Antihypertensive agents and risk of Parkinson's disease: a nationwide cohort study

Calcium channel blockers and mental health: a comprehensive meta-analysis of psychiatric adverse events in double-blind randomized controlled trials

OBJECTIVE

L-type calcium channel blockers (CCBs) are pivotal in managing cardiovascular disorders, such as hypertension and angina pectoris. Their action on L-type calcium channels, which are not only integral to cardiovascular function but also present in the brain, prompts questions about potential effects on mental health. While previous cohort studies explored this association with mixed results, our study aims to build upon these findings by systematically investigating psychiatric adverse events (PAEs) reported in double-blind randomized controlled trials (RCTs).

METHODS

A systematic search identified double-blind RCTs reporting frequencies of PAEs during CCB therapy across different indications. Separate meta-analyses were conducted for dihydropyridine (DHP) and nondihydropyridine (non-DHP) CCBs against placebo and active controls. This study was registered on INPLASY (INPLASY202480075).

RESULTS

In 187 studies, encompassing 28,201 patients exposed to CCBs, several PAEs were reported, with the most common being depression, insomnia, somnolence, and agitation. Meta-analyses revealed no significant difference in PAE occurrence for CCBs vs. placebo, β-blockers, renin-angiotensin system blockers, and thiazide/thiazide-like diuretics (all P > 0.05). Restricting the analyses to cardiovascular studies, DHP CCBs were linked to lower risks of depression and insomnia compared to placebo [odds ratio (OR) 0.84, confidence interval (CI) 0.70-1.00 and OR 0.38, CI 0.15-0.99, both P = 0.05); however, these results may be artifacts and should be interpreted with caution.

CONCLUSION

Concerns about negative mental health effects of CCBs appear to be unwarranted and should not deter clinicians from prescribing them when indicated. A detected signal towards positive mental health benefits in cardiovascular patients warrants further investigation.

Renin-angiotensin system inhibitor use and risk of Parkinson's disease: a meta-analysis

BACKGROUND

Hypertension is a recognized risk factor for Parkinson's disease (PD). The renin-angiotensin system (RAS) inhibitors are widely used to treat hypertension. However, the association of RAS inhibitor use with PD has still been an area of controversy.

METHODS

Thus, we conducted a meta-analysis to investigate the relationship between RAS inhibitor use and PD. PUBMED and EMBASE databases were searched for articles published up to Oct 2023. All studies that examined the relationship between RAS inhibitor use and the incidence of PD were included.

RESULTS

Seven studies with total 3,495,218 individuals met our inclusion criteria for this meta-analysis. Overall, RAS inhibitor use was associated with a reduction in PD risk (OR = 0.88, 95%CI = 0.79-0.98) compared with the controls. When restricted the analysis to individuals with RAS inhibitor use indication, RAS inhibitor exposure was also associated with a decreased risk of PD (OR = 0.76, 95%CI = 0.62-0.92). Pooled results of cohort studies also did support a protective role of angiotensin converting enzyme inhibitors (ACEIs) (OR = 0.97, 95%CI = 0.89-1.07) users and angiotensin II receptor blockers (ARBs) (OR = 0.8, 95%CI = 0.63-1.02) in PD.

CONCLUSION

Overall, RAS inhibitor use as a class is associated with a reduction in PD risk. However, the findings of ACEIs and ARBs may be limited by small sample size. Future well-designed studies considering the classification by inhibitor type, duration, dose, or property of BBB penetration of RAS inhibitors are needed to clarify the contribution of these exposure parameters on the risk of PD.

β-asarone relieves Parkinson's disease through reducing intracellular Ca2+ in PINK1 mutant Drosophila melanogaster

β-asarone, an effective volatile oil component of Acorus chinensis, has been found to hold beneficial effects on Parkinson's disease (PD), but its mechanism remains incompletely understood. Drosophila melanogaster with PTEN induced kinase 1 (PINK1) mutations, a prototype PD model, was used in this study. We found that calcium chelation profoundly alleviated a spectrum of PD symptoms. Whereas, calcium supplementation made the case worse, suggesting accumulated calcium contributes to progression of PD. β-asarone administration decreased Ca2+ level in PD flies, accompanied by alleviated behavioral and neural defects. Further study demonstrated that β-asarone downregulated L-type Ca2+ channels (Dmca1D), which was increased in PD flies. Besides, β-asarone decreased expression of 1,4,5 - trisphosphate receptor (Itpr), which is responsible for calcium release from endoplasmic reticulum (ER). Knockdown of either Dmca1D or Itpr specifically in dopaminergic neurons alleviated behavioral and neural defects in PD flies. While overexpression of Itpr aggravated PD symptoms. The results indicated that increased intracellular calcium influx and release triggers dysregulation of calcium homeostasis in PD flies. And β-asarone prevents PD by restoring Ca2+ homeostasis. Overall, the study demonstrated that β-asarone can serve as a new prospective medication against PD or other diseases associated with dysregulation of Ca2+ homeostasis.

Targeting calciumopathy for neuroprotection: focus on calcium channels Cav1, Orai1 and P2X7

As the uncontrolled entry of calcium ions (Ca2+) through plasmalemmal calcium channels is a cell death trigger, the conjecture is here raised that mitigating such an excess of Ca2+ entry should rescue from death the vulnerable neurons in neurodegenerative diseases (NDDs). However, this supposition has failed in some clinical trials (CTs). Thus, a recent CT tested whether isradipine, a blocker of the Cav1 subtype of voltage-operated calcium channels (VOCCs), exerted a benefit in patients with Parkinson's disease (PD); however, outcomes were negative. This is one more of the hundreds of CTs done under the principle of one-drug-one-target, that have failed in Alzheimer's disease (AD) and other NDDs during the last three decades. As there are myriad calcium channels to let Ca2+ ions gain the cell cytosol, it seems reasonable to predict that blockade of Ca2+ entry through a single channel may not be capable of preventing the Ca2+ flood of cells by the uncontrolled Ca2+ entry. Furthermore, as Ca2+ signaling is involved in the regulation of myriad functions in different cell types, it seems also reasonable to guess that a therapy should be more efficient by targeting different cells with various drugs. Here, we propose to mitigate Ca2+ entry by the simultaneous partial blockade of three quite different subtypes of plasmalemmal calcium channels that is, the Cav1 subtype of VOCCs, the Orai1 store-operated calcium channel (SOCC), and the purinergic P2X7 calcium channel. All three channels are expressed in both microglia and neurons. Thus, by targeting the three channels with a combination of three drug blockers we expect favorable changes in some of the pathogenic features of NDDs, namely (i) to mitigate Ca2+ entry into microglia; (ii) to decrease the Ca2+-dependent microglia activation; (iii) to decrease the sustained neuroinflammation; (iv) to decrease the uncontrolled Ca2+ entry into neurons; (v) to rescue vulnerable neurons from death; and (vi) to delay disease progression. In this review we discuss the arguments underlying our triad hypothesis in the sense that the combination of three repositioned medicines targeting Cav1, Orai1, and P2X7 calcium channels could boost neuroprotection and delay the progression of AD and other NDDs.

Therapeutic drug monitoring in Parkinson's disease

A patient-tailored therapy of the heterogeneous, neuropsychiatric disorder of Parkinson's disease (PD) aims to improve dopamine sensitive motor symptoms and associated non-motor features. A repeated, individual adaptation of dopamine substituting compounds is required throughout the disease course due to the progress of neurodegeneration. Therapeutic drug monitoring of dopamine substituting drugs may be an essential tool to optimize drug applications. We suggest plasma determination of levodopa as an initial step. The complex pharmacology of levodopa is influenced by its short elimination half-life and the gastric emptying velocity. Both considerably contribute to the observed variability of plasma concentrations of levodopa and its metabolite 3-O-methyldopa. These amino acids compete with other aromatic amino acids as well as branched chain amino acids on the limited transport capacity in the gastrointestinal tract and the blood brain barrier. However, not much is known about plasma concentrations of levodopa and other drugs/drug combinations in PD. Some examples may illustrate this lack of knowledge: Levodopa measurements may allow further insights in the phenomenon of inappropriate levodopa response. They may result from missing compliance, interactions e.g. with treatments for other mainly age-related disorders, like hypertension, diabetes, hyperlipidaemia, rheumatism or by patients themselves independently taken herbal medicines. Indeed, uncontrolled combination of compounds for accompanying disorders as given above with PD drugs might increase the risk of side effects. Determination of other drugs used to treat PD in plasma such as dopamine receptor agonists, amantadine and inhibitors of catechol-O-methyltransferase or monoamine oxidase B may refine and improve the value of calculations of levodopa equivalents. How COMT-Is change levodopa plasma concentrations? How other dopaminergic and non-dopaminergic drugs influence levodopa levels? Also, delivery of drugs as well as single and repeated dosing and continuous levodopa administrations with a possible accumulation of levodopa, pharmacokinetic behaviour of generic and branded compounds appear to have a marked influence on efficacy of drug treatment and side effect profile. Their increase over time may reflect progression of PD to a certain degree. Therapeutic drug monitoring in PD is considered to improve the therapeutic efficacy in the course of this devastating neurologic disorder and therefore is able to contribute to the patients' precision medicine. State-of-the-art clinical studies are urgently needed to demonstrate the usefulness of TDM for optimizing the treatment of PD.

Trial to assess the tolerability of using felodipine to upregulate autophagy as a treatment of Huntington's disease (FELL-HD): a phase II, single-centre, open-label, dose-finding trial protocol

INTRODUCTION

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that presents with a progressive movement disorder along with cognitive and psychiatric problems. It is caused by a Cytosine-adenin-guanine (CAG) expansion in exon 1 of the huntingtin gene which codes for mutant huntingtin (mHTT) that over time accumulates in cells, causing dysfunction and then death through new toxic gain-of-function mechanisms. Autophagy has been shown to be critical for the degradation of diverse intracytoplasmic aggregate-prone proteins that cause neurodegenerative disease, including mHTT. From a screen of a library enriched in approved drugs, felodipine was selected as the most suitable candidate showing strong autophagy-inducing effects in preclinical models of HD. We are, therefore, conducting a trial to assess the safety and tolerability of felodipine in people with early HD.

METHODS AND ANALYSIS

FELL-HD is a phase II, single-centre, open-label, dose-finding trial in people with early HD. 18 participants with early clinical features of the disease will be treated with felodipine for 58 weeks, with a further 4-week follow-up. The primary outcome measure is the number of adverse events attributable to felodipine. Exploratory outcomes include additional measures of motor and cognitive function, non-motor symptoms and quality of life scales, as well as peripheral and central disease biomarkers assessed through brain MRI. Analysis of blood and cerebrospinal fluid will also be performed through an associated sample study, FELL HD-s.

ETHICS AND DISSEMINATION

The study was approved by the London-Brent Research Ethics Committee (reference 22/LO/0387) and has been accepted by the Medicines and Healthcare products Regulatory Agency for clinical trials authorisation (reference CTA 12854/0256/001-0001). A lay summary of the results of the trial will be uploaded to our research group website which is publicly accessible. A webinar or in-person open day, to present results of the trial to participants and our wider cohort of patients who attend our centre, will be held once the trial is completed. The results of the trial will also be published in scientific journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBERS

EudraCT-2021-000897-27, ISRCTN56240656.

Update: Protective and risk factors for Parkinson disease

We review the epidemiologic literature on potential protective and risk factors in Parkinson's Disease (PD). Prior research identified numerous possible protective and risk factors. Potential protective factors include tobacco abuse, physical activity, urate levels, NSAID use, calcium channel blocker use, statin use, and use of some α1-adrenergic antagonists. Some potential protective factors could be products of reverse causation, including increased serum urate, tobacco abuse, and coffee-tea-caffeine consumption. Potential risk factors include traumatic brain injury, pesticide exposure, organic solvent exposure, lead exposure, air pollution, Type 2 Diabetes, some dairy products, cardiovascular disease, and some infections including Hepatitis C, H. pylori, and COVID-19. Potential non-environmental risk factors include bipolar disorder, essential tremor, bullous pemphigoid, and inflammatory bowel disease. There is an inverse relationship with PD and risk of most cancers. Though many potential protective and risk factors for PD were identified, research has not yet led to unique, rigorous prevention trials or successful disease-modifying interventions. While efforts to reduce exposure to some industrial toxicants are well justified, PD incidence might be most effectively reduced by mitigation of risks, such as Type 2 Diabetes, air pollution, traumatic brain injury, or physical inactivity, that are general public health intervention targets.

Epigenetic associations of GPNMB rs199347 variant with alcohol consumption in Parkinson's disease

Introduction

Alcohol consumption can induce a neuroinflammatory response and contribute to the progression of neurodegeneration. However, its association with Parkinson's disease (PD), the second most common neurodegenerative disorder, remains undetermined. Recent studies suggest that the glycoprotein non-metastatic melanoma protein B (GPNMB) is a potential biomarker for PD. We evaluated the association of rs199347, a variant of the GPNMB gene, with alcohol consumption and methylation upstream of GPNMB.

Methods

We retrieved genetic and DNA methylation data obtained from participants enrolled in the Taiwan Biobank (TWB) between 2008 and 2016. After excluding individuals with incomplete or missing information about potential PD risk factors, we included 1,357 participants in our final analyses. We used multiple linear regression to assess the association of GPNMB rs199347 and chronic alcohol consumption (and other potential risk factors) with GPNMB cg17274742 methylation.

Results

There was no difference between the distribution of GPNMB rs199347 genotypes between chronic alcohol consumers and the other study participants. A significant interaction was observed between the GPNMB rs199347 variant and alcohol consumption (p = 0.0102) concerning cg17274742 methylation. Compared to non-chronic alcohol consumers with the AA genotype, alcohol drinkers with the rs199347 GG genotype had significantly lower levels (hypomethylation) of cg17274742 (p = 0.0187).

Conclusion

Alcohol consumption among individuals with the rs199347 GG genotype was associated with lower levels of cg17274742 methylation, which could increase expression of the GPNMB gene, an important neuroinflammatory-related risk gene for PD.

The role of voltage-gated calcium channels in the pathogenesis of Parkinson's disease

Aim: Voltage-gated calcium (CaV) channels play an essential role in maintaining calcium homeostasis and regulating numerous physiological processes in neurons. Therefore, dysregulation of calcium signaling is relevant in many neurological disorders, including Parkinson's disease (PD). This review aims to introduce the role of CaV channels in PD and discuss some novel aspects of channel regulation and its impact on the molecular pathophysiology of the disease.

Methods: an exhaustive search of the literature in the field was carried out using the PubMed database of The National Center for Biotechnology Information. Systematic searches were performed from the initial date of publication to May 2022.

Results: Although α-synuclein aggregates are the main feature of PD, L-type calcium (CaV1) channels seem to play an essential role in the pathogenesis of PD. Changes in the functional expression of CaV1.3 channels alter Calcium homeostasis and contribute to the degeneration of dopaminergic neurons. Furthermore, recent studies suggest that CaV channel trafficking towards the cell membrane depends on the activity of the ubiquitin-proteasome system (UPS). In PD, there is an increase in the expression of L-type channels associated with a decrease in the expression of Parkin, an E3 enzyme of the UPS. Therefore, a link between Parkin and CaV channels could play a fundamental role in the pathogenesis of PD and, as such, could be a potentially attractive target for therapeutic intervention.

Conclusion: The study of alterations in the functional expression of CaV channels will provide a framework to understand better the neurodegenerative processes that occur in PD and a possible path toward identifying new therapeutic targets to treat this condition.

The role of the brain renin-angiotensin system in Parkinson´s disease

The renin-angiotensin system (RAS) was classically considered a circulating hormonal system that regulates blood pressure. However, different tissues and organs, including the brain, have a local paracrine RAS. Mutual regulation between the dopaminergic system and RAS has been observed in several tissues. Dysregulation of these interactions leads to renal and cardiovascular diseases, as well as progression of dopaminergic neuron degeneration in a major brain center of dopamine/angiotensin interaction such as the nigrostriatal system. A decrease in the dopaminergic function induces upregulation of the angiotensin type-1 (AT1) receptor activity, leading to recovery of dopamine levels. However, AT1 receptor overactivity in dopaminergic neurons and microglial cells upregulates the cellular NADPH-oxidase-superoxide axis and Ca2+ release, which mediate several key events in oxidative stress, neuroinflammation, and α-synuclein aggregation, involved in Parkinson's disease (PD) pathogenesis. An intraneuronal antioxidative/anti-inflammatory RAS counteracts the effects of the pro-oxidative AT1 receptor overactivity. Consistent with this, an imbalance in RAS activity towards the pro-oxidative/pro-inflammatory AT1 receptor axis has been observed in the substantia nigra and striatum of several animal models of high vulnerability to dopaminergic degeneration. Interestingly, autoantibodies against angiotensin-converting enzyme 2 and AT1 receptors are increased in PD models and PD patients and contribute to blood-brain barrier (BBB) dysregulation and nigrostriatal pro-inflammatory RAS upregulation. Therapeutic strategies addressed to the modulation of brain RAS, by AT1 receptor blockers (ARBs) and/or activation of the antioxidative axis (AT2, Mas receptors), may be neuroprotective for individuals with a high risk of developing PD or in prodromal stages of PD to reduce progression of the disease.

Recent research progress on metabolic syndrome and risk of Parkinson's disease

Parkinson's disease (PD) is one of the most widespread neurodegenerative diseases. PD is associated with progressive loss of substantia nigra dopaminergic neurons, including various motor symptoms (e.g., bradykinesia, rigidity, and resting tremor), as well as non-motor symptoms (e.g., cognitive impairment, constipation, fatigue, sleep disturbance, and depression). PD involves multiple biological processes, including mitochondrial or lysosomal dysfunction, oxidative stress, insulin resistance, and neuroinflammation. Metabolic syndrome (MetS), a collection of numerous connected cerebral cardiovascular conditions, is a common and growing public health problem associated with many chronic diseases worldwide. MetS components include central/abdominal obesity, systemic hypertension, diabetes, and atherogenic dyslipidemia. MetS and PD share multiple pathophysiological processes, including insulin resistance, oxidative stress, and chronic inflammation. In recent years, MetS has been linked to an increased risk of PD, according to studies; however, the specific mechanism remains unclear. Researchers also found that some related metabolic therapies are potential therapeutic strategies to prevent and improve PD. This article reviews the epidemiological relationship between components of MetS and the risk of PD and discusses the potentially relevant mechanisms and recent progress of MetS as a risk factor for PD. Furthermore, we conclude that MetS-related therapies are beneficial for the prevention and treatment of PD.

Epigenetic regulation of Parkinson's disease risk variant GPNMB cg17274742 methylation by sex and exercise from Taiwan Biobank

Background

Parkinson's disease (PD) is a complex neurodegenerative disease with an elusive etiology that involves the interaction between genetic, behavioral, and environmental factors. Recently, epigenetic modifications, particularly DNA methylation, have been recognized to play an important role in the onset of PD. Glycoprotein non-metastatic melanoma protein B (GPNMB), a type I transmembrane protein crucial for immune cell activation and maturation, has emerged as a potential biomarker for the risk of PD. This research aims to investigate the influence of exercise and gender on the regulation of methylation levels of GPNMB cg17274742 in individuals.

Methods

We analyze data from 2,474 participants in the Taiwan Biobank, collected from 2008 and 2016. Methylation levels at the GPNMB cg17274742 CpG site were measured using Illumina Infinium MethylationEPIC beads. After excluding individuals with incomplete data or missing information on possible risk factors, our final analysis included 1,442 participants. We used multiple linear regression models to assess the association between sex and exercise with adjusted levels of GPNMB cg17274742 for age, BMI, smoking, drinking, coffee consumption, serum uric acid levels, and hypertension.

Results

Our results demonstrated that exercise significantly influenced the methylation levels of GPNMB cg17274742 in males (β = -0.00242; p = 0.0026), but not in females (β = -0.00002362; p = 0.9785). Furthermore, male participants who exercised showed significantly lower levels of methylation compared to the reference groups of the female and non-exercising reference groups (β = -0.00357; p = 0.0079). The effect of the interaction between gender and exercise on the methylation of GPNMB cg17274742 was statistically significant (p = 0.0078).

Conclusion

This study suggests that gender and exercise can modulate GPNMB cg17274742, with hypomethylation observed in exercise men. More research is needed to understand the underlying mechanisms and implications of these epigenetic changes in the context of risk and prevention strategies.

Antihypertensive drugs may not delay the symptom progression of Parkinson's disease: A 2-year follow-up study

BACKGROUND

Parkinson's disease (PD) is one of the most common neurodegenerative disease, and half of PD patients have hypertension as well. The effect of antihypertensive drugs on the progression of PD has been less studied. The focus of this study was on the changes in dopamine transporter (DAT) levels to assess the effect of antihypertensive drugs on the progression of PD.

METHODS

Data from 321 drug-naïve patients from the Parkinson's Disease Progression Marker Initiative (PPMI) were collected over a 2-year period. Patients were divided into the PD with arterial hypertension (AH) group (102 cases) with antihypertensive drugs, the PD with other cardiovascular risk factors (CVRFs) group (60 cases) with antidiabetic and/or lipid-lowering drugs, and the pure PD group (159 cases) without CVRFs. The Movement Disorder Society Sponsored Revision Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and Hoehn-Yahr (H&Y) stage were used to assess progression. DAT semiquantitative values were used to evaluate damage to dopaminergic neurons in the substantia nigra, including the contralateral and ipsilateral count density ratio and asymmetry index.

RESULTS

There were no significant differences among the three groups in MDS-UPDRS score and H&Y stage. Changes in DAT levels among the three groups were without distinct differences in the first year and second year. In each group, DAT decreased more in the first year than in the second year. There was no decrease in DAT uptake in the PD with AH group compared with the other groups during the follow-up period.

CONCLUSIONS

There is no evidence that antihypertensive drugs can delay PD progression within 2 years.

Can chronic therapeutic drug use by the elderly affect Alzheimer’s disease risk and rate of progression?

There is no approved drug capable of halting the progression of the most prevalent neurodegenerative disorders, namely Alzheimer’s disease (AD) and Parkinson’s disease (PD). Current therapeutic strategies focus mainly on the inhibition of the formation of protein aggregates and their deposition in the central nervous system. However, after almost a hundred years, proper management of the disease is still lacking. The fact of not finding effective management tools in the various clinical trials already carried out suggests that new hypotheses and strategies should be explored. Although vast resources have been allocated to the investigation of protein aggregates and the pathophysiology is now better understood, clues to the actual etiology are lacking. It is well known that brain homeostasis is of paramount importance for the survival of neurons. Drugs that target the periphery are often not subject to evaluation for their potential effect on the central nervous system. While acute treatments may be irrelevant, pills used for chronic conditions can be detrimental to neurons, especially in terms of progressive damage leading to a long-term decline in neuronal survival. Due to the lack of advances in the search for a curative treatment for neurodegenerative diseases, and the lack of new hypotheses about their etiology, a novel hypothesis is here proposed. It consists of assuming that the effects of the drugs most commonly used by the elderly, such as antihypertensive, hypoglycemic, and hypocholesterolemic, could have a negative impact on neuronal survival.

Exploring the Role of ACE2 as a Connecting Link between COVID-19 and Parkinson's Disease

Coronavirus disease 2019 (COVID-19) is frequently accompanied by neurological manifestations such as headache, delirium, and epileptic seizures, whereas ageusia and anosmia may appear before respiratory symptoms. Among the various neurological COVID-19-related comorbidities, Parkinson's disease (PD) has gained increasing attention. Some cases of PD disease have been linked to COVID-19, and both motor and non-motor symptoms in Parkinson's disease patients frequently worsen following SARS-CoV-2 infection. Although it is still unclear whether PD increases the susceptibility to SARS-CoV-2 infection or whether COVID-19 increases the risk of or unmasks future cases of PD, emerging evidence sheds more light on the molecular mechanisms underlying the relationship between these two diseases. Among them, angiotensin-converting enzyme 2 (ACE2), a significant component of the renin-angiotensin system (RAS), seems to play a pivotal role. ACE2 is required for the entry of SARS-CoV-2 to the human host cells, and ACE2 dysregulation is implicated in the severity of COVID-19-related acute respiratory distress syndrome (ARDS). ACE2 imbalance is implicated in core shared pathophysiological mechanisms between PD and COVID-19, including aberrant inflammatory responses, oxidative stress, mitochondrial dysfunction, and immune dysregulation. ACE2 may also be implicated in alpha-synuclein-induced dopaminergic degeneration, gut-brain axis dysregulation, blood-brain axis disruption, autonomic dysfunction, depression, anxiety, and hyposmia, which are key features of PD.

How should future clinical trials be designed in the search for disease-modifying therapies for Parkinson's disease?

INTRODUCTION

Although there has been substantial progress in research and innovations in symptomatic treatments, similar success has not been achieved in disease-modifying therapy (DMT) for Parkinson's disease (PD). Considering the enormous motor, psychosocial and financial burden associated with PD, safe and effective DMT is of paramount importance.

AREAS COVERED

One of the reasons for the lack of progress in DMT for PD is poor or inappropriate design of clinical trials. In the first part of the article, the authors focus on the plausible reasons why the previous trials have failed and in the latter part, they provide their perspectives on future DMT trials.

EXPERT OPINION

There are several potential reasons why previous trials have failed, including broad clinical and etiopathogenic heterogeneity of PD, poor definition and documentation of target engagement, lack of appropriate biomarkers and outcome measures, and short duration of follow-up. To address these deficiencies, future trials may consider- (i) a more customized approach to select the most suitable participants and therapeutic approaches, (ii) explore combination therapies that would target multiple pathogenetic mechanisms, and (iii) moving beyond targeting only motor symptoms to also assessing non-motor features of PD in well-designed longitudinal studies.

Targeting G Protein-Coupled Receptors in the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized in part by the deterioration of dopaminergic neurons which leads to motor impairment. Although there is no cure for PD, the motor symptoms can be treated using dopamine replacement therapies including the dopamine precursor L-DOPA, which has been in use since the 1960s. However, neurodegeneration in PD is not limited to dopaminergic neurons, and many patients experience non-motor symptoms including cognitive impairment or neuropsychiatric disturbances, for which there are limited treatment options. Moreover, there are currently no treatments able to alter the progression of neurodegeneration. There are many therapeutic strategies being investigated for PD, including alternatives to L-DOPA for the treatment of motor impairment, symptomatic treatments for non-motor symptoms, and neuroprotective or disease-modifying agents. G protein-coupled receptors (GPCRs), which include the dopamine receptors, are highly druggable cell surface proteins which can regulate numerous intracellular signaling pathways and thereby modulate the function of neuronal circuits affected by PD. This review will describe the treatment strategies being investigated for PD that target GPCRs and their downstream signaling mechanisms. First, we discuss new developments in dopaminergic agents for alleviating PD motor impairment, the role of dopamine receptors in L-DOPA induced dyskinesia, as well as agents targeting non-dopamine GPCRs which could augment or replace traditional dopaminergic treatments. We then discuss GPCRs as prospective treatments for neuropsychiatric and cognitive symptoms in PD. Finally, we discuss the evidence pertaining to ghrelin receptors, β-adrenergic receptors, angiotensin receptors and glucagon-like peptide 1 receptors, which have been proposed as disease modifying targets with potential neuroprotective effects in PD.

Ca2+ channels couple spiking to mitochondrial metabolism in substantia nigra dopaminergic neurons

How do neurons match generation of adenosine triphosphate by mitochondria to the bioenergetic demands of regenerative activity? Although the subject of speculation, this coupling is still poorly understood, particularly in neurons that are tonically active. To help fill this gap, pacemaking substantia nigra dopaminergic neurons were studied using a combination of optical, electrophysiological, and molecular approaches. In these neurons, spike-activated calcium (Ca2+) entry through Cav1 channels triggered Ca2+ release from the endoplasmic reticulum, which stimulated mitochondrial oxidative phosphorylation through two complementary Ca2+-dependent mechanisms: one mediated by the mitochondrial uniporter and another by the malate-aspartate shuttle. Disrupting either mechanism impaired the ability of dopaminergic neurons to sustain spike activity. While this feedforward control helps dopaminergic neurons meet the bioenergetic demands associated with sustained spiking, it is also responsible for their elevated oxidant stress and possibly to their decline with aging and disease.

Brain-penetrant calcium channel blockers are associated with a reduced incidence of neuropsychiatric disorders

Calcium channel blockers (CCBs) differ in their ability to penetrate into the brain. Pharmacoepidemiological studies suggest that CCBs as a class may have beneficial effects on the risks and outcomes of some psychiatric and neurological disorders. It is plausible but unknown whether this effect relates to their brain penetrance. To address this, we used the TriNetX electronic health records network to identify people prescribed a brain-penetrant CCB (BP-CCB), or those given amlodipine, a CCB with low brain penetrability. We created cohorts of patients who, prior to first CCB exposure, either had to have, or could not have had, a recorded ICD-10 diagnosis in any of the following categories: psychotic disorder; affective disorder (including bipolar disorder and major depressive disorder); anxiety disorder; substance use disorder; sleep disorder; delirium; dementia, or movement disorder. Cohort pairs were propensity score matched for age, sex, race, blood pressure, body mass index, and a range of other variables. The outcomes were the incidence of these disorders measured over a two-year exposure period. Matched cohort sizes ranged from 17,896 to 49,987. In people with no prior history of psychiatric or neurodegenerative disorder, there was a significantly lower incidence of most disorders with BP-CCBs compared to amlodipine, with risk ratios ranging from 0.64 to 0.88 and an overall risk ratio of 0.88, i.e. a risk reduction of 12%. In people who did have a prior psychiatric or neurodegenerative diagnosis, differences were much smaller, but again showed lower risks for several disorders with BP-CCBs compared to amlodipine. The differences were somewhat more marked in women and in people less than 60 years old. Results were similar when comparing BP-CCBs with verapamil and diltiazem. We also compared BP-CCBs with angiotensin receptor blockers, and found an overall risk ratio of 0.94 in favour of BP-CCBs, but with differential effects across disorders including a higher risk of psychotic disorder and dementia, but a lower risk for anxiety and sleep disorders. In some analyses, there was evidence of residual confounding even after the extensive matching, in that negative control outcomes showed a reduced incidence with BP-CCBs relative to the comparator cohort. In summary, CCBs that readily penetrate the brain are associated with a lower incidence of neuropsychiatric disorders, especially first diagnoses, compared to CCBs which do not. This may reflect their blockade of neuronal voltage-gated calcium channels. The findings encourage repurposing trials using existing BP-CCBs, and suggest that novel BP-CCBs with enhanced and more selective central actions might have greater therapeutic potential for psychiatric and neurodegenerative disorders.

Association of Angiotensin Receptor Blockers with Incident Parkinson Disease in Patients with Hypertension: A Retrospective Cohort Study

BACKGROUND

Angiotensin receptor blockers (ARBs), which are commonly used antihypertensives, have been proposed to lower the risk of Parkinson disease by reducing oxidative stress based on animal and in vitro studies. Thus, this study aimed to test this association in patients with newly diagnosed hypertension.

METHODS

This retrospective cohort study enrolled 107,207 patients with newly diagnosed hypertension between 2001 and 2013. The hazard ratios for Parkinson disease were calculated for ARB treatment compared with those who never used ARBs and among the 5 subgroups receiving different cumulative ARB dosages.

RESULTS

We identified 527 (1.1%) Parkinson disease cases among patients with ARB treatment in a median observation period of 8.4 years compared to the 1,255 (2.2%) Parkinson disease cases among those without ARB treatment in a median observation period of 6.8 years. Overall, risk for developing Parkinson disease was statistically lower in the ARB-treated group with a hazard ratio of 0.56 (95% confidence interval: 0.51-0.63) than those without ARB.

CONCLUSIONS

ARB treatment was associated with a statistically important reduction of Parkinson disease risk in patients with newly diagnosed hypertension. Therefore, ARB may constitute an effective neuroprotective strategy to lower Parkinson disease risk in such patients.

Deciphering Intertwined Molecular Pathways Underlying Metabolic Syndrome Leading to Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder that gradually develops over time in a progressive manner. The main culprit behind the disease pathology is dopaminergic deficiency in Substantia nigra Pars Compacta (SNpc) due to neuronal degeneration. However, there are other factors that are not only associated with it but also somehow responsible for inception of pathology. Metabolic syndrome is one such risk factor for PD. Metabolic syndrome is a cluster of diseases mainly including diabetes, hypertension, obesity, and hyperlipidemia which pose a risk for developing cardiovascular disorders. All of these disorders have their own pathological pathways that intertwine with PD pathology. This leads to alpha-synuclein aggregation, neuroinflammation, mitochondrial dysfunction, and oxidative stress which are facets in initiating PD pathology. Although few reports are available, this area is underexplored and has contradictory views. Hence, further studies are needed in order to establish a definite relationship between PD and metabolic syndrome. In this review, we aim to elucidate the molecular mechanisms to confirm the association between them and pave the way for potential repurposing of therapies.

Beta-adrenergic drugs and risk of Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Parkinson's Disease (PD) is a neurodegenerative disorder manifested by rest tremor, rigidity, bradykinesia, and postural instability. Recent pharmaco-epidemiological studies evaluating beta-adrenergic drug use and risk of PD have reported conflicting findings.

OBJECTIVES

This systematic review and meta-analyses evaluate the association between beta-adrenergic (agonists and antagonists) drugs' use and PD.

METHODS

An electronic literature search of eight databases was performed from inception to July 2021 to identify pharmaco-epidemiological studies (case-control and cohort) reporting the risk of PD in beta-adrenergic users compared to non-users. We used the generic inverse variance method and RevMan (5.3.5) to estimate pooled adjusted risk ratios (aRRs) of PD using a random-effects model.

RESULTS

Of 3168 records, 15 studies (10 case-control; five cohort) with 6,508,877 participants, including 87,011 PD cases, were included. In the pooled analysis (n=10) including any beta-antagonist users, compared with non-users, the aRR for PD was 1.19 (CI: 1.05,1.35); for any beta-agonist users (n=8) aRR for PD was 0.87 (CI: 0.78,0.97). Propranolol users had a significantly increased risk of PD (aRR:1.91; CI:1.20,3.06), whereas salbutamol use was associated with reduced risk of PD (aRR:0.95; CI:0.92,0.99). Significant heterogeneity (I²>87%) was observed, but the majority (n=13) of the studies were of high quality, based on the JBI tool.

CONCLUSIONS

Beta-antagonist use was associated with a modestly increased risk of PD, whereas beta-agonist use was associated with a modest decreased risk of PD. Future epidemiological studies should address the issues of protopathic bias and indirect association using appropriate epidemiological methods.

Protective Effect of Renin-Angiotensin System Inhibitors on Parkinson's Disease: A Nationwide Cohort Study

Background: Renin-angiotensin system (RAS) inhibitors have been suggested as protective agents in Parkinson's disease (PD). However, epidemiological evidence on the association between RAS inhibitors and the development of PD is inconsistent. Objectives: To investigate the effect of RAS inhibitors on PD risk in patients with ischemic heart disease (IHD) by type and cumulative duration of RAS inhibitors and their degree of blood-brain barrier (BBB) penetration ability. Methods: This was a propensity score-matched retrospective cohort study using 2008-2019 healthcare claims data from the Korean Health Insurance Review and Assessment database. The association between RAS inhibitor use and PD in patients with IHD was evaluated using multivariate Cox proportional hazard regression analysis. The risks are presented as adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Results: Over a 10-year follow-up, 1,086 of 62,228 IHD patients developed PD. The Cox regression model showed that the use of RAS inhibitors was significantly associated with a lower risk of PD (aHR = 0.75; 95% CI 0.66-0.85) than the non-use of RAS inhibitors. Specifically, this reduced risk of PD only remained with the use of BBB-crossing angiotensin II receptor blockers (ARBs) (aHR = 0.62; 95% CI = 0.53-0.74), and this association was more definite with an increasing cumulative duration. A significantly reduced risk of PD was not observed with the use of BBB-crossing angiotensin-converting enzyme inhibitors. Conclusions: The use of ARBs with BBB-penetrating properties and a high cumulative duration significantly reduces the risk of PD in IHD patients. This protective effect could provide insight into disease-modifying drug candidates for PD.

Shared Molecular Targets in Parkinson’s Disease and Arterial Hypertension: A Systematic Review

(1) Background: Parkinson’s disease and arterial hypertension are likely to coexist in the elderly, with possible bidirectional interactions. We aimed to assess the role of antihypertensive agents in PD emergence and/or progression. (2) We performed a systematic search on the PubMed database. Studies enrolling patients with Parkinson’s disease who underwent treatment with drugs pertaining to one of the major antihypertensive drug classes (β-blockers, diuretics, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and calcium-channel blockers) prior to or after the diagnosis of parkinsonism were scrutinized. We divided the outcome into two categories: neuroprotective and disease-modifying effect. (3) We included 20 studies in the qualitative synthesis, out of which the majority were observational studies, with only one randomized controlled trial. There are conflicting results regarding the effect of antihypertensive drugs on Parkinson’s disease pathogenesis, mainly because of heterogeneous protocols and population. (4) Conclusions: There is low quality evidence that antihypertensive agents might be potential therapeutic targets in Parkinson’s disease, but this hypothesis needs further testing.

Post-Translational Modification of Cav1.2 and its Role in Neurodegenerative Diseases

Cav1.2 plays an essential role in learning and memory, drug addiction, and neuronal development. Intracellular calcium homeostasis is disrupted in neurodegenerative diseases because of abnormal Cav1.2 channel activity and modification of downstream Ca²⁺ signaling pathways. Multiple post-translational modifications of Cav1.2 have been observed and seem to be closely related to the pathogenesis of neurodegenerative diseases. The specific molecular mechanisms by which Cav1.2 channel activity is regulated remain incompletely understood. Dihydropyridines (DHPs), which are commonly used for hypertension and myocardial ischemia, have been repurposed to treat PD and AD and show protective effects. However, further studies are needed to improve delivery strategies and drug selectivity. Better knowledge of channel modulation and more specific methods for altering Cav1.2 channel function may lead to better therapeutic strategies for neurodegenerative diseases.

Sirtuin 3 (SIRT3) Pathways in Age-Related Cardiovascular and Neurodegenerative Diseases

Age-associated cardiovascular and neurodegenerative diseases lead to high morbidity and mortality around the world. Sirtuins are vital enzymes for metabolic adaptation and provide protective effects against a wide spectrum of pathologies. Among sirtuins, mitochondrial sirtuin 3 (SIRT3) is an essential player in preserving the habitual metabolic profile. SIRT3 activity declines as a result of aging-induced changes in cellular metabolism, leading to increased susceptibility to endothelial dysfunction, hypertension, heart failure and neurodegenerative diseases. Stimulating SIRT3 activity via lifestyle, pharmacological or genetic interventions could protect against a plethora of pathologies and could improve health and lifespan. Thus, understanding how SIRT3 operates and how its protective effects could be amplified, will aid in treating age-associated diseases and ultimately, in enhancing the quality of life in elders.

Parkinson Disease: Translating Insights from Molecular Mechanisms to Neuroprotection

Parkinson disease (PD) used to be considered a nongenetic condition. However, the identification of several autosomal dominant and recessive mutations linked to monogenic PD has changed this view. Clinically manifest PD is then thought to occur through a complex interplay between genetic mutations, many of which have incomplete penetrance, and environmental factors, both neuroprotective and increasing susceptibility, which variably interact to reach a threshold over which PD becomes clinically manifested. Functional studies of PD gene products have identified many cellular and molecular pathways, providing crucial insights into the nature and causes of PD. PD originates from multiple causes and a range of pathogenic processes at play, ultimately culminating in nigral dopaminergic loss and motor dysfunction. An in-depth understanding of these complex and possibly convergent pathways will pave the way for therapeutic approaches to alleviate the disease symptoms and neuroprotective strategies to prevent disease manifestations. This review is aimed at providing a comprehensive understanding of advances made in PD research based on leveraging genetic insights into the pathogenesis of PD. It further discusses novel perspectives to facilitate identification of critical molecular pathways that are central to neurodegeneration that hold the potential to develop neuroprotective and/or neurorestorative therapeutic strategies for PD. SIGNIFICANCE STATEMENT: A comprehensive review of PD pathophysiology is provided on the complex interplay of genetic and environmental factors and biologic processes that contribute to PD pathogenesis. This knowledge identifies new targets that could be leveraged into disease-modifying therapies to prevent or slow neurodegeneration in PD.

A zebrafish screen reveals Renin-angiotensin system inhibitors as neuroprotective via mitochondrial restoration in dopamine neurons

Parkinson’s disease (PD) is a common neurodegenerative disorder without effective disease-modifying therapeutics. Here, we establish a chemogenetic dopamine (DA) neuron ablation model in larval zebrafish with mitochondrial dysfunction and robustness suitable for high-content screening. We use this system to conduct an in vivo DA neuron imaging-based chemical screen and identify the Renin-Angiotensin-Aldosterone System (RAAS) inhibitors as significantly neuroprotective. Knockdown of the angiotensin receptor 1 (agtr1) in DA neurons reveals a cell-autonomous mechanism of neuroprotection. DA neuron-specific RNA-seq identifies mitochondrial pathway gene expression that is significantly restored by RAAS inhibitor treatment. The neuroprotective effect of RAAS inhibitors is further observed in a zebrafish Gaucher disease model and Drosophila pink1-deficient PD model. Finally, examination of clinical data reveals a significant effect of RAAS inhibitors in delaying PD progression. Our findings reveal the therapeutic potential and mechanisms of targeting the RAAS pathway for neuroprotection and demonstrate a salient approach that bridges basic science to translational medicine.

Parkinson’s disease is caused by the slow death and deterioration of brain cells, in particular of the neurons that produce a chemical messenger known as dopamine. Certain drugs can mitigate the resulting drop in dopamine levels and help to manage symptoms, but they cause dangerous side-effects. There is no treatment that can slow down or halt the progress of the condition, which affects 0.3% of the population globally.

Many factors, both genetic and environmental, contribute to the emergence of Parkinson’s disease. For example, dysfunction of the mitochondria, the internal structures that power up cells, is a known mechanism associated with the death of dopamine-producing neurons.

Zebrafish are tiny fish which can be used to study Parkinson’s disease, as they are easy to manipulate in the lab and share many characteristics with humans. In particular, they can be helpful to test the effects of various potential drugs on the condition.

Here, Kim et al. established a new zebrafish model in which dopamine-producing brain cells die due to their mitochondria not working properly; they then used this assay to assess the impact of 1,403 different chemicals on the integrity of these cells. A group of molecules called renin-angiotensin-aldosterone (RAAS) inhibitors was shown to protect dopamine-producing neurons and stopped them from dying as often. These are already used to treat high blood pressure as they help to dilate blood vessels. In the brain, however, RAAS worked by restoring certain mitochondrial processes.

Kim et al. then investigated whether these results are relevant in other, broader contexts. They were able to show that RAAS inhibitors have the same effect in other animals, and that Parkinson’s disease often progresses more slowly in patients that already take these drugs for high blood pressure.

Taken together, these findings therefore suggest that RAAS inhibitors may be useful to treat Parkinson’s disease, as well as other brain illnesses that emerge because of mitochondria not working properly. Clinical studies and new ways to improve these drugs are needed to further investigate and capitalize on these potential benefits.

Plasma membrane calcium ATPase downregulation in dopaminergic neurons alters cellular physiology and motor behaviour in Drosophila melanogaster

The accumulation of Ca²⁺ and its subsequent increase in oxidative stress is proposed to be involved in selective dysfunctionality of dopaminergic neurons, the main cell type affected in Parkinson's disease. To test the in vivo impact of Ca²⁺ increment in dopaminergic neurons physiology, we downregulated the plasma membrane Ca²⁺ ATPase (PMCA), a pump that extrudes cytosolic Ca²⁺ , by expressing PMCA^RNAi in Drosophila melanogaster dopaminergic neurons. In these animals, we observed major locomotor alterations paralleled to higher cytosolic Ca²⁺ and increased levels of oxidative stress in mitochondria. Interestingly, although no overt degeneration of dopaminergic neurons was observed, evidences of neuronal dysfunctionality were detected such as increases in presynaptic vesicles in dopaminergic neurons and in the levels of dopamine in the brain, as well as presence of toxic effects when PMCA was downregulated in the eye. Moreover, reduced PMCA levels were found in a Drosophila model of Parkinson's disease, Parkin knock-out, expanding the functional relevance of PMCA reduction to other Parkinson's disease-related models. In all, we have generated a new model to study motor abnormalities caused by increments in Ca²⁺ that lead to augmented oxidative stress in a dopaminergic environment, added to a rise in synaptic vesicles and dopamine levels.

COVID-19, ferrosenescence and neurodegeneration, a mini-review

Exacerbation of cognitive, motor and nonmotor symptoms have been described in critically ill COVID-19 patients, indicating that, like prior pandemics, neurodegenerative sequelae may mark the aftermath of this viral infection. Moreover, SARS-CoV-2, the causative agent of COVID-19 disease, was associated with hyperferritinemia and unfavorable prognosis in older individuals, suggesting virus-induced ferrosenescence. We have previously defined ferrosenescence as an iron-associated disruption of both the human genome and its repair mechanisms, leading to premature cellular senescence and neurodegeneration. As viruses replicate more efficiently in iron-rich senescent cells, they may have developed the ability to induce this phenotype in host tissues, predisposing to both immune dysfunction and neurodegenerative disorders. In this mini-review, we summarize what is known about the SARS-CoV-2-induced cellular senescence and iron dysmetabolism. We also take a closer look at immunotherapy with natural killer cells, angiotensin II receptor blockers ("sartans"), iron chelators and dipeptidyl peptidase 4 inhibitors ("gliptins") as adjunct treatments for both COVID-19 and its neurodegenerative complications.

Angiotensin-(1-7) and Mas receptor in the brain

The renin-angiotensin system (RAS) is a key regulator of blood pressure and electrolyte homeostasis. Besides its importance as regulator of the cardiovascular function, the RAS has also been associated to the modulation of higher brain functions, including cognition, memory, depression and anxiety. For many years, angiotensin II (Ang II) has been considered the major bioactive component of the RAS. However, the existence of many other biologically active RAS components has currently been recognized, with similar, opposite, or distinct effects to those exerted by Ang II. Today, it is considered that the RAS is primarily constituted by two opposite arms. The pressor arm is composed by Ang II and the Ang II type 1 (AT1) receptor (AT1R), which mediates the vasoconstrictor, proliferative, hypertensive, oxidative and pro-inflammatory effects of the RAS. The depressor arm is mainly composed by Ang-(1-7), its Mas receptor (MasR) which mediates the depressor, vasodilatory, antiproliferative, antioxidant and anti-inflammatory effects of Ang-(1-7) and the AT2 receptor (AT2R), which opposes to the effects mediated by AT1R activation. Central Ang-(1-7) is implicated in the control of the cardiovascular function, thus participating in the regulation of blood pressure. Ang-(1-7) also exerts neuroprotective actions through MasR activation by opposing to the harmful effects of the Ang II/AT1R axis. This review is focused on the expression and regulation of the Ang-(1-7)/MasR axis in the brain, its main neuroprotective effects and the evidence regarding its involvement in the pathophysiology of several diseases at cardiovascular and neurological level.

Management of Hypertension and Blood Pressure Dysregulation in Patients with Parkinson's Disease-a Systematic Review

PURPOSE OF REVIEW

The aim of this review article was to summarize the cardiovascular and blood pressure profile regarding Parkinson disease patients and to provide an update on the recent advancements in the field of the diagnosis and management of blood pressure abnormalities in these patients. Our goal was to guide physicians to avoid pitfalls in current practice while treating patients with Parkinson disease and blood pressure abnormalities. For this purpose, we searched bibliographic databases (PubMed, Google Scholar) for all publications published on blood pressure effects in Parkinson disease until May 2020. Furthermore, we highlight some thoughts and potential perspectives for the next possible steps in the field.

RECENT FINDINGS

Blood pressure dysregulation in patients with Parkinson's disease has several implications in clinical practice and presents an ongoing concern. Compared with chronic essential hypertension, the syndrome of combined neurogenic orthostatic hypotension and supine hypertension in Parkinson's disease has received little attention. If left untreated, hypertension may lead to cardiovascular disease whereas hypotension may lead to fall-related complications, with tremendous impact on the quality of life of affected individuals. The effect of blood Epressure control and the risk of death from cardiovascular disease in Parkinson disease are largely unexplored. Blood pressure abnormalities in Parkinson disease present bidirectional relationship and the rationale for treating and controlling hypertension in persons with Parkinson disease and concurrent neurogenic orthostatic hypotension and/or supine hypertension is compelling. Further research is warranted in order to clarify the mechanisms, clinical implications, and potential reversibility of compromised cardiovascular function, in persons with Parkinson disease.

Angiotensin Receptor Blockers Are Not Just for Hypertension Anymore

Beyond blood pressure control, angiotensin receptor blockers reduce common injury mechanisms, decreasing excessive inflammation and protecting endothelial and mitochondrial function, insulin sensitivity, the coagulation cascade, immune responses, cerebrovascular flow, and cognition, properties useful to treat inflammatory, age-related, neurodegenerative, and metabolic disorders of many organs including brain and lung.

Effects of angiotensin type 1 receptor antagonists on Parkinson's disease progression: An exploratory study in the PPMI database

INTRODUCTION

We explored the potential clinical effects of angiotensin-II AT1 receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) in patients from the Parkinson's Progress Marker Initiative (PPMI) study database.

METHODS

We included 423 newly diagnosed PD patients, free from antiparkinsonian treatment, from the PPMI. We compared the proportion of patients starting on l-DOPA during the first year of follow-up, and the changes in MDS-UPDRS total score and sub-scores during the first five follow-up years for patients exposed or not to ARBs or ACEIs.

RESULTS

Treatment with ARBs did not affect the proportion of patients on l-DOPA during the first year (adjusted OR, 95% CI = 0.26, 0.03-2.18, N.S.) while reduced MDS-UPDRS total score (0.85, 0.76-0.95, p < 0.01). Patients treated with ACEIs experienced no changes in either measure.

CONCLUSIONS

These results show potential signals for a beneficial effect with ARBs. Further clinical trials are warranted.

Neurological complications of cardiovascular drugs

Cardiovascular drugs are used to treat arterial hypertension, hyperlipidemia, arrhythmias, heart failure, and coronary artery disease. They also include antiplatelet and anticoagulant drugs that are essential for prevention of cardiogenic embolism. Most neurologic complications of the cardiovascular drugs are minor or transient and are far outweighed by the anticipated benefits of treatment. Other neurologic complications are more serious and require early recognition and management. Overtreatment of arterial hypertension may cause lightheadedness or fatigue but often responds readily to dose adjustment or an alternative drug. Other drug complications may be more troublesome as in myalgia associated with statins or headache associated with vasodilators. The recognized bleeding risk of the antithrombotics requires careful calculation of risk/benefit ratios for individual patients. Many neurologic complications of cardiovascular drugs are well documented in clinical trials with known frequency and severity, but others are rare and recognized only in isolated case reports or small case series. This chapter draws on both sources to report the adverse effects on muscle, nerve, and brain associated with commonly used cardiovascular drugs.

Using artificial intelligence to identify anti-hypertensives as possible disease modifying agents in Parkinson's disease

PURPOSE

Drug repurposing is an effective means of increasing treatment options for diseases, however identifying candidate molecules for the indication of interest from the thousands of approved drugs is challenging. We have performed a computational analysis of published literature to rank existing drugs according to predicted ability to reduce alpha synuclein (aSyn) oligomerization and analyzed real-world data to investigate the association between exposure to highly ranked drugs and PD.

METHODS

Using IBM Watson for Drug Discoveryâ (WDD) we identified several antihypertensive drugs that may reduce aSyn oligomerization. Using IBM MarketScanâ Research Databases we constructed a cohort of individuals with incident hypertension. We conducted univariate and multivariate Cox proportional hazard analyses (HR) with exposure as a time-dependent covariate. Diuretics were used as the referent group. Age at hypertension diagnosis, sex, and several comorbidities were included in multivariate analyses.

RESULTS

Multivariate results revealed inverse associations for time to PD diagnosis with exposure to the combination of the combination of angiotensin receptor II blockers (ARBs) and dihydropyridine calcium channel blockers (DHP-CCB) (HR = 0.55, p < 0.01) and angiotensin converting enzyme inhibitors (ACEi) and diuretics (HR = 0.60, p-value <0.01). Increased risk was observed with exposure to alpha-blockers alone (HR = 1.81, p < 0.001) and the combination of alpha-blockers and CCB (HR = 3.17, p < 0.05).

CONCLUSIONS

We present evidence that a computational approach can efficiently identify leads for disease-modifying drugs. We have identified the combination of ARBs and DHP-CCBs as of particular interest in PD.

Calcium, Bioenergetics, and Parkinson's Disease

Degeneration of substantia nigra (SN) dopaminergic (DAergic) neurons is responsible for the core motor deficits of Parkinson’s disease (PD). These neurons are autonomous pacemakers that have large cytosolic Ca²⁺ oscillations that have been linked to basal mitochondrial oxidant stress and turnover. This review explores the origin of Ca²⁺ oscillations and their role in the control of mitochondrial respiration, bioenergetics, and mitochondrial oxidant stress.

Angiotensin AT1 and AT2 receptor heteromer expression in the hemilesioned rat model of Parkinson's disease that increases with levodopa-induced dyskinesia

BACKGROUND/AIMS

The renin-angiotensin system (RAS) is altered in Parkinson's disease (PD), a disease due to substantia nigra neurodegeneration and whose dopamine-replacement therapy, using the precursor levodopa, leads to dyskinesias as the main side effect. Angiotensin AT₁ and AT₂ receptors, mainly known for their role in regulating water homeostasis and blood pressure and able to form heterodimers (AT_1/2Hets), are present in the central nervous system. We assessed the functionality and expression of AT_1/2Hets in Parkinson disease (PD).

METHODS

Immunocytochemistry was used to analyze the colocalization between angiotensin receptors; bioluminescence resonance energy transfer was used to detect AT_1/2Hets. Calcium and cAMP determination, MAPK activation, and label-free assays were performed to characterize signaling in homologous and heterologous systems. Proximity ligation assays were used to quantify receptor expression in mouse primary cultures and in rat striatal sections.

RESULTS

We confirmed that AT₁ and AT₂ receptors form AT_1/2Hets that are expressed in cells of the central nervous system. AT_1/2Hets are novel functional units with particular signaling properties. Importantly, the coactivation of the two receptors in the heteromer reduces the signaling output of angiotensin. Remarkably, AT_1/2Hets that are expressed in both striatal neurons and microglia make possible that candesartan, the antagonist of AT₁, increases the effect of AT₂ receptor agonists. In addition, the level of striatal expression increased in the unilateral 6-OH-dopamine lesioned rat PD model and was markedly higher in parkinsonian-like animals that did not become dyskinetic upon levodopa chronic administration if compared with expression in those that became dyskinetic.

CONCLUSION

The results indicate that boosting the action of neuroprotective AT₂ receptors using an AT₁ receptor antagonist constitutes a promising therapeutic strategy in PD.

Intoxication With Endogenous Angiotensin II: A COVID-19 Hypothesis

Severe acute respiratory syndrome coronavirus 2 has spread rapidly around the globe. However, despite its high pathogenicity and transmissibility, the severity of the associated disease, COVID-19, varies widely. While the prognosis is favorable in most patients, critical illness, manifested by respiratory distress, thromboembolism, shock, and multi-organ failure, has been reported in about 5% of cases. Several studies have associated poor COVID-19 outcomes with the exhaustion of natural killer cells and cytotoxic T cells, lymphopenia, and elevated serum levels of D-dimer. In this article, we propose a common pathophysiological denominator for these negative prognostic markers, endogenous, angiotensin II toxicity. We hypothesize that, like in avian influenza, the outlook of COVID-19 is negatively correlated with the intracellular accumulation of angiotensin II promoted by the viral blockade of its degrading enzyme receptors. In this model, upregulated angiotensin II causes premature vascular senescence, leading to dysfunctional coagulation, and immunity. We further hypothesize that angiotensin II blockers and immune checkpoint inhibitors may be salutary for COVID-19 patients with critical illness by reversing both the clotting and immune defects (Graphical Abstract).

Pneumonia risk and its associated factors in Parkinson's disease: A National Database Study

BACKGROUND

Despite pneumonia being an emerging burden on Parkinson's disease patients, there is essentially nothing known on whether they are at an increased risk of pneumonia occurrence and their associated factors.

OBJECTIVES

To determine whether Parkinson's disease is associated with the risk of pneumonia and its associated factors.

METHODS

Using nationwide database that covers the whole population in South Korea from 2002 to 2017, we identified newly diagnosed Parkinson's disease patients in 2004-2006, and selected four age- and sex-matched controls for each patient from the general population. From these patients and controls, we identified pneumonia occurrence until the end of the study period, and plotted Kaplan-Meier curves and Cox proportional hazards model to determine its risk.

RESULTS

We identified 10,159 Parkinson's disease patients and matched 39,574 controls. These patients showed a higher incidence rate than controls (11.21 vs. 3.61 events/1000 person-years) throughout the study period, and were at an increased risk of pneumonia (hazard ratio = 2.26; 95% CI, 2.17-2.36) even after adjusting for confounders. Old age, male sex, region of residence, diabetes mellitus, congestive heart failure, tuberculosis, atrial fibrillation, chronic kidney disease, cerebrovascular disease, dementia, chronic obstructive pulmonary disease, seizure disorder and antidiabetic drug usage were all associated with a higher risk of pneumonia, while dyslipidemia and antihypertensive medication usage lowered the risk.

CONCLUSIONS

Parkinson's disease patients may be more likely to experience pneumonia compared to the general population throughout the disease course from diagnosis. Therefore, physicians should focus on the modifiable risk factors of pneumonia in such patients.

Neural functions of the aging brain: Daily living, developmental and geriatric disabilities

Neuronal, microglial, astrocytic and oligodendrocytic functions of the brain are significantly affected during normal aging, and more so if inflicted with neurological diseases. Aging is a consistent risk factor for many neurodegenerative diseases that are sporadic in nature, whereas developmental neurological disabilities stem from errors in brain development. The neuronal functions are affected in both developmental disabilities and geriatric diseases. This special issue, is based on the two-days meeting at Thiruvanathapuram, India on 'Neural Functions of Aging Brain', which had several original presentations, as well as full reviews by neurobiologists and clinicians from India. Out of these, thirteen peer reviewed contributions are published in the present Special Issue of this Journal. This 'Foreword' is also a brief overview on the current scenario of neurobiology research on developmental disabilities and ageing in India based on the manuscripts included in the special issue, vis-s-vis the global scenario. Apparently, there is a void in geriatric and developmental neuroscience research in India since huge data mining and translation, concerted efforts on clinical neuroscience research, and consistent efforts on pure basic research resulting in 'first in the field' novelty are largely missing. Overall, Indian neuroscience excels in making meaningful relevance of contemporary discoveries in neuroscience and contributing towards advances in their applications.

L-type Calcium Channels are Involved in Iron-induced Neurotoxicity in Primary Cultured Ventral Mesencephalon Neurons of Rats

In the present study, we investigated the mechanisms underlying the mediation of iron transport by L-type Ca²⁺ channels (LTCCs) in primary cultured ventral mesencephalon (VM) neurons from rats. We found that co-treatment with 100 µmol/L FeSO₄ and MPP⁺ (1-methyl-4-phenylpyridinium) significantly increased the production of intracellular reactive oxygen species, decreased the mitochondrial transmembrane potential and increased the caspase-3 activation compared to MPP⁺ treatment alone. Co-treatment with 500 µmol/L CaCl₂ further aggravated the FeSO₄-induced neurotoxicity in MPP⁺-treated VM neurons. Co-treatment with 10 µmol/L isradipine, an LTCC blocker, alleviated the neurotoxicity induced by co-application of FeSO₄ and FeSO₄/CaCl₂. Further studies indicated that MPP⁺ treatment accelerated the iron influx into VM neurons. In addition, FeSO₄ treatment significantly increased the intracellular Ca²⁺ concentration. These effects were blocked by isradipine. These results suggest that elevated extracellular Ca²⁺ aggravates iron-induced neurotoxicity. LTCCs mediate iron transport in dopaminergic neurons and this, in turn, results in elevated intracellular Ca²⁺ and further aggravates iron-induced neurotoxicity.

Association of Antiviral Therapy With Risk of Parkinson Disease in Patients With Chronic Hepatitis C Virus Infection

Importance

Epidemiologic evidence suggests that hepatitis C virus (HCV) could be a risk factor for Parkinson disease (PD), but treatment for HCV infection has never been considered in these studies; hence, the association between antiviral therapy and PD incidence has remained unclear. Understanding this association may help in developing strategies to reduce PD occurrence.

Objective

To identify the risk of PD development in patients with HCV infection receiving antiviral treatment and in patients not receiving this treatment.

Design, Setting, and Participants

This cohort study obtained claims data from the Taiwan National Health Insurance Research Database. Adult patients with a new HCV diagnosis with or without hepatitis per International Classification of Diseases, Ninth Revision, Clinical Modification codes and anti-PD medications from January 1, 2003, to December 31, 2013, were selected for inclusion. After excluding participants not eligible for analysis, the remaining patients (n = 188 152) were categorized into treated and untreated groups according to whether they received antiviral therapy. Propensity score matching was performed to balance the covariates across groups for comparison of main outcomes. This study was conducted from July 1, 2017, to December 31, 2017.

Main Outcomes and Measures

Development of PD was the main outcome. A Cox proportional hazards regression model was used to compare the risk of PD, and the hazard ratio (HR) was calculated at 1 year, 3 years, and 5 years after the index date and at the end of the cohort.

Results

A total of 188 152 patients were included in the analysis. An equal number (n = 39 936) and comparable characteristics of participants were retained in the treated group (with 17 970 female [45.0%] and a mean [SD] age of 52.8 [11.4] years) and untreated group (with 17 725 female [44.4%] and a mean [SD] age of 52.5 [12.9] years) after matching. The incidence density of PD was 1.00 (95% CI, 0.85-1.15) in the treated group and 1.39 (95% CI, 1.21-1.57) per 1000 person-years in the untreated group. The advantage of antiviral therapy reached statistical significance at the 5-year follow-up (HR, 0.75; 95% CI, 0.59-0.96), and this advantage continued to increase until the end of follow-up (HR, 0.71; 95% CI, 0.58-0.87).

Conclusions and Relevance

Evidence suggested that the PD incidence was lower in patients with chronic HCV infection who received interferon-based antiviral therapy; this finding may support the hypothesis that HCV could be a risk factor for PD.

Chronic Use of β-Blockers and the Risk of Parkinson's Disease

BACKGROUND

Most patients with Parkinson's disease exhibit intracellular accumulation of the α-synuclein protein encoded by the α-synuclein gene. It was recently shown that β₂-adrenoreceptor agonists downregulate this gene, decreasing the apparent risk of Parkinson's disease by up to 40%. In contrast, exposure to β-blocking drugs increases production of the α-synuclein protein.

OBJECTIVE

The aim of this study was to examine whether chronic exposure to β-blockers is associated with an increased risk for Parkinson's disease.

PATIENTS AND METHODS

From the electronic charts of Maccabi Health Services, we identified all patients receiving their first β-blocker treatment between 1998 and 2004, and followed them up, for a diagnosis of Parkinson's disease, between 2005 and 2016. We calculated the morbidity hazard of Parkinson's disease diagnosis in users of β-blockers compared with non-users, as well as users of angiotensin-converting enzyme (ACE) inhibitors for hypertension, after adjusting for sex, age, weight, smoking status, cholesterol levels and use of statins, employing the Cox proportional hazard model. We also conducted a Kaplan-Meier survival analysis.

RESULTS

Overall, 145,098 patients received β-blockers, and 1,187,151 patients did not. The adjusted hazard ratio for Parkinson's disease among β-blocker users was 1.51 (95% confidence interval 1.28-1.77; p < 0.0001). In contrast, the Parkinson's disease morbidity hazard for patients receiving ACE inhibitors was no different than for the general population. The morbidity risk showed the effect of cumulative dose response with low threshold levels.

CONCLUSIONS

Chronic use of β-blockers confers a time- and dose-dependent increased risk for Parkinson's disease. In view of the available alternatives for β-blockers, their chronic use should be carefully reconsidered.

Felodipine induces autophagy in mouse brains with pharmacokinetics amenable to repurposing

Neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease and Huntington’s disease manifest with the neuronal accumulation of toxic proteins. Since autophagy upregulation enhances the clearance of such proteins and ameliorates their toxicities in animal models, we and others have sought to re-position/re-profile existing compounds used in humans to identify those that may induce autophagy in the brain. A key challenge with this approach is to assess if any hits identified can induce neuronal autophagy at concentrations that would be seen in humans taking the drug for its conventional indication. Here we report that felodipine, an L-type calcium channel blocker and anti-hypertensive drug, induces autophagy and clears diverse aggregate-prone, neurodegenerative disease-associated proteins. Felodipine can clear mutant α-synuclein in mouse brains at plasma concentrations similar to those that would be seen in humans taking the drug. This is associated with neuroprotection in mice, suggesting the promise of this compound for use in neurodegeneration.

A key challenge is to find/re-purpose approved drugs that could be used in humans to induce autophagy-associated clearance of neurodegenerative proteins. Here, authors demonstrate that felodipine, an anti-hypertensive drug, can induce autophagy and clear a variety of aggregated neurodegenerative disease-associated proteins in mouse brains at plasma concentrations similar to those that would be seen in humans taking the drug.

Improvements of symptoms of Alzheimer`s disease by inhibition of the angiotensin system

With ageing of the global society, the frequency of ageing-related neurodegenerative diseases such as Alzheimer`s disease (AD) is on the rise worldwide. Currently, there is no cure for AD, and the four drugs approved for AD only have very small effects on AD symptoms. Consequently, there are enormous efforts worldwide to identify new targets for treatment of AD. Approaches that interfere with classical neuropathologic features of AD, such as extracellular senile plaques formed of aggregated amyloid-beta (Abeta), and intracellular neurofibrillary tangles of hyperphosphorylated tau have not been successful so far. In search for a treatment approach of AD, we found that inhibition of the angiotensin-converting enzyme (ACE) by a centrally acting ACE inhibitor retards symptoms of neurodegeneration, Abeta plaque formation and tau hyperphosphorylation in experimental models of AD. Our approach is currently being investigated in a clinical setting. Initial evidence with AD patients shows that a brain-penetrating ACE inhibitor counteracts the process of neurodegeneration and dementia. Moreover, centrally acting ACE inhibitors given in addition to the standard therapy, cholinesterase inhibition, can improve cognitive function of AD patients for several months. This is one of the most promising results for AD treatment since more than a decade.

NADPH Oxidase Mediates Membrane Androgen Receptor-Induced Neurodegeneration

Oxidative stress (OS) is a common characteristic of several neurodegenerative disorders, including Parkinson disease (PD). PD is more prevalent in men than in women, indicating the possible involvement of androgens. Androgens can have either neuroprotective or neurodamaging effects, depending on the presence of OS. Specifically, in an OS environment, androgens via a membrane-associated androgen receptor (mAR) exacerbate OS-induced damage. To investigate the role of androgens on OS signaling and neurodegeneration, the effects of testosterone and androgen receptor activation on the major OS signaling cascades, the reduced form of NAD phosphate (NADPH) oxidase (NOX)1 and NOX2 and the Gαq/inositol trisphosphate receptor (InsP3R), were examined. To create an OS environment, an immortalized neuronal cell line was exposed to H2O2 prior to cell-permeable/cell-impermeable androgens. Different inhibitors were used to examine the role of G proteins, mAR, InsP3R, and NOX1/2 on OS generation and cell viability. Both testosterone and DHT/3-O-carboxymethyloxime (DHT)-BSA increased H2O2-induced OS and cell death, indicating the involvement of an mAR. Furthermore, classical AR antagonists did not block testosterone's negative effects in an OS environment. Because there are no known antagonists specific for mARs, an AR protein degrader, ASC-J9, was used to block mAR action. ASC-J9 blocked testosterone's negative effects. To determine OS-related signaling mediated by mAR, this study examined NOX1, NOX2, Gαq. NOX1, NOX2, and the Gαq complex with mAR. Only NOX inhibition blocked testosterone-induced cell loss and OS. No effects of blocking either Gαq or G protein activation were observed on testosterone's negative effects. These results indicate that androgen-induced OS is via the mAR-NOX complex and not the mAR-Gαq complex.

Evidence of Repurposing Drugs and Identifying Contraindications from Real World Study in Parkinson's Disease

There is great unmet need in discovering novel treatment for Parkinson's disease (PD) and identifying the new agents potentially causing drug-induced parkinsonism. New indications and contraindications of drugs are typically approved following rigorous randomized controlled trial (RCT) evaluation. However, RCTs have their inherent limitations, since they are usually conducted in ideal conditions, with high cost and limited follow-up periods. In the past decade, large cohort studies with long follow-up outcome data was derived from a PD database in a real-world setting. Studies based on real world data (RWD) can help to augment and extrapolate data obtained in RCTs and provide information about the safety and effectiveness of a medication in heterogeneous, large populations. In the present review, we focus on the published real world studies designed to develop new treatment strategies for repurposing drugs and identifying contraindications for PD. We also outline the challenges and limitations in these studies. Subsequently we introduce PaWei app platform, which hopefully can facilitate PD management and address real-world problems associated with PD. Better understanding of RWD collection and analysis is needed if RWD is to achieve its full potential.