Non-motor Parkinson disease: new concepts and personalised management

Mitochondrial Dysfunction and Parkinson's Disease-Near-Infrared Photobiomodulation as a Potential Therapeutic Strategy

As the main driver of energy production in eukaryotes, mitochondria are invariably implicated in disorders of cellular bioenergetics. Given that dopaminergic neurons affected in Parkinson's disease (PD) are particularly susceptible to energy fluctuations by their high basal energy demand, it is not surprising to note that mitochondrial dysfunction has emerged as a compelling candidate underlying PD. A recent approach towards forestalling dopaminergic neurodegeneration in PD involves near-infrared (NIR) photobiomodulation (PBM), which is thought to enhance mitochondrial function of stimulated cells through augmenting the activity of cytochrome C oxidase. Notwithstanding this, our understanding of the neuroprotective mechanism of PBM remains far from complete. For example, studies focusing on the effects of PBM on gene transcription are limited, and the mechanism through which PBM exerts its effects on distant sites (i.e., its "abscopal effect") remains unclear. Also, the clinical application of NIR in PD proves to be challenging. Efficacious delivery of NIR light to the substantia nigra pars compacta (SNpc), the primary site of disease pathology in PD, is fraught with technical challenges. Concerted efforts focused on understanding the biological effects of PBM and improving the efficiency of intracranial NIR delivery are therefore essential for its successful clinical translation. Nonetheless, PBM represents a potential novel therapy for PD. In this review, we provide an update on the role of mitochondrial dysfunction in PD and how PBM may help mitigate the neurodegenerative process. We also discussed clinical translation aspects of this treatment modality using intracranially implanted NIR delivery devices.

Factor Analysis and Clustering of the Movement Disorder Society-Non-Motor Rating Scale

BACKGROUND

The primary validation of the Movement Disorder Society Non-Motor Rating Scale was recently published, but 2 important structural analyses were not included. The objective of this study was to examine the structural characteristics of the Movement Disorder Society Non-Motor Rating Scale by factor and cluster analyses.

METHODS

Data came from the validation study, an international multicenter cross-sectional study of 402 Parkinson's disease patients. Demographic and clinical data, the Movement Disorder Society Non-Motor Rating Scale, and Hoehn and Yahr staging were used. Exploratory and confirmatory factor analysis and nonhierarchical cluster analysis were performed.

RESULTS

The exploratory factor analysis showed that all 13 domains of the Movement Disorder Society Non-Motor Rating Scale, except 1, and the Non-Motor Fluctuations subscale performed as unidimensional (variance explained: 0.36, sleep and wakefulness; -0.82, orthostatic hypotension). The confirmatory factor analysis could be carried out in 9 domains and showed that 6 of them and the Non-Motor Fluctuations subscale adjusted to the model satisfactorily according to the root mean square error of approximation. Furthermore, all domains had comparative fit index values >0.95, except depression and pain (both, 0.94) and sleep and wakefulness (0.90). The Non-Motor Fluctuations subscale showed satisfactory root mean square error of approximation (0.07), but a low comparative fit index value (0.91). A 5-cluster solution, correctly classifying 96% of the cases, was found.

CONCLUSIONS

Overall, most subscales of the Movement Disorder Society Non-Motor Rating Scale are unidimensional, and although each subscale is distinct in terms of content covered, factors and clusters that are of clinical relevance are discernible and contribute to our understanding of possible nonmotor subtypes in Parkinson's disease. © 2020 International Parkinson and Movement Disorder Society.

Cerebrospinal fluid proteomics implicates the granin family in Parkinson's disease

Parkinson's disease, the most common age-related movement disorder, is a progressive neurodegenerative disease with unclear etiology. Better understanding of the underlying disease mechanism(s) is an urgent need for the development of disease-modifying therapeutics. Limited studies have been performed in large patient cohorts to identify protein alterations in cerebrospinal fluid (CSF), a proximal site to pathology. We set out to identify disease-relevant protein changes in CSF to gain insights into the etiology of Parkinson's disease and potentially assist in disease biomarker identification. In this study, we used liquid chromatography-tandem mass spectrometry in data-independent acquisition (DIA) mode to identify Parkinson's-relevant biomarkers in cerebrospinal fluid. We quantified 341 protein groups in two independent cohorts (n = 196) and a longitudinal cohort (n = 105 samples, representing 40 patients) consisting of Parkinson's disease and healthy control samples from three different sources. A first cohort of 53 Parkinson's disease and 72 control samples was analyzed, identifying 53 proteins with significant changes (p < 0.05) in Parkinson's disease relative to healthy control. We established a biomarker signature and multiple protein ratios that differentiate Parkinson's disease from healthy controls and validated these results in an independent cohort. The second cohort included 28 Parkinson's disease and 43 control samples. Independent analysis of these samples identified 41 proteins with significant changes. Evaluation of the overlapping changes between the two cohorts identified 13 proteins with consistent and significant changes (p < 0.05). Importantly, we found the extended granin family proteins as reduced in disease, suggesting a potential common mechanism for the biological reduction in monoamine neurotransmission in Parkinson's patients. Our study identifies several novel protein changes in Parkinson's disease cerebrospinal fluid that may be exploited for understanding etiology of disease and for biomarker development.

Clinical and Cerebral Metabolic Changes in Parkinson's Disease With Basal Forebrain Atrophy

BACKGROUND

Cholinergic dysfunction plays a key role in cognitive dysfunction in Parkinson's disease (PD). Recent studies revealed that atrophy in the nucleus basalis of Meynert (NBM), the largest cholinergic nucleus in the basal forebrain, heralds cognitive decline in PD. Despite clinical importance of NBM atrophy in PD, clinical and radiological correlates of NBM atrophy remains to be elucidated.

OBJECTIVE

We investigated the longitudinal changes in clinical and cerebral glucose metabolic characteristics in PD with atrophy in the NBM.

METHODS

We analyzed the 3-year longitudinal data of 56 PD patients who underwent motor, nonmotor, and imaging evaluations at baseline. The patients were classified into PD with and without NBM atrophy based on the results of magnetic resonance imaging volumetry. We compared clinical characteristics and cerebral glucose metabolic changes between PD with and without NBM atrophy.

RESULTS

At baseline, 20 patients and 36 patients were classified into PD with and without NBM atrophy groups, respectively. At follow-up, the data of the 14 PD patients in the NBM atrophy group and the 18 patients in the group without NBM atrophy completed full assessments and were available for the analysis. The PD with NBM atrophy group showed severe cognitive dysfunction and psychiatric symptoms both at baseline and follow-up. The NBM volume significantly correlated with motor and nonmotor functions. The PD with NBM atrophy showed significantly reduced metabolism in the parietal and occipital cortices both at baseline and follow-up.

CONCLUSIONS

Basal forebrain atrophy is a simple and sensible marker of faster disease progression and cortical hypometabolism in PD. © 2020 International Parkinson and Movement Disorder Society.

The movement disorder society nonmotor rating scale: Initial validation study

BACKGROUND

The Movement Disorder Society-sponsored Nonmotor Rating Scale is an update of the existing Parkinson's disease Nonmotor Symptoms Scale modified to address some limitations in Nonmotor Symptoms Scale scoring, structure, and symptom coverage.

METHODS

PD patients were recruited from movement disorder centers in an international, multicenter study. The Movement Disorder Society Nonmotor Rating Scale, consisting of 13 domains plus a subscale for nonmotor fluctuations, was rater administered, along with the Nonmotor Symptoms Scale and other clinical assessments. Standard reliability and validity testing were conducted.

RESULTS

Four hundred and two PD patients were recruited (mean age ± standard deviation, 67.42 ± 9.96 years; mean age at PD onset ± standard deviation, 59.27 ± 10.67 years; median Hoehn and Yahr stage 2 (interquartile range 2-3). Data quality was satisfactory for all Movement Disorder Society Nonmotor Rating Scale domains except sexual (6.7% missing data). There were no floor or ceiling effects for the Movement Disorder Society Nonmotor Rating Scale and nonmotor fluctuations total score; domains had no ceiling effects, but some floor effects (13.5%-83.5%). The Movement Disorder Society Nonmotor Rating Scale and nonmotor fluctuations total score internal consistency were acceptable (average Cronbach's alpha, 0.66 and 0.84, respectively); interrater reliability was excellent (intraclass correlation coefficient, >0.95); for test-retest reliability, the intraclass correlation coefficient was 0.84 for the Movement Disorder Society Nonmotor Rating Scale and 0.70 for Movement Disorder Society nonmotor fluctuations total score, and precision was excellent for the Movement Disorder Society Nonmotor Rating Scale (standard error of measurement, 25.30) and fair for nonmotor fluctuations (standard error of measurement, 7.06). Correlations between Movement Disorder Society Nonmotor Rating Scale score and the corresponding Nonmotor Symptoms Scale and Movement Disorder Society UPDRS scores were high. There were no significant sex or age effects. The Movement Disorder Society Nonmotor Rating Scale score increased with increasing PD duration, disease severity, and PD medication dose (all P < 0.001).

CONCLUSIONS

The Movement Disorder Society Nonmotor Rating Scale is a valid measure for measuring the burden of a wide range of Nonmotor Rating Scale scores, including nonmotor fluctuations, in PD patients. © 2019 International Parkinson and Movement Disorder Society.

Progressive loss of raphe nuclei serotonin transporter in early Parkinson's disease: A longitudinal 123I-FP-CIT SPECT study

BACKGROUND

Serotonergic raphe nuclei dysfunction has been documented in Parkinson's disease, both in pathological and neuroimaging studies, and has been associated with scores of tremor and non-motor symptoms. However, no in vivo longitudinal investigations have been conducted to assess the rate of decline of raphe serotonin transporter availability in the early stages of the disease.

OBJECTIVE

To measure the rate of decline of raphe serotonin transporter availability over a two-year interval in patients with recently diagnosed disease and its association with non-motor symptoms over time.

METHODS

Baseline and two-year follow-up ¹²³ioflupane-fluoropropyl-carbomethoxy-3-beta-4-iodo-phenyltropane (¹²³I-FP-CIT) SPECT scans of 173 early Parkinson's disease patients enrolled in the Parkinson's Progressive Markers Initiative were analysed and non-motor symptoms scores recorded.

RESULTS

A 16.6 ± 20.9% (mean ± SD) reduction in raphe serotonin transporter availability was found from baseline to two-year follow-up in the entire cohort. No differences in progression were found between tremor dominant and postural instability/gait difficulty phenotypes. At follow-up 34.1% of patients showed a moderate-to-severe reduction of raphe serotonin transporter availability with respect to the controls' mean. We did not find any significant correlation between raphe serotonin transporter availability and scores of depression, excessive daytime sleepiness and REM sleep behaviour disorder.

CONCLUSION

¹²³I-FP-CIT SPECT was able to measure longitudinal reductions in raphe serotonin transporter availability in the early phases of Parkinson's disease. About four years after diagnosis, raphe serotonin transporter availability was significantly reduced in more than one third of the population, but does not appear to be correlated to non-motor symptoms at this stage.

Pilot Study of the International Parkinson and Movement Disorder Society-sponsored Non-motor Rating Scale (MDS-NMS)

Background

Non-motor symptoms (NMS) are integral to Parkinson's disease (PD) and have a detrimental effect on patients and their caregivers. Clinical quantification has been aided by the development of comprehensive assessments such as the Non-Motor Symptoms Questionnaire (NMSQuest) and Scale (NMSS). The NMSS has been widely used in clinical studies and trials; however, since its validation in 2007, our understanding of NMS has changed substantially. With the support of the International Parkinson and Movement Disorder Society (IPMDS), after a detailed peer review an initiative to develop an updated version of NMSS, the MDS-NMS was launched in 2015.

Objective

This paper encapsulates the data from the pre-validation phases carried out under the auspices of the IPMDS Non-Motor PD Study Group.

Methods

Item selection and wording (formatted as a rater-based tool) were based on the NMSS, literature review, and expert consensus. Neurologists, PD patients, and healthy controls were included in the cognitive pretesting and administration of the preliminary version of the MDS-NMS. Primary data on acceptability and reliability were obtained.

Results

The pilot study, carried out in English in the United Kingdom and the United States, demonstrated that the preliminary version of the MDS-NMS was comprehensive, understandable, and appropriate. Data quality was excellent; moderate floor effect was present in patients for most MDS-MNS domains, with some components showing weak internal consistency. The results led to additional instrument modifications.

Conclusion

Qualitative and quantitative research results have led to an updated NMSS, the definitive version of the MDS-NMS, which is currently being validated.

Update on treatments for nonmotor symptoms of Parkinson's disease-an evidence-based medicine review

OBJECTIVE

To update evidence-based medicine recommendations for treating nonmotor symptoms in Parkinson's disease (PD).

BACKGROUND

The International Parkinson and Movement Disorder Society Evidence-Based Medicine Committee's recommendations for treatments of PD were first published in 2002, updated in 2011, and now updated again through December 31, 2016.

METHODS

Level I studies testing pharmacological, surgical, or nonpharmacological interventions for the treatment of nonmotor symptoms in PD were reviewed. Criteria for inclusion and quality scoring were as previously reported. The disorders covered were a range of neuropsychiatric symptoms, autonomic dysfunction, disorders of sleep and wakefulness, pain, fatigue, impaired olfaction, and ophthalmologic dysfunction. Clinical efficacy, implications for clinical practice, and safety conclusions are reported.

RESULTS

A total of 37 new studies qualified for review. There were no randomized controlled trials that met inclusion criteria for the treatment of anxiety disorders, rapid eye movement sleep behavior disorder, excessive sweating, impaired olfaction, or ophthalmologic dysfunction. We identified clinically useful or possibly useful interventions for the treatment of depression, apathy, impulse control and related disorders, dementia, psychosis, insomnia, daytime sleepiness, drooling, orthostatic hypotension, gastrointestinal dysfunction, urinary dysfunction, erectile dysfunction, fatigue, and pain. There were no clinically useful interventions identified to treat non-dementia-level cognitive impairment.

CONCLUSIONS

The evidence base for treating a range of nonmotor symptoms in PD has grown substantially in recent years. However, treatment options overall remain limited given the high prevalence and adverse impact of these disorders, so the development and testing of new treatments for nonmotor symptoms in PD remains a top priority. © 2019 International Parkinson and Movement Disorder Society.

Novel Immunotherapeutic Approaches to Target Alpha-Synuclein and Related Neuroinflammation in Parkinson's Disease

The etiology of Parkinson’s disease (PD) is significantly influenced by disease-causing changes in the protein alpha-Synuclein (aSyn). It can trigger and promote intracellular stress and thereby impair the function of dopaminergic neurons. However, these damage mechanisms do not only extend to neuronal cells, but also affect most glial cell populations, such as astroglia and microglia, but also T lymphocytes, which can no longer maintain the homeostatic CNS milieu because they produce neuroinflammatory responses to aSyn pathology. Through precise neuropathological examination, molecular characterization of biomaterials, and the use of PET technology, it has been clearly demonstrated that neuroinflammation is involved in human PD. In this review, we provide an in-depth overview of the pathomechanisms that aSyn elicits in models of disease and focus on the affected glial cell and lymphocyte populations and their interaction with pathogenic aSyn species. The interplay between aSyn and glial cells is analyzed both in the basic research setting and in the context of human neuropathology. Ultimately, a strong rationale builds up to therapeutically reduce the burden of pathological aSyn in the CNS. The current antibody-based approaches to lower the amount of aSyn and thereby alleviate neuroinflammatory responses is finally discussed as novel therapeutic strategies for PD.

Societal Burden and Persisting Unmet Needs of Parkinson’s Disease

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[Parkinson disease and asthenic syndrome]

AIM

To study the clinical heterogeneity of fatigue syndrome and evaluate the efficacy of cytoflavin as an addition to standard treatment in patients with Parkinson's disease.

MATERIAL AND METHODS

One hundred patients with Parkinson's disease and fatigue took part in the study, 59 patients continued to participate in the study including 59.3% (32) women and 40.7% (27) men. All patients received standard treatment. The equivalent daily dose of levodopa (LEDD) was 736.9±419.1 mg/day. The average age of patients was 67±8.6 (from 65 to 85 years). Cytoflavin was used as an additional therapy in the standard dosage. All patients underwent neuropsychological examination for an estimate of the rate of fatigue, depression, health status, activity, mood and quality of life.

RESULTS AND CONCLUSION

Cytoflavin is well tolerated by patients with Parkinson's disease and fatigue syndrome at the standard dosage. It improves the health, mood, quality of life and reduces fatigue.

Amyloid-β and Parkinson's disease

Parkinson's disease (PD) is the second commonest neurodegenerative disorder in the world with a rising prevalence. The pathophysiology is multifactorial but aggregation of misfolded α-synuclein is considered to be a key underpinning mechanism. Amyloid-β (Aβ) and tau deposition are also comorbid associations and especially Aβ deposition is associated with cognitive decline in PD. Some existing evidence suggests that low cerebrospinal fluid (CSF) Aβ₄₂ is predictive of future cognitive impairment in PD. Recent studies also show that CSF Aβ is associated with the postural instability and gait difficulties (PIGD) or the newly proposed cholinergic subtype of PD, a possible risk factor for cognitive decline in PD. The glial-lymphatic system, responsible for convective solute clearance driven by active fluid transport through aquaporin-4 water channels, may be implicated in brain amyloid deposition. A better understanding of the role of this system and more specifically the role of Aβ in PD symptomatology, could introduce new treatment and repurposing drug-based strategies. For instance, apomorphine infusion has been shown to promote the degradation of Aβ in rodent models. This is further supported in a post-mortem study in PD patients although clinical implications are unclear. In this review, we address the clinical implication of cerebral Aβ deposition in PD and elaborate on its metabolism, its role in cognition and motor function/gait, and finally assess the potential effect of apomorphine on Aβ deposition in PD.

'Levodopa Phobia': a review of a not uncommon and consequential phenomenon

'Levodopa Phobia' is under-recognised in Parkinson's disease but can cause profound detrimental clinical complications if left to continue. Several types can be encountered in clinical practice and can be driven by a misplaced fear of levodopa-induced dyskinesias, other gastrointestinal side effects and also the theoretical notion that levodopa may be toxic to dopaminergic neurons in the brain. The condition can be underpinned by a sense of strong influence from the physicians or carers who are unwilling to prescribe or consider levodopa, and also high levels of anxiety or even impulsive compulsive traits in patients who have been influenced by available literature or social media-based information. If unrecognised, the clinical issue may lead to motor deterioration and related muscle contractures leading to social isolation as well as a range of non-motor symptoms. In some, there may be emergence of intrusive impulse control disorders because of reliance on only dopamine agonists related to the fear of taking levodopa. Four cases illustrate the different patterns of 'Levodopa Phobia' in this study. Management of levodopa phobia is complex and includes recognition and skilled neuropsychological interventions to break the misperceptions about the complications of levodopa therapy.