Alzheimer & Parkinson

Alzheimer's disease (AD) disproportionately affects women, yet mechanisms underlying this sex difference remain unclear. Histone variants are overrepresented components of aging neuronal chromatin, but their contribution to AD is unknown. Here, we identify the histone variant H2A.Z as a sex-specific regulator of AD in the postmortem human hippocampus and in 5xFAD mice. H2A.Z occupancy decreased in female but increased in male AD patients. In females, reduced H2A.Z occupancy at the transcription...

Alzheimer's disease (AD) is the most common cause of dementia and remains without a cure; recently introduced disease-modifying therapies provide only modest slowing in selected patients. Physical exercise is associated with better cognitive and functional outcomes, but the molecular mechanisms underlying these benefits remain incompletely understood. DNA methylation is a potential interface linking environmental stimuli to gene regulation and neural function. This narrative review examines...

Cellular senescence, characterized as a permanent arrest of cell proliferation, is triggered by various types of stress. Senescent cells are identified by markers, including senescence-associated β-galactosidase (SA-β-gal) activity and the secretion of senescence-associated secretory phenotype (SASP) factors. These senescent phenotypes have been observed in neurons, suggesting that cellular senescence may contribute to the pathogenesis of neurodegenerative diseases. Humanin (HN), an endogenous...

The consequences of oligodendrocyte involvement in Alzheimer's disease are poorly understood. Could a key role of gray-matter oligodendrocytes-activity-dependent adaptive myelination to sustain changes in activity-be perturbed, leading to cognitive loss?

Metabotropic glutamate receptor 5 (mGlu5) is essential for synaptic plasticity and memory, making it a potential therapeutic target in Alzheimer's disease (AD). While hemispheric asymmetries in hippocampal function have been observed in AD patients, the lateralized contribution of mGlu5 signaling to cognitive decline remains unclear. Here, we show a physiological left-right asymmetry in hippocampal mGlu5 expression in wild-type mice, with higher levels in the left hemisphere, consistent with...

Parkinson's disease (PD) is a systemic disorder linked to gut dysbiosis, yet key microbiota-regulated metabolites remain unclear. Here, we observe elevated taurochenodeoxycholic acid (TCDCA) in patients with PD that correlates with disease severity. Reduced bile salt hydrolase (BSH) gene abundance correlates inversely with circulating TCDCA, consistent with altered bile acid deconjugation. Exogenous TCDCA correlates with aggravated motor and gastrointestinal deficits, impaired blood-brain...

Tau phosphorylation is classically associated with neurodegeneration, yet similar phosphorylation patterns emerge during physiological states and acute stress responses. How these overlapping patterns of phosphorylated Tau (pTau) relate to neuronal adaptation and Alzheimer's disease pathology remains unresolved. We synthesize findings from human to rodent and fly brains and from neuronal cell models, across neurodevelopment, sleep, hibernation, cellular stress, and disease. Across these...

Alzheimer's disease (AD) presents distinct extracellular, intracellular and vascular delivery targets, yet brain exposure of candidate therapeutics remains difficult to establish. This narrative review compares hyaluronic acid, chitosan, cyclodextrin, dextran, alginate and pectin systems by construct architecture, route, blood-brain barrier (BBB) evidence, cargo release and biological response. The literature includes covalent drug conjugates, loaded or coated carriers, host-guest complexes and...

Synaptojanin 1 is a brain enriched phosphoinositide phosphatase implicated in endocytosis at the synapse. A mutation (R258Q) that selectively impairs its Sac1 phosphatase domain causes early onset familial Parkinsonism. Neurons of mice with this mutation display synaptic vesicle traffic defects across the brain, but selective dystrophic changes in a subset of dopaminergic axons in the dorsolateral striatum. Using correlative light microscopy-FIB-SEM of mutant mouse striata to visualize in 3D...

A growing body of preclinical research is demonstrating the therapeutic potential of chronic, continuous hypoxia (11% FIO(2)) for rare and common diseases. However, the chronic delivery of hypoxic gas poses both practical challenges and long-term safety concerns. We previously introduced a small-molecule, "hypoxia-in-a-pill" combining a hemoglobin affinity enhancer (GBT440) to limit oxygen delivery with a HIF-2α inhibitor (PT2399) to prevent detrimental compensatory erythropoiesis. Although this...

The proteostasis network (PN) safeguards the integrity of proteins by promoting various cellular activities. However, with aging, the PN's competence declines and aggregated proteins accrue within cells. This process underlies the development of neurodegenerative disorders such as Alzheimer's and Huntington's diseases. While the PN functions within cells, proteostasis is regulated across the organism by intertissue communication, which is partially governed by neurons. We previously found that...

Aging is associated with cognitive deterioration accompanied by a reduction in hippocampal neurogenesis. Murine models have been widely used to study aging and age-related cognitive decline, as they recapitulate many of the key features of the degenerative process. Among these, the SAMP8 strain represents a well-established model of accelerated aging, characterized by early-onset and progressive cognitive impairment, Alzheimer's disease-like neuropathology, and an initial increase in hippocampal...

Despite prolific genomic data from individuals with Alzheimer's disease (AD), translation into treatments has lagged. Here we applied Mendelian randomization to multiple AD genome-wide association studies and functional multiomics datasets to nominate druggable targets, identifying 19 targets for individuals of European ancestry and 7 for African ancestry. This included epoxide hydrolase 2 (EPHX2), for which we identified a protective missense variant (p.Arg287Gln). Experiments in induced...

Microglia are the primary immune cells of the brain, but their role in Parkinson's disease is not fully understood. Chronic microglial activation is toxic to neurons, but in the early stages of pathology, microglia also exert beneficial functions. We used induced pluripotent stem cell (iPSC)-derived coculture models to investigate how human microglia respond to α-synuclein aggregates that form de novo inside human dopaminergic neurons with α-synuclein gene triplication or are triggered by...

Nutritional status and metabolic homeostasis are intricately associated with the inflammatory response. However, the direct mechanistic link between nutrition, metabolism and inflammation remains unclear. Here, we show that the amino acid L-arginine (L-Arg) is a potent endogenous inhibitor of the NLRP3 inflammasome, a central component of the inflammatory signalling pathway. We show that L-Arg binds directly to the Asp31 site of the NLRP3 protein, blocking its interaction with the adaptor ASC...

Cognitive decline in Parkinson's disease (PD), progressing from mild cognitive impairment (PD-MCI) to severe dementia (PD-D), is a debilitating core feature driven by complex neuropathological interactions. While α-synuclein accumulation is the disease's hallmark, co-pathologies involving amyloid-β and tau, alongside chronic neuroinflammation, are critical accelerators of cognitive collapse. This review positions the receptor for advanced glycation end products (RAGE) as a key molecular...

Anti-amyloid antibodies substantially reduce amyloid plaque burden, yet the resulting cognitive benefit remains modest, exposing a limitation in the conventional storage-and-deletion model of memory. We propose that Alzheimer's disease (AD) is better understood as a progressive failure of the dynamic processes that continuously reconstruct memory and bind it to conscious experience, rather than static deletion of stored content following synaptic loss. Amyloid-beta oligomers and mislocalized tau...

Proprioceptive deficits are a core feature of Parkinson's disease (PD), but the neural mechanisms by which transcranial direct current stimulation (tDCS) may augment proprioceptive learning remain unknown. This study investigated whether six sessions of anodal tDCS combined with proprioceptive training modulates EEG‑derived aperiodic activity, Lempel‑Ziv complexity (LZC), and theta clustering in individuals with PD. Twenty‑four participants with mild‑to‑moderate PD were randomly assigned to...

Reduction in brain weight is a hallmark feature of human aging, which is exacerbated in pathologies, such as Alzheimer's disease and other dementias. However, it remains unclear whether a decrease in brain weight with age reflects a vulnerability unique to the human lineage or represents a consequence of an extension of aging processes shared with other primates. To address this question, we examined age-related changes in brain weight across our closest living relatives, the great apes...

Endosomal NHE6 (SLC9A6) and NHE9 (SLC9A9) transporters are essential for maintaining pH homeostasis within endosomes and their dysfunction has been linked to neurological and neurodegenerative disorders. NHE6 and NHE9 are widely considered to function as electroneutral exchangers that couple the export of protons to the import of sodium or potassium ions across cellular membranes, thereby forming the basis of proton leak pathways for internal pH balancing and fine-tuning. Among the 13 identified...