Beyond tremor and rigidity: non-motor features of Parkinson’s disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease and primarily considered as a movement disorder defined by the presence of motor symptoms, such as bradykinesia, tremor and rigidity. However, it is nowadays widely accepted that PD is associated with a wide variety of non-motor features, which affect the vast majority of patients during the course of the disease and may even precede the onset of motor symptoms. The spectrum of these non-motor disturbances is very broad and comprises neuropsychiatric conditions, such as depression, dementia and hallucinations, as well as autonomic, sensory and sleep disorders. Physicians need to be aware of these non-motor features, since they have substantial impact on the health-related quality of life of PD patients, even ahead of motor symptoms. This article aims to provide an overview of frequently observed non-motor features in PD and discusses prospects and limitations of currently available options for symptomatic treatment of these disturbances.     

Circadian rhythm of rest activity and autonomic nervous system activity at different stages in Parkinson's disease

Patients with Parkinson's disease (PD) often suffer from non-motor symptoms, including sleep and autonomic dysfunctions, controlled by circadian regulation. To evaluate the alteration of circadian rhythm in PD patients, we investigated both rest activities and autonomic functions. Twenty-seven patients with idiopathic PD and 30 age-matched control subjects were recruited. Group comparisons of controls (mean age: 68.93 years), early-PD patients classified as Hoehn-Yahr (HY) stage 1&2 (mean age: 70.78 years), and advanced-PD as HY 3&4 (mean age: 68.61 years) were conducted. Measurement of rest activities was performed using Actigraph for 7 continuous days, and included measuring rhythm patterns (activity patterns recorded in or out of bed) and circadian rhythm amplitudes (power of the cycle being closest to 24h). A power spectral analysis of heart rate variability (HRV) using 24-hour ambulatory ECG was also performed. The actigraphic measurements indicated that statistically PD patients have lower activity levels when out of bed and higher activity levels when in bed, and that, the circadian rest-activity rhythm in PD decreases with disease severity. The HRV analysis showed that the total frequency component and low frequency/high frequency ratio were low in PD patients, suggesting that autonomic activities and the circadian rhythm of the sympathetic nervous system are attenuated in PD. This study elucidated the disorganization in the rest activities and HRV of PD patients as well as the gradual alterations in the circadian rhythm. The circadian rhythm disturbances are important to consider the mechanism of non-motor symptoms that occur from early stage of PD.     

Non-motor symptoms in Parkinson's disease

Although still considered a paradigmatic movement disorder, Parkinson's disease (PD) is associated with a broad spectrum of non-motor symptoms. These include disorders of mood and affect with apathy, anhedonia and depression, cognitive dysfunction and hallucinosis, as well as complex behavioural disorders. Sensory dysfunction with hyposmia or pain is almost universal, as are disturbances of sleep–wake cycle regulation. Autonomic dysfunction including orthostatic hypotension, urogenital dysfunction and constipation is also present to some degree in a majority of patients. Whilst overall non-motor symptoms become increasingly prevalent with advancing disease, many of them can also antedate the first occurrence of motor signs – most notably depression, hyposmia or rapid eye movement sleep behaviour disorder (RBD). Although exact clinicopathological correlations for most of these non-motor features are still poorly understood, the occurrence of constipation, RBD or hyposmia prior to the onset of clinically overt motor dysfunction would appear consistent with the ascending hypothesis of PD pathology proposed by Braak and colleagues. Screening these early non-motor features might, therefore, be one approach towards early 'preclinical' diagnosis of PD. This review article provides an overview of the clinical spectrum of non-motor symptoms in PD together with a brief review of treatment options.     

The influence of age and gender on motor and non-motor features of early Parkinson's disease: Initial findings from the Oxford Parkinson Disease Center (OPDC) discovery cohort

BackgroundIdentifying factors influencing phenotypic heterogeneity in Parkinson's Disease is crucial for understanding variability in disease severity and progression. Age and gender are two most basic epidemiological characteristics, yet their effect on expression of PD symptoms is not fully defined. We aimed to delineate effects of age and gender on the phenotype in an incident cohort of PD patients and healthy controls from the Oxford Parkinson Disease Centre (OPDC).MethodsClinical features, including demographic and medical characteristics and non-motor and motor symptoms, were analyzed in a group of PD patients within 3 years of diagnosis and a group of healthy controls from the OPDC cohort. Disease features were stratified according to age and compared between genders, controlling for effects of common covariates.Results490 PD patients and 176 healthy controls were analyzed. Stratification by age showed increased disease severity with age on motor scales. Some non-motor features showed similar trend, including cognition and autonomic features. Comparison across genders highlighted a pattern of increased severity and greater symptom symmetricality in the face, neck and arms in men with women having more postural problems. Amongst the non-motor symptoms, men had more cognitive impairment, greater rate of REM behavior disorder (RBD), more orthostatic hypotension and sexual dysfunction.ConclusionsAge in PD is a strong factor contributing to disease severity even after controlling for the effect of disease duration. Gender-related motor phenotype can be defined by a vertical split into more symmetrical upper-body disease in men and disease dominated by postural symptoms in women.     

Is there room for new non-dopaminergic treatments in Parkinson’s disease?

The contribution of non-dopaminergic degeneration to disability in Parkinson’s disease (PD) is still debated. It has been argued that no additional advance can be expected in the management of PD by the development of new dopaminergic agents and suggested that future research should mainly focus on therapies targeting the non-dopaminergic systems involved in the pathogenesis of levodopa resistant motor and non-motor symptoms. We believe this is only partially true and the achievement of a stable dopaminergic restoration and modulation of the dopaminergic system is still an important, unmet need of current pharmacological therapies in PD. Currently available oral levodopa and dopamine agonist medications provide insufficient benefit, as the therapeutic window progressively narrows and motor fluctuations eventually develop in most patients. Conversely, the application of infusion and surgical therapies is limited by selective indications and possible irreversible adverse events and device-related problems. Research of new, safer and less invasive strategies, able to modulate the dopaminergic circuits, would certainly improve the management of motor complications, and most importantly such treatments would be also beneficial to axial and non-motor symptoms, which are universally regarded as the major cause of PD functional disability. Indeed, gait and balance problems may improve with dopaminergic treatment in most patients and they become unresponsive only at the very late stages of the disease. Moreover, several non-motor disturbances, including cognition and depression are often linked to oscillation of dopamine concentrations, and are frequently relieved by treatments providing continuous dopaminergic delivery. Finally, drug trials testing non-dopaminergic treatments for motor and non-motor symptoms of PD provided so far disappointing results. Despite the impressive advances of PD therapeutic strategy, we think there is still need for safe, non-invasive and easily manageable dopaminergic treatments able to provide constant dopamine receptor stimulation and ensure a more stable control of dopamine responsive motor and non-motor symptoms at any stage of the disease.     

Chronobiology of Parkinson's disease: Past,present and future

Parkinson's disease is a neurodegenerative disorder predominately affecting midbrain dopaminergic neurons that results in a broad range of motor and non-motor symptoms. Sleep complaints are among the most common non-motor symptoms, even in the prodromal period. Sleep alterations in Parkinson's disease patients may be associated with dysregulation of circadian rhythms, intrinsic 24-h cycles that control essential physiological functions, or with side effects from levodopa medication and physical and mental health challenges. The impact of circadian dysregulation on sleep disturbances in Parkinson's disease is not fully understood; as such, we review the systems, cellular and molecular mechanisms that may underlie circadian perturbations in Parkinson's disease. We also discuss the potential benefits of chronobiology-based personalized medicine in the management of Parkinson's disease both in terms of behavioural and pharmacological interventions. We propose that a fuller understanding of circadian clock function may shed important new light on the aetiology and symptomatology of the disease and may allow for improvements in the quality of life for the millions of people with Parkinson's disease.     

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.     

帕金森病非运动症状波动的临床研究进展

帕金森病患者通常伴随多种非运动症状,随病程进展,大部分非运动症状可以呈现类似运动波动的变化,称之为非运动症状波动。非运动症状波动发生频率较高,是影响帕金森病患者生活质量的重要原因,临床诊治过程中应受到重视。文中从流行病学特点和临床表现、危险因素、发生机制、临床干预等方面对帕金森病非运动症状波动相关研究进行综述。     

帕金森病非运动症状研究现状

帕金森病(Parkinson’s disease,PD)是一种中枢神经系统退行性病变,临床上通常以静止性震颤、运动迟缓、齿轮样肌僵直、姿势反射障碍等运动障碍为主要临床表现。一直以来针对帕金森病的治疗方案是以改善患者的运动症状为主要目标,但PD患者通常还会出现感觉障碍(疼痛等)、睡眠障碍(日间过度睡眠等)、自主神经功能异常及精神神经症状(抑郁、躁狂及情感障碍)等,称之为非运动症状(non-motor symptoms,NMS)。有资料显示PD的某些非运动症状与年龄、疾病的严重程度密切相关,对患者生活质量的影响较运动症状更加明显。一些非运动症状,如嗅觉障碍、便秘、抑郁、快速眼动期睡眠行为紊乱(RBD)等,可在疾病早期甚至运动症状出现之前出现,可能对PD的早期诊断有所帮助。非运动症状对患者造成的负担可远远超过运动障碍对患者日常生活和幸福感的影响,深入了解非运动症状,对于PD的预防、治疗及远期预后具有积极意义。本文总结近年来文献并以上述非运动症状的病理、常见临床表现、常用的临床评估及治疗方案为阐述架构,展现近年来PDNMS的研究进展。为了提供一种可以量化的工具,研究者还发明了非运动症状评价量表(NMSS)作为PD非运动症状的临床评价,对严重程度和发作频率进行评估,包含9个方面:心血管、睡眠/疲劳、情绪/认知、感知障碍、注意力/记忆、胃肠道症状、泌尿系统症状、性功能及混合症状,可为临床评价非运动症状的严重程度及治疗提供帮助。     

Decreased VIP and VPAC2 receptor expression in the biological clock of the R6/2 Huntington's disease mouse

Huntington's disease (HD) is a fatal genetic neurodegenerative disorder caused by a CAG triplet repeat expansion in the gene encoding the protein huntingtin. The most studied model of HD, the R6/2 transgenic mouse, replicates many features of the disease. In addition to motor, cognitive, and endocrine dysfunctions, these mice exhibit a progressive disruption of circadian rhythms. This is accompanied by an altered expression of the circadian clock genes in the suprachiasmatic nucleus/nuclei (SCN), the principal circadian pacemaker in the brain. The neuropeptide vasoactive intestinal polypeptide (VIP) and its receptor VPAC₂ are highly expressed in the SCN, and VIPergic signaling plays an essential role in maintenance of ongoing circadian rhythmicity. We found a marked reduction in both VIP mRNA and VPAC₂ receptor mRNA, quantified by RT-PCR, as well as a decrease in VIP immunostaining in the SCN of R6/2 mice. These changes were coupled to a disruption of circadian rhythm. We observed no loss of neurons in the SCN and therefore suggest that the changes in VIP and VPAC₂ receptor are due to their decreased expression. In conclusion, we propose that impaired VIPergic signaling is an additional candidate mechanism for disruption of circadian rhythms in R6/2 mice.     

Clinical features and varieties of non-motor fluctuations in Parkinson's disease: A Japanese multicenter study

ObjectiveThis multicenter cross-sectional study aimed to investigate the clinical features and varieties of non-motor fluctuation in Parkinson's disease (PD).MethodsTo identify motor and non-motor fluctuation, we employed the wearing-off questionnaire of 19 symptoms (WOQ-19) in 464 PD patients. We compared the frequency of levodopa-related fluctuation as identified by the WOQ-19 with recognition by neurologists. We compared patients with both motor and non-motor fluctuations with those who only had motor fluctuations. Non-motor fluctuations were separated into psychiatric, autonomic, and sensory categories for further analysis.ResultsThe patients' average age was 70.8 ± 8.4 years (mean ± SD) and disease duration was 6.6 ± 5.0 years. The frequency of motor fluctuations was 69% and for non-motor fluctuation 40%. Fifty-three percent of patients with motor fluctuations also had non-motor fluctuations, whereas 93% of patients with non-motor fluctuations also had motor fluctuations. The WOQ-19 showed a sensitivity of 82% but a specificity of only 40%. The patients with both non-motor and motor fluctuations exhibited more severe motor symptoms, more non-motor symptoms and higher levodopa daily doses (p < 0.05). Patients had significantly higher fluctuation rates if they had psychiatric (49%) and sensory (45%) symptoms than patients with autonomic symptoms (32%, p < 0.01). Forty-eight percent of patients with non-motor fluctuations exhibited more than one type of non-motor fluctuation.ConclusionForty percent of PD patients presented with non-motor fluctuations, and almost half of these exhibited more than one type. Appropriate recognition of levodopa-related fluctuations, both motor and non-motor, can lead to treatment modifications in PD patients.     

Motor and non-motor correlates of olfactory dysfunction in Parkinson's disease

Hyposmia is highly prevalent in the motor phase of Parkinson's disease (PD) and is an established pre-motor sign of PD that may precede the onset of motor symptoms by as long as 5 years. The data presented here are part of an ongoing study to determine the relationship of the olfactory deficit in PD with both motor and non-motor features of the disease. The study population so far includes 96 patients with a clinical diagnosis of PD (UK PD Society Brain Bank criteria; mean age 64.9 years; mean disease duration 4.8 years). Olfactory testing was performed using the 40-item UPSIT. We analyzed the relationship between UPSIT scores and measures of motor (disease duration, stage and severity) and non-motor (cognitive function, depression, anxiety and sleep) function. In 60 PD patients, [(123)I]FP-CIT SPECT scans were available to assess the relationship between UPSIT scores and striatal dopamine transporter (DAT) binding. Preliminary analyses revealed correlations of the olfactory deficit in PD with both motor and non-motor features, as well as with striatal DAT binding. These data suggest that the olfactory deficit in PD is not stationary by the time the motor phase is entered, but continues to progress over time. Hyposmia may therefore be useful as a marker of disease progression, at least in the early disease stages.     

Cerebrospinal Fluid C-Reactive Protein in Parkinson’s Disease: Associations with Motor and Non-motor Symptoms

Parkinson’ disease (PD) is characterized by motor symptoms including bradykinesia, resting tremor, postural instability, and rigidity and non-motor symptoms such as cognitive impairment, sleep disorder, and depression. Neuroinflammation has been recently implicated in pathophysiology of both motor and non-motor symptoms of PD. One of the most notable inflammatory proteins is C-reactive protein (CRP), which is elevated in the conditions of systemic inflammation. Using BioFIND database, we scrutinized the possible association between cerebrospinal fluid (CSF) levels of CRP and severity of PD motor and non-motor symptoms. Eighty-four healthy controls (HCs) and 109 PD subjects were entered into this study. A significant correlation was observed between CSF CRP levels and Movement Disorder Society-Unified Parkinson’s Disease Rating Scale Part III (MDS-UPDRS part III) score and Montreal Cognitive Assessment (MoCA) score in PD patients. We found significant correlations between MoCA score and CSF CRP levels in female patients and between CSF CRP and MDS-UPDRS part III score and MoCA score in male patients. In linear regression, CSF CRP could predict 6.9 and 10% of changes in MDS-UPDRS part III score in all PD patients male PD patients, respectively. In summary, we confirmed that CSF concentrations of CRP are in correlation with motor and non-motor severity in PD subjects. Our findings suggest that neuroinflammation plays an important role in the initiation and probably progression of PD motor and non-motor symptoms, which may give us a better insight into the underlying pathologic mechanisms in PD.     

An update on the rotenone models of Parkinson's disease: Their ability to reproduce the features of clinical disease and model gene–environment interactions

Parkinson's disease (PD) is the second most common neurodegenerative disorder that is characterized by two major neuropathological hallmarks: the degeneration of dopaminergic neurons in the substantia nigra (SN) and the presence of Lewy bodies in the surviving SN neurons, as well as other regions of the central and peripheral nervous system. Animal models have been invaluable tools for investigating the underlying mechanisms of the pathogenesis of PD and testing new potential symptomatic, neuroprotective and neurorestorative therapies. However, the usefulness of these models is dependent on how precisely they replicate the features of clinical PD with some studies now employing combined gene–environment models to replicate more of the affected pathways. The rotenone model of PD has become of great interest following the seminal paper by the Greenamyre group in 2000 (Betarbet et al., 2000). This paper reported for the first time that systemic rotenone was able to reproduce the two pathological hallmarks of PD as well as certain parkinsonian motor deficits. Since 2000, many research groups have actively used the rotenone model worldwide. This paper will review rotenone models, focusing upon their ability to reproduce the two pathological hallmarks of PD, motor deficits, extranigral pathology and non-motor symptoms. We will also summarize the recent advances in neuroprotective therapies, focusing on those that investigated non-motor symptoms and review rotenone models used in combination with PD genetic models to investigate gene–environment interactions.     

24-h activity rhythm and sleep in depressed outpatients

Disturbances in sleep and circadian rest-activity rhythms are key features of depression. Actigraphy, a non-invasive method for monitoring motor activity, can be used to objectively assess circadian rest-activity rhythms and sleep patterns. While recent studies have measured sleep and daytime activity of depressed patients using wrist-worn actigraphy, the actigraphic 24-h rest-activity rhythm in depression has not been well documented. We aimed to examine actigraphically measured sleep and circadian rest-activity rhythms in depressed outpatients. Twenty patients with DSM-IV major depressive episode and 20 age- and sex-matched healthy controls participated in this study. Participants completed 7 consecutive days of all-day actigraphic activity monitoring while engaging in usual activities. For sleep parameters, total sleep time, wake after sleep onset, and sleep fragmentation index were determined. Circadian rhythms were estimated by fitting individual actigraphy data to a cosine curve of a 24-h activity rhythm using the cosinor method, which generated three circadian activity rhythm parameters, i.e., MESOR (rhythm-adjusted mean), amplitude, and acrophase. Subjective sleep was also assessed using a sleep diary and the Pittsburgh Sleep Quality Index. Patients showed significantly lower MESOR and more dampened amplitude along with significant sleep disturbances. Logistic regression analysis revealed that lower MESOR and more fragmented sleep emerged as the significant predictors of depression. Correlations between subjectively and actigraphically measured parameters demonstrated the validity of actigraphic measurements. These results indicate marked disturbances in sleep and circadian rest-activity rhythms of depression. By simultaneously measuring sleep and rest-activity rhythm parameters, actigraphy might serve as an objective diagnostic aid for depression.     

Dopamine agonist-based strategies in the treatment of Parkinson’s disease

More therapeutic options have become available for Parkinson’s disease (PD) in recent years, leading to significant improvements in motor control both at early and advanced disease stages. More importantly, the need to expand disease management beyond motor symptom control has been recently highlighted and contribution of non-motor features to quality of life is now relevant. Dopamine agonists represent a valid therapeutic option in PD and their effect on non-motor domains like mood or cognition is now acknowledged as a key factor in fully addressing patients’ needs. Pramipexole is a well established dopamine agonist that is currently being investigated for its potential disease-modifying effect and action on mood in PD. In this review we will examine factors contributing to treatment decision-making and discuss how a proper balance between motor and non-motor features should be aimed for in approaching PD therapy.

     

Sleep and circadian alterations in people at risk for bipolar disorder: A systematic review

BackgroundSleep and circadian abnormalities have been mostly demonstrated in bipolar patients. However, it is not clear whether these alterations are present in population at high risk for bipolar disorder (BD), indicating a possible risk factor for this condition.ObjectiveThis systematic review aims to define current evidence about sleep and rhythm alterations in people at risk for BD and to evaluate sleep and circadian disorders as risk factor for BD.MethodsThe systematic review included all articles about the topic until February 2016. Two researchers performed an electronic search of PubMed and Cochrane Library. Keywords used were ‘sleep’ or ‘rhythm’ or ‘circadian’ AND ‘bipolar disorder’ or ‘mania’ or ‘bipolar depression’ AND ‘high-risk’ or ‘risk’.ResultsThirty articles were analyzed (7451 participants at risk for BD). Sleep disturbances are frequent in studies using both subjective measures and actigraphy. High-risk individuals reported irregularity of sleep/wake times, poor sleep and circadian rhythm disruption. Poor sleep quality, nighttime awakenings, and inadequate sleep are possible predictive factors for BD. A unique study suggested that irregular rhythms increase risk of conversion. People at risk for BD showed high cortisol levels in different times of day. Studies about anatomopathology, melatonin levels, inflammatory cytokines and oxidative stress were not identified. The most important limitations were differences in sleep and rhythm measures, heterogeneity of study designs, and lack of consistency in the definition of population at risk.ConclusionSleep and circadian disturbances are common in people at risk for BD. However, the pathophysiology of these alterations and the impact on BD onset are still unclear.     

How specific are non-motor symptoms in the prodrome of Parkinson's disease compared to other movement disorders?

The clinical diagnosis of Parkinson's disease (PD) based on motor signs is often preceded by several non-motor symptoms that can indicate early prodromal neurodegenerative processes. Such prodromal symptoms can aid the early detection of PD, but their specificity for prodromal PD in comparison to prodromes of other movement disorders is still largely unclear. We here aim to give a first insight into the published evidence of prodromal non-motor symptoms in PD, dementia with Lewy bodies (DLB), multiple system atrophy (MSA), Huntington's disease (HD), progressive supranuclear palsy (PSP) and spinocerebellar ataxia (SCA). REM-sleep behavior disorder (RBD) and autonomic dysfunction have been observed in the prodromes of PD, MSA, DLB and SCA. Depression and cognitive decline have been reported for prodromal PD, DLB, HD, SCA, and PSP. Olfactory loss has only been described in prodromal PD/DLB. However, estimating the specificity of prodromal non-motor symptoms in PD is so far complicated by scarce prospective evidence and study limitations. Information on marker specificity is a prerequisite for an accurate early (differential) diagnosis of prodromal diseases, as well as specific recruitment for targeted neuroprotective interventions. We here would like to raise awareness of these issues and encourage further prospective research of prodromal non-motor symptoms in neurodegenerative movement disorders and other diseases.     

Cognitive dysfunction and depression in Parkinson's disease: what can be learned from rodent models?

Parkinson's disease (PD) has for decades been considered a pure motor disorder and its cardinal motor symptoms have been attributed to the loss of dopaminergic (DAergic) neurons in the substantia nigra pars compacta and to nigral Lewy body pathology. However, there has more recently been a shift in the conceptualization of the disease, and its pathological features have now been recognized as involving several other areas of the brain and indeed even outside the central nervous system. There are a corresponding variety of intrinsic non-motor symptoms such as autonomic dysfunction, cognitive impairment, sleep disturbances and neuropsychiatric problems, which cannot be explained exclusively by nigral pathology. In this review, we will focus on cognitive impairment and affective symptoms in PD, and we will consider whether, and how, these deficits can best be modelled in rodent models of the disorder. As only a few of the non-motor symptoms respond to standard DA replacement therapies, the quest for a broader therapeutic approach remains a major research effort, and success in this area in particular will be strongly dependent on appropriate rodent models. In addition, better understanding of the different models, as well as the advantages and disadvantages of the available behavioural tasks, will result in better tools for evaluating new treatment strategies for PD patients suffering from these neuropsychological symptoms.