating patients at risk for nOH. It is advisable to screen for nOH in patients presenting with one or more of the following characteristics: those who have disorders associated with autonomic failure, those with episodes of falls or syncope, those with symptoms upon standing, those who are elderly or frail, or those taking multiple medications. Initial evaluations should include questions about postural symptoms and measurement of orthostatic BP and heart rate. A review of medications for potential agents that can have hypotensive effects should be performed before initiating treatment. Treatment for nOH may include non-pharmacologic measures and pharmacologic therapy. Droxidopa and midodrine are approved by the US Food and Drug Administration for the treatment of symptomatic nOH and symptomatic OH, respectively. nOH is associated with the coexistence of supine hypertension, and the two disorders must be carefully managed. In conclusion, timely screening and diagnosis of patients with nOH can streamline the path to disease management and treatment, potentially improving patient outcomes.

Potential Utility of 123I-MIBG Scintigraphy as a Predictor of Falls in Parkinson's Disease

Background: Falls are associated with poor prognosis in patients with Parkinson's disease (PD). Although several factors related to falls were reported in patients with PD, objective predictors of falls are not identified. We aimed to determine whether ¹²³I-meta-iodobenzylguanidine (MIBG) cardiac scintigraphy could be a useful biomarker to predict falls. Methods: Forty-five patients with PD were enrolled in this study. These subjects were followed up more than 5 years after MIBG scintigraphy and were divided into two groups: one with decreased uptake of MIBG and the other without decreased uptake of MIBG. The cut-off value for the delayed heart-to-mediastinum ratio was 1.8. Kaplan-Meier analysis and a log-rank test were performed to test the predictive power of MIBG cardiac scintigraphy for falls. Univariate analysis was selected because we did not have appropriate data for adjustment, such as motor and cognitive assessment. Results: The group with decreased uptake of MIBG had a significantly higher incidence of falls than that without decreased uptake of MIBG (P = 0.022, log-rank test). Conclusions: Although the limitations of this study were lack of several key factors including motor and cognitive assessment, MIBG cardiac scintigraphy may be used to predict falls in patients with PD.

Six-Month Use of Droxidopa for Neurogenic Orthostatic Hypotension

Background

Droxidopa is approved for adult patients with symptomatic neurogenic orthostatic hypotension (nOH); there is limited information regarding effects on symptoms, outcomes, and quality of life (QOL) beyond two weeks of treatment.

Objective

Examine the real‐world experience of patients taking droxidopa after six months of treatment.

Methods

This non‐interventional, US‐based, prospective cohort study utilized a pharmacy hub, identifying patients who recently started droxidopa for nOH treatment. Questionnaires for fall frequency and other patient‐reported outcomes (PROs) were completed at baseline and one, three, and six months following droxidopa initiation.

Results

179 enrolled patients completed baseline surveys. Droxidopa continuation rates were high at months one, three, and six (87%, 79%, and 75%, respectively). From baseline to month one, there was significant reduction in the proportion of patients reporting falling at least once (54.1% vs. 43.0%; P = 0.0039), with similar observations at month three (52.9% vs. 44.5%; P = 0.0588) and month six (51.4% vs. 40.0%; P = 0.0339). Significant improvements from baseline to month one were observed and maintained at months three and six for most PROs, including the Orthostatic Hypotension Symptom Assessment Item 1, Short Falls Efficacy Scale‐International, Sheehan Disability Scale, Physical Component of the 8‐item Short‐Form Health Survey, and Patient Health Questionnaire‐9.

Conclusions

In this non‐interventional prospective study, fewer nOH patients reported falling after one, three, and six months of droxidopa treatment. Further, improvements reported in nOH symptoms, physical function, and QOL measures were maintained for six months following treatment initiation. Results from randomized clinical trials are required to validate the findings.

Droxidopa for the treatment of neurogenic orthostatic hypotension in neurodegenerative diseases

INTRODUCTION

L-threo-3,4-dihydroxyphenylserine (droxidopa), a pro-drug metabolized to norepinephrine in nerve endings and other tissues, has been commercially available in Japan since 1989 for treating orthostatic hypotension symptoms in Parkinson's disease (PD) patients with a Hoehn & Yahr stage III rating, as well as patients with Multiple System Atrophy (MSA), familial amyloid polyneuropathy, and hemodialysis. Recently, the FDA has approved its use in symptomatic neurogenic orthostatic hypotension (NOH). Areas covered: The authors review the effects of droxidopa in NOH with a focus on the neurodegenerative diseases PD, MSA, and pure autonomic failure (PAF). Expert opinion: A few small and short placebo-controlled clinical trials in NOH showed significant reductions in the manometric drop in blood pressure (BP) after posture changes or meals. Larger Phase III studies showed conflicting results, with two out of four trials meeting their primary outcome and thus suggesting a positive yet short-lasting effect of the drug on OH Questionnaire composite score, light-headedness/dizziness score, and standing BP during the first two treatment-weeks. Results appear essentially similar in PD, MSA, and PAF. The FDA granted droxidopa approval in the frame of an 'accelerated approval program' provided further studies are conducted to assess its long-term effects on OH symptoms.

Integrated Analysis of Droxidopa for the Treatment of Neurogenic Orthostatic Hypotension in Patients with Parkinson Disease

Introduction

Neurogenic orthostatic hypotension (nOH) is associated with neurodegenerative conditions, may cause symptoms of end-organ hypoperfusion, increases fall risk, and can negatively impact quality of life. Droxidopa is approved for the treatment of symptomatic nOH in adults. As the largest subpopulation of patients with nOH has a diagnosis of Parkinson disease (PD), the efficacy and tolerability of droxidopa in patients with PD and nOH were examined using integrated clinical trial data.

Methods

Post hoc analyses included data from the phase 3, randomized, placebo-controlled clinical trials of droxidopa (two short-term [1-2 weeks] trials and one medium-term [8-10 weeks] trial) in the subset of participants with PD and symptomatic nOH. Efficacy was assessed using standing blood pressure (BP) measurements and the Orthostatic Hypotension Questionnaire (OHQ), a patient-reported evaluation of nOH symptoms (Orthostatic Hypotension Symptom Assessment [OHSA]), and their impact (Orthostatic Hypotension Daily Activity Scale [OHDAS]).

Results

The analysis included 307 patients with PD (droxidopa, n = 150; placebo, n = 157). Compared with placebo, droxidopa significantly improved the OHQ composite score (P = 0.014), the OHSA composite score (P = 0.022), and the OHDAS composite score (P = 0.029) from baseline to end of study/week one. We found significant increases in standing mean systolic/diastolic BP for droxidopa versus placebo (P = 0.003/0.002). Adverse event (AE) rates were qualitatively similar between groups; the most frequently reported AEs in the droxidopa groups included headache, dizziness, nausea, and hypertension.

Conclusions

These post hoc analyses suggest that droxidopa provides meaningful clinical benefits and is well tolerated in the treatment of symptomatic nOH in patients with PD.

Therapeutic strategies for Parkinson disease: beyond dopaminergic drugs

Existing therapeutic strategies for managing Parkinson disease (PD), which focus on addressing the loss of dopamine and dopaminergic function linked with degeneration of dopaminergic neurons, are limited by side effects and lack of long-term efficacy. In recent decades, research into PD pathophysiology and pharmacology has focused on understanding and tackling the neurodegenerative processes and symptomology of PD. In this Review, we discuss the challenges associated with the development of novel therapies for PD, highlighting emerging agents that aim to target cell death, as well as new targets offering a symptomatic approach to managing features and progression of the disease.

Beyond mean modelling: Bias due to misspecification of dispersion in Poisson-inverse Gaussian regression

In clinical trials one traditionally models the effect of treatment on the mean response. The underlying assumption is that treatment affects the response distribution through a mean location shift on a suitable scale, with other aspects of the distribution (shape/dispersion/variance) remaining the same. This work is motivated by a trial in Parkinson's disease patients in which one of the endpoints is the number of falls during a 10-week period. Inspection of the data reveals that the Poisson-inverse Gaussian (PiG) distribution is appropriate, and that the experimental treatment reduces not only the mean, but also the variability, substantially. The conventional analysis assumes a treatment effect on the mean, either adjusted or unadjusted for covariates, and a constant dispersion parameter. On our data, this analysis yields a non-significant treatment effect. However, if we model a treatment effect on both mean and dispersion parameters, both effects are highly significant. A simulation study shows that if a treatment effect exists on the dispersion and is ignored in the modelling, estimation of the treatment effect on the mean can be severely biased. We show further that if we use an orthogonal parametrization of the PiG distribution, estimates of the mean model are robust to misspecification of the dispersion model. We also discuss inferential aspects that are more difficult than anticipated in this setting. These findings have implications in the planning of statistical analyses for count data in clinical trials.

Pharmacotherapy of Cardiovascular Autonomic Dysfunction in Parkinson Disease

Cardiovascular autonomic dysfunctions, including neurogenic orthostatic hypotension, supine hypertension and post-prandial hypotension, are relatively common in patients with Parkinson disease. Recent evidence suggests that early autonomic impairment such as cardiac autonomic denervation and even neurogenic orthostatic hypotension occur prior to the appearance of the typical motor deficits associated with the disease. When neurogenic orthostatic hypotension develops, patients with Parkinson disease have an increased risk of mortality, falls, and trauma-related to falls. Neurogenic orthostatic hypotension reduces quality of life and contributes to cognitive decline and physical deconditioning. The co-existence of supine hypertension complicates the treatment of neurogenic orthostatic hypotension because it involves the use of drugs with opposing effects. Furthermore, treatment of neurogenic orthostatic hypotension is challenging because of few therapeutic options; in the past 20 years, the US Food and Drug Administration approved only two drugs for the treatment of this condition. Small, open-label or randomized studies using acute doses of different pharmacologic probes suggest benefit of other drugs as well, which could be used in individual patients under close monitoring. This review describes the pathophysiology of neurogenic orthostatic hypotension and supine hypertension in Parkinson disease. We discuss the mode of action and therapeutic efficacy of different pharmacologic agents used in the treatment of patients with cardiovascular autonomic failure.

Falls in Parkinson's disease: A complex and evolving picture

Falls are a major determinant of poor quality of life, immobilization, and reduced life expectancy in people affected by Parkinson's disease (PD) and in older adults more generally. Although many questions remain, recent research has advanced the understanding of this complex problem. The goal of this review is to condense new knowledge of falls in PD from prodromal to advanced disease, taking into account risk factors, assessment, and classification as well as treatment. The fundamental steps of clinical and research-based approaches to falls are described, namely, the identification of fall risk factors, clinical and instrumental methods to evaluate and classify fall risk, and the latest evidence to reduce or delay falls in PD. We summarize recent developments, the direction in which the field should be heading, and what can be recommended at this stage. We also provide a practical algorithm for clinicians.© 2017 International Parkinson and Movement Disorder Society.

Effect of Wnt1 and Wnt5a on the development of dopaminergic neurons, and toxicity induced by combined exposure to paraquat and maneb during gestation and lactation

Paraquat (PQ) and maneb (MB) are widely used herbicides. Wingless (Wnt) proteins serve a role in the development and differentiation of dopaminergic neurons. Previous studies demonstrated that combined exposure to PQ and MB damages dopaminergic neurons in the midbrain. Effects of PQ and MB exposure on midbrain Wnt proteins have also been previously reported. In the present study, from the 5th day of gestation to weaning of the offspring, pregnant Sprague‑Dawley rats were administrated saline, or PQ and MB at two different doses: high, 15 mg/kg body weight PQ + 45 mg/kg body weight MB; or low, 10 mg/kg body weight PQ + 30 mg/kg body weight MB. Dopamine content in the striatum was examined by high performance liquid chromatography with a fluorescence detector and mRNA and protein expression of Wnt1, Wnt5a, nuclear receptor related factor 1 (Nurr1) and tyrosine hydroxylase (TH) in the midbrain was examined by reverse transcription‑quantitative polymerase chain reaction and western blotting. Combined exposure to PQ and MB during development decreased mRNA and protein expression of Wnt1, TH and Nurr1 and increased expression of Wnt5a in the offspring.

Cardiovascular Safety of Droxidopa in Patients With Symptomatic Neurogenic Orthostatic Hypotension

The norepinephrine prodrug droxidopa improves symptoms of neurogenic orthostatic hypotension, a condition that is associated with diseases of neurogenic autonomic failure (e.g., Parkinson disease, multiple system atrophy, pure autonomic failure). These conditions are more prevalent in older patients who also have cardiovascular co-morbidities. Hence, we evaluated the cardiovascular safety of droxidopa in patients with symptomatic neurogenic orthostatic hypotension who participated in randomized controlled studies (short-term studies of 1 to 2 weeks and an intermediate 8- to 10-week study) and long-term open-label studies. Rates of cardiovascular adverse events (AEs) for patients treated with droxidopa were 4.4% in the intermediate study and 10.8% in the long-term open-label studies. Adjusting for exposure time, cardiovascular AE rates were 0.30 events/patient-year in the short-term and intermediate studies and 0.15 events/patient-year in the long-term open-label studies. The incidence of treatment discontinuation due to blood pressure-related events was approximately 2.5%. Among patients with a history of cardiac disorders at baseline, the rates of cardiovascular-related and blood pressure-related AEs were nominally higher with droxidopa compared to placebo. Most of these events were minor atrial arrhythmias; none were major adverse cardiovascular events or deaths. In conclusion, small increases in cardiovascular AEs were observed with droxidopa compared to placebo; this was most evident in patients with preexisting cardiac disorders.