Neurotransmission in Parkinson's disease: beyond dopamine

Cell reprogramming therapy for Parkinson's disease

Parkinson's disease is typically characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Many studies have been performed based on the supplementation of lost dopaminergic neurons to treat Parkinson's disease. The initial strategy for cell replacement therapy used human fetal ventral midbrain and human embryonic stem cells to treat Parkinson's disease, which could substantially alleviate the symptoms of Parkinson's disease in clinical practice. However, ethical issues and tumor formation were limitations of its clinical application. Induced pluripotent stem cells can be acquired without sacrificing human embryos, which eliminates the huge ethical barriers of human stem cell therapy. Another widely considered neuronal regeneration strategy is to directly reprogram fibroblasts and astrocytes into neurons, without the need for intermediate proliferation states, thus avoiding issues of immune rejection and tumor formation. Both induced pluripotent stem cells and direct reprogramming of lineage cells have shown promising results in the treatment of Parkinson's disease. However, there are also ethical concerns and the risk of tumor formation that need to be addressed. This review highlights the current application status of cell reprogramming in the treatment of Parkinson's disease, focusing on the use of induced pluripotent stem cells in cell replacement therapy, including preclinical animal models and progress in clinical research. The review also discusses the advancements in direct reprogramming of lineage cells in the treatment of Parkinson's disease, as well as the controversy surrounding in vivo reprogramming. These findings suggest that cell reprogramming may hold great promise as a potential strategy for treating Parkinson's disease.

Clinically established early Parkinson's disease patients do not show impaired use of priors in conditions of perceptual uncertainty

The ability to use past learned experiences to guide decisions is an important component of adaptive behavior, especially when decision-making is performed under time pressure or when perceptual information is unreliable. Previous studies using visual discrimination tasks have shown that this prior-informed decision-making ability is impaired in Parkinson's disease (PD), but the mechanisms underlying this deficit and the precise impact of dopaminergic denervation within cortico-basal circuits remain unclear. To shed light on this problem, we evaluated prior-informed decision-making under various conditions of perceptual uncertainty in a sample of 13 clinically established early PD patients, and compared behavioral performance with healthy control (HC) subjects matched in age, sex and education. PD patients and HC subjects performed a random dot motion task in which they had to decide the net direction (leftward vs. rightward) of a field of moving dots and communicate their choices through manual button presses. We manipulated prior knowledge by modulating the probability of occurrence of leftward vs. rightward motion stimuli between blocks of trials, and by explicitly giving these probabilities to subjects at the beginning of each block. We further manipulated stimulus discriminability by varying the proportion of dots moving coherently in the signal direction and speed-accuracy instructions. PD patients used choice probabilities to guide perceptual decisions in both speed and accuracy conditions, and their performance did not significantly differ from that of HC subjects. An additional analysis of the data with the diffusion decision model confirmed this conclusion. These results suggest that the impaired use of priors during visual discrimination observed at more advanced stages of PD is independent of dopaminergic denervation, though additional studies with larger sample sizes are needed to more firmly establish this conclusion.

Relationships between physical activities performed under free-living conditions and non-motor symptoms in people with Parkinson's: A systematic review and meta-analysis

BACKGROUND

Physical activities performed under free-living conditions that are unsupervised in the home or community have the potential to modulate non-motor symptoms in people with Parkinson's disease.

OBJECTIVE

This systematic review investigates the relationships between physical activities performed in free-living conditions and non-motor symptoms in people with Parkinson's disease: cognition, anxiety, apathy, depression, sleep disturbances, fatigue, and pain.

DATA SOURCES

A database search was performed on Scopus, Web of Science, Ovid (PsycINFO), CINAHL, PubMed, and ProQuest (Health and Medicine).

REVIEW METHODS

Observational studies published from 2000 to 2024 that examined the relationships between physical activity and non-motor symptoms were included. The methodological quality of reports was evaluated using critical appraisal checklists appropriate to the study design. Where appropriate, a meta-analysis was conducted to combine data from the included articles.

RESULTS

A total of 14 articles met the criteria and used various tools to evaluate non-motor symptoms and physical activity. Meta-analyses showed that people with Parkinson's who are more physically active have better global cognition [β ranged from 0.12 to 0.28; p = 0.00-0.02] and less affective disorders [β -0.20, p = 0.00]. Increased physical activity levels were also associated with better sleep quality (n = 1) and less chronic pain (n = 1). The overall methodological quality of the included articles was considered high.

CONCLUSION

Engagement in increased levels of physical activities performed under free-living conditions is associated with better cognition and less anxiety, apathy, and depression in people with Parkinson's disease.

An Anti-Inflammatory Diet and Its Potential Benefit for Individuals with Mental Disorders and Neurodegenerative Diseases-A Narrative Review

This narrative review synthesizes current evidence regarding anti-inflammatory dietary patterns and their potential benefits for individuals with mental disorders and neurodegenerative diseases. Chronic low-grade inflammation is increasingly recognized as a key factor in the etiology and progression of these conditions. The review examines the evidence for the anti-inflammatory and neuroprotective properties of dietary components and food groups, focusing on whole foods rather than specific nutrients or supplements. Key dietary components showing potential benefits include fruits and vegetables (especially berries and leafy greens), whole grains, legumes, fatty fish rich in omega-3, nuts (particularly walnuts), olive oil, and fermented foods. These foods are generally rich in antioxidants, dietary fiber, and bioactive compounds that may help modulate inflammation, support gut health, and promote neuroprotection. Conversely, ultra-processed foods, red meat, and sugary beverages may be harmful. Based on this evidence, we designed the Brain Anti-Inflammatory Nutrition (BrAIN) diet. The mechanisms of this diet include the modulation of the gut microbiota and the gut-brain axis, the regulation of inflammatory pathways, a reduction in oxidative stress, and the promotion of neuroplasticity. The BrAIN diet shows promise as an aid to manage mental and neurodegenerative disorders.

Escitalopram moderately outperforms citalopram towards anti-neuroinflammation and neuroprotection in 6-hydroxydopamine-induced mouse model of Parkinson's disease

Citalopram and escitalopram are structurally close-related antidepressants and both forms are widely used in the world. We aimed to comparatively evaluate the anti-neuroinflammatory and neuroprotective effects of escitalopram and citalopram in Parkinson's disease (PD) mouse model. Mice were randomly divided into six groups and received 6-hydroxydopamine (6-OHDA) or vehicle administration. The mice were then treated with escitalopram, citalopram or saline for consecutive 7 days. Behaviors, neuroinflammation, neurotransmitters, and neurotoxicity were assessed. Results showed that citalopram but not escitalopram worsened body weight loss and increased freezing time in the PD mice. Both drugs had no impact on the anxiety-like behaviors but ameliorated the depressive-like behaviors as in elevated plus maze and sucrose splash tests. Escitalopram but not citalopram ameliorated motor discoordination in the PD mice as in rotarod test. In accordance, escitalopram but not citalopram attenuated the 6-OHDA-induced nigrostriatal dopaminergic loss. Further mechanistic investigations showed that both drugs mitigated activations of microglia and astrocytes and/or levels of pro-inflammatory cytokines in the PD mice, but escitalopram showed appreciably better effects in the substantia nigra. Neurotransmitter examination in the prefrontal cortex suggested that the two drugs had comparable effects on the disturbed neurotransmitters in the PD mice, but citalopram was prone to disrupt certain normal homeostasis. In conclusion, escitalopram is moderately superior than citalopram to suppress neuroinflammation and to protect against dopaminergic neuronal death and motor discoordination in the 6-OHDA-induced PD mice. Our findings imply that escitalopram shall be prescribed with priority over citalopram to treat PD patients with depression as escitalopram may meanwhile provide greater additional benefits to the patients.

Rethinking neurodegenerative diseases: neurometabolic concept linking lipid oxidation to diseases in the central nervous system

ABSTRACT

Currently, there is a lack of effective medicines capable of halting or reversing the progression of neurodegenerative disorders, including amyotrophic lateral sclerosis, Parkinson's disease, multiple sclerosis, or Alzheimer's disease. Given the unmet medical need, it is necessary to reevaluate the existing paradigms of how to target these diseases. When considering neurodegenerative diseases from a systemic neurometabolic perspective, it becomes possible to explain the shared pathological features. This innovative approach presented in this paper draws upon extensive research conducted by the authors and researchers worldwide. In this review, we highlight the importance of metabolic mitochondrial dysfunction in the context of neurodegenerative diseases. We provide an overview of the risk factors associated with developing neurodegenerative disorders, including genetic, epigenetic, and environmental factors. Additionally, we examine pathological mechanisms implicated in these diseases such as oxidative stress, accumulation of misfolded proteins, inflammation, demyelination, death of neurons, insulin resistance, dysbiosis, and neurotransmitter disturbances. Finally, we outline a proposal for the restoration of mitochondrial metabolism, a crucial aspect that may hold the key to facilitating curative therapeutic interventions for neurodegenerative disorders in forthcoming advancements.

Phytoactive drugs used in the treatment of Alzheimer's disease and dementia

The prevalence of Alzheimer's disease and other forms of dementia is increasing worldwide, and finding effective treatments for these conditions is a major public health challenge. Natural bioactive drugs have been identified as a promising source of potential treatments, due to their ability to target multiple pathways and their low toxicity. This paper reviews the current state of research on natural bioactive drugs used in the treatment of Alzheimer's disease and other dementias. The paper summarizes the findings of studies on various natural compounds, including curcumin, resveratrol, caffeine, genistein, quercetin, GinkoBiloba, Withaniasomnifera, Ginseng Brahmi, Giloy, and huperzine, and their effects on cognitive function, neuroinflammation, and amyloid-beta accumulation. In this review, we discuss the mechanism of action involved in the treatment of Alzheimer's disease. The paper also discusses the challenges associated with developing natural bioactive drugs for dementia treatment, including issues related to bioavailability and standardization. Finally, the paper suggests directions for future research in this area, including the need for more rigorous clinical trials and the development of novel delivery systems to improve the efficacy of natural bioactive drugs. Overall, this review highlights the potential of natural bioactive drugs as a promising avenue for the development of safe and effective treatments for Alzheimer's disease and other dementias.

Depression is associated with the nonmotor symptoms of Parkinson's disease: A comparative analysis

Background and aims

The nonmotor symptoms (NMS) of Parkinson's disease (PD) and their potential role in early diagnosis are recent debates. Herein, we aimed to investigate the association between depression and NMS of PD including sleep disorders, hyposexuality, hyposmia, constipation, and orthostatic hypotension.

Methods

A total of 93 PD patients with depression and 67 PD patients without depression were included in the study, and NMS were compared between the two groups. Furthermore, the possible associations between depression severity measured by Beck Depression Inventory (BDI) and NMS were investigated using linear regression or binary logistic regression models controlled for possible confounders. Eventually, we performed a subgroup analysis in each mild, moderate, and severe depression group.

Results

Orthostatic hypotension, constipation, and hyposexuality showed a significant difference between PD patients with and without depression (p < 0.001, p = 0.029, and p < 0.001, respectively). The BDI score was significantly associated with hyposexuality, Montreal cognitive assessment (MoCA), and Pittsburgh Sleep Quality (p = 0.016, p = 0.010, and p = 0.011, respectively); however, after adjustments for possible confounders, the associations of the BDI score with the MoCA score and hyposexuality remained significant (p = 0.015 and p = 0.019, respectively). Considering subgroup analysis, a similar pattern of significant results was observed particularly in the severe group.

Conclusions

This study suggests a possible association between depression in PD patients and some NMS observed in the course of PD. These findings could be beneficial for early diagnosis of the disease, which eventually could make a considerable difference in the management of PD patients. Additional interventional longitudinal studies are warranted to explore how controlling depression could impact the NMS of patients with PD.

Dose-Ranging Effects of the Intracerebral Administration of Atsttrin in Experimental Model of Parkinson's Disease Induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in Mice

Parkinson's disease is one of the most common neurodegenerative disorders characterized by a multitude of motor and non-motor clinical symptoms resulting from the progressive and long-lasting abnormal loss of nigrostriatal dopaminergic neurons. Currently, the available treatments for patients with Parkinson's disease are limited and exert only symptomatic effects, without adequate signs of delaying or stopping the progression of the disease. Atsttrin constitutes the bioengineered protein which ultrastructure is based on the polypeptide chain frame of the progranulin (PGRN), which exerts anti-inflammatory effects through the inhibition of TNFα. The conducted preclinical studies suggest that the therapeutic implementation of Atsttrin may be potentially effective in the treatment of neurodegenerative diseases that are associated with the occurrence of neuroinflammatory processes. The aim of the proposed study was to investigate the effect of direct bilateral intracerebral administration of Atsttrin using stereotactic methods in the preclinical C57BL/6 mouse model of Parkinson's disease inducted by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication. The analysis of the dose dependency effects of the increasing doses of Atsttrin has covered a number of parameters and markers regarding neurodegenerative processes and inflammatory responses including IL-1α, TNFα, IL-6, TH, and TG2 mRNA expressions. Accordingly, the evaluation of the changes in the neurochemical profile included DA, DOPAC, 3-MT, HVA, NA, MHPG, 5-HT, and 5-HIAA concentration levels. The intracerebral administration of Atsttrin into the striatum effectively attenuated the neuroinflammatory reaction in evaluated neuroanatomical structures. Furthermore, the partial restoration of monoamine content and its metabolic turnover were observed. In this case, taking into account the previously described pharmacokinetic profile and extrapolated bioavailability as well as the stability characteristics of Atsttrin, an attempt was made to describe as precisely as possible the quantitative and qualitative effects of increasing doses of the compound within the brain tissue microenvironment in the presented preclinical model of the disease. Collectively, this findings demonstrated that the intracerebral administration of Atsttrin may represent a potential novel therapeutic method for the treatment of Parkinson's disease.

Reusable graphite-based electrochemical sensors for L-dopa and dopamine detection

A fully reusable electrochemical device is proposed for the first time made from laser cutting and a homemade conductive ink composed of carbon and nail polish. As a sensor substrate, we applied polymethyl methacrylate, which allows the surface to be renewed by simply removing and reapplying a new layer of ink. In addition to the ease of renewing the sensor's conductive surface, the design of the device has allowed for the integration of different forms of analysis. The determination of L-Dopa was performed using DPV, which presented a linear response range between 5.0 and 1000.0 μmol L-1, and a LOD of 0.11 μmol L-1. For dopamine, a flow injection analysis system was employed, and using the amperometric technique measurements were performed with a linear ranging from 2.0 to 100.0 μmol L-1 and a LOD of 0.26 μmol L-1. To demonstrate its applicability, the device was used in the quantification of analytes in pharmaceutical drug and synthetic urine samples.

Sleep disorders cause Parkinson's disease or the reverse is true: Good GABA good night

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative brain disease due to degeneration of dopaminergic neurons (DNs) presented with motor and non-motor symptoms. PD symptoms are developed in response to the disturbance of diverse neurotransmitters including γ-aminobutyric acid (GABA). GABA has a neuroprotective effect against PD neuropathology by protecting DNs in the substantia nigra pars compacta (SNpc). It has been shown that the degeneration of GABAergic neurons is linked with the degeneration of DNs and the progression of motor and non-motor PD symptoms. GABA neurotransmission is a necessary pathway for normal sleep patterns, thus deregulation of GABAergic neurotransmission in PD could be the potential cause of sleep disorders in PD.

AIM

Sleep disorders affect GABA neurotransmission leading to memory and cognitive dysfunction in PD. For example, insomnia and short sleep duration are associated with a reduction of brain GABA levels. Moreover, PD-related disorders including rigidity and nocturia influence sleep patterns leading to fragmented sleep which may also affect PD neuropathology. However, the mechanistic role of GABA in PD neuropathology regarding motor and non-motor symptoms is not fully elucidated. Therefore, this narrative review aims to clarify the mechanistic role of GABA in PD neuropathology mainly in sleep disorders, and how good GABA improves PD. In addition, this review of published articles tries to elucidate how sleep disorders such as insomnia and REM sleep behavior disorder (RBD) affect PD neuropathology and severity. The present review has many limitations including the paucity of prospective studies and most findings are taken from observational and preclinical studies. GABA involvement in the pathogenesis of PD has been recently discussed by recent studies. Therefore, future prospective studies regarding the use of GABA agonists in the management of PD are suggested to observe their distinct effects on motor and non-motor symptoms.

CONCLUSION

There is a bidirectional relationship between the pathogenesis of PD and sleep disorders which might be due to GABA deregulation.

Serum neurofilament indicates accelerated neurodegeneration and predicts mortality in late-stage Parkinson's disease

Different stages of Parkinson's disease (PD) are defined by clinical criteria, while late-stage PD is marked by the onset of morbidity milestones and rapid clinical deterioration. Based on neuropathological evidence, degeneration in the dopaminergic system occurs primarily in the early stage of PD, raising the question of what drives disease progression in late-stage PD. This study aimed to investigate whether late-stage PD is associated with increased neurodegeneration dynamics rather than functional decompensation using the blood-based biomarker serum neurofilament light chain (sNfL) as a proxy for the rate of neurodegeneration. The study included 118 patients with PD in the transition and late-stage (minimum disease duration 5 years, mean (SD) disease duration 15 (±7) years). The presence of clinical milestones (hallucinations, dementia, recurrent falls, and admission to a nursing home) and mortality were determined based on chart review. We found that sNfL was higher in patients who presented with at least one clinical milestone and increased with a higher number of milestones (Spearman's ρ = 0.66, p < 0.001). Above a cutoff value of 26.9 pg/ml, death was 13.6 times more likely during the follow-up period (95% CI: 3.53-52.3, p < 0.001), corresponding to a sensitivity of 85.0% and a specificity of 85.7% (AUC 0.91, 95% CI: 0.85-0.97). Similar values were obtained when using an age-adjusted cutoff percentile of 90% for sNfL. Our findings suggest that the rate of ongoing neurodegeneration is higher in advanced PD (as defined by the presence of morbidity milestones) than in earlier disease stages. A better understanding of the biological basis of stage-dependent neurodegeneration may facilitate the development of neuroprotective means.

Defining Parkinson's Disease: Past and Future

Parkinson's disease (PD) is the second most common still relentlessly progressive neurodegenerative disorder with a long period in which the pathophysiological process is already spreading but cardinal motor symptoms are not present. This review outlines the major developments and milestones in our understanding of PD that have shaped the way we define this disorder. Past criteria and definitions of PD have been based on clinical motor manifestations enabling diagnosis of the disease only in later symptomatic stages. Nevertheless, with advancing knowledge of disease pathophysiology and aim of early disease detection, a major shift of the diagnostic paradigm is being advocated towards a biological definition similar to other neurodegenerative disorders including Alzheimer's disease and Huntington's disease, with the ultimate goal of an earlier, disease course modifying therapy. We summarize the major pillars of this possible approach including in vivo detection of neuronal α-synuclein aggregation, neurodegeneration and genetics and outline their possible application in different contexts of use in the frame of biological PD definition.

Cortical Disinhibition Drives Freezing of Gait in Parkinson's Disease and an Exploratory Repetitive Transcranial Magnetic Stimulation Study

BACKGROUND

Dysfunction of the primary motor cortex, participating in regulation of posture and gait, is implicated in freezing of gait (FOG) in Parkinson's disease (PD).

OBJECTIVE

The aim was to reveal the mechanisms of "OFF-period" FOG (OFF-FOG) and "levodopa-unresponsive" FOG (ONOFF-FOG) in PD.

METHODS

We measured the transcranial magnetic stimulation (TMS) indicators and gait parameters in 21 healthy controls (HCs), 15 PD patients with ONOFF-FOG, 15 PD patients with OFF-FOG, and 15 PD patients without FOG (Non-FOG) in "ON" and "OFF" medication conditions. Difference of TMS indicators in the four groups and two conditions and its correlations with gait parameters were explored. Additionally, we explored the effect of 10 Hz repetitive TMS on gait and TMS indicators in ONOFF-FOG patients.

RESULTS

In "OFF" condition, short interval intracortical inhibition (SICI) exhibited remarkable attenuation in FOG patients (both ONOFF-FOG and OFF-FOG) compared to Non-FOG patients and HCs. The weakening of SICI correlated with impaired gait characteristics in FOG. However, in "ON" condition, SICI in ONOFF-FOG patients reduced compared to OFF-FOG patients. Pharmacological treatment significantly improved SICI and gait in OFF-FOG patients, and high-frequency repetitive TMS distinctly improved gait in ONOFF-FOG patients, accompanied by enhanced SICI.

CONCLUSIONS

Motor cortex disinhibition, represented by decreased SICI, is related to FOG in PD. Refractory freezing in ONOFF-FOG patients correlated with the their reduced SICI insensitive to dopaminergic medication. SICI can serve as an indicator of the severity of impaired gait characteristics in FOG and reflect treatments efficacy for FOG in PD patients. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Peripheral hearing in Parkinson's disease: a systematic review

OBJECTIVE

To investigate the implications of Parkinson's disease (PD) in the peripheral auditory system, a systematic survey of the scientific literature was conducted.

DESIGN

Systematic review.

STUDY SAMPLE

An electronic search of the non-gray literature in the last decade was conducted using the digital databases MEDLINE® (PubMed interface), LILACS® (Virtual Health Library), Web of Science® (CAPES publications portal), and SciELO®. Studies addressing peripheral auditory function as part of the range of nonmotor PD symptoms were selected for analysis.

RESULTS

Pure tone audiometry data suggested that sensorineural hearing loss was more severe in the PD population than in the control groups. The effects of PD on cochlear function were evidenced by a decrease in the levels of otoacoustic emissions.

CONCLUSIONS

Sensorineural hearing loss and cochlear impairment are more severe in the PD population than in the control groups. Additional studies are recommended to further understand the characteristics of the peripheral auditory system in PD patients, which constitutes an emerging subject in the scientific literature.

Sudomotor deficits in Parkinson's disease with special reference to motor subtypes

INTRODUCTION

Parkinson's disease which shows clinically heterogeneous motor derangement may also accompany various autonomic disorders, but results of previous research on incidence and degree of each autonomic dysfunction have been inconsistent. As for sudomotor dysfunction, some investigators emphasize hypo- or anhidrois, whereas others stress hyperhidrosis.

SUBJECTS AND METHODS

To elucidate sudomotor dysfunctions in Parkinson's disease (PD) with respect to subtypes, 225 clinically probable patients PD patients were stratified by motor phenotype (tremor-dominant group: 33; mixed group: 105; and akinesia-rigidity group: 87) and subjected to thermal and acetylcholine-induced (focal) sweating tests. Thermal sweating was qualitatively assessed with a modified version of Minor's colorimetric methods. Thermoregulatory and acetylcholine-induced focal sweat rates were measured with capacitance hydrometers.

RESULTS

Thermoregulatory sweating was almost normal without anhidrotic area in 29.8% of PD patients, slightly defective in 38.7%, with anhidrotic area across <1/4 of the body surface, moderately defective in 22.2% with anhidrotic area across approximately 1/2 of the body surface, and extremely defective in 9.3% with anhidrotic area across more than 3/4 of the body surface. Patchy sweating was observed in 104 patients, implicating involvement of the hypothalamo-spinal and/or preganglionic systems in the disease process. Hyperhidrosis was seen in 15% of patients. Tremor-dominant group showed least impairment.

CONCLUSION

This study suggests that PD is associated with various patterns and degree of sudomotor abnormalities, and that sudomotor sympathetic deficits may be related with the pathophysiology of akinesia and rigidity rather than that of resting tremor.

Pimavanserin treatment increases plasma brain-derived neurotrophic factor levels in rats

Background

Pimavanserin, a serotonin 5HT-2A receptor inverse agonist is the first-line, FDA-approved treatment of hallucinations and delusions associated with Parkinson's Disease psychosis (PDP), which occurs in up to 50% of PD patients. The neurobiological mechanism underlying the therapeutic effectiveness of Pimavanserin in PDP remains unknown. Several earlier studies have shown that treatment with 5HT-2A antagonists and other drugs acting on the serotonergic system such as SSRIs increase Brain derived neurotrophic factor (BDNF) levels in rodents. BDNF is synthesized as the precursor proBDNF, that undergoes cleavage intra or extracellularly to produce a mature BDNF (mBDNF) protein. mBDNF is believed to play a key role in neuroplasticity and neurogenesis. The present study tested the hypothesis that treatment with Pimavanserin is associated with higher and sustained elevations of mBDNF.

Methods

Adult Sprague-Dawley male rats were treated with Pimavanserin, Fluoxetine or vehicle for 4 weeks (chronic) or 2 h (acute). BDNF levels were determined by enzyme-linked Immunosorbent assay (ELISA).

Results

We found significant increases in plasma mBDNF levels in rats following chronic Pimavanserin treatment, but not in Fluoxetine-treated rats. No significant changes in mBDNF levels were found in the prefrontal cortex or hippocampus following Pimavanserin or Fluoxetine treatment.

Conclusion

These findings suggest that increase in mBDNF levels could be a contributing mechanism for the neuroprotective potential of Pimavanserin.

Association of Cortical and Subcortical Microstructure With Clinical Progression and Fluid Biomarkers in Patients With Parkinson Disease

BACKGROUND AND OBJECTIVES

Mean diffusivity (MD) of diffusion MRI (dMRI) has been used to measure cortical and subcortical microstructural properties. This study investigated relationships of cortical and subcortical MD, clinical progression, and fluid biomarkers in Parkinson disease (PD).

METHODS

This longitudinal study using data from the Parkinson's Progression Markers Initiative was collected from April 2011 to July 2022. Clinical symptoms were assessed with Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (UPDRS) and Montreal Cognitive Assessment (MoCA) scores. Clinical assessments were followed up to 5 years. Linear mixed-effects (LME) models were performed to examine associations of MD and the annual rate of changes in clinical scores. Partial correlation analysis was conducted to examine the associations of MD and fluid biomarker levels.

RESULTS

A total of 174 patients with PD (age 61.9 ± 9.7 years, 63% male) with baseline dMRI and at least 2 years of clinical follow-up were included. Results of LME models revealed a significant association between MD values, predominantly in subcortical regions, temporal lobe, occipital lobe, and frontal lobe, and annual rate of changes in clinical scores (UPDRS-Part-I, standardized β > 2.35; UPDRS-Part-II, standardized β > 2.34; postural instability and gait disorder score, standardized β > 2.47; MoCA, standardized β < -2.42; all p < 0.05, false discovery rate [FDR] corrected). In addition, MD was associated with the levels of neurofilament light chain in serum (r > 0.22) and α-synuclein (right putamen r = 0.31), β-amyloid 1-42 (left hippocampus r = -0.30), phosphorylated tau at 181 threonine position (r > 0.26), and total tau (r > 0.23) in CSF at baseline (all p < 0.05, FDR corrected). Furthermore, the β coefficients derived from MD and annual rate of changes in the clinical score recapitulated the spatial distribution of dopamine (DAT, D1, and D2), glutamate (mGluR5 and NMDA), serotonin (5-HT1a and 5-HT2a), cannabinoid (CB1), and γ-amino butyric acid A receptor neurotransmitter receptors/transporters (p < 0.05, FDR corrected) derived from PET scans in the brain of healthy volunteers.

DISCUSSION

In this cohort study, cortical and subcortical MD values at baseline were associated with clinical progression and baseline fluid biomarkers, suggesting that microstructural properties could be useful for stratification of patients with fast clinical progression.

Past, present, and future of tools for dopamine detection

Dopamine (DA) is a critical neuromodulator involved in various brain functions. To understand how DA regulates neural circuits and behaviors in the physiological and pathological conditions, it is essential to have tools that enable the direct detection of DA dynamics in vivo. Recently, genetically encoded DA sensors based on G protein-coupled receptors revolutionized this field, as it allows us to track in vivo DA dynamic with unprecedented spatial-temporal resolution, high molecular specificity, and sub-second kinetics. In this review, we first summarize traditional DA detection methods. Then we focus on the development of genetically encoded DA sensors and feature its significance to understanding dopaminergic neuromodulation across diverse behaviors and species. Finally, we present our perspectives about the future direction of the next-generation DA sensors and extend their potential applications. Overall, this review offers a comprehensive perspective on the past, present, and future of DA detection tools, with important implications for the study of DA functions in health and disease.

Fatigue in fluctuating Parkinson's disease patients: possible impact of safinamide

Fatigue is a common non-motor symptom in Parkinson's disease (PD). Among other pathophysiological mechanisms, neuroinflammation, a pathological PD hallmark associated with changes in glutamatergic transmission in basal ganglia, has been proposed as a crucial factor closely related to fatigue. To test the hypothesis that safinamide could represent an effective treatment of fatigue in PD patients, given its dual mechanism of action (it selectively and reversibly inhibits MAOB and modulates glutamate release), we administered the validated versions of fatigue severity scale (FSS) and Parkinson fatigue scale-16 (PFS-16) to 39 fluctuating PD patients with fatigue before and after a 24-week treatment period with safinamide as add-on therapy. An assessment of secondary variables such as depression, quality of life (QoL), and motor and non-motor symptoms (NMS) was conducted. After 24 weeks of treatment with safinamide, both FSS (p < 0.001) and PF-S16 (p = 0.02) scores were significantly lower than at baseline. Moreover, 46.2% and 41% of patients scored below the cut-off for the presence of fatigue according to FSS and PFS-16, respectively (responders). At follow-up, a significant difference emerged between responders and non-responders in mood, QoL, and NMS. Fatigue improved in fluctuating PD, and more than 40% of patients were "fatigue-free" after a 6 month treatment with safinamide. Patients without fatigue at follow-up displayed significantly better scores in QoL domains, such as mobility or activities of daily living, although disease severity remained stable, supporting the hypothesis that fatigue could considerably affect QoL. Drugs that interact with multiple neurotransmission systems, such as safinamide, could be useful in reducing this symptom.

Dopamine D1 Agonists: First Potential Treatment for Late-Stage Parkinson's Disease

Current pharmacotherapy has limited efficacy and/or intolerable side effects in late-stage Parkinson's disease (LsPD) patients whose daily life depends primarily on caregivers and palliative care. Clinical metrics inadequately gauge efficacy in LsPD patients. We explored if a D1/5 dopamine agonist would have efficacy in LsPD using a double-blind placebo-controlled crossover phase Ia/b study comparing the D1/5 agonist PF-06412562 to levodopa/carbidopa in six LsPD patients. Caregiver assessment was the primary efficacy measure because caregivers were with patients throughout the study, and standard clinical metrics inadequately gauge efficacy in LsPD. Assessments included standard quantitative scales of motor function (MDS-UPDRS-III), alertness (Glasgow Coma and Stanford Sleepiness Scales), and cognition (Severe Impairment and Frontal Assessment Batteries) at baseline (Day 1) and thrice daily during drug testing (Days 2-3). Clinicians and caregivers completed the clinical impression of change questionnaires, and caregivers participated in a qualitative exit interview. Blinded triangulation of quantitative and qualitative data was used to integrate findings. Neither traditional scales nor clinician impression of change detected consistent differences between treatments in the five participants who completed the study. Conversely, the overall caregiver data strongly favored PF-06412562 over levodopa in four of five patients. The most meaningful improvements converged on motor, alertness, and functional engagement. These data suggest for the first time that there can be useful pharmacological intervention in LsPD patients using D1/5 agonists and also that caregiver perspectives with mixed method analyses may overcome limitations using methods common in early-stage patients. The results encourage future clinical studies and understanding of the most efficacious signaling properties of a D1 agonist for this population.

CHCHD2 p.Thr61Ile knock-in mice exhibit motor defects and neuropathological features of Parkinson's disease

The p.Thr61Ile (p.T61I) mutation in coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) was deemed a causative factor in Parkinson's disease (PD). However, the pathomechanism of the CHCHD2 p.T61I mutation in PD remains unclear. Few existing mouse models of CHCHD2-related PD completely reproduce the features of PD, and no transgenic or knock-in (KI) mouse models of CHCHD2 mutations have been reported. In the present study, we generated a novel CHCHD2 p.T61I KI mouse model, which exhibited accelerated mortality, progressive motor deficits, and dopaminergic (DA) neurons loss with age, accompanied by the accumulation and aggregation of α-synuclein and p-α-synuclein in the brains of the mutant mice. The mitochondria of mouse brains and induced pluripotent stem cells (iPSCs)-derived DA neurons carrying the CHCHD2 p.T61I mutation exhibited aberrant morphology and impaired function. Mechanistically, proteomic and RNA sequencing analysis revealed that p.T61I mutation induced mitochondrial dysfunction in aged mice likely through repressed insulin-degrading enzyme (IDE) expression, resulting in the degeneration of the nervous system. Overall, this CHCHD2 p.T61I KI mouse model recapitulated the crucial clinical and neuropathological aspects of patients with PD and provided a novel tool for understanding the pathogenic mechanism and therapeutic interventions of CHCHD2-related PD.

Neurobiology of depression in Parkinson's disease: Insights into epidemiology, molecular mechanisms and treatment strategies

Parkinson's disease (PD) is characterized mainly by motor dysfunctions due to the progressive loss of dopaminergic neurons. However, PD patients experience a multitude of debilitating non-motor symptoms, including depression, which may have deleteriously detrimental effects on life. Depression is multifactorial and exhibits a bimodal progression in PD, but its underlying molecular mechanisms are poorly understood. Studies demonstrating the pathophysiology of depression in PD and the specific treatment strategies for depression-like symptoms in PD patients are largely lacking, often underrated, under-recognized and, consequently, inadequately/under-treated. Nevertheless, reports suggest that the incidence of depression is approximately 20-30% of PD patients and may precede the onset of motor symptoms. Diagnosing depression in PD becomes difficult due to the clinical overlap in symptomatology between the two diseases, and the nigrostriatal dysfunction alone is insufficient to explain depressive symptoms in PD. Therefore, the current study provides an overview of the molecular mechanisms underlying the development of depression in PD and new insights into developing current antidepressant strategies to treat depression in PD. This review will identify and understand the molecular pathological mechanisms of depression in PD that will fundamentally help tailoring therapeutic interventions for depressive symptoms in PD.

Switching from Rasagiline to Safinamide as an Add-On Therapy Regimen in Patients with Levodopa: A Literature Review

Parkinson's disease (PD) is a complex disease, and the treatment is focused on the patient's clinical symptoms. Levodopa continues to be the most effective drug for symptomatic PD treatment. However, chronic levodopa treatment is associated with the development of motor complications in most patients. Add-on therapeutic drugs, such as dopamine agonists and monoamine oxidase B (MAO-B) inhibitors, for example, safinamide and rasagiline, may be a desirable addition to continuously increase the levodopa dose for the optimization of motor control in PD. The scientific literature shows that safinamide significantly alleviated motor fluctuations with no increase in troublesome dyskinesia, thanks to its unique double mechanism, providing further benefits to fluctuating PD patients when compared to a placebo or other drugs. Switching from rasagiline to safinamide has been shown to improve the wearing-off phenomena, which is defined as the recurrent, predictable worsening of symptoms of parkinsonism at the end of the levodopa dose until the next dose reaches a clinical effect. In this situation, safinamide may be helpful for reducing the total daily dose of levodopa, improving the OFF time and ON time without troublesome dyskinesias, and being more effective than other MAO-B inhibitors. In this narrative review, we explore the switch from rasagiline to safinamide in patients with motor complications as a feasible and effective alternative to optimize antiparkinsonian treatment.

Multilingual evaluation of interpretable biomarkers to represent language and speech patterns in Parkinson's disease

Motor impairments are only one aspect of Parkinson's disease (PD), which also include cognitive and linguistic impairments. Speech-derived interpretable biomarkers may help clinicians diagnose PD at earlier stages and monitor the disorder's evolution over time. This study focuses on the multilingual evaluation of a composite array of biomarkers that facilitate PD evaluation from speech. Hypokinetic dysarthria, a motor speech disorder associated with PD, has been extensively analyzed in previously published studies on automatic PD evaluation, with a relative lack of inquiry into language and task variability. In this study, we explore certain acoustic, linguistic, and cognitive information encoded within the speech of several cohorts with PD. A total of 24 biomarkers were analyzed from American English, Italian, Castilian Spanish, Colombian Spanish, German, and Czech by conducting a statistical analysis to evaluate which biomarkers best differentiate people with PD from healthy participants. The study leverages conceptual robustness as a criterion in which a biomarker behaves the same, independent of the language. Hence, we propose a set of speech-based biomarkers that can effectively help evaluate PD while being language-independent. In short, the best acoustic and cognitive biomarkers permitting discrimination between experimental groups across languages were fundamental frequency standard deviation, pause time, pause percentage, silence duration, and speech rhythm standard deviation. Linguistic biomarkers representing the length of the narratives and the number of nouns and auxiliaries also provided discrimination between groups. Altogether, in addition to being significant, these biomarkers satisfied the robustness requirements.

Comparison of Half-Effective Concentration of Propofol in Patients with Parkinson's Disease and Non-Parkinson's Disease

Objective

This study aimed to compare the half-effective concentration (EC50) of propofol required for the bispectral index (BIS) 50 in patients with Parkinson's disease (PD) and non-PD (NPD) during induction by the Dixon's improved sequential method.

Methods

This prospective study recruited 20 patients with PD undergoing deep brain stimulation and 20 patients with NPD accompanied by meningioma or glioma undergoing intracranial surgery from March 2018 to March 2019. The patients were induced by propofol via target-controlled infusion. The target effect-site concentration of propofol was determined by the Dixon's improved sequential method. The results of the pilot experiment showed that the target effect-site concentration for the first patient with PD and NPD was 3.5 µg/mL and 2.8 µg/mL, respectively. BIS values were recorded after achieving a constant effect-site concentration of propofol. The increment or decrement of the target effect-site concentration of the next patient was 0.1 µg/mL.

Results

Demographic data, general physical condition, and hemodynamic values were similar between the PD and the NPD groups. The target effect-site concentration of propofol induction doses was significantly higher in the PD group than in the NPD group. The EC50 of propofol required for BIS 50 was 3.213 µg/mL [95% confidence interval (CI), 3.085-3.287 µg/mL] in the PD group and 2.77 µg/mL (95% CI, 2.568-2.977 µg/mL) in the NPD group.

Conclusion

The EC50 of propofol required for BIS 50 was higher in patients with PD than in patients with NPD.

Health care resource utilization patterns among patients with Parkinson's disease psychosis: analysis of Medicare beneficiaries treated with pimavanserin or other-atypical antipsychotics

BACKGROUND

Pimavanserin (PIM) is the only FDA-approved atypical antipsychotic (AAP) for hallucinations and delusions associated with Parkinson's disease psychosis (PDP). Comparative real-world analyses demonstrating its benefits are needed.

OBJECTIVES

To evaluate health care resource utilization (HCRU) outcomes among PDP patients treated with PIM vs. other-AAPs.

METHODS

Retrospective cohort analysis of Parts A, B, and D claims from 100% Medicare sample from 01 January 2013-31 December 2019 was conducted. PDP Patients initiating (i.e. index date) continuous monotherapy (PIM vs. other-AAPs) for ≥12-months during 01 January 2014-31 December 2018 without 12-months pre-index AAP use were selected after 1:1 propensity score matching (PSM) on 31 variables (sex, race, region, age, and 27 Elixhauser comorbidities). HCRU outcomes included: annual all-cause and psychiatric hospitalization (short-term stay, long-term stay, and SNF-stay [skilled nursing facility]) rates, annual all-cause and psychiatric-ER visit rates, mean per-patient-per-year (PPPY) hospitalizations, and average length of stay (ALOS). PIM and other-AAPs were compared using generalized linear models (GLM) controlled for demographic characteristics, comorbidities, coexisting-dementia, and coexisting insomnia.

RESULTS

Of 12,164 PDP patients, 48.41% (n = 5,889) were female, and mean age was 77 (±8.14) years. Among 1:1 matched patients (n = 842 in each), 37.8% (n = 319) on PIM vs. 49.8% (n = 420) on other-AAPs (p < .05) reported ≥1 all-cause hospitalizations, respectively. Specifically, short-term and SNF-stay among PIM patients vs. other-AAPs were: 34% (n = 286) vs. 46.2% (n = 389) and 20.2% (n = 170) vs. 31.8% (n = 267) (p < .05), respectively. Similarly, 9.6% (n = 81) of PIM vs. 14.6% (n = 123) of other-AAPs patients had ≥1 psychiatric hospitalization (p < .05). Furthermore, ≥1 all-cause and psychiatric ER visit among PIM vs. other-AAPs were 61.6% (n = 519) vs. 69.4% (n = 584) and 5.2% (n = 43) vs. 10.2% (n = 86) (p < .05), respectively. PIM also had significantly lower ALOS, and mean PPPY short-term hospitalization and SNF-stays.

CONCLUSIONS

In this analysis of PDP patients, PIM monotherapy resulted in nearly 12% and 7% lower all-cause hospitalizations and ER visits vs. other-AAPs.

Proteomic and Targeted Metabolomic Studies on a Silkworm Model of Parkinson's Disease

Parkinson's disease (PD) is a chronic and progressive movement disorder that is characterized by the loss of dopaminergic neurons in the brain. Animal models of PD have become very popular in the past two decades to understand the etiology, pathology, and molecular and cellular pathways associated with PD. In this study, we report the first neurotoxin-induced silkworm model for PD by chronic feeding with 6-hydroxydopamine (6-OHDA) and explore the possible molecular mechanisms associated with PD using proteomic and targeted metabolomic approaches. Although silkworm is phylogenetically distant from humans and rats, 6-OHDA treatment produced similar PD phenotypes, including motor dysfunction, dopaminergic neuron degeneration, and decreased levels of dopamine. Major neurotransmitters in the silkworm head tissue were profiled, revealing key molecules implicating neurodegenerative disorder. Proteomics analysis revealed a major downregulation of nearly 50 structural proteins constituting cuticles and microfilaments, indicating mechanical damage in the silkworm tissues. The results suggest that 6-OHDA treatment could induce PD-like symptoms in silkworms and activate similar proteomic and metabolic pathways to those in rats or higher animals. This study demonstrates the feasibility and value of the silkworm-based PD model, which may provide important clues for understanding the molecular and cellular mechanisms underlying PD. The mass spectrometry raw files have been deposited to iProx via the project ID IPX0004206000.

DA-9805, a Herbal Mixture, Restores Motor Manifestations in 6-Hydroxydopamine-induced Parkinson’s Disease Mouse Model by Regulating Striatal Dopamine and Acetylcholine Levels

Loss of dopamine (DA) is one of the primary features of Parkinson’s disease (PD); however, imbalances of non-dopaminergic neurotransmitters significantly contribute to the disabilities noted in advanced PD patients. DA-9805 is the ethanolic extraction of the root bark of Paeonia × suffruticosa Andrews (Paeoniaceae), the root of Angelica dahurica (Hoffm.) Benth. and Hook.f. ex Franch. and Sav. (Apiaceae) and the root of Bupleurum falcatum L. (Apiaceae), which have been widely utilized as an enhancer of motor function in East Asia. This study aimed to investigate whether DA-9805 modified motor dysfunctions and imbalances associated with DA and other neurotransmitters in a 6-hydroxydopamine-induced PD mouse. We confirmed the expressions of proteins related with neurotransmissions in the striatum. In addition, we measured the striatal neurotransmitters using HPLC and analyzed their correlation. DA-9805 significantly improved motor impairments and restored the altered levels of neurotransmitters in the striatum. Moreover, DA-9805 improved the altered expressions of tyrosine hydroxylase (TH), DA transporter, and choline acetyltransferase (ChAT) in the ipsilateral part of mouse striatum or SNpc, which implies the neuroprotection. We also found that the level of striatal acetylcholine (Ach) has the moderate negative correlation with motor functions and TH expression in the SNpc. This study indicates that DA-9805 restores motor dysfunctions by normalizing the increased levels of striatal Ach via modulating DA transmission and ChAT expressions as well as its neuroprotective effects.

Role of dopamine and clinical heterogeneity in cognitive dysfunction in Parkinson's disease

Parkinson's disease (PD) is commonly treated with dopaminergic medication, which enhances some, while impairing other cognitive functions. It can even contribute to impulse control disorder and addiction. We describe the history of research supporting the dopamine overdose hypothesis, which accounts for the large within-patient variability in dopaminergic medication effects across different tasks by referring to the spatially non-uniform pattern of dopamine depletion in dorsal versus ventral striatum. However, there is tremendous variability in dopaminergic medication effects not just within patients across distinct tasks, but also across different patients. In the second part of this chapter we review recent studies addressing the large individual variability in the negative side effects of dopaminergic medication on functions that implicate dopamine, such as value-based learning and choice. These studies begin to unravel the mechanisms of dopamine overdosing, thus revising the strict version of the overdose hypothesis. For example, the work shows that the canonical boosting of reward-versus punishment-based choice by medication is greater in patients with depression and a non-tremor phenotype, which both implicate, among other pathology, more rather than less severe dysregulation of the mesolimbic dopamine system. Future longitudinal cohort studies are needed to identify how to optimally combine different clinical, personality, cognitive, neural, genetic and molecular predictors of detrimental medication effects in order to account for as much of the relevant variability as possible. This will provide a useful tool for precision neurology, allowing individual and contextual tailoring of (the dose of) dopaminergic medication in order to maximize its cognitive benefits, yet minimize its side effects.

The Effects of Safinamide Adjunct Therapy on Depression and Apathy in Patients With Parkinson's Disease: Post-hoc Analysis of a Japanese Phase 2/3 Study

Background and Purpose

Neuropsychiatric symptoms in Parkinson's disease (PD) have been shown to significantly affect quality of life (QOL). We investigated the impact of safinamide on depression and apathy when administered as an adjunct to levodopa in Japanese patients with PD.

Methods

This was a post-hoc analysis of data from a phase 2/3 clinical study of safinamide in Japanese patients with PD experiencing wearing-off (JapicCTI-153056; https://www.clinicaltrials.jp/cti-user/trial/ShowDirect.jsp?japicId=JapicCTI-153056). Patients received placebo, safinamide 50 mg, or safinamide 100 mg as an adjunct therapy. The endpoints for this analysis were changes from baseline to Week 24 in the Unified Parkinson's Disease Rating Scale (UPDRS) Part I item 3 (depression) and item 4 (apathy) scores and the Parkinson's Disease Questionnaire (PDQ-39) “emotional well-being” domain score. Subgroup analyses investigated the relationship between neuropsychologic symptoms and improvements in motor fluctuation and assessed which patient populations might be expected to obtain neuropsychologic benefit from safinamide.

Results

Compared with placebo, safinamide (both doses) significantly improved UPDRS Part I item 3 scores in the overall analysis population, and the 100-mg dose improved UPDRS Part I item 4 scores in the population with apathy at baseline. Changes in the PDQ-39 “emotional well-being” score showed numerical, but not significant, dose-related improvements. Notable reductions in depression were associated with a change in daily ON-time ≥1 h, pain during OFF-time at baseline, and female sex.

Conclusions

The results from this post-hoc analysis of the Japanese phase 2/3 study suggest that safinamide could bring benefits to patients with PD who have mild depression, pain during the OFF phase. In addition, safinamide might provide particular benefits for patients with PD who have mild apathy and female.

In vitro and in vivo evaluations of antioxidative, anti-Alzheimer, antidiabetic and anticancer potentials of hydroponically and soil grown Lactuca sativa

BACKGROUND

Lactuca sativa is an edible plant commonly used by local communities to manage diabetes and stomach problems.

METHODS

This work aimed to investigate the anti-oxidant, anticancer, antidiabetic and Anti-Alzheimer effects of hydroponically (HyL) and soil-grown (SoL) Lactuca sativa. Streptozotocin-induced diabetes and AlCl3-induced Alzheimer's disease model was used to evaluate the medicinal effects of Lactuca sativa.

RESULTS

HyL showed significant activity in lipid peroxidation assay, DPPH and DNA protection assay, while SoL extract showed moderated activity, respectively. A similar activity response was quantified for α-glucosidase, α-amylase, acetylcholinesterase and butyrylcholinesterase inhibition assays. The cytotoxic potential of HyL and SoL extracts against MCF7, and HePG2 cancer cell lines exhibited significant activity. HyL and SoL showed a substantial decrease in blood glucose levels in streptozotocin-induced diabetic rats. Diabetes-related liver/kidney biomarkers and anti-oxidant enzyme trends moved toward normal after HyL and SoL treatment. In Anti-Alzheimer's based Morris water and elevated plus maze tests, HyL and SoL displayed memory-enhancing response and anti-anxiety behaviour, respectively. HPLC quantification of dopamine and serotonin revealed a moderate but significant (p<0.05) increase in the level of these neurotransmitters in HyL and SoL groups.

CONCLUSION

Overall, the study revealed that hydroponic Lactuca sativa possesses the therapeutic potential to treat diseases like Alzheimer's and diabetes.

Tele-yoga for the management of Parkinson disease: A safety and feasibility trial

Objectives

Despite current standard treatments, persons with Parkinson disease (PD) still experience motor and non-motor symptoms that impact daily function and quality of life, warranting the investigation of additional interventions. Holistic complementary interventions such as yoga have been shown to be beneficial for persons with PD. However, there are multiple barriers to in-person interventions such as transportation difficulties and disease-related mobility impairments which may be mitigated by digital health applications. Therefore, this study’s purpose was to assess the safety and feasibility of a synchronous tele-yoga intervention for persons with PD.

Methods

Sixteen participants were enrolled in a single group safety and feasibility trial. The entire study was conducted remotely and consisted of a baseline assessment followed by a six-week waiting period, then a second assessment, a six-week tele-yoga intervention period, a post-intervention assessment, a six-week follow-up period, and lastly a follow-up assessment. During the tele-yoga period, participants completed two one-on-one 30-minute tele-yoga sessions weekly for a total of 12 sessions. Primary outcomes included adverse events, adherence, technological challenges, and usability. Secondary outcomes included enjoyment and clinically relevant outcome measures assessing both motor and non-motor symptoms.

Results

No severe adverse events were attributed to the intervention. Retention was 87.5%, assessment session adherence was 100%, and intervention session adherence was 97%. Technological challenges did not impact feasibility. The intervention was usable and enjoyable. While this study was not powered or designed to assess the efficacy of the intervention, preliminary improvements were shown for some of the clinically relevant outcome measures.

Conclusions

Overall, this study showed that the implementation of a synchronous one-on-one tele-yoga intervention was safe, feasible, usable, and enjoyable for persons with PD. Randomized control trials investigating its efficacy should be initiated. The study was registered with ClinicalTrials.gov (NCT04240899, https://clinicaltrials.gov/ct2/show/NCT04240899).

Dietary Regulation of Gut-Brain Axis in Alzheimer's Disease: Importance of Microbiota Metabolites

Alzheimer's disease (AD) is a neurodegenerative disease that impacts 45 million people worldwide and is ranked as the 6th top cause of death among all adults by the Centers for Disease Control and Prevention. While genetics is an important risk factor for the development of AD, environment and lifestyle are also contributing risk factors. One such environmental factor is diet, which has emerged as a key influencer of AD development/progression as well as cognition. Diets containing large quantities of saturated/trans-fats, refined carbohydrates, limited intake of fiber, and alcohol are associated with cognitive dysfunction while conversely diets low in saturated/trans-fats (i.e., bad fats), high mono/polyunsaturated fats (i.e., good fats), high in fiber and polyphenols are associated with better cognitive function and memory in both humans and animal models. Mechanistically, this could be the direct consequence of dietary components (lipids, vitamins, polyphenols) on the brain, but other mechanisms are also likely to be important. Diet is considered to be the single greatest factor influencing the intestinal microbiome. Diet robustly influences the types and function of micro-organisms (called microbiota) that reside in the gastrointestinal tract. Availability of different types of nutrients (from the diet) will favor or disfavor the abundance and function of certain groups of microbiota. Microbiota are highly metabolically active and produce many metabolites and other factors that can affect the brain including cognition and the development and clinical progression of AD. This review summarizes data to support a model in which microbiota metabolites influence brain function and AD.

Effects of safinamide on pain in patients with fluctuating Parkinson's disease

BACKGROUND

Non-motor symptoms (NMS) are integral to Parkinson's Disease (PD) and management remains a challenge. Safinamide is a novel molecule in relation to addressing NMS due to its multifocal mechanism of action with both dopaminergic and non-dopaminergic properties.

OBJECTIVE

To investigate the efficacy of safinamide on NMS and its burden in PD patients with motor fluctuations after 6 months of treatment.

METHODS

This observational, multicenter, open-label, pilot study assessed a wide range of NMS using the following rating scales, NMSS (non-motor symptom scale), KPPS (King's PD pain scale), HADS (hospital anxiety and depression scale), PDQ-8 (Parkinson's disease quality of life questionnaire), and PDSS-2 (Parkinson's disease sleep scale), EuroQol-5D 3 level version (EQ-5D-3L), CGI-I (clinical global impression of improvement), and PGI-C (patient global impression of change). Motor examination using UPDRS part III (Unified Parkinson's disease rating scale, motor examination), UPDRS IV (complications of therapy) and Hoehn and Yahr staging were also obtained.

RESULTS

27 patients were included in the analysis and were evaluated at baseline and ≥ 6 months after safinamide treatment. 26 patients had a daily maintenance dose of 100 mg and 1 patient a daily dose of 50 mg. Significant improvements in UPDRS IV, KPPS item 5 (region-specific "off" dystonia), KPPS domain 3 (items 4-6, fluctuation related pain) and KPPS total score were observed after treatment with safinamide, while maintaining stable dopaminergic medication. No statistically significant differences were found in NMSS, HADS, PDSS-2, EQ-5D-3L, and PDQ-8 after treatment.

CONCLUSIONS

Our results suggest that safinamide may have a beneficial effect on pain, a key unmet need in fluctuating PD patients.

Current advances in metabolomic studies on non-motor psychiatric manifestations of Parkinson's disease (Review)

Life expectancy has increased worldwide and, along with it, a greater prevalence of age-dependent disorders, chronic illnesses and comorbidities can be observed. In 2019, in both Europe and the Americas, dementias ranked 3rd among the top 10 causes of death. Parkinson's disease (PD) is the second most frequent type of neurodegenerative disease. In the last decades, globally, the number of people suffering from PD has more than doubled to over 6 million. Of all the neurological disorders, PD increased with the fastest rate. This troubling trend highlights the stringent need for accurate diagnostic biomarkers, especially in the early stages of the disease and to evaluate treatment response. To gain a broad and complex understanding of the recent advances in the '-omics' research fields, electronic databases such as PubMed, Google Academic, and Science Direct were searched for publications regarding metabolomic studies on PD to identify specific biomarkers for PD, and especially PD with associated psychiatric symptomatology. Discoveries in the fields of metagenomics, transcriptomics and proteomics, may lead to an improved comprehension of the metabolic pathways involved in disease etiology and progression and contribute to the discovery of novel therapeutic targets for effective treatment options.

Noninvasive vagus nerve stimulation in Parkinson's disease: current status and future prospects

INTRODUCTION

Parkinson's disease (PD) is a common progressive neurodegenerative disorder with multifactorial etiology. While dopaminergic medication is the standard therapy in PD, it provides limited symptomatic treatment and non-pharmacological interventions are currently being trialed.

AREAS COVERED

Recent pathophysiological theories of Parkinson's suggest that aggregated α-synuclein form in the gut and spread to nuclei in the brainstem via autonomic connections. In this paper, we review the novel hypothesis that noninvasive vagus nerve stimulation (nVNS), targeting efferent and afferent vagal projections, is a promising therapeutic tool to improve gait and cognitive control and ameliorate non-motor symptoms in people with Parkinson's. We conducted an unstructured search of the literature for any studies employing nVNS in PD as well as for studies examining the efficacy of nVNS on improving cognitive function and where nVNS has been applied to co-occurring conditions in PD.

EXPERT OPINION

Evidence of nVNS as a novel therapeutic to improve gait in PD is preliminary, but early signs indicate the possibility that nVNS may be useful to target dopa-resistant gait characteristics in early PD. The evidence for nVNS as a therapeutic tool is, however, limited and further studies are needed in both brain health and disease.

Intrasubject relationship between striatal 18F-FP-CIT uptake and cardiac 123I-MIBG uptake differs by motor subtype in early Parkinson disease

Parkinson disease (PD) is a heterogeneous neurodegenerative disorder. Dopamine transporter imaging using 123I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (FP-CIT) and noradrenergic cardiac imaging using 123I-meta-iodobenzylguanidine (MIBG) have been used in combination or separately to study PD patients. Published results regarding uptake of the 2 tracers in each motor subtype are fairly abundant and mostly in agreement. However, data on the intrasubject association between dopaminergic and noradrenergic systems in PD patients are relatively scant and vary. We aimed to assess the intrasubject relationship between striatal dopamine transporter density using a PET tracer and cardiac sympathetic innervation in tremor-dominant subtype (TD) and akinetic-rigid subtype (AR) of PD.This study has a cross-sectional design. Thirty-one patients with early PD (17 TD/14 AR) who underwent both 123I-MIBG cardiac scintigraphy and 18F-FP-CIT PET/CT were retrospectively selected. We assessed the relationship between heart-to-mediastinum ratio (H/M) of 123I-MIBG and specific (striatal)-to-nonspecific (cerebellar) dopamine transporter binding ratio (S/N) measured from 4 separate regions-of-interest (bilateral caudate nuclei and lentiform nuclei) of 18F-FP-CIT in each motor subtype.S/N of all 4 striatal regions were significantly lower in the AR subgroup than in the TD subgroup. H/M was not significantly different. There was a significant intrasubject correlation between H/M and S/N of the lentiform nucleus in AR-PD but no correlation between H/M and any of 4 S/N in TD-PD.Our data suggest a coupled degeneration of nigrostriatal dopaminergic and myocardial sympathetic denervation in AR subtype, but not in TD subtype, of early PD patients. These different results between the 2 motor subtypes likely reflects the heterogeneous pathophysiology of PD.

Relationships Between Sensorimotor Inhibition and Mobility in Older Adults With and Without Parkinson's Disease

BACKGROUND

Reduced cortical sensorimotor inhibition is associated with mobility and cognitive impairments in people with Parkinson's disease (PD) and older adults (OAs). However, there is a lack of clarity regarding the relationships among sensorimotor, cognitive, and mobility impairments. The purpose of this study was to determine how cortical sensorimotor inhibition relates to impairments in mobility and cognition in people with PD and OAs.

METHOD

Cortical sensorimotor inhibition was characterized with short-latency afferent inhibition (SAI) in 81 people with PD and 69 OAs. Six inertial sensors recorded single- and dual-task gait and postural sway characteristics during a 2-minute walk and a 1-minute quiet stance. Cognition was assessed across the memory, visuospatial, executive function, attention, and language domains.

RESULTS

SAI was significantly impaired in the PD compared to the OA group. The PD group preformed significantly worse across all gait and postural sway tasks. In PD, SAI significantly correlated with single-task foot strike angle and stride length variability, sway area, and jerkiness of sway in the coronal and sagittal planes. In OAs, SAI significantly related to single-task gait speed and stride length, dual-task stride length, and immediate recall (memory domain). No relationship among mobility, cognition, and SAI was observed.

CONCLUSIONS

Impaired SAI related to slower gait in OA and to increased gait variability and postural sway in people with PD, all of which have been shown to be related to increased fall risk.

Monoamine Levels and Parkinson's Disease Progression: Evidence From a High-Performance Liquid Chromatography Study

Parkinson’s disease (PD) is associated with dysfunction of monoamine neurotransmitter systems. We investigated changes in the levels of monoamine and their metabolites in PD patients, together with their association to clinical profiles. PD patients and age-matched control subjects (n = 40 per group) were enrolled. Using high-performance liquid chromatography (HPLC) with an electrochemical detector, levels of monoamines (dopamine, DA; norepinephrine, NE; epinephrine, EPI; and serotonin, 5-HT) were measured in plasma, while the metabolites (homovanillic acid, HVA; vanillylmandelic acid, VMA; and 5-hydroxyindoleacetic acid, 5-HIAA) were measured in urine. Plasma DA level was not significantly different between PD and control groups. PD patients had significantly higher plasma NE but lower EPI and 5-HT levels. PD patients had a significantly higher HVA/DA ratio and lower VMA/NE ratio than control subjects, while the 5-HIAA/5-HT ratio was not different between the groups. Regarding the association between monoamine levels and clinical profiles, the DA level had a negative relationship with disease duration and the 5-HT level had a negative relationship with severity of motor impairment. These findings emphasized the involvements of several neurotransmission systems and their association with clinical profiles in PD patients, demonstrated by quantification of monoamine levels in peripheral body fluids. This could benefit appropriate pharmacological treatment planning in respect of monoamine changes and might also help predict subsequent clinical symptoms.

The role of glutamatergic neurotransmission in the motor and non-motor symptoms in Parkinson's disease: Clinical cases and a review of the literature

Glutamate is the major excitatory neurotransmitter in the central nervous system and, as such, many brain regions, including the basal ganglia, are rich in glutamatergic neurons. The importance of the basal ganglia in the control of voluntary movement has long been recognised, with the effect of dysfunction of the region exemplified by the motor symptoms seen in Parkinson's disease (PD). However, the basal ganglia and the associated glutamatergic system also play a role in the modulation of emotion, nociception and cognition, dysregulation of which result in some of the non-motor symptoms of PD (depression/anxiety, pain and cognitive deficits). Thus, while the treatment of PD has traditionally been approached from the perspective of dopaminergic replacement, using agents such as levodopa and dopamine receptor agonists, the glutamatergic system offers a novel treatment target for the disease. Safinamide has been approved in over 20 countries globally for fluctuating PD as add-on therapy to levodopa regimens for the management of 'off' episodes. The drug has both dopaminergic and non-dopaminergic pharmacological effects, the latter including inhibition of abnormal glutamate release. The effect of safinamide on the glutamatergic system might present some advantages over dopamine-based therapies for PD by providing efficacy for motor (levodopa-induced dyskinesia) as well as non-motor (anxiety, mood disorders, pain) symptoms. In this article, we discuss the potential role of glutamatergic inhibition on these symptoms, using illustrative real-world examples of patients we have treated with safinamide.

Treating Parkinson's disease by astrocyte reprogramming: Progress and challenges

Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, is typified by both motor and nonmotor symptoms. The current medications provide symptomatic relief but do not stimulate the production of new dopaminergic neurons in the substantia nigra. Astrocyte reprogramming has recently received much attention as an avenue for increasing functional dopaminergic neurons in the mouse PD brain. By targeting a microRNA (miRNA) loop, astrocytes in the mouse brain could be reprogrammed into functional dopaminergic neurons. Such in vivo astrocyte reprogramming in the mouse model of PD has successfully added new dopaminergic neurons to the substantia nigra and increased dopamine levels associated with axonal projections into the striatum. This review deliberates the astrocyte reprogramming methods using specific transcription factors and mRNAs and the progress in generating dopaminergic neurons in vivo. In addition, the translational potential, challenges, and potential risks of astrocyte reprogramming for an enduring alleviation of parkinsonian symptoms are conferred.

The Promise of the Zebrafish Model for Parkinson's Disease: Today's Science and Tomorrow's Treatment

The second most prevalent neurodegenerative disorder in the elderly is Parkinson's disease (PD). Its etiology is unclear and there are no available disease-modifying medicines. Therefore, more evidence is required concerning its pathogenesis. The use of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is the basis of most animal models of PD. MPTP is metabolized by monoamine oxidase B (MAO B) to MPP + and induces the loss of dopaminergic neurons in the substantia nigra in mammals. Zebrafish have been commonly used in developmental biology as a model organism, but owing to its perfect mix of properties, it is now emerging as a model for human diseases. Zebrafish (Danio rerio) are cheap and easy to sustain, evolve rapidly, breed transparent embryos in large amounts, and are readily manipulated by different methods, particularly genetic ones. Furthermore, zebrafish are vertebrate species and mammalian findings obtained from zebrafish may be more applicable than those derived from genetic models of invertebrates such as Drosophila melanogaster and Caenorhabditis elegans. The resemblance cannot be taken for granted, however. The goal of the present review article is to highlight the promise of zebrafish as a PD animal model. As its aminergic structures, MPTP mode of action, and PINK1 roles mimic those of mammalians, zebrafish seems to be a viable model for studying PD. The roles of zebrafish MAO, however, vary from those of the two types of MAO present in mammals. The benefits unique to zebrafish, such as the ability to perform large-scale genetic or drug screens, should be exploited in future experiments utilizing zebrafish PD models.

Bipolar Disorder and Parkinson's Disease: A 123I-Ioflupane Dopamine Transporter SPECT Study

Objectives: Bipolar disorder (BD) has been suggested to be a risk factor for the development of Parkinson's disease (PD). Standard treatment of BD includes drugs that are known to induce drug-induced parkinsonism (DIP). Clinical differentiation between PD and DIP is crucial and might be aided by functional neuroimaging of the dopaminergic nigrostriatal pathway.

Methods: Twenty consecutive BD patients with parkinsonism were clinically assessed and underwent ¹²³I-ioflupane dopamine transporter single-photon emission computer tomography (SPECT). Imaging data of BD patients with pathological scans were further compared to a population of 40 de novo PD patients.

Results: Four BD patients had abnormal scans, but their clinical features and cumulative exposure to both antipsychotic drugs and lithium were similar to those of BD patients with normal dopamine transporter imaging. BD patients with pathological scans had putaminal binding ratio and putamen-to-caudate ratios higher than those of PD patients despite a similar motor symptom burden.

Conclusions: Up to 20% of BD patients with parkinsonism might have an underlying dopaminergic deficit, which would not be due to cumulative exposure to offending drugs and is ostensibly higher than expected in the general population. This supports the evidence that BD represents a risk factor for subsequent development of neurodegenerative parkinsonism, the nature of which needs to be elucidated.

Neurophysiological investigation of auditory intensity dependence in patients with Parkinson's disease

There is accumulating evidence for auditory dysfunctions in patients with Parkinson's disease (PD). Moreover, a possible relationship has been suggested between altered auditory intensity processing and the hypophonic speech characteristics in PD. Nonetheless, further insight into the neurophysiological correlates of auditory intensity processing in patients with PD is needed primarily. In the present study, high-density EEG recordings were used to investigate intensity dependence of auditory evoked potentials (IDAEPs) in 14 patients with PD and 14 age- and gender-matched healthy control participants (HCs). Patients with PD were evaluated in both the on- and off-medication states. HCs were also evaluated twice. Significantly increased IDAEP of the N1/P2 was demonstrated in patients with PD evaluated in the on-medication state compared to HCs. Distinctive results were found for the N1 and P2 component. Regarding the N1 component, no differences in latency or amplitude were shown between patients with PD and HCs regardless of the medication state. In contrast, increased P2 amplitude was demonstrated in patients with PD evaluated in the on-medication state compared to the off-medication state and HCs. In addition to a dopaminergic deficiency, deficits in serotonergic neurotransmission in PD were shown based on increased IDAEP. Due to specific alterations of the N1-P2 complex, the current results suggest deficiencies in early-attentive inhibitory processing of auditory input in PD. This interpretation is consistent with the involvement of the basal ganglia and the role of dopaminergic and serotonergic neurotransmission in auditory gating.

GABA and glutamate deficits from frontotemporal lobar degeneration are associated with disinhibition

Behavioural disinhibition is a common feature of the syndromes associated with frontotemporal lobar degeneration (FTLD). It is associated with high morbidity and lacks proven symptomatic treatments. A potential therapeutic strategy is to correct the neurotransmitter deficits associated with FTLD, thereby improving behaviour. Reductions in the neurotransmitters glutamate and GABA correlate with impulsive behaviour in several neuropsychiatric diseases and there is post-mortem evidence of their deficit in FTLD. Here, we tested the hypothesis that prefrontal glutamate and GABA levels are reduced by FTLD in vivo, and that their deficit is associated with impaired response inhibition. Thirty-three participants with a syndrome associated with FTLD (15 patients with behavioural variant frontotemporal dementia and 18 with progressive supranuclear palsy, including both Richardson's syndrome and progressive supranuclear palsy-frontal subtypes) and 20 healthy control subjects were included. Participants undertook ultra-high field (7 T) magnetic resonance spectroscopy and a stop-signal task of response inhibition. We measured glutamate and GABA levels using semi-LASER magnetic resonance spectroscopy in the right inferior frontal gyrus, because of its strong association with response inhibition, and in the primary visual cortex, as a control region. The stop-signal reaction time was calculated using an ex-Gaussian Bayesian model. Participants with frontotemporal dementia and progressive supranuclear palsy had impaired response inhibition, with longer stop-signal reaction times compared with controls. GABA concentration was reduced in patients versus controls in the right inferior frontal gyrus, but not the occipital lobe. There was no group-wise difference in partial volume corrected glutamate concentration between patients and controls. Both GABA and glutamate concentrations in the inferior frontal gyrus correlated inversely with stop-signal reaction time, indicating greater impulsivity in proportion to the loss of each neurotransmitter. We conclude that the glutamatergic and GABAergic deficits in the frontal lobe are potential targets for symptomatic drug treatment of frontotemporal dementia and progressive supranuclear palsy.