scholarly journals Attentional compensation in neurodegenerative diseases: the model of premanifest Huntington's disease mutation carriers

Author(s):  
Lorna Le Stanc ◽  
Marine Lunven ◽  
Maria Giavazzi ◽  
Agnes Sliwinski ◽  
Pierre Brugieres ◽  
...  

The ability of the brain to actively cope with neuropathological insults is known as neural compensation. It explains the delayed appearance of cognitive symptoms in neurodegenerative diseases. In contrast to the neural signature of compensation, its cognitive counterpart is largely unknown due to the difficulty of identifying cognitive dysfunctions concealed by compensation mechanisms. We combined computational modelling and neuroanatomical analysis to explore cognitive compensation. We used Huntington's disease (HD) as a genetic model of neurodegenerative disease allowing to study compensation in premanifest mutation carriers (preHDs) free from overt cognitive deficits despite incipient brain atrophy. Twenty preHDs, 28 HD patients and 45 controls performed a discrimination task. We investigated the processes underlying cognitive compensation using drift diffusion models. They assume that the discrimination process relies on the accumulation of evidence at a certain rate and terminates when a response threshold is reached. HD patients' performances were lower than controls' and explained by a higher response threshold and a lower accumulation rate compared to controls. PreHDs performed similarly to controls but had a response threshold between those of controls and HD patients. This nascent increase in response threshold predicted the accumulation rate, which was faster than controls. This suggests that the higher accumulation rate conceals the nascent deficit in response threshold corroborating the capacity of the brain to resist neuropathological insults in preHDs. The higher accumulation rate was associated with parietal hypertrophy in mutation carriers, and with higher hippocampal volumes in preHDs suggesting that cognitive compensation may rely on attentional capacities.

2020 ◽  
Author(s):  
Tarik S. Onur ◽  
Andrew Laitman ◽  
He Zhao ◽  
Ryan Keyho ◽  
Hyemin Kim ◽  
...  

AbstractMost research on neurodegenerative diseases has focused on neurons, yet glia help form and maintain the synapses whose loss is so prominent in these conditions. To investigate the contributions of glia to Huntington’s disease (HD), we studied transcriptomic changes in HD human, HD mice, and Drosophila expressing human mutant Huntingtin (mHTT) in either glia, neurons or both. A large portion of conserved genes are concordantly dysregulated across the three species; we tested these genes in a high-throughput behavioral assay and found that downregulation of genes involved in synapse assembly mitigated pathogenesis and behavioral deficits. To our surprise, mitigating glial pathogenesis by dNRXN3 knockdown was sufficient to improve the phenotype of flies expressing mHTT in neurons, suggesting that mHTT’s toxic effects in glia ramify throughout the brain. This supports a model in which dampening synaptic function is protective because it attenuates the excitotoxicity that characterizes HD.


2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Annapurna Nayak ◽  
Rafia Ansar ◽  
Sunil K. Verma ◽  
Domenico Marco Bonifati ◽  
Uday Kishore

Huntington's disease (HD) is a progressive neurodegenerative disorder that is caused by abnormal expansion of CAG trinucleotide repeats. Neuroinflammation is a typical feature of most neurodegenerative diseases that leads to an array of pathological changes within the affected areas in the brain. The neurodegeneration in HD is also caused by aberrant immune response in the presence of aggregated mutant huntingtin protein. The effects of immune activation in HD nervous system are a relatively unexplored area of research. This paper summarises immunological features associated with development and progression of HD.


2020 ◽  
Author(s):  
Giulia Birolini ◽  
Marta Valenza ◽  
Ilaria Ottonelli ◽  
Alice Passoni ◽  
Monica Favagrossa ◽  
...  

AbstractSupplementing brain cholesterol is emerging as a potential treatment for Huntington’s disease (HD), a genetic neurodegenerative disorder characterized, among other abnormalities, by inefficient brain cholesterol biosynthesis. However, delivering cholesterol to the brain is challenging due to the bloodbrain barrier (BBB), which prevents it from reaching the striatum, especially, with therapeutically relevant doses.Here we describe the distribution, kinetics, release, and safety of novel hybrid polymeric nanoparticles made of PLGA and cholesterol which were modified with an heptapeptide (g7) for BBB transit (hybrid-g7-NPs-chol). We show that these NPs rapidly reach the brain and target neural cells. Moreover, deuterium-labeled cholesterol from hybrid-g7-NPs-chol is released in a controlled manner within the brain and accumulates over time, while being rapidly removed from peripheral tissues and plasma. We confirm that systemic and repeated injections of the new hybrid-g7-NPs-chol enhanced endogenous cholesterol biosynthesis, prevented cognitive decline, and ameliorated motor defects in HD animals, without any inflammatory reaction.In summary, this study provides insights about the benefits and safety of cholesterol delivery through advanced brain-permeable nanoparticles for HD treatment.


2021 ◽  
Vol 22 (22) ◽  
pp. 12499
Author(s):  
Chaebin Kim ◽  
Ali Yousefian-Jazi ◽  
Seung-Hye Choi ◽  
Inyoung Chang ◽  
Junghee Lee ◽  
...  

Huntington’s disease (HD) is a rare neurodegenerative disorder caused by an expansion of CAG trinucleotide repeat located in the exon 1 of Huntingtin (HTT) gene in human chromosome 4. The HTT protein is ubiquitously expressed in the brain. Specifically, mutant HTT (mHTT) protein-mediated toxicity leads to a dramatic degeneration of the striatum among many regions of the brain. HD symptoms exhibit a major involuntary movement followed by cognitive and psychiatric dysfunctions. In this review, we address the conventional role of wild type HTT (wtHTT) and how mHTT protein disrupts the function of medium spiny neurons (MSNs). We also discuss how mHTT modulates epigenetic modifications and transcriptional pathways in MSNs. In addition, we define how non-cell autonomous pathways lead to damage and death of MSNs under HD pathological conditions. Lastly, we overview therapeutic approaches for HD. Together, understanding of precise neuropathological mechanisms of HD may improve therapeutic approaches to treat the onset and progression of HD.


2021 ◽  
Vol 19 ◽  
Author(s):  
Julieta Saba ◽  
Federico López Couselo ◽  
Julieta Bruno ◽  
Lila Carniglia ◽  
Daniela Durand ◽  
...  

: Huntington’s disease (HD) is a neurodegenerative genetic disorder caused by a CAG repeat expansion in the huntingtin gene. HD causes motor, cognitive, and behavioral dysfunction. Since no existing treatment affects the course of this disease, new treatments are needed. Inflammation is frequently observed in HD patients before symptom onset. Neuroinflammation, characterized by the presence of reactive microglia and astrocytes and inflammatory factors within the brain, is also detected early. However, in comparison with other neurodegenerative diseases, the role of neuroinflammation in HD is much less known. Work has been dedicated to altered microglial and astrocytic functions in the context of HD, but less attention has been given to glial participation in neuroinflammation. This review describes evidence of inflammation in HD patients and animal models. It also discusses recent knowledge on neuroinflammation in HD, highlighting astrocyte and microglia involvement in the disease and considering anti-inflammatory therapeutic approaches.


Author(s):  
Ravi Ranjan Kumar ◽  
Lovekesh Singh ◽  
Amandeep Thakur ◽  
Shamsher Singh ◽  
Bhupinder Kumar

Background: Vitamins are the micronutrients required for boosting the immune system and managing any future infection. Vitamins are involved in neurogenesis, a defense mechanism working in neurons, metabolic reactions, neuronal survival, and neuronal transmission. Their deficiency leads to abnormal functions in the brain like oxidative stress, mitochondrial dysfunction, accumulation of proteins (synuclein, Aβ plaques), neurodegeneration, and excitotoxicity. Methods: In this review, we have compiled various reports collected from PubMed, Scholar Google, Research gate, and Science direct. The findings were evaluated, compiled, and represented in this manuscript. Conclusion: The deficiency of vitamins in the body causes various neurological disorders like Alzheimer’s disease, Parkinson’s disease, Huntington's disease, and depression. We have discussed the role of vitamins in neurological disorders and the normal human body. Depression is linked to a deficiency of vitamin-C and vitamin B. In the case of Alzheimer’s disease, there is a lack of vitamin-B1, B12, and vitamin-A, which results in Aβ-plaques. Similarly, in Parkinson’s disease, vitamin-D deficiency leads to a decrease in the level of dopamine, and imbalance in vitamin D leads to accumulation of synuclein. In MS, Vitamin-C and Vitamin-D deficiency causes demyelination of neurons. In Huntington's disease, vitamin- C deficiency decreases the antioxidant level, enhances oxidative stress, and disrupts the glucose cycle. Vitamin B5 deficiency in Huntington's disease disrupts the synthesis of acetylcholine and hormones in the brain.


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