bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Impact of Mild Episodic Memory Difficulties on Everyday Tasks in Older Adults
Authors: Tassoni Molly B. , Cutrone Una , Simone Stephanie M. , Holmqvist Sophia L. , Mckniff Moira , Halberstadter Kimberly , Kaplan Marina , Chaturvedi Riya , Rosahl Melissa , Callahan Anna , Giovannetti Tania
Published: January 2025

Background

The Goal‐Control Model posits that episodic memory impairment leads to premature decay of everyday task goals, which contributes to task omissions (failure to accomplish task steps) in those with moderate to severe impairment. Although task omissions are not observed in those with mild episodic memory (mildEM) impairment, it has yet to be investigated if goal decay is reflected by subtle errors during task completion. We hypothesized that goal decay in mildEM impairment is reflected by imprecision in task performance at the end of everyday tasks.

Method

54 participants (M age = 73; 39 healthy control [HC], 15 MCI/mild dementia) were videorecorded while preparing a breakfast and a lunch according to specific instructions (Naturalistic Action Task). Performance errors were classified by two coders and another organized them into segments occurring in the beginning, middle or end of the task, all blind to participant diagnosis and study hypothesis. Analyses compared errors in each segment between those with mildEM impairment (MCI/mild dementia) and HC. Correlation analyses examined relations between errors and demographically adjusted standard scores on tests of episodic memory (HVLT and BVMT‐R delayed free recall) and executive function (Digits Backward, Trail Making Test B).

Result

Participants with mildEM impairment made significantly more errors than healthy controls only during the end task segment, t(52) = 2.83, p = .04. The groups did not differ in total errors during the beginning (p = .35) or middle task segments (p = .08). Correlations including the full sample showed significant relations between total errors during the end segment and scores on tests of episodic memory (HVLT r = ‐.33, p = .01; BVMT r = ‐.37, p <.01) but not scores on tests of executive function (Digits Backward r = .01, p = .92; TMT‐B r = .01, p = .97).

Conclusion

Consistent with hypotheses informed by the Goal‐Control Model, older adults with mildEM impairment exhibited increased imprecision towards the end of the task, suggesting that even those with mildEM deficits can experience premature decay of task goals. Behavioral strategies to strengthen goal activations, including reminder cues and/or overt verbalization of task goals, should be investigated as an avenue to improve everyday function in older adults with mild memory difficulties.
Early hippocampal hyperexcitability precedes synaptic reorganization in mouse models of amyloidosis
Authors: Ray Ajit , Loghinov Iulia , Barth Alison L
Published: January 2025

Background

The failure of amyloid plaque‐reducing drugs to reverse cognitive decline in Alzheimer’s disease (AD) has suggested that treatments might be more effective in early or prodromal stages of the disease. However, the progression of synaptic and circuit changes associated with Aβ overexpression, particularly at very early ages, have not been well‐characterized. Indeed, evidence from both human and animal studies indicates that brain structure and function might be altered months to years before plaques can be detected.

Method

Here we used quantitative, fluorescence‐based methods for synapse detection in CA1 pyramidal neurons (Pyr) to investigate the interaction between abnormal circuit activity, measured by Fos‐immunoreactivity (Fos‐IR), and synapse reorganization in mouse models of amyloidosis.

Result

Using a fluorescently‐tagged molecule (FAPpost) for both excitatory and inhibitory synapses, we find that Aβ overproduction is associated with early synapse gain and loss, depending on the dendritic compartment. Juvenile APP/PS1 and Tg2576 transgenic mice both show a reduction in synapses at the apical tuft of CA1 Pyr and an increase in synapse density along the apical dendrite, which receives inputs from CA3 in animals. These effects were observed at just 6 weeks of age, well before cognitive deficits and amyloid plaques can be detected. Elevated hippocampal activity precedes this reorganization, with elevated Fos‐IR in both CA3 and CA1 present at weaning.

Conclusion

These data indicate that elevated Aβ may initiate abnormal activity and subsequently input‐specific synapse plasticity. Taken together, our findings indicate that sustained amyloidosis drives heterogeneous and progressive circuit‐wide abnormalities.
Shared transcriptomic similarities between mouse and C. elegans transgenic models of Alzheimer’s disease
Authors: Ryssina Vitória Vitalina Margarita , De Bastiani Marco , Pereira Flávia Suelen De Oliveira , Carello‐Collar Giovanna , Zimmer Karine Rigon , Zimmer Eduardo R.
Published: January 2025

Background

The molecular mechanisms associated with Alzheimer’s Disease (AD) have been extensively studied in mouse models (Mus musculus). However, experimental research in these models is costly and time‐consuming. In this context, the nematode Caenorhabditis elegans (C. elegans) is an interesting alternative model for studying AD. Nonetheless, whether C. elegans and mouse models of AD share transcriptomic similarities remains unclear. Thus, this study aims to investigate the transcriptomics overlap between C. elegans and M. musculus AD models.

Method

We obtained hippocampus and whole‐body transcriptomics data, respectively, from transgenic strains of AD mice (APP/PS1 and 3xTg) and C. elegans (RB809, GMC101, and CL4176) from the NCBI GEO database. The nematode strain RB809 presents a mutation in the microtubule‐associated protein homolog to human Tau. GMC101 and CL4176 strains aggregate the amyloid‐beta peptide (Aβ). We performed differential expression analysis (DEA) (FDR‐adjusted p‐value < 0.05) using the DESeq2 and Limma package to evaluate the differentially expressed genes (DEGs). Additionally, we conducted a functional enrichment analysis (FEA) to obtain Gene ontology of Biological Processes (GOBP) and Molecular Function (GOMF) terms (p‐value < 0.01).

Result

The pattern of gene expression can be visualized in Figure 1A. All nematode strains exhibited greater similarity with APP/PS1 mice compared to the 3xTg. Specifically, 94 DEGs were identified as shared between APP/PS1 mice and nematode strain RB809 (Figure 1B). Concerning GMC101 and CL4176 strains, 41 and 12 DEGs were found shared, respectively. FEA analysis revealed GOBP terms shared among models involved in similar biological processes (Figure 2). Notably, “Aβ binding”, “calcium ion homeostasis”, “neuroinflammatory response”, and “regulation of inflammatory response” (Figure 3) were identified.

Conclusion

Our results indicate significant overlaps in genes and biological processes associated with AD and neurodegeneration between AD nematode and mice models, highlighting the translational conservation of fundamental pathological mechanisms. The differences in expression and processes between the various strains of C. elegans and the mouse models offer a unique window to investigate specific molecular aspects of AD.
Synergistic effects of α‐synuclein, tau, and amyloid pathology on mitophagy in dementia with Lewy bodies
Authors: Hou Xu , Richardson Tyrique , Fiesel Fabienne C , Heckman Michael G. , Koga Shunsuke , Dickson Dennis W. , Springer Wolfdieter
Published: January 2025

Background

Directed by the enzyme pair PINK1 and PRKN, mitophagy is a crucial mitochondrial quality control mechanism that selectively decorates damaged mitochondria with phosphorylated ubiquitin (pS65‐Ub), facilitating their lysosomal degradation. The dynamic pS65‐Ub signal accumulates upon enhanced activation from increased mitochondrial damage or upon reduced autophagic‐lysosomal flux. Previous studies including ours demonstrated altered mitophagy and elevated pS65‐Ub levels in Parkinson’s and Alzheimer’s disease brains that also independently associated with α‐synuclein, tau, or amyloid pathology. However, their combined impact on mitophagy and organelle function remains unclear. Notably these three pathologies often coexist in susceptible brain areas of a neurodegenerative condition named dementia with Lewy bodies (DLB). We herein investigated the interactions of α‐synuclein, tau, and amyloid pathology to uncover their combined effects on mitophagy in a large DLB cohort.

Method

This study included 371 DLB autopsy brains with neurologically normal cases as controls. Immunohistochemistry for the mitophagy marker pS65‐Ub in the hippocampus and amygdala was performed and associations of pS65‐Ub levels with neuropathological measures from the same region were evaluated. Immunofluorescence co‐staining of pS65‐Ub, phospho‐α‐synuclein, and phospho‐tau was conducted to study their interactions at single‐cell level.

Result

pS65‐Ub positive cells were significantly more abundant in the hippocampus and amygdala of DLB cases compared to controls. Significant associations were observed between pS65‐Ub levels with age, brain weight, Braak stage, Thal phase as well as counts of Lewy body (LB), neurofibrillary tangle (NFT), and senile plaque (SP) in both regions. Strong synergistic effects of LB and NFT pathologies on pS65‐Ub accumulation were found in the amygdala, while only additive effects of LB and SP pathologies were observed. Single‐cell analysis in the amygdala showed that most affected cells contained either LB or NFT inclusion rather than co‐residing two pathologies within the same cell. Notably, cells harboring LB pathology exhibited mainly smaller, granular pS65‐Ub deposits (type G), possibly associated with increased mitochondrial dysfunction. Conversely, those containing NFT showed larger, vacuolar pS65‐Ub deposits (type V), likely resulting from reduced lysosomal degradation.

Conclusion

Our study revealed complex interactions of α‐synuclein, tau, and amyloid pathology on mitophagy alteration in DLB brains, highlighting different molecular mechanisms underlying α‐synuclein‐ and tau‐associated mitophagy alterations.
Environmental Triggers for Different Behavioral Symptom Clusters
Authors: Pickering Carolyn E , Winstead Vicki , Yildiz Mustafa
Published: January 2025

Background

We have previously shown that there are 3 unique behavioral symptom clusters, or groupings of temporally related co‐occurring behavioral and psychological symptoms (BPSD) representing how an individual’s daily BPSD group together relative to their own typical BPSD manifestation across a 21‐day period. To further validate these symptom cluster concepts, we examined whether they are predicted by different environmental triggers.

Method

Family caregivers completed daily diary surveys for 8 consecutive days reporting on the physical, social and care environment in addition to their care recipients different BPSD. Guided by the unmet needs theory, progressively lowered stress threshold theory and environmental theory of BPSD, we used a generalized linear mixed model to assess the effects of different hypothesized environmental triggers on the likelihood of the previously identified symptom clusters manifesting the same day.

Result

The behavioral symptom cluster had significant 2 unique predictors, routine disruption (OR 19, p = 0.005) and skipped care that same day (OR 2, p = 0.005). The psychological‐mood symptom cluster had 5 unique predictors including daily social demands (OR 1.59, p = 0.046), participating in household chores that day (OR 0.38, p = 0.025), number of prescription medications (OR 1.03, p<.001), number of routine over‐the‐counter medications (OR 1.08, p<.001) and larger household composition size (OR 1.28, p<.001). Finally, the psychosis‐like symptom cluster was predicted by use of pain medication that same day (OR 1.51, p = 0.49).

Conclusion

These findings validate that the symptom clusters are mechanistically unique concepts. The findings also highlight modifiable environmental targets that could help to prevent or reduce the occurrence of BPSD. Importantly, findings highlighted the importance of novel concepts like social demands (e.g., decision‐making that is beyond the person with dementia’s capacity) and unmanaged pain in the etiology of BPSD. The increased likelihood of the psychological‐mood cluster due to increased household size may indicate other aspects of the physical environment like noise and available space may impact BPSD.
xploring Neuromelanin Accumulation in the Locus Corelulus: Implications for Early Alzheimer’s Disease Pathology
Authors: Hassanein Leslie , Weinshenker David , Lab Weinshenker
Published: January 2025

Background

Alzheimer’s Disease (AD) is a pressing global health concern, particularly among the elderly population. Early detection and intervention are vital for effective management. Recent research has identified the Locus Corelulus (LC) as one of the initial sites of pathology in AD, characterized by the degeneration of norepinephrine (NE) producing cells, resulting in cognitive and mood disturbances. This study investigates the relationship between neuromelanin (NM) and AD pathology, focusing on its accumulation in the LC. NM, a pigment‐like substance synthesized from catecholamine neurotransmitters such as NE, has been proposed to have a neuroprotective role. However, its potential toxicity remains unexplored.

Method

We employed a novel approach involving the introduction of NM production in mice using a cre‐dependent human tyrosinase (hTyr) virus. This technique allowed us to observe significant NM accumulation in the LC and the emergence of neurodegenerative disease‐like phenotypes in mice. Our investigations extended to examining LC‐NE dependent behavior, NM accumulation, and cell death at distinct time points (1, 6, and 10 weeks).

Result

Our results show a longitudinal degradation of the LC, with almost complete loss of the region at 6 weeks.

Conclusion

The progressive LC loss and behavioral changes suggest NM’s involvement in AD pathogenesis. Further research is needed to explore NM‐induced neurodegeneration and its potential for early AD detection and intervention.
Polytranscriptomic risk score for Alzheimer Disease in a large diverse multi‐center brain bank study
Authors: Cieza Basilio , Yang Zikun , Reyes‐Dumeyer Dolly , Lee Annie J. , Dugger Brittany N , Jin Lee‐Way , Murray Melissa E. , Dickson Dennis W. , Pericak‐Vance Margaret A , Vance Jeffery M. , Foroud Tatiana M. , Mayeux Richard , Tosto Giuseppe
Published: January 2025

Background

Alzheimer’s disease (AD) missing heritability remains extensive despite numerous genetic risk loci identified by genome‐wide association or sequencing studies. This has been attributed, at least partially, to mechanisms not currently investigated by traditional single‐marker/gene approaches. Polygenic Risk Scores (PRS) aggregate sparse genetic information across the genome to identify individual genetic risk profiles for disease prediction and patient risk stratification. Recent advancements have pivoted on innovative approaches utilizing OMICS data to construct such risk scores.

Method

We employed a random forest algorithm to identify a list of gene candidates from bulk RNA sequencing data in prefrontal cortex from 565 AD brain samples (non‐Hispanic Whites, n = 399; Hispanics, n = 113; African American, n = 12) across six U.S. brain banks. Subsequently, we calculated their effect size on Braak staging using regression models to construct a polytranscriptomic risk score (PTRS). We employed two distinct models: “Ethnicity‐Agnostic” Model (randomly assigning samples to training and testing samples) and “Ethnicity‐Aware” Model (assigning NHW samples to training and Hispanics to testing sample). Analysis of variance and the receiver operating characteristics area under the curve (ROC AUC) was used to evaluate PTRS’s classification performances. We validated findings using the Religious Orders Study/Memory and Aging Project study (ROS/MAP, n = 1,095).

Result

We found a significant difference in PTRS between samples with low vs. high Braak stages (≤4 vs. ≥5, p = 1*E‐04; Figure 1 upper panel). AUC was found to be 79‐81%, consistently in both Ethnicity‐Agnostic and Ethnicity‐Aware models (Figure 1 lower panel). Finally, the PTRS in ROS/MAP yielded a similar classification performance (p = 2*E‐04, AUC = 77%).

Conclusion

contrary to prior studies, we developed a PTRS with optimal transferability across ethnicities. This underscores the importance of developing novel tools to stratify and harmonize large brain repositories for AD.
CRFR1‐Antagonism Ameliorates Early AD Pathology and Alters Stress‐Induced Changes in Pathology
Authors: Ellisman Maya Anne , Sarsoza Floyd , Rissman Robert A.
Published: January 2025

Background

Chronic stress has been linked to an increased risk for various health issues, including Alzheimer’s disease (AD). While novel therapies for AD have improved disease prognosis, a deeper understanding of the link between stress and AD may delineate potential novel preventative treatments. Within the stress system, corticotrophin‐releasing factor receptor 1 (CRFR1) has been shown to influence AD pathological hallmarks. Drugs targeting CRFR1 may elucidate how CRFR1 alters AD and provide a potential novel treatment approach.

Methods

To examine the effects of CRFR1‐antagonism and chronic stress on AD pathology, young WT/PSAPP mice (6‐month) underwent treatment with vehicle/R121919 alongside chronic restraint stress. Then, subjects were assessed with a series of behavioral tests measuring learning, memory, and cognitive flexibility. Additionally, brain regions were immunohistologically analyzed for plaque deposition and biochemically analyzed for various Aβ species.

Results

CRFR1‐antagonist treatment in early AD improves learning and cognitive flexibility, lowers plaque levels throughout the hippocampus and cortex, and lowers highly toxic cortical soluble Aβ oligomers while increasing insoluble Aβ monomers. Chronic restraint stress improves learning and memory, increasing plaques in the hippocampus and lowering cortical plaques while increasing insoluble cortical Aβ monomers. With CRFR1‐antagonism, stress‐induced benefits to learning are more pronounced, yet the stress effects on memory are abolished. At the same time, stress combined with CRFR1‐antagonism lowers the number of cortical plaques and insoluble cortical Aβ monomers, while increasing cortical Aβ soluble oligomers.

Conclusions

CRFR1‐antagonism has the potential to improve and may be beneficial for stress‐induced AD pathogenesis in the early phases of AD.
RARE‐LacZ Mice as a Model to Study of Retinoic Acid Signaling in Alzheimer’s Disease
Authors: Hindle Ashly , Smith Shane , Hernandez Matthew , Baker Adam , Strickland Jake , Medina Jocelyn , Lawrence J. Josh
Published: January 2025

Background

Disrupted balance between amyloidogenic and non‐amyloidogenic pathways leads to cognitive decline in Alzheimer’s disease (AD). Evidence suggests vitamin A (VA) supplementation favors the non‐amyloidogenic pathway through upregulation of α‐secretase. Originally used to map embryonic retinoic acid (RA) signaling, RARE‐LacZ mice possess multiple LacZ genes controlled by retinoic acid response elements (RAREs). We crossed RARE‐LacZ mice with AD mouse models to determine their suitability for quantitative studies into the effects of VA on dentate gyrus (DG) RA signaling and learning in AD.

Methods

Relative LacZ gene copy ratio was determined by qPCR of LacZ in gDNA, normalized to ultra‐conserved region 329. Dietary intervention compared VA supplemented (20 IU/g) AIN‐93M to standard AIN‐93M (4 IU/g VA). Mice were tested at postnatal day (P)125 via water T‐maze (WTM, 9 simple discrimination, 9 reversal trials). PFA‐fixed sections (40µm) were immunostained for LacZ, doublecortin, and/or calbindin, confocally imaged, and analyzed using ImageJ.

Results

RARE‐lacZ mice were first crossed with C57BL/6J, ‐NJ, and CD1 mice (wildtype strains of J20, hAβ‐KI, and RARE‐LacZ mice, respectively). The relative LacZ gene copy ratio was ∼2.6:1 between RARE‐LacZ mice (N = 12) and crosses (N = 34). Values for 32/34 offspring fell within ±50% of the mean. Strain affected latency to platform on WTM during simple discrimination and reversal (N = 11‐12, p<0.05, Friedman), however total distance traveled was unaffected suggesting intact learning in all backgrounds. In WT strains, hippocampal LacZ immunoreactivity was localized to a subset of mature doublecortin‐negative, calbindin‐positive DG granule cells, appearing higher on C57BL/6J and ‐NJ than CD1 backgrounds. Offspring from J20± AD and RARE‐LacZ mice exhibited impaired learning (N = 16, p<0.05, Kolmogorov‐Smirnov). No significant difference in behavior between supplemented (20 IU/g) and standard (4 IU/g) VA was observed in AD mice. However, DG LacZ signal was completely silenced in 7/32 mice evaluated by immunostaining.

Conclusions

RARE‐LacZ mice appear to have behavioral and genetic characteristics appropriate for testing VA‐mediated interventions in AD models. RA signaling is prominent in mature DG cells associated with successful reversal learning. Although reversal of AD‐related learning deficits by VA supplementation was not observed, testing AD mice on a VA deficient (0.4 IU/g) diet is planned.
Sex differences in the impact of arterial stiffness on cerebrovascular function
Authors: Reeve Emily H , Hogan Ainsley P , Cullen Abigail E , Walker Ashley E
Published: January 2025

Background

Stiffening of the large arteries is a hallmark feature of vascular aging and is associated with cognitive impairment and Alzheimer’s disease pathology. Increased large artery stiffness leads to higher‐than‐normal pulse pressure in the cerebral circulation, damaging endothelial cells. It is known that short‐term exposure to stiffer large arteries causes cerebral artery endothelial dysfunction and hypoperfusion in young mice. However, the impact of long‐term exposure to large artery stiffness on cerebrovascular function is unknown. As there are known sex differences in Alzheimer’s disease risk, we sought to understand the influence of sex on the impact of large artery stiffness on cerebrovascular function.

Method

We studied an established model of greater large artery stiffness, the elastin haploinsufficient (Eln±) mouse, at young (6 months) and old (24 months) ages and compared with wildtype (Eln+/+) mice. We measured endothelium‐dependent dilation ex vivo in pre‐constricted, pressurized posterior cerebral arteries by the maximal response to acetylcholine. Nitric oxide bioavailability was determined by the acetylcholine response with and without the presence of L‐NAME, a nitric oxide synthase inhibitor. Endothelium‐independent dilation was assessed by the maximal response to sodium nitroprusside.

Result

With the sexes combined, posterior cerebral artery endothelium‐dependent dilation was better for young compared with old mice (p<0.001) and for Eln+/+ compared with Eln± mice (p = 0.03). In males, Eln+/+ mice had better posterior cerebral artery endothelium‐dependent dilation than Eln± mice at young ages (p = 0.05), but not at old ages (p = 0.35). The opposite occurred in females, as Eln+/+ mice had better posterior cerebral artery endothelium‐dependent dilation than Eln± at old ages (p = 0.04) but not at young ages (p = 0.71). Group differences in endothelium‐dependent dilation were mediated by differences in nitric oxide bioavailability. There was no effect of genotype, age, or sex on endothelium‐independent dilation.

Conclusion

Our results suggest males are more vulnerable at young ages, while females are more vulnerable at old ages, to the detrimental effects of large artery stiffness on cerebrovascular function. These age‐dependent differences in vulnerability could underlie sex differences in Alzheimer’s disease risk. Funded by AARG‐200675709, TL1TR002371.
Repeated infection by cytomegalovirus induces neuroinflammation and compromises BBB integrity
Authors: Barahona Natasha B , Garfinkel Lucas P , Wang Hanyun , Marcus Miayla , Subramanian Advaith , Willis Kennedy N , Harrison Mark A , Morris Sara , Zwezdaryk Kevin , Engler‐Chiurazzi Elizabeth
Published: January 2025

Background

It is well established that genetic factors are implicated in the development of Alzheimer’s disease (AD), but there is growing interest in how environmental factors like infection contribute to its progression. Recent evidence suggests that greater exposure to infections across the lifespan can potentiate the rate and severity of cognitive decline. In addition to contributing to mechanisms underlying the aggregation of Aβ fragments and phosphorylation of tau proteins, the infectious etiology of dementia may be caused by infectious agents triggering neuroinflammatory pathways and degradation of the blood‐brain barrier (BBB). To further understand neurological changes following viral infection, we investigated the effects of repeated intermittent exposure to cytomegalovirus (CMV) on neuroinflammation and BBB integrity. We hypothesized that if infection burden promotes a dementia phenotype, then mice with a higher lifetime history of intermittent viral exposure will display increased neuroinflammation and BBB permeability.

Method

Beginning at 2 months of age, we exposed female Balb/c mice to murine CMV infection or mock infection every 3 months until they reached 8, 14, or 20 months of age, corresponding to 2, 4, or 6 exposures. We used immunofluorescence staining to evaluate the presence of neuroinflammatory markers GFAP and Iba‐1 and barrier permeability markers IgG, Claudin‐5, and Fibrinogen in the hippocampus and striatum, brain regions central to learning and memory function and in which dysfunction is implicated in AD.

Result

Across age groups, we saw a significant increase in astrocytic activity in the hippocampus as measured by GFAP (p< 0.05). For barrier permeability markers, IgG was increased in the hippocampus across age groups (p<0.05), while there was a decrease in claudin‐5 (p = 0.0272) and an increase in fibrinogen (p = 0.0232) at 14 m.o. Changes in striatum were modest though we identified significant increases in Iba‐1 and fibrinogen at 14 months. Measurement of markers in 20 m.o. mice are ongoing.

Conclusion

A history of intermittent CMV infection led to significant increases in reactive astrocytic and microglial activity in conjunction with compromised BBB integrity in the hippocampus. These results together provide a framework for how infection burden alters neurobiology and contributes to the progression of cognitive decline.
Comparing methods of cellular segmentation in prefrontal and primary visual cortices in Alzheimer’s disease
Authors: McKendell Alec K , McDonough Elizabeth , Lowery Lisa , Abate Samantha , Meyer Daniel , Luebke Jennifer , Hof Patrick R , Varghese Merina
Published: January 2025

Background

In Alzheimer’s disease (AD), specific brain regions become vulnerable to pathology while others remain resilient. New methods of imaging such as highly multiplexed immunofluorescence (MxIF) provide an abundance of spatial information, while analytical techniques like machine learning (ML) can address questions of cellular contributors to this regional vulnerability.

Method

We performed MxIF staining for 26 markers and compared postmortem human samples from an AD‐susceptible brain area, the prefrontal cortex (PFC, Brodmann’s areas 9, 10 or 46) to an AD‐resilient brain area, the primary visual cortex (V1, area 17). Subjects included AD (n = 3, clinical dementia rating CDR 3, Thal stages 3‐4, Braak stages V‐VI), mild cognitive impairment (n = 4, CDR 0.5, Thal stages 1‐3, Braak stages I‐V), and age‐matched healthy controls (n = 5, CDR 0, Thal stages 0‐1, Braak stages I‐II), including both females and males. We first used a custom Fiji plugin that leverages iterative ML to segment the images via DAPI or HUD signals. For the DAPI segmentation, ML subsequently classifies the cell type based on relevant channels. The second method used QuPath to segment exclusively using DAPI signal followed by cell‐type classifications. Segmentations and classifications in QuPath used static thresholds.

Result

Using Fiji for HUD segmentation and filtering by the presence of nuclei, we found a decrease specifically in layer 5 PFC neurons from CDR 0 to CDR 0.5. Surprisingly, this decrease did not hold in QuPath when segmenting first using DAPI. Both methods found an increase in GFAP‐expressing astrocytes primarily in layer 1. However, the pan‐astrocyte marker ALDH1L1 showed an inverse relationship, with higher density found in layers 2 through 6. Both findings held true regardless of brain region or CDR. Finally, in addition to the white matter, both methods found an increase in oligodendrocytes (MBP+, MBP+/HUD+) within layer 4 of V1 and driven by CDR 0.5.

Conclusion

Comparisons between the image analysis modalities demonstrate that the method by which cells are segmented and classified can impact the interpretation of MxIF data. Combining knowledge of disease biology with a deeper understanding of when and how to use these techniques will improve data precision.
Single‐nucleus RNA sequencing reveals hippocampal cell type‐specific transcriptional alterations in Alzheimer’s‐linked ACE variant R1284Q knock‐in mice
Authors: Salvo Miranda A , Cuddy Leah K , Chandra Sidhanth , Ramakrishnan Abhirami , Piehl Natalie , Watson Thomas J , Gate David , Popovic Jelena , Prokopenko Dmitry , Tanzi Rudolph E. , Vassar Robert J.
Published: January 2025

Background

Angiotensin‐converting enzyme (ACE) is a validated risk locus for developing late‐onset Alzheimer’s disease (LOAD). ACE1 controls blood pressure through the renin‐angiotensin system (RAS), but it is also present and acts locally in the brain. Hypertension is associated with an increased risk for developing AD, and people taking select RAS‐targeting therapeutics have reduced incidence of AD. The ACE variant rs4980 (R1284Q murine mutation) was discovered in LOAD families through WGS. Our group previously showed that ACE1 R1284Q caused age‐associated hippocampal neurodegeneration and gliosis in mutant knock‐in (KI) mice, which was more aggressive in females. Importantly, these phenotypes were rescued by treatment with anti‐hypertensive drugs. Our previous study showed that ACE1 R1284Q caused neuron death in mice, however the mechanism is still unknown. This work aims to identify vulnerable hippocampal cell populations and pathways which might clarify the mechanism of ACE1 R1284Q‐mediated neurodegeneration.

Method

Single nuclei were extracted from 30mg of flash‐frozen hippocampi from 6‐, and 12‐month‐old R1284Q ACE+/+ (WT) and ACEKI/KI (KI) and processed using 10X Genomics 3’ Dual‐Index chemistry. Libraries were sequenced using the NovaSeq 6000. Preprocessing, quality control, and integration was performed on reads before subjecting them to cluster, differential expression, and pathway analyses.

Result

Together, the samples were represented by 143,000 nuclei in 23 clusters encompassing all neuronal and glial populations in the hippocampus. We identified the expression of every RAS component, excluding renin, in the hippocampus. Notably, inhibitory and excitatory neurons had the most differentially expressed genes (DEGs) in 12‐month KI samples compared to controls. Additionally, 12‐month KI females had upregulated microglial C1q genes compared to males.

Conclusion

We found expression of RAS genes in the hippocampus, which to our knowledge has not yet been characterized by single‐nucleus RNA sequencing. Furthermore, inhibitory neuron transcriptomes are the most affected in 12‐month KI mice, suggesting altered neuron communication that may lead to neuron loss. Additionally, we identified sex‐specific differences in 12‐month KI female microglia, which may explain the more aggressive gliosis seen in female KIs compared to males. Future directions include performing ingenuity pathway analysis to identify upstream regulators of DEGs and experimental perturbations to test our hypotheses.
Herpesviruses infections associations in people with young onset dementia – Herpes simplex infection appears to be relevant
Authors: Hosseini Akram A. , Maple Peter A.C , Tanasescu Radu , Gran Bruno
Published: January 2025

Background

Early Onset Alzheimer’s Disease (EOAD) is thought to result from a combination of environmental, genetic, and lifestyle factors. Herpesvirus infections may contribute to the development of EOAD and the objective of our study is to identify potential associations between herpes virus infections and the risk of developing EOAD.

Method

Amyloid‐status Alzheimer’s disease was diagnosed based on clinical history and ATN criteria, determined by the measuring the Amyloidß42:40 ratio, tau, and 181‐Phospho‐tau in the cerebrospinal fluid. EOAD was defined as the onset of symptoms before the age of 65. Antibodies to herpesviruses were detected in patients’ sera using commercially available enzyme immunoassays. The following markers were tested: cytomegalovirus IgG, total (HSV1/HSV2) herpes simplex virus IgG, IgM and IgA, and varicella‐zoster virus (VZV) IgG. The Mann‐Whitney U test and the Fisher’s exact test assessed differences in population and categorized data, with statistical significance set at p<0.05.

Result

Sera from 20 individuals with Amyloid‐status EOAD and 20 age‐ and sex‐matched healthy controls (HCs) were tested. There were 13 females and seven males in the EOAD and HCs groups with a mean age of 60.4 years and 60.7 years, respectively. All individuals were VZV IgG seropositive with geometric mean levels of 967 mIU/ml and 827 mIU/ml in EOAD and HCs, respectively. The seroprevalences of CMV IgG were 45.0% and 35.0% in EOAD and HCs, respectively. The geometric mean CMV IgG levels were significantly higher (p = 0.029) in EOAD (678 Paul Ehrlich International units/ml) versus HCs (380 Paul Ehrlich International units/ml). The seroprevalences of HSV IgG were 90.0% in EOAD and 65.0% in HCs (difference not significant). Total HSV IgG levels were similar in EOAD (geometric mean level = 594 EU/ml) and HCs (geometric mean level = 640 EU/ml). Two individuals with EOAD and none in the HCs group showed evidence of HSV reactivation.

Conclusion

The sample sets tested are small; however, testing is ongoing. Currently, it appears that individuals with EOAD have higher levels of CMV IgG compared to healthy controls.
Analysing the Genetic Mosaic of Relapsing Remitting vs Clinically isolated syndrome Multiple Sclerosis: A Bioinformatics Perspective on Subtype‐Specific Variations
Authors: Bhonsale Aman Milind , Varma Ishita , Subhedar Atharva , Khankar Shreya , Chandak Snehal , Suryawanshi Mahima , Mast Siddhali , Lalotra Tapesh , Phadke Parth , Pakhmode Sarthak , Tripathi Satyendra , Deshmukh Vishwajit , Patil Ashlesh
Published: January 2025

Background

Multiple Sclerosis (MS) is a chronic, etiologically complex disease of the central nervous system (CNS) characterized by inflammation, demyelination, and neuronal damage. MS has seven categories based on disease course. Seventy to eighty percent of individuals with MS initially develop a clinical pattern with periodic relapses and remissions, called relapsing‐remitting MS (RRMS). Clinically isolated syndrome (CIS) refers to a single clinical inflammatory attack on the CNS. Evidence suggests that CD8+ T cells play a substantial role in MS pathophysiology. In this bioinformatic study, we aim to identify specific genes and pathways up‐regulated or down‐regulated in CD8+ T cells of RRMS and CIS subtypes.

Method

The GSE19285 dataset on the Gene Expression Omnibus (GEO) consists of the whole transcriptome of sorted T cells (CD8+) from treatment‐naive MS patients. Age‐matched sampling maintained uniformity. Data analysis used GEO2R with the Benjamini & Hochberg method (False discovery rate, padj < 0.05), and log fold change threshold greater than 1.5 or less than 1.5. We explored genetic profiles in immune cells, comparing RR (n = 17, age 30.76±7.05 years), CIS (n = 17, age 30.76±6.90 years), and healthy controls (n = 17, age 30.71±7.09 years). Gene pathway and protein‐protein interaction analyses of differentially expressed genes used the STRING platform.

Result

The study revealed upregulation of TRBV4‐2 gene in CD8+ cells of RRMS patients compared to healthy controls, while several genes, including AATK, PPP1R14C and TRIM36, were downregulated in RRMS. Two genes, DACT1 and CD4, were identified as upregulated in CD8+ cells, while several genes, including MYOM2, AATK, GPR27, LOC105370088, TRR‐ACG1‐2, KIR2DL3, and SIGLEC10, were downregulated in CIS compared to healthy controls. Additionally, CD4, DACT1, and CYBRD1 genes were up‐regulated in CIS compared to RRMS.

Conclusion

In RRMS, TRIM36’s role in proteostasis and neurodegeneration is highlighted, with protein‐protein interaction analysis showing dysfunctional ubiquitination. Altered antigen processing and presentation in CIS compared to healthy individuals and RRMS suggest differences in pathophysiology in this subtype. Furthermore, recent study has suggested CYBRD1 as a potential MS biomarker.
Fit for purpose high‐throughput absolute quantitation of chimeric aducanumab in mouse cortex and plasma
Authors: Doud Emma H. , Haynes Kathryn A , Santos Diogo Francisco Silva , Mosley Amber L. , Quinney Sara K , Rizzo Stacey J Sukoff , Territo Paul R
Published: January 2025

Background

Although pharmacokinetics and pharmacodynamics of biotherapeutics are commonly studied through ELISAs; however, the extremely strong binding of modern antibody‐based therapeutics result in background, inability of secondary antibody binding, and nonlinear response curves. The selectivity and specificity imparted through the use of liquid chromatography‐targeted mass spectrometry (LC‐MS/MS) allows for absolute quantitation of chosen peptides. For MODEL‐AD, here we present a high‐throughput workflow for absolute quantification of chimeric aducanumab from cortex and plasma of 5XFAD mice.

Methods

A targeted MS assay for quantitation of aducanumab was designed utilizing guidelines described by the National Cancer Institute’s Clinical Proteomic Tumor Analysis Consortium. Proteotryptic peptides unique for chimeric aducanumab were selected, and stable isotope versions were purchased as spike in controls. Given that aducanumab was present in mouse cortex at very low levels, a high sensitivity and high throughput methodology was optimized with Protein A enrichment, reduction, alkylation, trypsin digestion, loading samples onto Evotips using an AssayMap Bravo (Agilent). Evosep LC was paired with a Lumos Tribrid orbitrap (Thermo Fisher Scientific) and data were analyzed in Skyline (MacCoss lab) with a concentration curve of pure protein in matrix normalized to spike in stable isotope labeled peptides.

Results

The three tryptic peptides used for quantitation of aducanumab had lower limits of detection and quantification of 1‐500 Amol pure peptide on column and 2‐5 ng aducanumab/uL in plasma and 0.225 ng/ug brain homogenate. This assay was sensitive and linear over 1 to 500,000 Amol range with high reproducibility (CV 3‐10%). Using a protein A purification, the lower limit of quantification was decreased by 100 fold. This assay was micronized for 96 sample formats, where a single plate could be analyzed in 48‐72 hours.

Conclusions

Although unique peptides will vary, we anticipate this general workflow will allow for quantitation of AD focused biotherapeutics. As part of the open science framework, this methodology will be made available to the broader research community to facilitate broad application.
Intranasally Administered EVs from hiPSC‐derived NSCs Alter the Transcriptomic Profile of Activated Microglia and Conserve Brain Function in an Alzheimer’s Model
Authors: Madhu Leelavathi N , Kodali Maheedhar , Upadhya Raghavendra , Rao Shama , Shuai Bing , Somayaji Yogish , Attaluri Sahithi , Kirmani Maha , Gupta Shreyan , Maness Nathaniel , Rao Xiaolan , Cai James , Shetty Ashok K
Published: January 2025

Background

Current treatments for Alzheimer’s disease (AD) lack disease‐modifying interventions. Hence, novel therapies capable of restraining AD progression and maintaining better brain function for extended periods after the initial diagnosis have great significance. Extracellular vesicles (EVs) from human induced pluripotent stem cell (hiPSC)‐derived neural stem cells (NSCs) are attractive in this context due to their robust antiinflammatory properties.

Method

Three‐month‐old 5x familial AD (5xFAD) mice received IN administration of hiPSC‐NSC‐EVs (∼30 billion EVs) or the vehicle (weekly for two weeks). Seventy‐two hours later, a cohort of mice was euthanized, fresh microglia were isolated from the brain, and the expression of genes linked to DAM and NLRP3‐inflammasome signaling was examined via scRNA‐sequencing. Another cohort of 5xFAD mice was investigated for cognitive and mood function commencing one‐month post‐EV/Veh administration and euthanized two months post‐EV/Veh administration to assess the effects on long‐term progressive increases in neuroinflammation, amyloid‐beta plaques, and phosphorylated tau (p‐tau).

Result

Microglia in all brain regions, including plaque‐associated microglia, internalized hiPSC‐NSC‐EVs entering the brain. Single‐cell RNA sequencing at 72 hours post‐EV administration revealed microglia with transcriptomic changes indicative of diminished activation. Multiple genes linked to disease‐associated microglia, NOD‐, LRR‐ and pyrin domain‐containing protein 3 (NLRP3)‐inflammasome and interferon‐1 signaling displayed reduced expression. Adding hiPSC‐NSC‐EVs to cultured human microglia challenged with amyloid‐beta oligomers also resulted in similar effects. Furthermore, the modulatory effects of hiPSC‐NSC‐EVs on microglia in the hippocampus persisted even two months post‐EV treatment, evidenced by reductions in microglial clusters and inflammasome complexes, concentrations of mediators, and end products of NLRP3 inflammasome activation, the expression of genes and proteins involved in p38/mitogen‐activated protein kinase hyperactivation, and proteins linked to activation of interferon‐1 signaling. The hippocampus also exhibited reduced amyloid‐beta plaques and p‐tau. Such modulatory effects of hiPSC‐NSC‐EVs also led to better cognitive and mood function.

Conclusion

Early hiPSC‐NSC‐EV intervention in AD can maintain better brain function by reducing adverse neuroinflammatory signaling cascades, amyloid‐beta plaque load, and p‐tau.

Supported by a grant from the National Institute for Aging (1RF1AG074256‐01A1 to A.K.S.)
Association between Long COVID and neuropsychological outcomes in a Brazilian Cohort: preliminary results
Authors: Senger Joana Emilia , Machado Luiza Santos , Silveira Maiele Dornelles , da Silva Ana Paula Bornes , Ferrari‐Souza João Pedro , de Bastiani Marco Antônio , Povala Guilherme , Borelli Wyllians Vendramini , de Mello Guilherme Bastos , da Ros João Pedro Uglione , Jotz Arthur Viana , Kadan Matheus Fakhri , Radaelli Graciane , Pascoal Tharick A. , Matushita Cristina Sebastião , Soder Ricardo Benardi , Schumacher‐Schuh Artur Francisco , Souza Diogo O. , Lourenco Mychael V. , de Paula de Paula Faria Daniele , Coutinho Artur Martins , da Costa Jaderson Costa , de Souza Débora Guerini , Zimmer Eduardo R.
Published: January 2025

Background

COVID‐19 pandemic has brought long‐lasting social, emotional, and cognitive consequences. Long COVID is characterized by a myriad of symptoms and complications that persist long after the infection, including cognitive decline and mental health impairment. This study aims to investigate depressive symptoms and cognitive performance stratified by sex and group in adults with and without long COVID.

Method

Community‐dwelling individuals from Porto Alegre, Brazil, were divided into control and long COVID groups. We recruited 49 individuals, aged >50 years. Individuals were evaluated with the mini mental state examination (MMSE), Clock Drawing Test, Trail Making Test (TMT‐B), Wechsler Memory Scale (WMS‐R) and PHQ‐9 scale of depressive symptoms. A regression model was conducted stratified by sex, age and group. PHQ‐9 was used as an interaction of the same variables. Data were analyzed using R, considering p‐value < 0.05.

Result

A total of 49 individuals (59.8 ± 8.06 mean years of age, 63.3% females), having high education (>11 years of study) were included. The control group was comprised of 18 individuals (36.73%) and the long COVID group had 31 individuals (63.26%). The Long COVID group had a worse performance in WMS‐A (p <0.011) and WMS‐B (p <0.03) in the immediate test and WSM‐B recall (p <0.02). The PHQ‐9 test differed between groups, with long COVID individuals presenting depressive symptoms (p <0.003). We also found an interaction of long COVID and PHQ‐9 impacting on the TMT‐ B test (p <0.03).

Conclusion

Preliminary results showed that long COVID induced impairment in executive functions, specifically in working memory and episodic memory scores. Additionally, there was an impact of depressive symptoms in the relationship between group and TMT‐B scores. Participants with depressive symptoms had worsened cognitive performance on the regression analysis. A larger sample should corroborate these findings and provide further insights into the long COVID cognitive impact.
Clinical and neuropathological differences in dementia and the correlation between the sexes
Authors: Socher Karen L R , Justo Alberto Fernando Oliveira , Rodriguez Roberta Diehl , Leite Renata Elaine Paraizo , Jacob‐Filho Wilson , Pasquallucci Carlos Augusto , Nitrini Ricardo , Grinberg Lea T. , Suemoto Claudia Kimie , Brucki Sonia Maria Dozzi
Published: January 2025

Background

The study of dementia and its differences between the sexes is widely investigated, mainly in Alzheimer’s disease. However, most studies on dementia are not carried out in a multiethnic population. Here we analyze demographic data, clinical symptoms, and neuropathological characteristics of a large mixed Brazilian sample.

Method

The Biobank for Aging Studies has a unique collection of brain samples that we selected over 50 years of age. All were examined for the presence of dementia pathology according to internationally accepted criteria for pathological staging and diagnosis. All cases have a complete semi‐structured interview carried out to obtain sociodemographic data, lifestyle, past medical history, and the presence of cognitive impairment (CI) was defined according to the Clinical Dementia Rating Scale (CDR≥0.5).

Result

Of the 1,611 cases included, 801 were men and 811 were women. Regarding ethnicity, 65.2% were identified by family members as white for both groups. Regarding differences between sexes, women were older, less literate and had greater cognitive impairment in the CDR and Sum of Boxes (p>0.001). The neuropathological findings showed a sample of women with a lower percentage (48.9%) of initial Braak stages and a higher percentage (51.3%) of Braak stage ≥III (p>0.001). Higher prevalence of moderate and frequent CERAD score (p>0.001), as well as TDP‐43 proteinopathy. Concerning other pathologies such as Lewy Body Diseases, Lacunar Infarction, Arteriosclerosis, and Cerebral Amyloid Angiopathy, no significance was found. When analyzing sex and clinical symptoms using a multivariate linear regression model, there was significance for both the final CDR score and the sum of the boxes. The association of neuropathological and clinical findings through logistic regression with adjustment for age and education, there is a tendency for women to present more symptoms, regardless of the subtype of neuropathological lesion. For Alzheimer’s disease pathology, there was statistical significance with the clinical pathology and continuous staging with prevalence in women, as well as in the presence of TDP‐43 pathology and hyaline arteriosclerosis in vascular pathology.

Conclusion

Sex in the neuropathology of dementia plays an important role in cognitive symptoms, highlighting the need to consider it in future prevention and treatment strategies.