Background A significant proportion of individuals maintain cognition despite extensive Alzheimer’s disease (AD) pathology, known as cognitive resilience. Understanding the molecular mechanisms that protect these individuals could reveal therapeutic targets for AD. Methods This study defines molecular and cellular signatures of cognitive resilience by integrating bulk RNA and single-cell transcriptomic data with genetics across multiple brain regions. We analyzed data from the Religious Order Study and the Rush Memory and Aging Project (ROSMAP), including bulk RNA sequencing (n = 631 individuals) and multiregional single-nucleus RNA sequencing (n = 48 individuals). Subjects were categorized into AD, resilient, and control based on β-amyloid and tau pathology, and cognitive status. We identified and prioritized protected cell populations using whole-genome sequencing-derived genetic variants, transcriptomic profiling, and cellular composition. Results Transcriptomics and polygenic risk analysis position resilience as an intermediate AD state. Only GFAP and KLF4 expression distinguished resilience from controls at tissue level, whereas differential expression of genes involved in nucleic acid metabolism and signaling differentiated AD and resilient brains. At the cellular level, resilience was characterized by broad downregulation of LINGO1 expression and reorganization of chaperone pathways, specifically downregulation of Hsp90 and upregulation of Hsp40, Hsp70, and Hsp110 families in excitatory neurons. MEF2C, ATP8B1, and RELN emerged as key markers of resilient neurons. Excitatory neuronal subtypes in the entorhinal cortex (ATP8B+ and MEF2Chigh) exhibited unique resilience signaling through activation of neurotrophin (BDNF-NTRK2, modulated by LINGO1) and angiopoietin (ANGPT2-TEK) pathways. MEF2C+ inhibitory neurons were over-represented in resilient brains, and the expression of genes associated with rare genetic variants revealed vulnerable somatostatin (SST) cortical interneurons that survive in AD resilience. The maintenance of excitatory-inhibitory balance emerges as a key characteristic of resilience. Conclusions We have defined molecular and cellular hallmarks of cognitive resilience, an intermediate state in the AD continuum. Resilience mechanisms include preserved neuronal function, balanced network activity, and activation of neurotrophic survival signaling. Specific excitatory neuronal populations appear to play a central role in mediating cognitive resilience, while a subset of vulnerable interneurons likely provides compensation against AD-associated hyperexcitability. This study offers a framework to leverage natural protective mechanisms to mitigate neurodegeneration and preserve cognition in AD.

Background A significant proportion of individuals maintain cognition despite extensive Alzheimer’s disease (AD) pathology, known as cognitive resilience. Understanding the molecular mechanisms that protect these individuals could reveal therapeutic targets for AD. Methods This study defines molecular and cellular signatures of cognitive resilience by integrating bulk RNA and single-cell transcriptomic data with genetics across multiple brain regions. We analyzed data from the Religious Order Study and the Rush Memory and Aging Project (ROSMAP), including bulk RNA sequencing (n = 631 individuals) and multiregional single-nucleus RNA sequencing (n = 48 individuals). Subjects were categorized into AD, resilient, and control based on β-amyloid and tau pathology, and cognitive status. We identified and prioritized protected cell populations using whole-genome sequencing-derived genetic variants, transcriptomic profiling, and cellular composition. Results Transcriptomics and polygenic risk analysis position resilience as an intermediate AD state. Only GFAP and KLF4 expression distinguished resilience from controls at tissue level, whereas differential expression of genes involved in nucleic acid metabolism and signaling differentiated AD and resilient brains. At the cellular level, resilience was characterized by broad downregulation of LINGO1 expression and reorganization of chaperone pathways, specifically downregulation of Hsp90 and upregulation of Hsp40, Hsp70, and Hsp110 families in excitatory neurons. MEF2C, ATP8B1, and RELN emerged as key markers of resilient neurons. Excitatory neuronal subtypes in the entorhinal cortex (ATP8B+ and MEF2Chigh) exhibited unique resilience signaling through activation of neurotrophin (BDNF-NTRK2, modulated by LINGO1) and angiopoietin (ANGPT2-TEK) pathways. MEF2C+ inhibitory neurons were over-represented in resilient brains, and the expression of genes associated with rare genetic variants revealed vulnerable somatostatin (SST) cortical interneurons that survive in AD resilience. The maintenance of excitatory-inhibitory balance emerges as a key characteristic of resilience. Conclusions We have defined molecular and cellular hallmarks of cognitive resilience, an intermediate state in the AD continuum. Resilience mechanisms include preserved neuronal function, balanced network activity, and activation of neurotrophic survival signaling. Specific excitatory neuronal populations appear to play a central role in mediating cognitive resilience, while a subset of vulnerable interneurons likely provides compensation against AD-associated hyperexcitability. This study offers a framework to leverage natural protective mechanisms to mitigate neurodegeneration and preserve cognition in AD.

Microglia are resident immune cells of the central nervous system (CNS) and critical regulators of neural homeostasis, mediating immune surveillance, synaptic remodeling, debris clearance, and inflammatory signaling. Emerging evidence highlights the extracellular matrix (ECM) as important to microglial behavior in both physiological and pathological contexts. The CNS ECM is a dynamic and bioactive scaffold composed of three primary compartments: interstitial matrix, basement membranes at neurovascular and neuroepithelial interfaces, and perineuronal nets (PNNs). Each compartment exhibits distinct molecular architectures, ranging from fibrillar collagens and glycoproteins in basement membranes to chondroitin sulfate proteoglycans and hyaluronan-rich structures in PNNs. In this review we examine how microglia engage with and reshape the ECM to dynamically respond to disruptions in homeostasis with aging and disease. We discuss the concept of the microglial–ECM “interactome”, which may represent a molecular interface through which microglia sense, modify, and respond to their extracellular environment. This interactome enables microglia to enact fine-scale ECM remodeling during routine surveillance, as well as large-scale alterations under pathological conditions to help preserve function and motility. In aging and disease, dysregulation of the microglial-ECM interactome is characterized by aberrant mechanotransduction, elevated proteinase activity, remodeling of the ECM, and sustained pro-inflammatory cytokine release. These pathological changes compromise ECM integrity, challenge microglial activity, and contribute to progressive neurovascular and synaptic dysfunction. Deciphering the molecular mechanisms underpinning microglial–ECM interactions is essential for understanding region-specific vulnerability in neurodegeneration and may reveal new therapeutic targets for preserving ECM structure and countering CNS disorders.

The Hippo signaling pathway is well-known for its regulation of organ size, cell proliferation, apoptosis, and cell migration and differentiation. Recent studies have demonstrated that Hippo signaling also plays important roles in the nervous system, being involved in neuroinflammation, neuronal differentiation, and neuronal death and degeneration. As such, dysregulation of Hippo signaling, particularly of its core kinases MST1/2 and LATS1/2, has begun to attract attention in the Alzheimer’s disease (AD) field. Here, we discuss the therapeutic potential of targeting the Hippo pathway in AD by providing an overview of Hippo signaling with regards to its function in the nervous system, evidence for its dysregulation in AD patients and models, and recent studies involving genetic or pharmacological modulation of this pathway in AD.

Background Proteostasis, in particular the impairment of autophagic activity, is linked to sleep dysregulation and is an early sign of dementias including Alzheimer’s disease (AD). This coupling of events may be a critical alteration driving proteinopathy and AD progression. In the present study, we investigated sleep–wake and memory regulating neurons for vulnerability to autophagic impediment, and related these findings to progression of the sleep and cognitive phenotype. Methods Using the double knock-in AD mouse model, AppNL−G−FxMAPT, we examined phenotypic and pathological alterations at several timepoints and compared to age-matched single knock-in MAPT mice. Spatial learning, memory and executive Function were investigated in the Barnes maze. Sleep was investigated by 24-h locomotor activity and EEG. Immunostaining for autophagic, neuronal and pathological markers was conducted in brain regions related to memory (hippocampus, prefrontal cortex, entorhinal cortex) and the sleep–wake cycle (hypothalamus, locus coeruleus). Hippocampal electrophysiological recordings were conducted to probe neuronal Function during object investigation. A 3-day sleep disruption was conducted in MAPT mice to investigate autophagic changes following sleep loss. Autophagy was activated in MAPT mice with trehalose to probe effects on sleep recovery. Results We identified that disrupted sleep occurred from early-stages in AppNL−G−FxMAPT mice, that sleep declined over age, and sleep deficits preceded cognitive impairments in late-stages. Cytoplasmic autophagic impediment in hypothalamic and locus coeruleus sleep–wake neurons occurred in early-stage AppNL−G−FxMAPT mice, prior to significant β-amyloid deposition in these regions, with a failure of lysosomal flux over disease progression. Autophagic changes in the hippocampus and cortex at early-stage were predominantly in processes and less frequently associated with the lysosome. Plaque-associated autophagic and lysosomal accumulations were frequent from the early-stage. Sex differences in the AD phenotype were prominent, including greater cognitive decline in males than females, linked to increased proteostasis burden in EC layer II neurons and hippocampal tau in the late-stage. Conversely, sleep impairments were more rapid in females including less REM sleep recovery than males, along with greater autophagic burden in hippocampal processes of female AppNL−G−FxMAPT mice. We probed the sleep-cognition linkage demonstrating hippocampal electrophysiological slowing during cognitive processing in mid-stage AppNL−G−FxMAPT mice, prior to cognitive decline. We provide evidence for a positive feedback loop in the autophagic-sleep relationship by demonstrating that disrupted sleep in MAPT mice led to arrhythmic sleep patterns and accumulations of autophagic aggregates in the hippocampus and hypothalamus, similar to as was seen in the early Alzheimer’s phenotype. We further probed the autophagy-sleep linkage by treating MAPT mice with trehalose to activate autophagy and demonstrate an improvement in sleep recovery following a sleep disruption. Conclusions These findings demonstrate the vulnerability of sleep-regulating neurons to proteostatic dysfunction and the sleep-autophagy linkage as an early, and treatable, Alzheimer’s disease mechanism. Graphical Abstract Morrone et al provide evidence for the linkage between sleep and autophagic disruptions in Alzheimer’s disease (AD) progression. At early AD stages, sleep-wake regulating neurons in the hypothalamus and locus coeruleus exhibit increased cytoplasmic inclusions concomitant with the onset of sleep disturbances. Early-stage autophagic aggregates in the hippocampus appear more prominently in neuronal processes and in the cortex linked to plaques. This pathology worsens over AD progression, including advanced sleep and cognitive deficits, autophagic aggregates in entorhinal cortex-hippocampus projecting neurons. Disrupting sleep in control mice mimics the hippocampal, hypothalamic and sleep patterns impairments observed in early-stage AD, and therapeutic activation of autophagy improves sleep recovery. See also Table 1 for a summary of changes along with sex differences in autophagy and behavioral readouts.

Background Parkinson’s disease (PD) affects millions of people worldwide, but only 5–10% of patients suffer from a monogenic forms of the disease with Mendelian inheritance. SNCA, the gene encoding for the protein alpha-synuclein (aSyn), was the first to be associated with familial forms of PD and, since then, several missense variants and multiplications of the gene have been established as rare causes of autosomal dominant forms of PD. In this study, we report the identification of a novel SNCA mutation in a patient that presented with a complex neurogenerative disorder, and unconventional neuropathological findings. We also performed in depth molecular studies of the effects of the novel aSyn mutation. Methods A patient carrying the novel aSyn missense mutation and the family members were studied. We present the clinical features, genetic testing—whole exome sequencing (WES), and neuropathological findings. The functional consequences of this aSyn variant were extensively investigated using biochemical, biophysical, and cellular assays. Results The patient exhibited a complex neurodegenerative disease that included generalized myocloni, bradykinesia, dystonia of the left arm and apraxia. WES identified a novel heterozygous SNCA variant (cDNA 40G > A; protein G14R). Neuropathological examination showed extensive atypical aSyn pathology with frontotemporal lobar degeneration (FTLD)-type distribution and nigral degeneration pattern with abundant ring-like neuronal inclusions, and few oligodendroglial inclusions. Sanger sequencing confirmed the SNCA variant in one healthy, 86-year-old parent of the patient suggesting incomplete penetrance. NMR studies suggest that the G14R mutation induces a local structural alteration in aSyn, and lower thioflavin T binding in in vitro fibrillization assays. Interestingly, the G14R aSyn fibers display different fibrillar morphologies than Lewy bodies as revealed by cryo-electron microscopy. Cellular studies of the G14R variant revealed increased inclusion formation, enhanced membrane association, and impaired dynamic reversibility of serine‐129 phosphorylation. Conclusions The atypical neuropathological features observed, which are reminiscent of those observed for the G51D aSyn variant, suggest a causal role of the SNCA variant with a distinct clinical and pathological phenotype, which is further supported by the properties of the mutant aSyn.

Alzheimer’s disease (AD) risk and progression are significantly influenced by APOE genotype with APOE4 increasing and APOE2 decreasing susceptibility compared to APOE3. While the effect of those genot...

To define how Aβ pathology alters microglia function in Alzheimer’s disease, we profiled the microglia surfaceome following treatment with Aβ fibrils. Our findings reveal that Aβ-associated human micr...

The autophagy-lysosomal pathway is crucial for maintaining homeostasis and survival of neurons, hence defects in this system have been associated with neurodegeneration, including Parkinson's disease ...

Background Alzheimer’s disease (AD) is the most common type of dementia. Genetic polymorphisms are associated with altered risks of AD onset, pointing to biological processes and potential targets for...

Diagnosis of Frontotemporal dementia (FTD) and its specific underlying neuropathologies (frontotemporal lobar degeneration; FTLD-Tau and FTLD-TDP) are challenging, and thus, fluid biomarkers are neede...

Lewy body dementia (LBD) is a neurodegenerative disorder characterized by a combination of progressive dementia and spontaneous parkinsonian symptoms. As the second most prevalent form of neurodegener...

Background Pathogenic variants in LRRK2 lead to increased kinase activity, and LRRK2 kinase inhibition is being explored in clinical studies as a therapeutic approach for Parkinson’s Disease (PD). LRR...

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease affecting the adult motor system, with no effective treatments available. Despite extensive research efforts, the exact p...

Although different neurodegenerative diseases are defined by distinct pathological proteins, they share many common features including protein aggregation. Despite this commonality, most current thera...

Background Alzheimer’s disease (AD) is a multifaceted neurodegenerative disorder with a complex etiology that extends beyond the well-documented amyloid-β and tau pathologies. Growing evidence implica...