Young-onset and late-onset Parkinson's disease exhibit a different profile of fluid biomarkers and clinical features

Plasma and urinary metabolomic signatures differentiate genetic and idiopathic Parkinson's disease

Parkinson's disease (PD) is marked by alpha-synuclein accumulation and progressive dopaminergic neuron loss. Using Nuclear Magnetic Resonance (NMR)-based metabolomics, we uncovered metabolic disturbances in idiopathic PD (iPD) and PD linked to LRRK2, GBA1, and PRKN variants in a Brazilian ethnically diverse cohort, free of comorbidities, in comparison to healthy, age-matched controls. In plasma, significant PD-associated metabolites included histidine, acetate, acetoacetate, glutamine, glucose, lipids and lipoproteins, N-acetyl-glycoproteins, and sarcosine. Urine samples revealed alterations in creatine, creatinine, L-asparagine, trimethylamine, 3-beta-hydroxybutyrate, isovaleric acid, glutamine, urea, glycine, choline, arginine, and cysteine in association with PD. Notably, creatine, creatinine, acetate, glucose, and histidine showed pathway influences from LRRK2, GBA1, and PRKN variants. Enrichment analyses highlighted disruptions in glyoxylate and dicarboxylate metabolism (plasma) as well as serine, threonine, and glycine metabolism (urine). Additionally, a metabolite-gene-disease interaction network identified 15 genes associated with PD that interact with key metabolites, highlighting MAPT, SNCA, RERE, and KCNN3 as key players in both plasmaandurine. NMR in saliva samples did not show significant differences between PD groups and controls. Our findings underscore PD-associated metabolites, particularly related to arginine metabolism, the urea cycle, glutamate metabolism, glucose metabolism, and gut microbiota. These pathways and gene interactions may serve as potential biomarkers for PD diagnosis and precision medicine strategies.

Emerging Insights into Brain Inflammation: Stem-Cell-Based Approaches for Regenerative Medicine

Neuroinflammation is a complex immune response triggered by brain injury or pathological stimuli, and is highly exacerbated in neurodegenerative diseases. It plays a dual role in the central nervous system, promoting repair in acute stages while aggravating disease progression by contributing to neuronal loss, synaptic dysfunction, and glial dysregulation in chronic phases. Inflammatory responses are mainly orchestrated by microglia and infiltrated monocytes, which, when dysregulated, not only harm existing neurons, but also impair the survival and differentiation of neural stem and progenitor cells in the affected brain regions. Modulating neuroinflammation is crucial for harnessing its protective functions while minimizing its detrimental effects. Current therapeutic strategies focus on fine-tuning inflammatory responses through pharmacological agents, bioactive molecules, and stem cell-based therapies. These approaches aim to restore immune homeostasis, support neuroprotection, and promote regeneration in various neurological disorders. However, animal models sometimes fail to reproduce human-specific inflammatory responses in the brain. In this context, stem-cell-derived models provide a powerful tool to study neuroinflammatory mechanisms in a patient-specific and physiologically relevant context. These models facilitate high-throughput screening, personalized medicine, and the development of targeted therapies while addressing the limitations of traditional animal models, paving the way for more targeted and effective treatments.

Male sex accelerates cognitive decline in GBA1 Parkinson's disease

We evaluated 128 GBA and 432 nonGBA Parkinson's disease (PD) subjects available from Parkinson's Progression Markers Initiative. Baseline clinical features and dopaminergic activity were assessed, together with clinical follow-up (6.87 ± 3.2 years). Survival analyses assessed the independent and interactive effects of sex and GBA1 mutations on cognitive decline. At baseline, GBA-PD males showed severe motor impairment, sleep disorders and memory deficits. Despite milder motor deficit, compared to GBA-PD males, GBA-PD females showed greater dopaminergic denervation, suggesting the effect of neural reserve. In longitudinal assessment, GBA-PD males showed greater MoCA rate of change per year and greater risk of cognitive impairment than GBA-PD females and nonGBA-PD. In GBA-PD males, both late age at onset and "severe/mild" GBA variants were associated with increased risk of cognitive impairment. Male sex and GBA1 carrier status have an additive value in increasing the risk of cognitive decline in PD. The effect of sex on GBA1-related pathology warrants further examination to address future trials design and patients' selection.

History of Traumatic Brain Injury Does Not Influence Rate of Progression of Clinical or Pathological Outcomes in Two Early Parkinson's Disease Cohorts

BACKGROUND

A history of traumatic brain injury (TBI) is associated with an increased risk of developing neurodegenerative disorders, including Parkinson's Disease (PD). However, TBI's influences on disease progression remain underassessed. This study explored whether a history of TBI influences the progression of pathological and clinical outcomes up to 5 years of follow-up in individuals with early PD.

METHODS

Longitudinal data were extracted from the Parkinson's Progression Markers Initiative (PPMI) and the PostCEPT observational study. Participants in PostCEPT had complete head injury data, while PPMI participants were eligible if they completed the head injury section of the PD Risk Factor Questionnaire (n = 208). Principal component analysis was used to derive composite scores of cognitive ability and mood dysfunction, with motor outcomes calculated using the Movement Disorders Society Unified Parkinson's Disease Rating Scale. Progression of clinical and pathological outcomes up to 5 years and 4 years following study entry were compared, including subset analyses in PPMI examining injury severity.

RESULTS

Individuals with a history of TBI in the PPMI dataset exhibited a younger age of onset; however, a history of TBI did not affect progression rates of any assessed variables across both cohorts. Exploratory analysis determined that injury severity significantly predicted striatal dopamine transporter binding but accounted for only a small portion of outcome variance.

CONCLUSION

While the history of TBI was associated with earlier PD onset, it did not correspond to a differential disease course. However, given differences in TBI characterisation between cohorts, additional research must be conducted to validate these findings.

Parkinson's disease and glucose metabolism impairment

Parkinson's disease (PD) is the second most common neurodegenerative disorder. PD patients exhibit varying degrees of abnormal glucose metabolism throughout disease stages. Abnormal glucose metabolism is closely linked to the PD pathogenesis and progression. Key glucose metabolism processes involved in PD include glucose transport, glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, the pentose phosphate pathway, and gluconeogenesis. Recent studies suggest that glucose metabolism is a potential therapeutic target for PD. In this review, we explore the connection between PD and abnormal glucose metabolism, focusing on the underlying pathophysiological mechanisms. We also summarize potential therapeutic drugs related to glucose metabolism based on results from current cellular and animal model studies.

Challenging Diagnosis of Fahr's Disease Mimicking Parkinson's Disease: A Case Report

Patients presenting with parkinsonism symptoms such as severe bradykinesia and significant hypophonia, along with an atypical clinical course, should be evaluated for secondary parkinsonism syndromes and other causes of parkinsonism. One of these causes is known as Fahr's disease, which is often overlooked by neurologists and other physicians.

Enhanced glycolysis-derived lactate promotes microglial activation in Parkinson's disease via histone lactylation

The switch from oxidative phosphorylation to glycolysis is crucial for microglial activation. Recent studies highlight that histone lactylation promotes macrophage homeostatic gene expression via transcriptional regulation, but its role in microglia activation in Parkinson's disease (PD) remains unclear. Here, we demonstrated that inhibiting glycolysis with 2-deoxy-D-glucose alleviates microgliosis, neuroinflammation and dopaminergic neurons damage by reducing lactate accumulation in PD mice. Notably, we observed a marked increase in histone lactylation, particularly H3K9 lactylation, in microglia in the substantia nigra of PD mice. Mechanistically, CUT&Tag and Chip-qPCR analyses revealed that H3K9 lactylation enriched at the SLC7A11promoter and activated its expression. Importantly, inhibiting SLC7A11 by sulfasalazine mitigated microglia-mediated neuroinflammation and improved motor function in PD mice. Moreover, we found that lactate-induce histone lactylation is dependent on P300/CBP. Collectively, our findings demonstrate that glycolysis-derived lactate promotes microglial activation via histone lactylation and provide a potential therapeutic strategy for PD.

Association between GRIN2B polymorphism and Parkinson's disease risk, age at onset, and progression in Southern China

Background and objectives

The role of N-methyl-D-aspartate receptor 2B (GRIN2B) single nucleotide polymorphisms (SNPs) in influencing the risk and progression of Parkinson's disease (PD) is still unclear. This study aimed to assess the impact of GRIN2B genotype status on PD susceptibility and symptom progression.

Methods

We enrolled 165 individuals with sporadic PD and 154 healthy controls, all of whom had comprehensive clinical data available at the start and during follow-up. We used chi-squared (χ2) analysis to compare the allele and genotype frequency distributions between the patient and control groups. Linear mixed-effect models were employed to investigate the link between the GRIN2B genotype and the progression of motor and cognitive symptoms.

Results

The prevalence of the GG + GT genotype and G allele was higher in patients compared to controls (p = 0.032 and p = 0.001, respectively). Subgroup analysis revealed that the GG + GT genotype and G allele were significantly more frequently observed in late-onset PD (LOPD) patients compared to early-onset PD (EOPD) patients (p = 0.014 and p = 0.035, respectively). Notably, individuals with the GG + GT genotype exhibited an estimated annual progression rate of 6.10 points on the Unified Parkinson's Disease Rating Scale (UPDRS), which is significantly higher than that of the TT genotype carriers. Furthermore, the GG + GT carriers showed a markedly rapid progression in rigidity. In addition, the GG + GT carriers demonstrated significantly faster progression rates in rigidity (1.83 points/year) and axial impairment (1.2 points/year) compared to the TT carriers. Notably, the GG genotype carriers exhibited a more rapid decline in recall function.

Conclusion

The GRIN2B rs219882 G allele is associated with increased PD susceptibility, particularly in LOPD. The carriers of the GG + GT genotype exhibited more rapid motor symptom progression, with a pronounced impact on rigidity and axial impairment.

Lactate metabolism and histone lactylation in the central nervous system disorders: impacts and molecular mechanisms

Brain takes up approximately 20% of the total body oxygen and glucose consumption due to its relatively high energy demand. Glucose is one of the major sources to generate ATP, the process of which can be realized via glycolysis, oxidative phosphorylation, pentose phosphate pathways and others. Lactate serves as a hub molecule amid these metabolic pathways, as it may function as product of glycolysis, substrate of a variety of enzymes and signal molecule. Thus, the roles of lactate in central nervous system (CNS) diseases need to be comprehensively elucidated. Histone lactylation is a novel lactate-dependent epigenetic modification that plays an important role in immune regulation and maintaining homeostasis. However, there's still a lack of studies unveiling the functions of histone lactylation in the CNS. In this review, we first comprehensively reviewed the roles lactate plays in the CNS under both physiological and pathological conditions. Subsequently, we've further discussed the functions of histone lactylation in various neurological diseases. Furthermore, future perspectives regarding histone lactylation and its therapeutic potentials in stroke are also elucidated, which may possess potential clinical applications.

Friend or foe: Lactate in neurodegenerative diseases

Lactate, a byproduct of glycolysis, was considered as a metabolic waste until identified by studies on the Warburg effect. Increasing evidence elucidates that lactate functions as energy fuel, signaling molecule, and donor for protein lactylation. Altered lactate utilization is a common metabolic feature of the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease and Huntington's disease. This review offers an overview of lactate metabolism from the perspective of production, transportation and clearance, and the role of lactate in neurodegenerative progression, as well as a summary of protein lactylation and the signaling function of lactate in neurodegenerative diseases. Besides, this review delves into the dual roles of changed lactate metabolism during neurodegeneration and explores prospective therapeutic methods targeting lactate. We propose that elucidating the correlation between lactate and neurodegeneration is pivotal for exploring innovative therapeutic interventions for neurodegenerative diseases.

Clinical and diagnostic implications of Alzheimer's disease copathology in Lewy body disease

Concomitant Alzheimer's disease (AD) pathology is a frequent event in the context of Lewy body disease (LBD), occurring in approximately half of all cases. Evidence shows that LBD patients with AD copathology show an accelerated disease course, a greater risk of cognitive decline and an overall poorer prognosis. However, LBD-AD cases may show heterogeneous motor and non-motor phenotypes with a higher risk of dementia and, consequently, be not rarely misdiagnosed. In this review, we summarize the current understanding of LBD-AD by discussing the synergistic effects of AD neuropathological changes and Lewy pathology and their clinical relevance. Furthermore, we provide an extensive overview of neuroimaging and fluid biomarkers under assessment for use in LBD-AD and their possible diagnostic and prognostic values. AD pathology can be predicted in vivo by means of CSF, MRI and PET markers, whereas the most promising technique to date for identifying Lewy pathology in different biological tissues is the α-synuclein seed amplification assay. Pathological imaging and CSF AD biomarkers are associated with a higher likelihood of cognitive decline in LBD but do not always mirror the neuropathological severity as in pure AD. Implementing the use of blood-based AD biomarkers might allow faster screening of LBD patients for AD copathology, thus improving the overall diagnostic sensitivity for LBD-AD. Finally, we discuss the literature on novel candidate biomarkers being exploited in LBD-AD to investigate other aspects of neurodegeneration, such as neuroaxonal injury, glial activation and synaptic dysfunction. The thorough characterization of AD copathology in LBD should be taken into account when considering differential diagnoses of dementia syndromes, to allow prognostic evaluation on an individual level, and to guide symptomatic and disease-modifying therapies.

Sympathetic 123I-metaiodobenzylguanidine index for Lewy body disease: probability-based diagnosis and identifying patients exempt from late imaging

OBJECTIVE

We aimed to establish a practical diagnostic index for Lewy body diseases (LBD), such as Parkinson's disease and dementia, with Lewy bodies in outpatient settings and criteria for exempting patients from late imaging.

METHODS

We acquired early and late 123I-metaiodobenzylguanidine (MIBG) images from 108 consecutive patients with suspected LBD and standardized heart-to-mediastinum (H/M) ratios for collimator conditions. Exclusions included young-onset Parkinson's disease (age < 50 years) and genetic transthyretin-type amyloidosis. We developed logistic models incorporating H/M ratios with or without age (n = 92). The sympathetic MIBG index for LBD (SMILe index), categorized LBD likelihood from 0 (lowest) to 1 (highest). Diagnostic accuracy was assessed as the area under the receiver operating characteristic (ROC) curve (AUC). The characteristics of the new index were compared with H/M ratios. The need for late imaging was explored using the SMILe index.

RESULTS

Early or late SMILe indexes using a single H/M ratio variable discriminated LBD from non-LBD. The AUC values for early and late SMILe indexes were 0.880 and 0.894 (p < 0.0001 for both), identical to those for early and late H/M ratios. The sensitivity and the specificity of early SMILe indexes with a 0.5 threshold were 76% and 90%, achieving accuracy of accuracy 86%. Similarly, the late SMILe index demonstrated a sensitivity of 76% and specificity of 87%, with an accuracy of 84%. Early SMILe indexes < 0.3 or > 0.7 (representing 84% patients) indicated a diagnosis without a late MIBG study.

CONCLUSION

The 123I-MIBG-derived SMILe indexes provide likelihood of LBD, and those with a 50% threshold demonstrated optimal diagnostic accuracy for LBD. The index values of either < 0.3 or > 0.7 accurately selected patients who do not need late imaging.

Lactic acid regulates lipid droplet aggregation through a microglia-neuron axis in neuroinflammation

Neuroinflammation, marked by the release of proinflammatory cytokines and resulting neuronal death, is a multifaceted process extending beyond traditional inflammatory pathways. Microglia, primary cells in the inflammatory response, rapidly activate during neuroinflammation and produce proinflammatory and cytotoxic factors that affect neuronal function. Recent evidence highlights the significant role of abnormal lipid droplet (LD) deposition in the pathogenesis of neuroinflammation. While microglia are known to influence LD aggregation during neuroinflammation, the regulatory mechanism within neurons is not well understood. Our study demonstrates that lipopolysaccharide-activated microglia induce the accumulation of LD in neurons, identifying microglial-derived lactic acid as a key mediator in this process. Excessive lipid accumulation threatens neuronal function, a phenomenon reversed by eliminating microglia. Our study demonstrates that lipopolysaccharide-activated microglia induce the accumulation of LD in neurons, identifying microglial-derived lactic acid as a key mediator in this process. Excessive lipid accumulation threatens neuronal function, a phenomenon reversed by eliminating microglia.

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

A biological characterization of patients with postmenopausal Parkinson's disease

Menopause increases the risk for Parkinson's disease (PD), although the underlying biological mechanisms have not been established in patients. Here, we aimed to understand the basis of menopause-related vulnerability to PD. Main motor and non-motor scores, blood levels of estradiol, testosterone, follicle-stimulating hormone, and luteinizing hormone, CSF levels of total α-synuclein, amyloid-β-42, amyloid-β-40, total tau, and phosphorylated-181-tau were examined in 45 women with postmenopausal-onset PD and 40 age-matched controls. PD patients had higher testosterone and lower estradiol levels than controls, and the residual estradiol production was associated with milder motor disturbances and lower dopaminergic requirements. In PD but not in controls, follicle-stimulating hormone levels correlated with worse cognitive scores and CSF markers of amyloidopathy and neuronal loss. In conclusion, menopause-related hormonal changes might differentially contribute to clinical-pathological trajectories of PD, accounting for the peculiar vulnerability to the disease.

The Contribution of Type 2 Diabetes to Parkinson's Disease Aetiology

Type 2 diabetes (T2D) and Parkinson's disease (PD) are chronic disorders that have a significant health impact on a global scale. Epidemiological, preclinical, and clinical research underpins the assumption that insulin resistance and chronic inflammation contribute to the overlapping aetiologies of T2D and PD. This narrative review summarises the recent evidence on the contribution of T2D to the initiation and progression of PD brain pathology. It also briefly discusses the rationale and potential of alternative pharmacological interventions for PD treatment.

Potential Metabolite Biomarkers of Multiple Sclerosis from Multiple Biofluids

Multiple sclerosis (MS) is a chronic and progressive neurological disorder without a cure, but early intervention can slow disease progression and improve the quality of life for MS patients. Obtaining an accurate diagnosis for MS is an arduous and error-prone task that requires a combination of a detailed medical history, a comprehensive neurological exam, clinical tests such as magnetic resonance imaging, and the exclusion of other possible diseases. A simple and definitive biofluid test for MS does not exist, but is highly desirable. To address this need, we employed NMR-based metabolomics to identify potentially unique metabolite biomarkers of MS from a cohort of age and sex-matched samples of cerebrospinal fluid (CSF), serum, and urine from 206 progressive MS (PMS) patients, 46 relapsing-remitting MS (RRMS) patients, and 99 healthy volunteers without a MS diagnosis. We identified 32 metabolites in CSF that varied between the control and PMS patients. Utilizing patient-matched serum samples, we were able to further identify 31 serum metabolites that may serve as biomarkers for PMS patients. Lastly, we identified 14 urine metabolites associated with PMS. All potential biomarkers are associated with metabolic processes linked to the pathology of MS, such as demyelination and neuronal damage. Four metabolites with identical profiles across all three biofluids were discovered, which demonstrate their potential value as cross-biofluid markers of PMS. We further present a case for using metabolic profiles from PMS patients to delineate biomarkers of RRMS. Specifically, three metabolites exhibited a variation from healthy volunteers without MS through RRMS and PMS patients. The consistency of metabolite changes across multiple biofluids, combined with the reliability of a receiver operating characteristic classification, may provide a rapid diagnostic test for MS.

Pregnancy, fertile life factors, and associated clinical course in PRKN early-onset Parkinson's disease

INTRODUCTION

As the most common cause of autosomal recessive early onset Parkinson's disease (EOPD), parkin type Parkinson's disease (PRKN-PD) may affect female patients in childbearing age. Accordingly, issues related to fertility must be adequately addressed. Here, we landscaped fertile life factors and pregnancy course of a PRKN-PD cohort, including both novel cases directly observed at our center and published ones.

METHODS

Six patients with confirmed PRKN-PD were examined by a structured interview on reproductive factors and associated modifications of PD disturbances, including one case followed up throughout pregnancy which was described in greater detail. Six studies reporting fertile life factors of nine PRKN-PD patients were reviewed collecting homogeneous data on fertile life and pregnancy course.

RESULTS

PRKN-PD female patients experienced motor fluctuations with the menstrual cycle, pregnancy, and puerperium, which suggests a role for sex hormones in PD clinical burden. In some cases, abortion and miscarriages occurred during the organogenesis phase in patients receiving oral antiparkinsonian therapy; however, levodopa/benserazide monotherapy resulted to be the safest choice in pregnancy.

CONCLUSION

Collectively these data disclose the importance of pre-conception counseling in childbearing age PRKN-PD patients and EOPD in general.

The function of previously unappreciated exerkines secreted by muscle in regulation of neurodegenerative diseases

The initiation and progression of neurodegenerative diseases (NDs), distinguished by compromised nervous system integrity, profoundly disrupt the quality of life of patients, concurrently exerting a considerable strain on both the economy and the social healthcare infrastructure. Exercise has demonstrated its potential as both an effective preventive intervention and a rehabilitation approach among the emerging therapeutics targeting NDs. As the largest secretory organ, skeletal muscle possesses the capacity to secrete myokines, and these myokines can partially improve the prognosis of NDs by mediating the muscle-brain axis. Besides the well-studied exerkines, which are secreted by skeletal muscle during exercise that pivotally exert their beneficial function, the physiological function of novel exerkines, e.g., apelin, kynurenic acid (KYNA), and lactate have been underappreciated previously. Herein, this review discusses the roles of these novel exerkines and their mechanisms in regulating the progression and improvement of NDs, especially the significance of their functions in improving NDs' prognoses through exercise. Furthermore, several myokines with potential implications in ameliorating ND progression are proposed as the future direction for investigation. Elucidation of the function of exerkines secreted by skeletal muscle in the regulation of NDs advances the understanding of its pathogenesis and facilitates the development of therapeutics that intervene in these processes to cure NDs.

Risk factors associated with age at onset of Parkinson's disease in the UK Biobank

Substantial evidence shown that the age at onset (AAO) of Parkinson's disease (PD) is a major determinant of clinical heterogeneity. However, the mechanisms underlying heterogeneity in the AAO remain unclear. To investigate the risk factors with the AAO of PD, a total of 3156 patients with PD from the UK Biobank were included in this study. We evaluated the effects of polygenic risk scores (PRS), nongenetic risk factors, and their interaction on the AAO using Mann-Whitney U tests and regression analyses. We further identified the genes interacting with nongenetic risk factors for the AAO using genome-wide environment interaction studies. We newly found physical activity (P < 0.0001) was positively associated with AAO and excessive daytime sleepiness (P < 0.0001) was negatively associated with AAO, and reproduced the positive associations of smoking and non-steroidal anti-inflammatory drug intake and the negative association of family history with AAO. In the dose-dependent analyses, smoking duration (P = 1.95 × 10-6), coffee consumption (P = 0.0150), and tea consumption (P = 0.0008) were positively associated with AAO. Individuals with higher PRS had younger AAO (P = 3.91 × 10-5). In addition, we observed a significant interaction between the PRS and smoking for AAO (P = 0.0316). Specifically, several genes, including ANGPT1 (P = 7.17 × 10-7) and PLEKHA6 (P = 4.87 × 10-6), may influence the positive relationship between smoking and AAO. Our data suggests that genetic and nongenetic risk factors are associated with the AAO of PD and that there is an interaction between the two.

Lactate metabolism in neurodegenerative diseases

Lactate, a byproduct of glycolysis, was thought to be a metabolic waste until the discovery of the Warburg effect. Lactate not only functions as a metabolic substrate to provide energy but can also function as a signaling molecule to modulate cellular functions under pathophysiological conditions. The Astrocyte-Neuron Lactate Shuttle has clarified that lactate plays a pivotal role in the central nervous system. Moreover, protein lactylation highlights the novel role of lactate in regulating transcription, cellular functions, and disease development. This review summarizes the recent advances in lactate metabolism and its role in neurodegenerative diseases, thus providing optimal perspectives for future research.

Pain is common in early onset Parkinson's disease and pain severity is associated with age and worsening of motor and non-motor symptoms

The consequences of pain in early onset Parkinson's disease (EOPD) remain under appreciated even though pain may exert an increasingly negative impact on patient quality of life as motor and non-motor symptoms worsen. In this prospective study, we investigate the prevalence and severity of pain in 135 Vietnamese patients with EOPD from three medical centers using the King's PD Pain Scale (KPPS), the Mini Mental Status Exam (MMSE), the Unified Parkinson's Disease Rating Scale (UPDRS) and the Non-Motor Symptoms Scale (NMSS). Pain was reported by 79.3%. The most common subtype of pain was musculoskeletal (70.1%), followed by nocturnal (43.9%), radicular (43.0%), chronic (42.1%), fluctuation-related (34.6%) and orofacial pain (16.8%). Most patients (74.8%) experienced more than one pain subtype. Fluctuation-related pain and orofacial pain were significantly more prevalent among patients with higher Hoehn & Yahr (H&Y) stages (3-5) versus lower H&Y stages (1-2). Pain subtype and severity were not significantly related to gender or age of PD onset. Patients with H&Y stages 3-5 had statistically significantly higher KPPS scores for fluctuation-related pain (p = 0.018) and radicular pain (p = 0.026). Independent associations were found between pain severity and age (p = 0.028), depression severity (p = 0.018), perceptual problems/hallucinations (p = 0.033) and sexual function (p = 0.024). Patients with depression and higher H&Y stages (3-5) had statistically significantly higher mean KPPS scores versus patients without depression and at lower H&Y stages (1-2). Pain may be more common and severe in EOPD patients than previously appreciated. Older age, depression, perceptual problems/hallucinations and sexual dysfunction were independently associated with higher pain severity.

Clinical and neurochemical correlates of the APOE genotype in early-stage Parkinson's disease

Emerging evidence indicates that apolipoprotein E (APOE) genotype may influence Parkinson's disease (PD) course, although clinical and neurochemical correlates have not been completely established. This study aimed to determine the associations of APOE genotypes (ε4 vs. non-ε4) with cerebrospinal fluid (CSF) neurodegeneration biomarkers and clinical parameters in early-stage PD patients. One hundred and seventy-five PD patients and 89 non-neurodegenerative controls grouped in APOE-ε4 carriers (28 PD; 12 controls) and non-APOE-ε4 carriers (147 PD; 78 controls) were enrolled. CSF levels of amyloid-β-42, amyloid-β-40, total and 181-phosphorylated tau, and clinical scores were compared among groups adjusting for main covariates. APOE genotypes prevalence was similar in PD and controls. PD APOE-ε4 carriers had lower amyloid-β-42 CSF levels than PD non-APOE-ε4 carriers and controls, independently from age. PD APOE-ε4 carriers also had higher total and "item 5" (attention and memory) non-motor symptoms scale scores than PD non-APOE-ε4 carriers, independently from confounding factors. APOE-ε4 genotype might thus account for a more vulnerable PD subtype characterized by prominent amyloidopathy and a greater burden of non-motor symptoms in the early disease stages. DATA AVAILABILITY: Data are available upon reasonable request.

Shaping the course of early-onset Parkinson's disease: insights from a longitudinal cohort

INTRODUCTION

Early -onset Parkinson's disease (EOPD) labels those cases with onset earlier than fifty. Although peculiarities emerged either in clinical or pathological features, EOPD is managed alike typical, late-onset PD. A customized approach would be, instead, better appropriate. Accordingly, a deeper characterization of the clinical course, with an estimation of the disease progression rate, the therapy flow, and the main motor and non-motor complications occurrence, is needed.

METHODS

A longitudinal cohort of 193 EOPD patients (selected on a single-centre population of 2000 PD cases) was retrospectively analysed, providing descriptive statics on a series of clinical parameters (genetics, phenotype, comorbidities, therapies, motor and non-motor complications, marital and gender issues) and modelling the trajectories from diagnosis to 10 years later of both Hoehn and Yahr (H&Y) stage and levodopa equivalent daily dose (LEDD).

RESULTS

EOPD had a prevalence of 9.7%, including few monogenic cases. It mostly appeared as a motor syndrome, with asymmetric, rigid-akinetic presentation. H&Y linearly progressed with an increment of 0.92 points/10 years; LEDD flow had a non-linear trend, increasing of 526.90 mg/day in 0-5 years, and 166.83 mg/day in 5-10 years. Motor fluctuations started 6.5 ± 3.2 years from onset, affecting up to 80% of the cohort. Neuropsychiatric troubles interested the 50%, sexual complaints the 12%. Gender-specific motor disturbances emerged.

CONCLUSION

We shaped EOPD course, modelling a "brain-first" PD subtype, slowly progressive, with non-linear dopaminergic requirement. Major burden mostly resulted from motor fluctuations, neuropsychiatric complications, sexual and marital complaints, with a considerable gender-effect.

Uric acid and neurological disease: a narrative review

Hyperuricemia often accompanies hypertension, diabetes, dyslipidemia, metabolic syndrome, and chronic renal disease; it is also closely related to cardiovascular disease. Moreover, several epidemiological studies have linked hyperuricemia and ischemic stroke. However, uric acid may also have neuroprotective effects because of its antioxidant properties. An association between low uric acid levels and neurodegenerative diseases has been suggested, which may be attributed to diminished neuroprotective effects as a result of reduced uric acid. This review will focus on the relationship between uric acid and various neurological diseases including stroke, neuroimmune diseases, and neurodegenerative diseases. When considering both the risk and pathogenesis of neurological diseases, it is important to consider the conflicting dual nature of uric acid as both a vascular risk factor and a neuroprotective factor. This dual nature of uric acid is important because it may help to elucidate the biological role of uric acid in various neurological diseases and provide new insights into the etiology and treatment of these diseases.

Time to workforce exit after a Parkinson's disease diagnosis

The impact of Parkinson's disease (PD) on workforce participation has received little attention even though demographic, lifestyle, and political changes together will result in an increased burden of PD on the working-age population. In this study, we investigate workforce survival after a PD diagnosis, as well as what demographic factors that are associated with workforce survival. As an exploratory outcome, we investigate workforce survival in persons with and without device-aided treatment (DAT). This is a nested case-cohort study based on Swedish national data from 2001-2016. Controls were matched on year of birth, sex, and municipality of residence. The used registers contain data on demographics, social insurance, in- and outpatient visits, filled drug prescriptions, and cause of death on the person-level. A total of 4781 persons with PD and 23,905 controls were included. The median survival until all-cause workforce exit was 43 months among persons that were workforce-active at the time of PD diagnosis, compared to 66 months in non-PD controls. Being female, ≥50 years old at diagnosis, or having a lower education were contributing factors to health-related workforce exit. Persons receiving DAT during follow-up exhibited shorter workforce survival than controls. However, this needs further investigation, particularly as patients have generally already left the workforce at the time for start of DAT. It is evident that PD has grave negative effects on workforce participation. Thus, supportive measures need to start at an early stage after diagnosis, and the development of new interventions is urgently needed.

Mitochondrial Bioenergy in Neurodegenerative Disease: Huntington and Parkinson

Strong evidence suggests a correlation between degeneration and mitochondrial deficiency. Typical cases of degeneration can be observed in physiological phenomena (i.e., ageing) as well as in neurological neurodegenerative diseases and cancer. All these pathologies have the dyshomeostasis of mitochondrial bioenergy as a common denominator. Neurodegenerative diseases show bioenergetic imbalances in their pathogenesis or progression. Huntington's chorea and Parkinson's disease are both neurodegenerative diseases, but while Huntington's disease is genetic and progressive with early manifestation and severe penetrance, Parkinson's disease is a pathology with multifactorial aspects. Indeed, there are different types of Parkinson/Parkinsonism. Many forms are early-onset diseases linked to gene mutations, while others could be idiopathic, appear in young adults, or be post-injury senescence conditions. Although Huntington's is defined as a hyperkinetic disorder, Parkinson's is a hypokinetic disorder. However, they both share a lot of similarities, such as neuronal excitability, the loss of striatal function, psychiatric comorbidity, etc. In this review, we will describe the start and development of both diseases in relation to mitochondrial dysfunction. These dysfunctions act on energy metabolism and reduce the vitality of neurons in many different brain areas.

Age at Onset Influences Progression of Motor and Non-Motor Symptoms during the Early Stage of Parkinson's Disease: A Monocentric Retrospective Study

The interactions between the age at onset with other pathogenic mechanisms and the interplays between the disease progression and the aging processes in Parkinson's disease (PD) remain undefined, particularly during the first years of illness. Here, we retrospectively investigated the clinical presentation and evolution of the motor and non-motor symptoms and treatment-related complications during the first 5 years of illness in subjects categorized according to age at onset. A total of 131 subjects were divided into "Early-Onset-PD" (EOPD; onset ≤49 years), "Middle-Onset-PD" (MOPD; onset 50-69 years) and "Late-Onset-PD" (LOPD; onset ≥70 years). The T0 visit was set at the time of the clinical diagnosis; the T1 visit was 5 years (±5 months) later. At T0, there were no significant differences in the motor features among the groups. At T1, the LOPD patients displayed a significantly higher frequency of gait disturbances and a higher frequency of postural instability. Moreover, at T1, the LOPD subjects reported a significantly higher frequency of non-motor symptoms; in particular, cardiovascular, cognitive and neuropsychiatric domains. The presented results showed a significantly different progression of motor and non-motor symptoms in the early course of PD according to the age at onset. These findings contribute to the definition of the role of age at onset on disease progression and may be useful for the pharmacological and non-pharmacological management of PD.

Motor Symptoms in Early- versus Late-Onset Alzheimer's Disease

BACKGROUND

Age at onset was suggested as one possible risk factor for motor dysfunction in Alzheimer's disease (AD).

OBJECTIVE

We investigated the association of motor symptoms with cognition or neurodegeneration in patients with AD, and whether this association differs by the age at onset.

METHODS

We included 113 amyloid positive AD patients and divided them into early-onset AD (EOAD) and late-onset AD (LOAD), who underwent the Unified Parkinson's Disease Rating Scale (UPDRS)-Part III (=UPDRS) scoring, Mini-Mental State Examination (MMSE)/Clinical Deterioration Rating Sum-of-Boxes (CDR-SOB), and magnetic resonance image (MRI). Multiple linear regression was used to evaluate the association of UPDRS and MMSE/CDR-SOB or MRI neurodegeneration measures, and whether the association differs according to the group.

RESULTS

The prevalence of motor symptoms and their severity did not differ between the groups. Lower MMSE (β= -1.1, p < 0.001) and higher CDR-SOB (β= 2.0, p < 0.001) were significantly associated with higher UPDRS. There was no interaction effect between MMSE/CDR-SOB and AD group on UPDRS. Global or all regional cortical thickness and putaminal volume were negatively associated with UPDRS score, but the interaction effect of neurodegeneration and AD group on UPDRS score was significant only in parietal lobe (p for interaction = 0.035), which showed EOAD to have a more pronounced association between parietal thinning and motor symptoms.

CONCLUSION

Our study suggested that the severity of motor deterioration in AD is related to the severity of cognitive impairment itself rather than age at onset, and motor symptoms might occur through multiple mechanisms including cortical and subcortical atrophy.

Cerebral cortical thinning in Parkinson's disease depends on the age of onset

Patients with older-onset Parkinson's disease (PD) have more severe motor symptoms, faster progression, and a worse prognosis. The thinning of the cerebral cortex is one of the causes of these issues. Patients with older-onset PD manifest more extended neurodegeneration associated with α-synuclein deposition in the cerebral cortex; however, the cortical regions that undergo thinning are unclear. We aimed to identify cortical regions with different thinning depending on the age of onset in patients with PD. Sixty-two patients with PD were included in this study. Patients with PD onset at <63 years old were included in the early or middle-onset PD group, and those with PD onset at >63 years old were included in the late-onset PD (LOPD) group. Brain magnetic resonance imaging data of these patients were processed using FreeSurfer to measure their cortical thickness. The LOPD group displayed less cortical thickness in the superior frontal gyrus, middle frontal gyrus, precentral gyrus, postcentral gyrus, superior temporal gyrus, temporal pole, paracentral lobule, superior parietal lobule, precuneus, and occipital lobe than the early or middle-onset PD group. Compared with patients with early and middle-onset PD, elderly patients displayed extended cortical thinning with disease progression. Differences in the clinical manifestations of PD according to the age of onset were partly due to variations in the morphological changes in the brain.

Incidence of Parkinson disease in North America

Parkinson disease (PD) is the second most common age-related neurodegenerative condition diagnosed in North America. We recently demonstrated, using multiple epidemiological data sources, that the prevalence of PD diagnoses was greater than previously reported and currently used for clinical, research, and policy decision-making. Prior PD incidence estimates have varied, for unclear reasons. There is a need for improved estimates of PD incidence, not only for care delivery planning and future policy but also for increasing our understanding of disease risk. The objective of this study was thus to investigate the incidence of Parkinson disease across five epidemiological cohorts in North America in a common year, 2012. The cohorts contained data on 6.7 million person-years of adults ages 45 and older, and 9.3 million person-years of adults ages 65 and older. Our estimates of age-sex-adjusted incidence of PD ranged from 108 to 212 per 100,000 among persons ages 65 and older, and from 47 to 77 per 100,00 among persons ages 45 and older. PD incidence increased with age and was higher among males. We also found persistent spatial clustering of incident PD diagnoses in the U.S. PD incidence estimates varied across our data sources, in part due to case ascertainment and diagnosis methods, but also possibly due to the influence of population factors (prevalence of genetic risk factors or protective markers) and geographic location (exposure to environmental toxins). Understanding the source of these variations will be important for health care policy, research, and care planning.

Subtyping of early-onset Parkinson's disease using cluster analysis: A large cohort study

BACKGROUND

Increasing evidence suggests that early-onset Parkinson's disease (EOPD) is heterogeneous in its clinical presentation and progression. Defining subtypes of EOPD is needed to better understand underlying mechanisms, predict disease course, and eventually design more efficient personalized management strategies.

OBJECTIVE

To identify clinical subtypes of EOPD, assess the clinical characteristics of each EOPD subtype, and compare the progression between EOPD subtypes.

MATERIALS AND METHODS

A total of 1,217 patients were enrolled from a large EOPD cohort of the Parkinson's Disease & Movement Disorders Multicenter Database and Collaborative Network in China (PD-MDCNC) between January 2017 and September 2021. A comprehensive spectrum of motor and non-motor features were assessed at baseline. Cluster analysis was performed using data on demographics, motor symptoms and signs, and other non-motor manifestations. In 454 out of total patients were reassessed after a mean follow-up time of 1.5 years to compare progression between different subtypes.

RESULTS

Three subtypes were defined: mild motor and non-motor dysfunction/slow progression, intermediate and severe motor and non-motor dysfunction/malignant. Compared to patients with mild subtype, patients with the severe subtype were more likely to have rapid eye movement sleep behavior disorder, wearing-off, and dyskinesia, after adjusting for age and disease duration at baseline, and showed a more rapid progression in Unified Parkinson's Disease Rating Scale (UPDRS) total score (P = 0.002), UPDRS part II (P = 0.014), and III (P = 0.001) scores, Hoehn and Yahr stage (P = 0.001), and Parkinson's disease questionnaire-39 item version score (P = 0.012) at prospective follow-up.

CONCLUSION

We identified three different clinical subtypes (mild, intermediate, and severe) using cluster analysis in a large EOPD cohort for the first time, which is important for tailoring therapy to individuals with EOPD.

Diffusion along perivascular spaces provides evidence interlinking compromised glymphatic function with aging in Parkinson's disease

AIMS

The aim of the study was to evaluate the glymphatic function and its related factors in patients with Parkinson's disease (PD) and patients with PD of different ages using the diffusion tensor image analysis along the perivascular space (DTI-ALPS) method.

METHODS

Medical records and imaging data of 93 patients with idiopathic PD and 42 age- and sex-matched healthy controls (HCs) were retrospectively reviewed and analyzed. The diffusivity along the perivascular spaces, projection fibers, and association fibers were calculated on diffusion tensor imaging (DTI) to acquire the analysis along the perivascular space (ALPS) index.

RESULTS

PD patients exhibited a reduced ALPS index compared with the HCs. Negative correlations between the ALPS index and clinical information including age, age at disease onset, Parkinson's disease sleep scale 2nd version (PDSS-2) scores, and history of diabetes mellitus were revealed in the PD group. Besides, a negative correlation between the ALPS index and the severity of motor symptoms was identified in the subgroup aged 65 and above, rather than in the younger ones.

CONCLUSIONS

The results demonstrate that reduced ALPS index, a potential noninvasive measure of compromised glymphatic activity, is involved in the pathophysiology of PD, especially in the aged ones and those with sleep disorders.

Age Cutoff for Early-Onset Parkinson's Disease: Recommendations from the International Parkinson and Movement Disorder Society Task Force on Early Onset Parkinson's Disease

Background

Early-onset Parkinson's disease (EOPD)/young-onset Parkinson's disease (YOPD) is defined as Parkinson's disease (PD) with an age at onset (AAO) after age 21 years but before the usual AAO for PD. Consensus is lacking, and the reported maximal age for EOPD/YOPD has varied from 40 to 60 years, leading to a lack of uniformity in published studies and difficulty in harmonization of data. EOPD and YOPD have both been used in the literature, somewhat interchangeably.

Objective

To define the nomenclature and AAO cutoff for EOPD/YOPD.

Methods

An extensive review of the literature and task force meetings were conducted. Conclusions were reached by consensus.

Results

First, the literature has seen a shift from the use of YOPD toward EOPD. This seems motivated by an attempt to avoid age-related stigmatization of patients. Second, in defining EOPD, 56% of the countries use 50 or 51 years as the cutoff age. Third, the majority of international genetic studies in PD use an age cutoff of younger than 50 years to define EOPD. Fourth, many studies suggest that changes in the estrogen level can affect the predisposition to develop PD, making the average age at menopause of 50 years an important factor to consider when defining EOPD. Fifth, considering the differential impact of the AAO of PD on professional and social life, using 50 years as the upper cutoff for the definition of EOPD seems reasonable.

Conclusions

This task force recommends the use of EOPD rather than YOPD. It defines EOPD as PD with AAO after 21 years but before 50 years.

Pattern of Mitochondrial Respiration in Peripheral Blood Cells of Patients with Parkinson's Disease

Mitochondria are central in the pathogenesis of Parkinson’s disease (PD), as they are involved in oxidative stress, synaptopathy, and other immunometabolic pathways. Accordingly, they are emerging as a potential neuroprotection target, although further human-based evidence is needed for therapeutic advancements. This study aims to shape the pattern of mitochondrial respiration in the blood leukocytes of PD patients in relation to both clinical features and the profile of cerebrospinal fluid (CSF) biomarkers of neurodegeneration. Mitochondrial respirometry on the peripheral blood mononucleate cells (PBMCs) of 16 PD patients and 14 controls was conducted using Seahorse Bioscience technology. Bioenergetic parameters were correlated either with standard clinical scores for motor and non-motor disturbances or with CSF levels of α-synuclein, amyloid-β peptides, and tau proteins. In PD, PBMC mitochondrial basal respiration was normal; maximal and spare respiratory capacities were both increased; and ATP production was higher, although not significantly. Maximal and spare respiratory capacity was directly correlated with disease duration, MDS-UPDRS part III and Hoehn and Yahr motor scores; spare respiratory capacity was correlated with the CSF amyloid-β-42 to amyloid-β-42/40 ratio. We provided preliminary evidence showing that mitochondrial respiratory activity increases in the PBMCs of PD patients, probably following the compensatory adaptations to disease progression, in contrast to the bases of the neuropathological substrate.

Stacked Model-Based Classification of Parkinson’s Disease Patients Using Imaging Biomarker Data

Parkinson’s disease (PSD) is a neurological disorder of the brain where nigrostriatal integrity functions lead to motor and non-motor-based symptoms. Doctors can assess the patient based on the patient’s history and symptoms; however, the symptoms are similar in various neurodegenerative diseases, such as progressive supranuclear palsy (PSP), multiple system atrophy—parkinsonian type (MSA), essential tremor, and Parkinson’s tremor. Thus, sometimes it is difficult to identify a patient’s disease based on his or her symptoms. To address the issue, we have used neuroimaging biomarkers to analyze dopamine deficiency in the brains of subjects. We generated the different patterns of dopamine levels inside the brain, which identified the severity of the disease and helped us to measure the disease progression of the patients. For the classification of the subjects, we used machine learning (ML) algorithms for a multivariate classification of the subjects using neuroimaging biomarkers data. In this paper, we propose a stacked machine learning (ML)-based classification model to identify the HC and PSD subjects. In this stacked model, meta learners can learn and combine the predictions from various ML algorithms, such as K-nearest neighbor (KNN), random forest algorithm (RFA), and Gaussian naive Bayes (GANB) to achieve a high performance model. The proposed model showed 92.5% accuracy, outperforming traditional schemes.

Biochemical Discrimination of the Down Syndrome-Related Metabolic and Oxidative/Nitrosative Stress Alterations from the Physiologic Age-Related Changes through the Targeted Metabolomic Analysis of Serum

Down Syndrome (DS) is a neurodevelopmental disorder that is characterized by an accelerated aging process, frequently associated with the development of Alzheimer’s disease (AD). Previous studies evidenced that DS patients have various metabolic anomalies, easily measurable in their serum samples, although values that were found in DS patients were compared with those of age-matched non-DS patients, thus hampering to discriminate the physiologic age-related changes of serum metabolites from those that are truly caused by the pathologic processes associated with DS. In the present study we performed a targeted metabolomic evaluation of serum samples from DS patients without dementia of two age classes (Younger DS Patients, YDSP, aging 20–40 years; Aged DS Patients, ADSP, aging 41–60 years), comparing the results with those that were obtained in two age classes of non-DS patients (Younger non-DS Patients, YnonDSP, aging 30–60 years; Aged-nonDS Patients, AnonDSP, aging 75–90 years). Of the 36 compounds assayed, 30 had significantly different concentrations in Pooled non-DS Patients (PnonDSP), compared to Pooled DS Patients (PDSP). Age categorization revealed that 11/30 compounds were significantly different in AnonDSP, compared to YnonDSP, indicating physiologic, age-related changes of their circulating concentrations. A comparison between YDSP and ADSP showed that 19/30 metabolites had significantly different values from those found in the corresponding classes of non-DS patients, strongly suggesting pathologic, DS-associated alterations of their serum levels. Twelve compounds selectively and specifically discriminated PnonDSP from PDSP, whilst only three discriminated YDSP from ADSP. The results allowed to determine, for the first time and to the best of our knowledge, the true, age-independent alterations of metabolism that are measurable in serum and attributable only to DS. These findings may be of high relevance for better strategies (pharmacological, nutritional) aiming to specifically target the dysmetabolism and decreased antioxidant defenses that are associated with DS.

The Chinese Parkinson's Disease Registry (CPDR): Study Design and Baseline Patient Characteristics

BACKGROUND

There is a lack of large multicenter Parkinson's disease (PD) cohort studies and limited data on the natural history of PD in China.

OBJECTIVES

The objective of this study was to launch the Chinese Parkinson's Disease Registry (CPDR) and to report its protocol, cross-sectional baseline data, and prospects for a comprehensive observational, longitudinal, multicenter study.

METHODS

The CPDR recruited PD patients from 19 clinical sites across China between January 2018 and December 2020. Clinical data were collected prospectively using at least 17 core assessment scales. Patients were followed up for clinical outcomes through face-to-face interviews biennially.

RESULTS

We launched the CPDR in China based on the Parkinson's Disease & Movement Disorders Multicenter Database and Collaborative Network (PD-MDCNC). A total of 3148 PD patients were enrolled comprising 1623 men (51.6%) and 1525 women (48.4%). The proportions of early-onset PD (EOPD, age at onset ≤50 years) and late-onset PD (LOPD) were 897 (28.5%) and 2251 (71.5%), respectively. Stratification by age at onset showed that EOPD manifested milder motor and nonmotor phenotypes and was related to increased probability of dyskinesia. Comparison across genders suggested a slightly older average age at PD onset, milder motor symptoms, and a higher rate of developing levodopa-induced dyskinesias in women.

CONCLUSIONS

The CPDR is one of the largest multicenter, observational, longitudinal, and natural history studies of PD in China. It offers an opportunity to expand the understanding of clinical features, genetic, imaging, and biological markers of PD progression. © 2022 International Parkinson and Movement Disorder Society.

Tau and Amyloid-β Peptides in Serum of Patients With Parkinson's Disease: Correlations With CSF Levels and Clinical Parameters

Relevance of blood-based biomarkers is increasing into the neurodegenerative diseases field, but data on Parkinson's disease (PD) remain still scarce. In this study, we used the SiMoA technique to measure serum content of total tau protein and amyloid-β peptides (Aβ-42, Aβ-40) in 22 PD patients and ten control subjects. Serum levels of each biomarker were correlated with the respective CSF levels in both the groups; in PD patients, also the correlations between serum biomarkers and main clinical parameters were tested (motor, non-motor, cognitive scores and levodopa equivalent daily dose). Serum biomarkers did not exhibit quantitative differences between patients and controls; however, only PD patients had inter-fluids (serum-CSF) associations in tau and amyloid-β-42 levels. Moreover, serum content of tau protein was inversely correlated with cognitive performances (MoCA score). These findings, albeit preliminary, indicate that brain-derived peptides may change in parallel in both peripheral blood and CSF of PD patients, eventually even in association with some clinical features. Further studies are now needed to validate the use of blood-based biomarkers in PD.

Upregulated hexokinase 2 expression induces the apoptosis of dopaminergic neurons by promoting lactate production in Parkinson's disease

Parkinson's disease (PD) is characterized by impaired mitochondrial function and decreased ATP levels. Aerobic glycolysis and lactate production have been shown to be upregulated in dopaminergic neurons to sustain ATP levels, but the effect of upregulated glycolysis on dopaminergic neurons remains unknown. Since lactate promotes apoptosis and α-synuclein accumulation in neurons, we hypothesized that the lactate produced upon upregulated glycolysis is involved in the apoptosis of dopaminergic neurons in PD. In this study, we examined the expression of hexokinase 2 (HK2) and lactate dehydrogenase (LDH), the key enzymes in glycolysis, and lactate levels in the substantia nigra pars compacta (SNpc) of a MPTP-induced mouse model of PD and in MPP⁺-treated SH-SY5Y cells. We found that the expression of HK2 and LDHA and the lactate levels were markedly increased in the SNpc of MPTP-treated mice and in MPP⁺-treated SH-SY5Y cells. Exogenous lactate treatment led to the apoptosis of SH-SY5Y cells. Intriguingly, lactate production and the apoptosis of dopaminergic neurons were suppressed by the application of 3-bromopyruvic acid (3-Brpa), a HK2 inhibitor, or siRNA both in vivo and in vitro. 3-Brpa treatment markedly improved the motor behaviour of MPTP-treated mice in pole test and rotarod test. Mechanistically, lactate increases the activity of adenosine monophosphate-activated protein kinase (AMPK) and suppresses the phosphorylation of serine/threonine kinase 1 (Akt) and mammalian target of rapamycin (mTOR). Together, our data suggest that upregulated HK2 and LDHA and increased lactate levels prompt the apoptosis of dopaminergic neurons in PD. Inhibition of HK2 expression attenuated the apoptosis of dopaminergic neurons by downregulating lactate production and AMPK/Akt/mTOR pathway in PD.

Biomarkers of Cerebral Glucose Metabolism and Neurodegeneration in Parkinson's Disease: A Cerebrospinal Fluid-Based Study

BACKGROUND

Several biomarkers have been evaluated in Parkinson's disease (PD); cerebrospinal fluid (CSF) levels of lactate may reflect cerebral metabolism function and CSF amyloid-β42 (Aβ42), total tau (t-tau) and phosphorylated tau (p-tau) concentrations may detect an underlying neurodegenerative process.

OBJECTIVE

CSF levels of lactate, Aβ42, t-tau, and p-tau were measured in patients with mild to moderate PD. CSF levels of dopamine (DA) and its metabolite 3,4-Dihydroxyphenylacetic acid (DOPAC) were also assessed, exploring their relations with the other CSF biomarkers.

METHODS

101 drug-naive PD patients and 60 controls were included. Participants underwent clinical assessments and CSF biomarker analysis. Patients were divided into subgroups according to their Hoehn & Yahr stage (PD-1, PD-2, PD-3).

RESULTS

PD patients showed higher lactate levels (M = 1.91; p = 0.03) and lower Aβ42 (M = 595; p < 0.001) and DA levels (M = 0.32; p = 0.04) than controls (Mlactate = 1.72; MAβ42 = 837; MDA = 0.50), while no significant differences were found in t-tau, p-tau and DOPAC concentrations. Considering the subgroup analysis, PD-3 group had higher lactate (M = 2.12) and t-tau levels (M = 333) than both PD-1 (Mlactate = 1.75, p = 0.006; Mt - tau = 176, p = 0.008) and PD-2 groups (Mlactate = 1.91, p = 0.01; Mt - tau = 176, p = 0.03), as well as the controls (Mlactate = 1.72, p = 0.04; Mt - tau = 205, p = 0.04). PD-2 group showed higher lactate levels than PD-1 group (p = 0.04) and controls (p = 0.03). Finally, CSF lactate levels negatively correlated with DA (r = -0.42) and positively with t-tau CSF levels (r = 0.33).

CONCLUSION

This CSF-based study shows that lactate levels in PD correlated with both clinical disease progression and neurodegeneration biomarkers, such as tau proteins and DA. Further studies should explore the clinical potential of measuring CSF biomarkers for better understanding the role of brain energy metabolism in PD, for research and therapeutic options.

Clinical and Dopamine Transporter Imaging Trajectories in a Cohort of Parkinson's Disease Patients with GBA Mutations

BACKGROUND

Glucosylceramidase (GBA) mutations are considered the most common genetic risk factors for developing Parkinson's disease (PD).

OBJECTIVES

We aimed to assess, at different time points, the integrity of brain striatal and extra-striatal dopamine pathways and clinical phenotype of a group of PD subjects bearing heterozygous GBA mutations (GBA-PD), compared with a group of idiopathic PD patients (iPD) stratified by age at disease onset. A longitudinal approach was adopted to evaluate the progression over time for clinical and ¹²³ I-FP-CIT SPECT imaging features.

METHODS

We considered 46 GBA-PD patients and 339 iPD patients, subdivided into two groups according to age at PD onset (n = 58 < 50 years and n = 281 > 50 years). We measured differences in the occurrence/severity/progression of motor and non-motor features, ¹²³ I-FP-CIT standard uptake value ratios (SUVr) in striatal and extra-striatal regions, and global cognitive deterioration over time in a subset of 168 cases with available follow-up.

RESULTS

At baseline, the GBA-PD cohort showed more severe motor and cognitive deficits than the early-iPD cohort. The ¹²³ I-FP-CIT SUVr reduction in the striatal and the extra-striatal regions was more marked in the GBA-PD than the early- and late-iPD cohorts. Both GBA-PD and late-iPD patients had a significant annual deterioration in their global cognitive performance, while the early-iPD group showed global cognitive stability over time. At follow-up, the iPD cohorts became similar to the GBA-PD group in ¹²³ I-FP-CIT SUVr reduction.

CONCLUSION

These new findings support the hypothesis of a biological role of GBA mutations in accelerating the early neurodegenerative processes in PD, leading to the malignant clinical phenotype. © 2021 International Parkinson and Movement Disorder Society.

A Practical Approach to Early-Onset Parkinsonism

Early-onset parkinsonism (EO parkinsonism), defined as subjects with disease onset before the age of 40 or 50 years, can be the main clinical presentation of a variety of conditions that are important to differentiate. Although rarer than classical late-onset Parkinson’s disease (PD) and not infrequently overlapping with forms of juvenile onset PD, a correct diagnosis of the specific cause of EO parkinsonism is critical for offering appropriate counseling to patients, for family and work planning, and to select the most appropriate symptomatic or etiopathogenic treatments. Clinical features, radiological and laboratory findings are crucial for guiding the differential diagnosis. Here we summarize the most important conditions associated with primary and secondary EO parkinsonism. We also proposed a practical approach based on the current literature and expert opinion to help movement disorders specialists and neurologists navigate this complex and challenging landscape.

Effects of head trauma and sport participation in young-onset Parkinson's disease

Head trauma (HT) is emerging as an event anticipating onset of neurodegenerative disorders. However, the potential contribution of HT in young-onset cases (YOPD, age at onset < 50) of Parkinson’s disease (PD) has not been examined yet. Here, we systematically assessed HT history in PD patients to estimate the risk associated, especially in terms of age of onset, and define the correlations with the clinical-biochemical profile. The Brain Injury Screening Questionnaire (BISQ) was administered to 94 PD patients (31 with YOPD, known monogenic forms excluded) and 70 controls. HT history was correlated with motor and non-motor scores in all patients, and to CSF biomarkers of neurodegeneration (α-synuclein, amyloid-β42, total and phosporiled-181 tau, lactate, CSF/serum albumin) into a subgroup. HT increased the risk for both PD and YOPD. In PD patients, but not in those with YOPD, the number of HTs directly correlated with CSF total-tau levels. No other correlations resulted between HT and clinical parameters. Sport-related HT was a specific risk factor for YOPD; conversely, the prolonged sporting life represented a protective factor. HTs can favor PD onset, even as YOPD. Sport-related HT resulted a risk factor for YOPD, although the longer sporting practice delayed PD onset, protecting from YOPD. Tauopathy may underlie the overall association between HT and PD. Additional mechanisms could be instead implicated in HT contribution to YOPD onset.

Amyloid-β42/Neurogranin Ratio as a Potential Index for Cognitive Impairment in Parkinson's Disease

BACKGROUND

Synaptopathy is critical in pathophysiology of Parkinson's disease (PD). Cerebrospinal fluid (CSF) levels of neurogranin (NG) and amyloid-β42 (Aβ42) are considered markers of synaptic dysfunction in neurodegenerative diseases.

OBJECTIVE

To evaluate the CSF synaptopathy-related biomarkers, especially the novel Aβ42/NG ratio, in PD, establishing possible associations with cognitive level and other clinical parameters.

METHODS

Levels of NG, Aβ42, amyloid-β40, total and phosphorylated tau, and Aβ42/NG ratio were measured in 30 PD patients and 30 controls and correlated with cognitive and motor parameters. The accuracy in distinguishing the cognitive status was determined.

RESULTS

NG and Aβ42 were significantly reduced in PD, with higher NG levels in patients with worse cognition. The Aβ42/NG ratio showed a direct correlation with Mini-Mental State Examination, independently from age and sex, and differentiated cognitively impaired patients with 92% sensitivity and 71.4% specificity, accuracy higher than NG alone. No correlations resulted with motor disturbances or therapy.

CONCLUSIONS

The novel Aβ42/NG ratio couples either presynaptic or postsynaptic markers of synaptic dysfunction, representing a potential global index of synaptopathy, useful to track cognitive functions in PD.

Design of an Innovative Methodology for Cerebrospinal Fluid Analysis: Preliminary Results

Cerebrospinal fluid (CSF) analysis supports diagnosis of neurodegenerative diseases (NDs), however a number of issues limits its potentialities in clinical practice. Here, a newly developed technique for fluid voltammetry, relying on a simple sensor (BIOsensor-based multisensorial system for mimicking Nose, Tongue and Eyes, BIONOTE), was used to test the applicability for CSF analysis. BIONOTE was initially calibrated on an artificial CSF-like solution and then applied on human CSF, either immediately after collection or after refrigerated storage. Following optimization, it was used to evaluate 11 CSF samples correlating the electrochemical dataset with CSF routine parameters and biomarkers of neurodegeneration. Multivariate data analysis was performed for model elaboration and calibration using principal component analysis and partial least squares discriminant analysis. BIONOTE presented a high capacity to predict both physiological and pathological constituents of artificial CSF. It differentiated distinct fresh human CSF samples well but lost accuracy after refrigerated storage. The electrochemical analysis-derived data correlated with either CSF routine cytochemical indexes or a biomarker of neurodegeneration. BIONOTE resulted as being a reliable system for electrochemical analysis of CSF. The CSF fingerprint provided by the sensor has shown itself to be sensitive to CSF modification, thus it is potentially representative of CSF alteration. This result opens the way to its testing in further study addressed at assessing the clinical relevance of the methodology. Because of its advantages due to the ease and rapidity of the methodology, a validation study is now required to translate the technique into clinical practice and improve diagnostic workup of NDs.

Effects of baseline serum uric acid and apolipoprotein E4 on longitudinal cognition and cerebral metabolism

Serum uric acid, a natural antioxidant, may have a protective effect on the progression of Alzheimer's disease (AD). To investigate the effect of serum uric acid on longitudinal cognitive and brain metabolic changes, we utilized data on baseline serum uric acid levels, APOE genotyping, and longitudinal cognitive scores from the Alzheimer's Disease Neuroimaging Initiative for 1,343 participants with normal cognition (NC), mild cognitive impairment (MCI), or dementia. In 979 participants, brain metabolism was measured using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) images. Higher serum uric acid levels exhibited a detrimental effect on NC, whereas a protective trend was observed in individuals with cognitive impairment. Interestingly, higher uric acid levels were associated with a slower decline in cognitive scores and brain metabolism in females with MCI, and this effect was found in APOE4 carriers, but not in non-carriers. Longitudinal AD-like patterns of brain metabolism on FDG-PET images also appeared to mediate the effects of baseline uric acid levels on longitudinal cognitive decline. In summary, higher serum uric acid may interact with APOE4 to alleviate longitudinal metabolic changes and cognitive decline in female MCI patients.

COVID-19: dealing with a potential risk factor for chronic neurological disorders

SARS-CoV2 infection is responsible for a complex clinical syndrome, named Coronavirus Disease 2019 (COVID-19), whose main consequences are severe pneumonia and acute respiratory distress syndrome. Occurrence of acute and subacute neurological manifestations (encephalitis, stroke, headache, seizures, Guillain-Barrè syndrome) is increasingly reported in patients with COVID-19. Moreover, SARS-CoV2 immunopathology and tissue colonization in the gut and the central nervous system, and the systemic inflammatory response during COVID-19 may potentially trigger chronic autoimmune and neurodegenerative disorders. Specifically, Parkinson's disease, multiple sclerosis and narcolepsy present several pathogenic mechanisms that can be hypothetically initiated by SARS-CoV2 infection in susceptible individuals. In this short narrative review, we summarize the clinical evidence supporting the rationale for investigating SARS-CoV2 infection as risk factor for these neurological disorders, and suggest the opportunity to perform in the future SARS-CoV2 serology when diagnosing these disorders.

How Comorbidity Reflects on Cerebrospinal Fluid Biomarkers of Neurodegeneration in Aging

Systemic comorbidity precipitates the risk for dementia. To comprehend the underlying mechanisms into a therapeutic perspective, we analyzed how comorbidity affects neurodegeneration-related cerebrospinal fluid (CSF) biomarkers of 55 cognitively intact subjects. The Charson Comorbidity Index (CCI) was correlated with CSF amyloid-β42 (Aβ42), amyloid-β40, total-tau, 181-phosphorylated-tau (p-tau), the Aβ42/p-tau ratio, neurogranin, and lactate. The age-related brain lesions at imaging were also considered. CCI had a raw association with Aβ42/p-tau and p-tau, and a stronger, age-independent correlation with lactate. These preliminary findings suggested that, in normal subjects, systemic comorbidity might increase CNS oxidative stress and, together with aging, contribute to develop an Alzheimer's disease-like biochemical profile.