Pathological substrate of memory impairment in multiple system atrophy

The Role of α-Synuclein in Etiology of Neurodegenerative Diseases

A presynaptic protein called α-synuclein plays a crucial role in synaptic function and neurotransmitter release. However, its misfolding and aggregation have been implicated in a variety of neurodegenerative diseases, particularly Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Emerging evidence suggests that α-synuclein interacts with various cellular pathways, including mitochondrial dysfunction, oxidative stress, and neuroinflammation, which contributes to neuronal cell death. Moreover, α-synuclein has been involved in the propagation of neurodegenerative processes through prion-like mechanisms, where misfolded proteins induce similar conformational changes in neighboring neurons. Understanding the multifaced roles of α-synuclein in neurodegeneration not only aids in acquiring more knowledge about the pathophysiology of these diseases but also highlights potential biomarkers and therapeutic targets for intervention in alpha-synucleinopathies. In this review, we provide a summary of the mechanisms by which α-synuclein contributes to neurodegenerative processes, focusing on its misfolding, oligomerization, and the formation of insoluble fibrils that form characteristic Lewy bodies. Furthermore, we compare the potential value of α-synuclein species in diagnosing and differentiating selected neurodegenerative diseases.

Intranasal administration of trehalose reduces α-synuclein oligomers and accelerates α-synuclein aggregation

Abnormal α-synuclein (αSyn), including an oligomeric form of αSyn, accumulates and causes neuronal dysfunction in the brains of patients with multiple system atrophy. Neuroprotective drugs that target abnormal αSyn aggregation have not been developed for the treatment of multiple system atrophy. In addition, treating diseases at an early stage is crucial to halting the progress of neuronal damage in neurodegeneration. In this study, using early-stage multiple system atrophy mouse model and in vitro kinetic analysis, we investigated how intranasal and oral administration of trehalose can improve multiple system atrophy pathology and clinical symptoms. The multiple system atrophy model showed memory impairment at least four weeks after αSyn induction. Behavioural and physiological analyses showed that intranasal and oral administration of trehalose reversed memory impairments to near-normal levels. Notably, trehalose treatment reduced the amount of toxic αSyn and increased the aggregated form of αSyn in the multiple system atrophy model brain. In vitro kinetic analysis confirmed that trehalose accelerated the aggregate formation of αSyn. Based on our findings, we propose a novel strategy whereby accelerated αSyn aggregate formation leads to reduced exposure to toxic αSyn oligomers, particularly during the early phase of disease progression.

Psychiatric Manifestations of Neurological Diseases: A Narrative Review

Neurological diseases often manifest with psychiatric symptoms, profoundly impacting patients' well-being and treatment outcomes. This comprehensive review examines the psychiatric manifestations associated with Alzheimer's disease, frontotemporal dementia (FTD), Parkinson's disease, multiple sclerosis (MS), stroke, epilepsy, Huntington's disease, amyotrophic lateral sclerosis (ALS), traumatic brain injury (TBI), and multiple system atrophy (MSA). Key psychiatric symptoms include agitation, depression, anxiety, apathy, hallucinations, impulsivity, and aggression across these diseases. In addition, ethical considerations in treating these symptoms are paramount, particularly regarding genetic testing implications, end-of-life discussions, informed consent, and equitable access to innovative treatments. Effective management necessitates interdisciplinary collaboration, personalized interventions, and a focus on patient autonomy. Understanding the psychiatric burden of neurological diseases is crucial for enhancing patients' quality of life. Further research is needed to elucidate underlying mechanisms and develop targeted interventions. This review underscores the importance of comprehensive assessment and ethical treatment practices to address psychiatric manifestations effectively.

Frequency of Comorbid Pathologies and Their Clinical Impact in Multiple System Atrophy

BACKGROUND

Mixed pathology is common at autopsy for a number of age-associated neurodegenerative disorders; however, the frequency of comorbid pathologies in multiple system atrophy (MSA) and their clinical correlations are poorly understood.

OBJECTIVE

We determined the frequency of comorbid pathologic processes in autopsy-confirmed MSA and assessed their clinical correlates.

METHODS

This study included 160 neuropathologically established MSA from the Mayo Clinic brain bank. Clinical information, including age at onset or death, clinical subtype, initial symptoms, antemortem clinical diagnosis, and cognitive dysfunction was collected. We assessed comorbid pathologies including Alzheimer's disease neuropathologic change, Lewy-related pathology, argyrophilic grain disease, age-related τ astrogliopathy, transactive DNA-binding protein 43 pathology, cerebral amyloid angiopathy, and cerebrovascular small vessel disease and examined their clinical impact.

RESULTS

The majority of MSA patients (62%) had no significant comorbid pathologies. There was a positive correlation between age at onset or death with the number of comorbid pathologies; however, even in the highest quartile group (average age at death 78 ± 6 years), the average number of comorbid pathologies was <2. Logistic regression analysis revealed that none of the assessed variables, including sex, age at onset, and the presence or absence of each comorbid pathology, were significantly associated with cognitive dysfunction.

CONCLUSIONS

The majority of MSA patients do not have comorbid pathologies, even in advanced age, indicating that MSA is unique among neurodegenerative disorders in this regard. There was minimal clinical impact of comorbid pathologies in MSA. These findings warrant focusing on α-synuclein for the treatment strategy for MSA. © 2023 International Parkinson and Movement Disorder Society.

Globular glial tauopathy presenting clinically as atypical parkinsonism with dementia: A clinicopathological case report

•Globular Glial Tauopathy presents as atypical parkinsonism with dementia.•Globular Glial Tauopathy is underrecognized among movement disorders specialists.•Globular Glial Tauopathy type III without preferential language dysfunction or semantic dementia.

An update on the role of Hippo signaling pathway in ischemia-associated central nervous system diseases

The most frequent reason of morbidity and mortality in the world, cerebral ischemia sets off a chain of molecular and cellular pathologies that associated with some central nervous system (CNS) disorders mainly including ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy and other CNS diseases. In recent times, despite significant advancements in the treatment of the pathological processes underlying various neurological illnesses, effective therapeutic approaches that are specifically targeted to minimizing the damage of such diseases remain absent. Hippo signaling pathway, characterized by enzyme linked reactions between MSTI/2, LAST1/2, and YAP or TAZ proteins, controls cell division, survival, and differentiation, as well as being engaged in a variety of biological activities, such as the development and transformation of the nervous system. Recently, accumulating studies demonstrated that Hippo pathway takes part in the processes of ischemic stroke, AD, PD, etc., including but not limited to oxidative stress, inflammatory response, blood-brain barrier damage, mitochondrial disorders, and neural cells death. Thus, it's crucial to understand the molecular basis of the Hippo signaling pathway for determining potential new therapeutic targets against ischemia-associated CNS diseases. Here, we discuss latest advances in the deciphering of the Hippo signaling pathway and highlight the therapeutic potential of targeting the pathway in treating ischemia-associated CNS diseases.

Alpha-synuclein in Parkinson's disease and other synucleinopathies: from overt neurodegeneration back to early synaptic dysfunction

Although the discovery of the critical role of α-synuclein (α-syn) in the pathogenesis of Parkinson's disease (PD) is now twenty-five years old, it still represents a milestone in PD research. Abnormal forms of α-syn trigger selective and progressive neuronal death through mitochondrial impairment, lysosomal dysfunction, and alteration of calcium homeostasis not only in PD but also in other α-syn-related neurodegenerative disorders such as dementia with Lewy bodies, multiple system atrophy, pure autonomic failure, and REM sleep behavior disorder. Furthermore, α-syn-dependent early synaptic and plastic alterations and the underlying mechanisms preceding overt neurodegeneration have attracted great interest. In particular, the presence of early inflammation in experimental models and PD patients, occurring before deposition and spreading of α-syn, suggests a mechanistic link between inflammation and synaptic dysfunction. The knowledge of these early mechanisms is of seminal importance to support the research on reliable biomarkers to precociously identify the disease and possible disease-modifying therapies targeting α-syn. In this review, we will discuss these critical issues, providing a state of the art of the role of this protein in early PD and other synucleinopathies.

Discrepancy between distribution of alpha-synuclein oligomers and Lewy-related pathology in Parkinson's disease

The pathological hallmarks of Parkinson’s disease (PD) are α-synuclein (αSYN)-positive inclusions referred to as Lewy bodies and Lewy neurites, collectively referred to as Lewy-related pathology (LRP). LRP is thought to propagate in an ascending manner throughout the brain as the disease progresses. LRP is visible with histologic methods and is thought to represent a later stage of the disease process, while αSYN oligomers, which are not visible with routine histologic methods, are considered earlier. There is increasing evidence to suggest that αSYN oligomers may be more toxic than visible LRP. Detecting αSYN oligomers requires special techniques, and their distribution and association with clinical features are important research objectives. In this report, we describe the distribution of αSYN oligomers in multiple cortical and subcortical regions of PD using a proximity ligation assay (PLA). We observe widespread distribution of αSYN oligomers with PLA and more restricted distribution of LRP with αSYN immunohistochemistry. The distribution of αSYN oligomers differed from LRP in that αSYN oligomer burden was significantly greater in the neocortex, while LRP was greater in vulnerable subcortical regions, including the brainstem. We also found that cognitive impairment was associated with αSYN oligomers in the hippocampus. These results suggest that αSYN oligomers may be widely distributed in PD early in the disease process and that they may contribute to cognitive impairment in PD.