Alzheimer & Parkinson

Neuronal injury is a common complication in patients with diabetes. These injuries include a wide range of neurobehavioral complications that significantly reduce the neuronal network efficiency and quality of life in affected individuals. Currently, diabetes-induced neuronal complications are a major global health challenge, and many studies have been performed to prevent or slow their progression. Semaglutide is a novel form of glucagon-like peptide-1 (GLP-1) agonist agents that has recently...

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Abnormal aggregation of amyloid-β protein (1-42) (Aβ(42)) is the primary pathology in Alzheimer's disease (AD). Two types of Aβ(42) fibrils have been identified in the insoluble fraction of diseased human brains. Here, we report that the fraction previously deemed 'soluble' during sarkosyl extraction of AD brains actually harbors numerous amyloid fibrils, with a looser bundling than those in the insoluble fraction. Using cryo-electron microscopy (cryo-EM), we discover a third type (type III) of...

During brain development, synapses are initially formed in excess and are later eliminated in an activity-dependent manner. Weak synapses are preferentially removed, but the mechanism linking neuronal activity to synapse removal is unclear. Here, we show that, in the developing mouse visual pathway, inhibiting synaptic transmission induces postsynaptic activation of caspase-3. Caspase-3 deficiency results in defects in synapse elimination driven by both spontaneous and experience-dependent...

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Accurate classification of neurodegenerative disorders remains a challenge in neuroscience. Using open-source electroencephalography (EEG) data, we investigated electrophysiological signatures to differentiate frontotemporal dementia (FTD) from Alzheimer's disease (AD) via complexity measures. Traditional relative band power analysis showed consistent increases in lower-frequency activity but did not distinguish the two disorders after correction. In contrast, fractal dimension and long-range...

Genome-wide association studies have identified many gene polymorphisms associated with an increased risk of developing late-onset Alzheimer's disease (LOAD). Many of these LOAD risk-associated alleles alter disease pathogenesis by influencing innate immune responses and lipid metabolism of microglia (MG). Here we show that boosting the expression of angiotensin-converting enzyme (ACE), a genome-wide association study LOAD risk-associated gene product, specifically in MG, reduces amyloid-β (Aβ)...

The β-N-methylamino-L-alanine (BMAA) is an emerging neurotoxin associated with human neurodegenerative diseases such as Alzheimer's disease. Here, we report the prevalence of BMAA synthesis in protein forms by marine diatoms and reconstruct its tentative biosynthesis pathway. Remarkably, the BMAA production is strongly induced by iron limitation. Transcriptomic analyses suggest that cysteine synthase (CysK) is involved in BMAA synthesis. This is verified as CRISPR/Cas9-based CysK knockout...

In this issue, Chadarevian et al. showed that engraftment of human iPSC-derived microglia (iMG) engineered to express secreted neprilysin (sNEP) under the plaque-responsive CD9 promoter reduces amyloid burden, neuronal damage, and inflammation in an Alzheimer's disease (AD) mouse model.¹ These findings establish a cell-based strategy to treat neurological diseases.

Parkinson's disease (PD), characterized by the selective loss of midbrain dopaminergic neurons (mDANs), is a promising target for cell replacement therapy. Two recent clinical trials¹^(,)² published in Nature report the safety and potential efficacy of human pluripotent stem cell-based approaches, representing a major milestone in regenerative medicine for PD.

N⁶-methyladenosine (m6A) is an abundant internal RNA modification that can impact gene expression at both post-transcriptional and transcriptional levels. However, the landscapes and functions of m6A in human brains and neurodegenerative diseases, including Alzheimer's disease (AD), are under-explored. Here, we examined RNA m6A methylome using total RNA-seq and meRIP-seq in middle frontal cortex of post-mortem brains from individuals with or without AD, which revealed m6A alteration on both...

Recent work leveraging artificial intelligence has offered promise to dissect disease heterogeneity by identifying complex intermediate brain phenotypes, called dimensional neuroimaging endophenotypes (DNEs). We advance the argument that these DNEs capture the degree of expression of respective neuroanatomical patterns measured, offering a dimensional neuroanatomical representation for studying disease heterogeneity and similarities of neurologic and neuropsychiatric diseases. We investigate the...

Disruption in neuronal and synaptic metabolic homeostasis is a key driver of neurodegeneration in Parkinson's disease (PD). Mitochondrial activity, biomass, and efficiency are critical to this balance. While activity and biomass are well characterized in PD pathology, mitochondrial metabolic efficiency remains insufficiently explored. Our previous studies showed that the protein product of PD-associated gene DJ-1 modulates metabolic efficiency through its interaction with the F1Fo-ATP-synthase β...

Duplication of the SNCA gene (SNCA^(Dupl)), linked to elevated levels of α-synuclein (aSyn), is a genetic cause of Parkinson's disease (PD). Our prior work with human-induced pluripotent stem cell (hiPSC)-derived midbrain neurons generated from patients with PD SNCA^(Dupl) identified neuritic deficits, accompanied by decreased levels of cytoskeletal element β-tubulin-III (bTubIII). To explore mechanisms underlying these effects in SNCA^(Dupl) neurons, we used CRISPR-Cas9 to generate isogenic...

The age-associated neurodegenerative disorder, Lewy body dementia (LBD), encompasses neuropsychiatric symptom-overlapping Dementia with Lewy bodies (DLB) and Parkinson's Disease with Dementia (PDD). We characterised how differential mitochondrial DNA (mtDNA) profiles contribute to neurotype-specific neurodegeneration and thereby clinicopathological heterogeneity, between LBD's syndromes. We further characterised key nuclear-encoding genes' recalibrations in response to such mtDNA changes. In...

Fatigue is a nonmotor symptom that negatively affects Parkinson's disease (PD) patients' quality of life. The study of fatigue is complex and the brain functional neural underpinnings of fatigue in PD are yet to be clarified. The aim of this study was to investigate the functional connectivity (FC) of the fatigue brain network in PD-related fatigue symptomatology. Forty-nine PD patients, divided into PD patients with fatigue (PD-f) and PD patients with no fatigue (PD-nf), and 33 healthy controls...

Advancements in human induced pluripotent stem cell (hiPSC) technology have enabled co-culture models for disease modeling in physiologically relevant systems. However, co-culturing protocols face challenges in usability and consistency. Here, we introduce a robust, reproducible hiPSC-derived co-culture system integrating astrocytes, neurons, and microglia. This model leverages cryopreserved cells, enabling co-cultures within 20 days post-thaw. Comparing monocultures and tricultures, we...

The role of beta band activity in cortico-basal ganglia interactions during motor control has been studied extensively in resting-state and for simple movements, such as button pressing. However, little is known about how beta oscillations change and interact in more complex situations involving rapid changes of movement in various contexts. To close this knowledge gap, we combined magnetoencephalography (MEG) and local field potential recordings from the subthalamic nucleus (STN) in Parkinson's...

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Defining how amyloid-β and pTau together lead to neurodegeneration is fundamental to understanding Alzheimer's disease (AD). We used imaging mass cytometry to identify neocortical neuronal subtypes lost with AD in post-mortem brain middle temporal gyri from non-diseased and AD donors. Here we showed that L5,6 RORB^(+)FOXP2^(+) and L3,5,6 GAD1^(+)FOXP2^(+) neurons, which accumulate amyloid-β intracellularly from early Braak stages, are selectively vulnerable to degeneration in AD, while L3...