New clinical trials for nonmotor manifestations of Parkinson's disease

Parkinson disease

Parkinson disease is the second-most common neurodegenerative disorder that affects 2-3% of the population ≥65 years of age. Neuronal loss in the substantia nigra, which causes striatal dopamine deficiency, and intracellular inclusions containing aggregates of α-synuclein are the neuropathological hallmarks of Parkinson disease. Multiple other cell types throughout the central and peripheral autonomic nervous system are also involved, probably from early disease onwards. Although clinical diagnosis relies on the presence of bradykinesia and other cardinal motor features, Parkinson disease is associated with many non-motor symptoms that add to overall disability. The underlying molecular pathogenesis involves multiple pathways and mechanisms: α-synuclein proteostasis, mitochondrial function, oxidative stress, calcium homeostasis, axonal transport and neuroinflammation. Recent research into diagnostic biomarkers has taken advantage of neuroimaging in which several modalities, including PET, single-photon emission CT (SPECT) and novel MRI techniques, have been shown to aid early and differential diagnosis. Treatment of Parkinson disease is anchored on pharmacological substitution of striatal dopamine, in addition to non-dopaminergic approaches to address both motor and non-motor symptoms and deep brain stimulation for those developing intractable L-DOPA-related motor complications. Experimental therapies have tried to restore striatal dopamine by gene-based and cell-based approaches, and most recently, aggregation and cellular transport of α-synuclein have become therapeutic targets. One of the greatest current challenges is to identify markers for prodromal disease stages, which would allow novel disease-modifying therapies to be started earlier.

Rivastigmine as a Symptomatic Treatment for Apathy in Parkinson's Dementia Complex: New Aspects for This Riddle

Over 90% of PDD patients show at least one neuropsychiatric symptom (NPS); in the 60-70% two or more NPS are present. Their incidence is important in terms of prognosis and severity of pathology. However, among all NPS, apathy is often the most disturbing, associated with greater caregiver's burden. Similar to other NPS, apathy may be due to a dysfunction of the nigrostriatal pathway, even though, not all the PD patients become apathetic, indicating that apathy should not entirely be considered a dopamine-dependent syndrome, and in fact it might also be related to acetylcholine defects. Apathy has been treated in many ways, without sure benefits; among these, Rivastigmine may present benefic properties. We present a series of 48 patients, suffering from PDD, treated with Rivastigmine, and followed-up for one year; they have been devotedly studied for apathy, even though all the other NPS disorders have been registered. Rivastigmine did not have a prolonged benefic effect on apathy, in our work, on the contrary of what had been observed in the literature, probably due to the longer follow-up of our patients.

Response of non-motor symptoms to levodopa in late-stage Parkinson's disease: Results of a levodopa challenge test

BACKGROUND

Non-motor symptoms (NMS) are extremely common among late-stage Parkinson's disease (LSPD) patients. Levodopa (L-dopa) responsiveness seems to decrease with disease progression but its effect on NMS in LSPD still needs to be investigated.

OBJECTIVE

To assess the response of blood pressure (BP), pain, fatigue and anxiety to L-dopa in LSPD patients.

METHODS

20 LSPD patients, defined as Schwab and England ADL Scale <50 or Hoehn Yahr Stage >3 (MED ON) and 22 PD patients treated with subthalamic deep brain stimulation (advanced PD group) underwent an L-dopa challenge. BP and orthostatic hypotension (OH) assessment, a visual analogue scale (VAS) for pain and fatigue and the Strait Trait Anxiety (STAI) were evaluated before and after the L-dopa challenge.

RESULTS

Systolic BP dropped significantly after L-dopa intake (p < 0.05) in LSPD patients, while there was no change in pain, fatigue or anxiety. L-dopa significantly improved (p < 0.05) pain and anxiety in the advanced PD group, whereas it had no effect on BP or fatigue. L-dopa-related adverse effects (AEs), namely OH and sleepiness, were more common among LSPD patients. 40% and 65% of LSPD patients were not able to fill out the VAS and the STAI, respectively, while measurement of orthostatic BP was not possible in four LSPD patients.

CONCLUSIONS

This exploratory study concludes that some non-motor variables in LSPD do not benefit from the acute action of L-dopa while it can still induce disabling AEs. There is a need for assessment tools of NMS adapted to these disabled LSPD patients.

Parkinson's: a syndrome rather than a disease?

Emerging concepts suggest that a multitude of pathology ranging from misfolding of alpha-synuclein to neuroinflammation, mitochondrial dysfunction, and neurotransmitter driven alteration of brain neuronal networks lead to a syndrome that is commonly known as Parkinson’s disease. The complex underlying pathology which may involve degeneration of non-dopaminergic pathways leads to the expression of a range of non-motor symptoms from the prodromal stage of Parkinson’s to the palliative stage. Non-motor clinical subtypes, cognitive and non-cognitive, have now been proposed paving the way for possible subtype specific and non-motor treatments, a key unmet need currently. Natural history of these subtypes remains unclear and need to be defined. In addition to in vivo biomarkers which suggest variable involvement of the cholinergic and noradrenergic patterns of the Parkinson syndrome, abnormal alpha-synuclein accumulation have now been demonstrated in the gut, pancreas, heart, salivary glands, and skin suggesting that Parkinson’s is a multi-organ disorder. The Parkinson’s phenotype is thus not just a dopaminergic motor syndrome, but a dysfunctional multi-neurotransmitter pathway driven central and peripheral nervous system disorder that possibly ought to be considered a syndrome and not a disease.

Unmet needs in Parkinson's disease: New horizons in a changing landscape

The success of levodopa and other classes of drugs have meant that most people with Parkinson's disease enjoy a good quality of life for many years. However, despite the availability of several drugs and formulations that can be used as monotherapy and in combination, there are a number of disease features that the current therapies are unable to address. The disease continues to progress despite treatment, patients suffer from a myriad of motor and non-motor symptoms, and a neuroprotective therapy is urgently required. To move forward with medical and surgical management, it is important to consider new insights that recent research offers and in this review we examine how a better understanding of the disease pathology and progression might improve and enrich our daily clinical practice. It is also timely to consider the service provision changes that will increasingly be needed to effectively manage the needs of the aging population.

Pharmacotherapies for Parkinson's disease symptoms related to cholinergic degeneration

INTRODUCTION

Dopamine depletion is one of the most important features of Parkinson's Disease (PD). However, insufficient response to dopaminergic replacement therapy suggests the involvement of other neurotransmitter systems in the pathophysiology of PD. Cholinergic degeneration contributes to gait impairments, cognitive impairment, psychosis, and REM-sleep disturbances, among other symptoms. Areas covered: In this review, we explore the idea that enhancing cholinergic tone by pharmacological or neurosurgical procedures could be a first-line therapeutic strategy for the treatment of symptoms derived from cholinergic degeneration in PD. Expert opinion: Rivastigmine, a drug that increases cholinergic tone by inhibiting the enzyme cholinesterase, is effective for dementia, whereas the use of Donepezil is still in the realm of investigation. Interesting results suggest the efficacy of these drugs in the treatment of gait dysfunction. Evidence on the clinical effects of these drugs for psychosis and REM-sleep disturbances is still weak. Stimulation of the pedunculo-pontine tegmental nuclei (which provide cholinergic innervation to the brain stem and subcortical nuclei) has also been used with some success for the treatment of gait dysfunction. Anticholinergic drugs should be used with caution in PD, as they may aggravate cholinergic symptoms. Notwithstanding, in some patients they might help control parkinsonian motor symptoms.

Sequential Addition Reaction of Sulfanylmethyllithiums and Grignard Reagents to Thioformamides Leading to the Formation of 2-Phenyl-2-sulfanylethyl Tertiary Amines

The reaction of sulfanylmethyllithiums generated from benzylsulfanes and n-BuLi with N,N-dimethylthioformamide followed by the addition of Grignard reagents gave 2-phenyl-2-sulfanyl tertiary amines in moderate to good yields. A range of Grignard reagents involving primary alkyl, aryl, vinyl, and alkynyl Grignard reagents were used. Two carbon-carbon bond-forming reactions were achieved through a one-pot reaction. The reaction showed good to high diastereoselectivity, particularly with alkynyl Grignard reagents.

Piribedil for the Treatment of Motor and Non-motor Symptoms of Parkinson Disease

Dopamine agonists are well-established symptomatic medications for treating early and advanced Parkinson disease (PD). Piribedil was one of the first agonists to be marketed (1969) and is widely used as an extended-release oral formulation in European, Latin-American, and Asian countries. Piribedil acts as a non-ergot partial dopamine D2/D3-selective agonist, blocks alpha2-adrenoreceptors and has minimal effects on serotoninergic, cholinergic, and histaminergic receptors. Animal models support the efficacy of piribedil to improve parkinsonian motor symptoms with a lower propensity than levodopa to induce dyskinesia. In PD patients, randomized double-blind studies show that piribedil (150-300 mg/day, three times daily) is superior to placebo in improving motor disability in early PD patients. Based on such evidence, piribedil was considered in the last Movement Disorder Society Evidence-Based Medicine review as "efficacious" and "clinically useful" for the symptomatic treatment of PD, either as monotherapy or in conjunction with levodopa, in non-fluctuating early PD patients. This effect appears comparable to what is known from other D2 agonists. However, randomized controlled trials are not available to assess the effect of piribedil in managing levodopa-induced motor complications. Pilot clinical studies suggest that piribedil may improve non-motor symptoms, such as apathy, but confirmatory trials are needed. The tolerability and safety profile of piribedil fits with that of the class of dopaminergic agonists. As for other non-ergot agonists, pneumo-pulmonary, retroperitoneal, and valvular fibrotic side effects are not a concern with piribedil. The original combination of piribedil D2 dopaminergic and alpha-2 adrenergic properties deserve further investigations to better understand its antiparkinsonian profile.

Pathophysiology of Motor Dysfunction in Parkinson's Disease as the Rationale for Drug Treatment and Rehabilitation

Cardinal motor features of Parkinson's disease (PD) include bradykinesia, rest tremor, and rigidity, which appear in the early stages of the disease and largely depend on dopaminergic nigrostriatal denervation. Intermediate and advanced PD stages are characterized by motor fluctuations and dyskinesia, which depend on complex mechanisms secondary to severe nigrostriatal loss and to the problems related to oral levodopa absorption, and motor and nonmotor symptoms and signs that are secondary to marked dopaminergic loss and multisystem neurodegeneration with damage to nondopaminergic pathways. Nondopaminergic dysfunction results in motor problems, including posture, balance and gait disturbances, and fatigue, and nonmotor problems, encompassing depression, apathy, cognitive impairment, sleep disturbances, pain, and autonomic dysfunction. There are a number of symptomatic drugs for PD motor signs, but the pharmacological resources for nonmotor signs and symptoms are limited, and rehabilitation may contribute to their treatment. The present review will focus on classical notions and recent insights into the neuropathology, neuropharmacology, and neurophysiology of motor dysfunction of PD. These pieces of information represent the basis for the pharmacological, neurosurgical, and rehabilitative approaches to PD.

Therapeutic approaches in Parkinson's disease and related disorders

The lack of effective therapies for neurodegenerative disorders is one of the most relevant challenges of this century, considering that, as the global population ages, the incidence of these type of diseases is quickly on the rise. Among these disorders, synucleinopathies, which are characterized by the abnormal accumulation and spreading of the synaptic protein alpha-synuclein in the brain, already constitute the second leading cause of parkinsonism and dementia in the elderly population. Disorders with alpha-synuclein accumulation include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Numerous therapeutic alternatives for synucleinopathies are being tested in pre-clinical models and in the clinic; however, only palliative treatments addressing the dopaminergic deficits are approved to date, and no disease-modifying options are available yet. In this article, we provide a brief overview of therapeutic approaches currently being explored for synucleinopathies, and suggest possible explanations to the clinical trials outcomes. Finally, we propose that a deeper understanding of the pathophysiology of synucleinopathies, together with a combination of therapies tailored to each disease stage, may lead to better therapeutic outcomes in synucleinopathy patients. Synucleinopathies, neurodegenerative disorders characterized by the abnormal accumulation of the protein alpha-synuclein, constitute the second leading cause of parkinsonism and dementia in the elderly population, however, no disease-modifying options are available yet. In this review, we summarize the therapeutic approaches currently being explored for synucleinopathies, suggest possible explanations to the clinical outcomes, and propose areas of further therapeutic improvement. This article is part of a special issue on Parkinson disease.

Assessment of fatigue in Parkinson's disease: Indian perspective

Context:

Fatigue is one of the most frequent nonmotor manifestations in Parkinson's disease (PD), having a major effect on quality of life but is not reported in Indian patients.

Aims:

To evaluate the frequency of fatigue in a cohort of PD population and its correlation with disease.

Settings and Design:

Fatigue Severity Scale (FSS) was translated and validated in local vernacular language. All patients of PD visiting neurology outpatient department of a tertiary care hospital.

Subjects and Methods:

A total of 150 patients were screened, and 104 were included in this study. They were divided into – Group I with fatigue (score of >4 in each item) and Group II without fatigue.

Statistical Analysis:

Data were analyzed by SPSS software version 20.0. Spearman correlation was used to evaluate the convergent validity of the FSS-Ind score with PD-related variables. The principal components analysis was applied to detect the domain structure of the FSS.

Results:

Of the total 104 patients, 68 (65.3%) patients experienced fatigue. The duration of disease was significantly more (P = 0.021) in Group I (4.39 ± 3.8 years) than in the Group II (3.13 ± 1.6 years). The severity of disease also showed a positive correlation with fatigue with 50.9% patients in H and Y stage >3 experiencing fatigue. 69.1% patients of tremor phenotype experienced fatigue as compared to 32.3% of rigid phenotype. There was no relation of fatigue with age, gender, H and Y stage, levodopa equivalent dose and mean Unified PD Rating Scale motor III score.

Conclusions:

Translated version of the FSS, FSS-Ind has high internal consistency and validity which supports its application as an effective tool in detecting fatigue in patients with PD. Fatigue in PD was related to duration and phenotype of the disease.

Value of cerebrospinal fluid α-synuclein species as biomarker in Parkinson's diagnosis and prognosis

Since diagnosis of Parkinson's disease (PD) is mostly based on clinical criteria, it is almost impossible to formulate an early diagnosis, as well as a timely differential diagnosis versus other parkinsonisms. A great effort in searching reliable biomarkers both for early diagnosis and prognosis in PD is currently ongoing. Cerebrospinal fluid has been widely investigated as potential source for such biomarkers, with particular emphasis on α-synuclein (α-syn) species. We reviewed all the clinical studies carried out so far on cerebrospinal fluid quantification of α-syn species in PD. Current evidence supports the value of total and oligomeric α-syn in PD diagnosis and in the differential diagnosis of PD and other parkinsonisms. Conversely, the role of α-syn species in PD prognosis remains unsatisfactory.