Synaptic Proteome Compensation and Resilience to Psychosis in Alzheimer's Disease

Psychosis in Alzheimer's disease is associated with specific changes in brain MRI volume, cognition and neuropathology

Psychosis in Alzheimer's Disease (AD) is prevalent and indicates poor prognosis. However, the neuropathological, cognitive and brain atrophy patterns underlying these symptoms have not been fully elucidated. In this study, we evaluated 178 patients with AD neuropathological change (ADNC) and ante-mortem volumetric brain magnetic resonance imaging (MRI). Presence of psychosis was determined using the Neuropsychiatric Inventory Questionnaire. Clinical Dementia Rating Sum-of-boxes (CDR-SB) was longitudinally compared between groups with a follow-up of 3000 days using mixed-effects multiple linear regression. Neuropsychological tests closest to the time of MRI and brain regional volumes were cross-sectionally compared. Psychosis was associated with lower age of death, higher longitudinal CDR-SB scores, multi-domain cognitive deficits, higher neuritic plaque severity, Braak stage, Lewy Body pathology (LB) and right temporal lobe regional atrophy. Division according to the presence of LB showed differential patterns of AD-typical pathology, cognitive deficits and regional atrophy. In conclusion, psychosis in ADNC with and without LB has clinical value and associates with subgroup patterns of neuropathology, cognition and regional atrophy.

Beyond memory impairment: the complex phenotypic landscape of Alzheimer's disease

Neuropsychiatric symptoms (NPSs) in Alzheimer's disease (AD) constitute multifaceted behavioral manifestations that reflect processes of emotional regulation, thinking, and social behavior. They are as prevalent in AD as cognitive impairment and develop independently during the progression of neurodegeneration. As studying NPSs in AD is clinically challenging, most AD research to date has focused on cognitive decline. In this opinion article we summarize emerging literature on the prevalence, time course, and the underlying genetic, molecular, and pathological mechanisms related to NPSs in AD. Overall, we propose that NPSs constitute a cluster of core symptoms in AD, and understanding their neurobiology can lead to a more holistic approach to AD research, paving the way for more accurate diagnostic tests and personalized treatments embracing the goals of precision medicine.

Subcellular proteomics insights into Alzheimer's disease development

Alzheimer's disease (AD), one of the most common dementias, is a neurodegenerative disease characterized by cognitive impairment and decreased judgment function. The expected number of AD patient is increasing in the context of the world's advancing medical care and increasing human life expectancy. Since current molecular mechanism studies on AD pathogenesis are incomplete, there is no specific and effective therapeutic agent. Mass spectrometry (MS)-based unbiased proteomics studies provide an effective and comprehensive approach. Many advances have been made in the study of the mechanism, diagnostic markers, and drug targets of AD using proteomics. This paper focus on subcellular level studies, reviews studies using proteomics to study AD-associated mitochondrial dysfunction, synaptic, and myelin damage, the protein composition of amyloid plaques (APs) and neurofibrillary tangles (NFTs), changes in tissue extracellular vehicles (EVs) and exosome proteome, and the protein changes in ribosomes and lysosomes. The methods of sample separation and preparation and proteomic analysis as well as the main findings of these studies are involved. The results of these proteomics studies provide insights into the pathogenesis of AD and provide theoretical resource and direction for future research in AD, helping to identify new biomarkers and drugs targets for AD.

Unique transcriptional signatures correlate with behavioral and psychological symptom domains in Alzheimer's disease

Despite the significant burden, cost, and worse prognosis of Alzheimer's disease (AD) with behavioral and psychological symptoms of dementia (BPSD), little is known about the molecular causes of these symptoms. Using antemortem assessments of BPSD in AD, we demonstrate that individual BPSD can be grouped into 4 domain factors in our cohort: affective, apathy, agitation, and psychosis. Then, we performed a transcriptome-wide analysis for each domain utilizing bulk RNA-seq of post-mortem anterior cingulate cortex (ACC) tissues. Though all 4 domains are associated with a predominantly downregulated pattern of hundreds of differentially expressed genes (DEGs), most DEGs are unique to each domain, with only 22 DEGs being common to all BPSD domains, including TIMP1. Weighted gene co-expression network analysis (WGCNA) yielded multiple transcriptional modules that were shared between BPSD domains or unique to each domain, and NetDecoder was used to analyze context-dependent information flow through the biological network. For the agitation domain, we found that all DEGs and a highly associated transcriptional module were functionally enriched for ECM-related genes including TIMP1, TAGLN, and FLNA. Another unique transcriptional module also associated with the agitation domain was enriched with genes involved in post-synaptic signaling, including DRD1, PDE1B, CAMK4, and GABRA4. By comparing context-dependent changes in DEGs between cases and control networks, ESR1 and PARK2 were implicated as two high-impact genes associated with agitation that mediated significant information flow through the biological network. Overall, our work establishes unique targets for future study of the biological mechanisms of BPSD and resultant drug development.

Genetic associations with psychosis and affective disturbance in Alzheimer's disease

INTRODUCTION

Individuals with Alzheimer's disease (AD) commonly experience neuropsychiatric symptoms of psychosis (AD+P) and/or affective disturbance (depression, anxiety, and/or irritability, AD+A). This study's goal was to identify the genetic architecture of AD+P and AD+A, as well as their genetically correlated phenotypes.

METHODS

Genome-wide association meta-analysis of 9988 AD participants from six source studies with participants characterized for AD+P AD+A, and a joint phenotype (AD+A+P).

RESULTS

AD+P and AD+A were genetically correlated. However, AD+P and AD+A diverged in their genetic correlations with psychiatric phenotypes in individuals without AD. AD+P was negatively genetically correlated with bipolar disorder and positively with depressive symptoms. AD+A was positively correlated with anxiety disorder and more strongly correlated than AD+P with depressive symptoms. AD+P and AD+A+P had significant estimated heritability, whereas AD+A did not. Examination of the loci most strongly associated with the three phenotypes revealed overlapping and unique associations.

DISCUSSION

AD+P, AD+A, and AD+A+P have both shared and divergent genetic associations pointing to the importance of incorporating genetic insights into future treatment development.

Highlights

It has long been known that psychotic and affective symptoms are often comorbid in individuals diagnosed with Alzheimer's disease. Here we examined for the first time the genetic architecture underlying this clinical observation, determining that psychotic and affective phenotypes in Alzheimer's disease are genetically correlated.Nevertheless, psychotic and affective phenotypes in Alzheimer's disease diverged in their genetic correlations with psychiatric phenotypes assessed in individuals without Alzheimer's disease. Psychosis in Alzheimer's disease was negatively genetically correlated with bipolar disorder and positively with depressive symptoms, whereas the affective phenotypes in Alzheimer's disease were positively correlated with anxiety disorder and more strongly correlated than psychosis with depressive symptoms.Psychosis in Alzheimer's disease, and the joint psychotic and affective phenotype, had significant estimated heritability, whereas the affective in AD did not.Examination of the loci most strongly associated with the psychotic, affective, or joint phenotypes revealed overlapping and unique associations.

Neuropsychiatric Manifestations in Alzheimer's Disease Patients: Genetics and Treatment Options

BACKGROUND

Alzheimer's disease (AD) is characterized by neuropsychiatric symptoms (NPS), which cause great misery to those with dementia and those who care for them and may lead to early institutionalization.

OBJECTIVE

The present systematic review aims to discuss the various aspects of Alzheimer's, including treatment options.

METHODS

The databases Embase, PubMed, and Web of Science were searched to collect data.

RESULTS

Incipient cognitive deterioration is commonly accompanied by these early warning signals of neurocognitive diseases. The neurobiology of NPSs in Alzheimer's disease, as well as particular symptoms, including psychosis, agitation, apathy, sadness, and sleep disorders, will be examined in this review. For NPSs in Alzheimer's disease, clinical trial designs, as well as regulatory issues, were also addressed. A fresh wave of research, however, is helping to push the discipline ahead. For medication development and repurposing, we highlight the most recent results in genetics, neuroimaging, and neurobiology. Even though identifying and treating psychosis in adults with dementia is still a challenging endeavor, new options are coming up that give the field fresh focus and hope. Conclsuion: It can be concluded from the complete literature survey that Alzheimer's-related psychosis as well as other symptoms that are not psychotic, have made significant progress in the last decade. These milestones in the development of safer, more effective treatments have been achieved as a consequence of great focus on non-pharmacological interventions like DICE or WHELD; the investigation into ways to improve existing drugs like aripiprazole, risperidone, amisulpride, and Escitalopram for safer precision-based treatment; and the development of a clinical trial program for pimavanserin.

Unveiling the Enigma: Exploring Risk Factors and Mechanisms for Psychotic Symptoms in Alzheimer's Disease through Electronic Medical Records with Deep Learning Models

Around 50% of patients with Alzheimer's disease (AD) may experience psychotic symptoms after onset, resulting in a subtype of AD known as psychosis in AD (AD + P). This subtype is characterized by more rapid cognitive decline compared to AD patients without psychosis. Therefore, there is a great need to identify risk factors for the development of AD + P and explore potential treatment options. In this study, we enhanced our deep learning model, DeepBiomarker, to predict the onset of psychosis in AD utilizing data from electronic medical records (EMRs). The model demonstrated superior predictive capacity with an AUC (area under curve) of 0.907, significantly surpassing conventional risk prediction models. Utilizing a perturbation-based method, we identified key features from multiple medications, comorbidities, and abnormal laboratory tests, which notably influenced the prediction outcomes. Our findings demonstrated substantial agreement with existing studies, underscoring the vital role of metabolic syndrome, inflammation, and liver function pathways in AD + P. Importantly, the DeepBiomarker model not only offers a precise prediction of AD + P onset but also provides mechanistic understanding, potentially informing the development of innovative treatments. With additional validation, this approach could significantly contribute to early detection and prevention strategies for AD + P, thereby improving patient outcomes and quality of life.

Targeting the post-synaptic proteome has therapeutic potential for psychosis in Alzheimer Disease

Individuals with Alzheimer Disease who develop psychotic symptoms (AD + P) experience more rapid cognitive decline and have reduced indices of synaptic integrity relative to those without psychosis (AD-P). We sought to determine whether the postsynaptic density (PSD) proteome is altered in AD + P relative to AD-P, analyzing PSDs from dorsolateral prefrontal cortex of AD + P, AD-P, and a reference group of cognitively normal elderly subjects. The PSD proteome of AD + P showed a global shift towards lower levels of all proteins relative to AD-P, enriched for kinases, proteins regulating Rho GTPases, and other regulators of the actin cytoskeleton. We computationally identified potential novel therapies predicted to reverse the PSD protein signature of AD + P. Five days of administration of one of these drugs, the C-C Motif Chemokine Receptor 5 inhibitor, maraviroc, led to a net reversal of the PSD protein signature in adult mice, nominating it as a novel potential treatment for AD + P.

Unique Transcriptional Signatures Correlate with Behavioral and Psychological Symptom Domains in Alzheimer's Disease

Despite the significant burden, cost, and worse prognosis of Alzheimer's disease (AD) with behavioral and psychological symptoms of dementia (BPSD), little is known about the molecular causes of these symptoms. Using antemortem assessments of BPSD in AD, we demonstrate that individual BPSD can be grouped into 4 domain factors in our sample: affective, apathy, agitation, and psychosis. Then, we performed a transcriptome-wide analysis for each domain utilizing bulk RNA-seq of post-mortem anterior cingulate cortex (ACC) tissue. Though all 4 domains are associated with a predominantly downregulated pattern of hundreds of differentially expressed genes (DEGs), most DEGs are unique to each domain, with only 22 DEGs being common to all BPSD domains, including TIMP1. Weighted gene co-expression network analysis (WGCNA) yielded multiple transcriptional modules that were shared between BPSD domains or unique to each domain, and NetDecoder was used to analyze context-dependent information flow through the biological network. For the agitation domain, we found that all DEGs and a highly correlated transcriptional module were functionally enriched for ECM-related genes including TIMP1, TAGLN, and FLNA. Another unique transcriptional module also associated with the agitation domain was enriched with genes involved in post-synaptic signaling, including DRD1, PDE1B, CAMK4, and GABRA4. By comparing context-dependent changes in DEGs between cases and control networks, ESR1 and PARK2 were implicated as two high impact genes associated with agitation that mediated significant information flow through the biological network. Overall, our work establishes unique targets for future study of the biological mechanisms of BPSD and resultant drug development.

Genome-Transcriptome-Functional Connectivity-Cognition Link Differentiates Schizophrenia From Bipolar Disorder

BACKGROUND AND HYPOTHESIS

Schizophrenia (SZ) and bipolar disorder (BD) share genetic risk factors, yet patients display differential levels of cognitive impairment. We hypothesized a genome-transcriptome-functional connectivity (frontoparietal)-cognition pathway linked to SZ-versus-BD differences, and conducted a multiscale study to delineate this pathway.

STUDY DESIGNS

Large genome-wide studies provided single nucleotide polymorphisms (SNPs) conferring more risk for SZ than BD, and we identified their regulated genes, namely SZ-biased SNPs and genes. We then (a) computed the polygenic risk score for SZ (PRSSZ) of SZ-biased SNPs and examined its associations with imaging-based frontoparietal functional connectivity (FC) and cognitive performances; (b) examined the spatial correlation between ex vivo postmortem expressions of SZ-biased genes and in vivo, SZ-related FC disruptions across frontoparietal regions; (c) investigated SZ-versus-BD differences in frontoparietal FC; and (d) assessed the associations of frontoparietal FC with cognitive performances.

STUDY RESULTS

PRSSZ of SZ-biased SNPs was significantly associated with frontoparietal FC and working memory test scores. SZ-biased genes' expressions significantly correlated with SZ-versus-BD differences in FC across frontoparietal regions. SZ patients showed more reductions in frontoparietal FC than BD patients compared to controls. Frontoparietal FC was significantly associated with test scores of multiple cognitive domains including working memory, and with the composite scores of all cognitive domains.

CONCLUSIONS

Collectively, these multiscale findings support the hypothesis that SZ-biased genetic risk, through transcriptome regulation, is linked to frontoparietal dysconnectivity, which in turn contributes to differential cognitive deficits in SZ-versus BD, suggesting that potential biomarkers for more precise patient stratification and treatment.

Psychosis as a Treatment Target in Dementia: A Roadmap for Designing Interventions

Psychotic phenomena are among the most severe and disruptive symptoms of dementias and appear in 30% to 50% of patients. They are associated with a worse evolution and great suffering to patients and caregivers. Their current treatments obtain limited results and are not free of adverse effects, which are sometimes serious. It is therefore crucial to develop new treatments that can improve this situation. We review available data that could enlighten the future design of clinical trials with psychosis in dementia as main target. Along with an explanation of its prevalence in the common diseases that cause dementia, we present proposals aimed at improving the definition of symptoms and what should be included and excluded in clinical trials. A review of the available information regarding the neurobiological basis of symptoms, in terms of pathology, neuroimaging, and genomics, is provided as a guide towards new therapeutic targets. The correct evaluation of symptoms is transcendental in any therapeutic trial and these aspects are extensively addressed. Finally, a critical overview of existing pharmacological and non-pharmacological treatments is made, revealing the unmet needs, in terms of efficacy and safety. Our work emphasizes the need for better definition and measurement of psychotic symptoms in dementias in order to highlight their differences with symptoms that appear in non-dementing diseases such as schizophrenia. Advances in neurobiology should illuminate the development of new, more effective and safer molecules for which this review can serve as a roadmap in the design of future clinical trials.

Alzheimer's Disease-Related Psychosis: An Overview of Clinical Manifestations, Pathogenesis, and Current Treatment

Behavioral and psychotic manifestations, including aggression, delusions, and hallucinations, are frequent comorbidities in patients with debilitating nervous illnesses such as Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis, Multiple Sclerosis, and Parkinson's disease. AD-related psychosis may be linked to a poor disease prognosis, highlighting that early detection and management are mandatory. The manifestations are variable and may be very heterogeneous, imposing a real diagnostic issue. Some assessment tools such as BEHAVE-AD, CERAD-BRSD, and the Psycho-Sensory Hallucinations Scale have been designed to facilitate the diagnosis. The mechanisms behind neurodegeneration-related psychosis are complex and are not fully understood, imposing a burden on researchers to find appropriate management modalities. Familial history and some genetic disturbances may have a determinant role in these delusions and hallucinations in cases with AD. The loss of neuronal cells, atrophy in some regions of the central nervous, and synaptic dysfunction may also contribute to these comorbidities. Furthermore, inflammatory disturbances triggered by pro-inflammatory agents such as interleukins and tumor necrosis factors are stratified among the potential risk factors of the onset of numerous psychotic symptoms in Alzheimer's patients. Little is known about the possible management tools; therefore, it is urgent to conduct well-designed trials to investigate pharmacological and non-pharmacological interventions that can improve the care process of these patients. This review summarizes the current findings regarding the AD-related psychosis symptoms, pathological features, assessment, and management.

Psychosis in Alzheimer's Disease Is Associated With Increased Excitatory Neuron Vulnerability and Post-transcriptional Mechanisms Altering Synaptic Protein Levels

Alzheimer's disease with psychosis (AD+P) is a heritable phenotypic variant of the disease which is associated with more rapid cognitive deterioration compared to Alzheimer's disease without psychosis (AD–P). Cognitive decline in AD correlates with synapse loss, and our previous studies suggest that those with AD+P have a differentially affected synaptic proteome relative to those with AD–P. In this study, we utilized RNA-sequencing of dorsolateral prefrontal cortex (DLPFC) in a cohort of 80 AD cases to evaluate novel transcriptomic signatures that may confer risk of psychosis in AD. We found that AD+P was associated with a 9% reduction in excitatory neuron proportion compared to AD–P [Mean (SD) AD+P 0.295 (0.061); AD–P 0.324 (0.052), p = 0.026]. mRNA levels contributed only modestly to altered synaptic proteins in AD+P relative to AD–P. Instead, network analysis identified altered expression of gene modules from protein ubiquitination, unfolded protein response, eukaryotic initiation factor 2 (EIF2) signaling and endoplasmic reticulum stress pathways in AD+P. We previously found that neuropathologies account for ~18% of the variance in the occurrence of psychosis in AD. Further inclusion of cell type proportions and differentially expressed modules increased the percent of the variance in psychosis occurrence accounted for in our AD cohort to 67.5%.

Psychosis in Alzheimer disease - mechanisms, genetics and therapeutic opportunities

Psychosis is a common and distressing symptom in people with Alzheimer disease, and few safe and effective treatments are available. However, new approaches to symptom assessment and treatment are beginning to drive the field forward. New nosological perspectives have been provided by incorporating the emergence of psychotic symptoms in older adults - even in advance of dementia - into epidemiological and neurobiological frameworks as well as into diagnostic and research criteria such as the International Psychogeriatric Association criteria for psychosis in neurocognitive disorders, the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART) research criteria for psychosis in neurodegenerative disease, and the ISTAART criteria for mild behavioural impairment. Here, we highlight the latest findings in genomics, neuroimaging and neurobiology that are informing approaches to drug discovery and repurposing. Current pharmacological and non-pharmacological treatment options are discussed, with a focus on safety and precision medicine. We also explore trial data for pimavanserin, a novel agent that shows promise for the treatment of psychosis in people with dementia, and discuss existing agents that might be useful but need further exploration such as escitalopram, lithium, cholinesterase inhibitors and vitamin D. Although the assessment and management of psychosis in people with dementia remain challenging, new opportunities are providing direction and hope to the field.

Fingolimod mitigates synaptic deficits and psychosis-like behavior in APP/PSEN1 mice

INTRODUCTION

Current treatments for psychosis in Alzheimer's disease (AD), a syndrome characterized by more rapid deterioration and reduced synaptic protein abundance relative to non-psychotic AD, are inadequate. Fingolimod, a currently US Food and Drug Administration (FDA)-approved pharmacotherapy for multiple sclerosis, alters synaptic protein expression and warrants preclinical appraisal as a candidate pharmacotherapy for psychosis in AD.

METHODS

Presenilin and amyloid precursor protein transgenic mice (APPswe/PSEN1dE9) and wild-type mice were randomized to fingolimod or saline for 7 days. Psychosis-associated behaviors were quantified by open field testing, pre-pulse inhibition of the acoustic startle response testing, and habituation of the acoustic startle response testing. Synaptic proteins were quantified by liquid chromatography/mass spectrometry in homogenate and postsynaptic density fractions.

RESULTS

Fingolimod treatment increased the synaptic protein abundance in cortical homogenates and normalized psychosis-associated behaviors in APPswe/PSEN1dE9 mice relative to saline. Mitochondrial-related proteins were preferentially altered by fingolimod treatment and correlated with improvements in psychosis-associated behaviors.

DISCUSSION

Preclinical studies employing complementary psychosis-associated behavioral assessments and proteomic evaluations across multiple AD-related models are warranted to replicate the current study and further investigate fingolimod as a candidate treatment for psychosis in AD.

Region-based analysis of rare genomic variants in whole-genome sequencing datasets reveal two novel Alzheimer's disease-associated genes: DTNB and DLG2

Alzheimer's disease (AD) is a genetically complex disease for which nearly 40 loci have now been identified via genome-wide association studies (GWAS). We attempted to identify groups of rare variants (alternate allele frequency <0.01) associated with AD in a region-based, whole-genome sequencing (WGS) association study (rvGWAS) of two independent AD family datasets (NIMH/NIA; 2247 individuals; 605 families). Employing a sliding window approach across the genome, we identified several regions that achieved association p values <10^-6, using the burden test or the SKAT statistic. The genomic region around the dystobrevin beta (DTNB) gene was identified with the burden and SKAT test and replicated in case/control samples from the ADSP study reaching genome-wide significance after meta-analysis (p_meta = 4.74 × 10^-8). SKAT analysis also revealed region-based association around the Discs large homolog 2 (DLG2) gene and replicated in case/control samples from the ADSP study (p_meta = 1 × 10^-6). In conclusion, in a region-based rvGWAS of AD we identified two novel AD genes, DLG2 and DTNB, based on association with rare variants.

Genome-wide association identifies the first risk loci for psychosis in Alzheimer disease

Psychotic symptoms, defined as the occurrence of delusions or hallucinations, are frequent in Alzheimer disease (AD with psychosis, AD + P). AD + P affects ~50% of individuals with AD, identifies a subgroup with poor outcomes, and is associated with a greater degree of cognitive impairment and depressive symptoms, compared to subjects without psychosis (AD - P). Although the estimated heritability of AD + P is 61%, genetic sources of risk are unknown. We report a genome-wide meta-analysis of 12,317 AD subjects, 5445 AD + P. Results showed common genetic variation accounted for a significant portion of heritability. Two loci, one in ENPP6 (rs9994623, O.R. (95%CI) 1.16 (1.10, 1.22), p = 1.26 × 10-8) and one spanning the 3'-UTR of an alternatively spliced transcript of SUMF1 (rs201109606, O.R. 0.65 (0.56-0.76), p = 3.24 × 10-8), had genome-wide significant associations with AD + P. Gene-based analysis identified a significant association with APOE, due to the APOE risk haplotype ε4. AD + P demonstrated negative genetic correlations with cognitive and educational attainment and positive genetic correlation with depressive symptoms. We previously observed a negative genetic correlation with schizophrenia; instead, we now found a stronger negative correlation with the related phenotype of bipolar disorder. Analysis of polygenic risk scores supported this genetic correlation and documented a positive genetic correlation with risk variation for AD, beyond the effect of ε4. We also document a small set of SNPs likely to affect risk for AD + P and AD or schizophrenia. These findings provide the first unbiased identification of the association of psychosis in AD with common genetic variation and provide insights into its genetic architecture.

Current molecular approaches to investigate pre-synaptic dysfunction

Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.

Psychosis in Alzheimer's Disease

PURPOSE OF REVIEW

To review the incidence, treatment and genetics of psychosis in people with mild cognitive impairment (MCI) and Alzheimer's disease (AD).

RECENT FINDINGS

Psychosis in Alzheimer's disease (AD) has an incidence of ~ 10% per year. There is limited evidence regarding psychological interventions. Pharmacological management has focused on atypical antipsychotics, balancing modest benefits with evidence of long-term harms. The 5HT2A inverse agonist pimavanserin appears to confer benefit in PD psychosis with initial evidence of benefit in AD. Cholinesterase inhibitors give modest benefits in DLB psychosis. The utility of muscarinic agonists, lithium, glutamatergic and noradrenergic modulators needs further study. Recent work has confirmed the importance of psychosis in MCI as well as AD. The lack of evidence regarding psychological therapies is an urgent knowledge gap, but there is encouraging evidence for emerging pharmacological treatments. Genetics will provide an opportunity for precision medicine and new treatment targets.

Hippocampal sclerosis, TDP-43, and the duration of the symptoms of dementia of AD patients

OBJECTIVES

To examine the relationship between duration of the cognitive symptoms, from the earliest reported symptom to death, and hippocampal sclerosis (HS) and TAR-DNA binding protein of 43kDA (TDP-43) in Alzheimer's disease (AD) patients.

METHODS

The study was conducted in 359 cognitively impaired patients who met the pathological criteria for AD (NIA-Reagan intermediate or high). The mean age at onset was 69.5 ± 8.8 years (range 37-95) and the mean duration of the symptoms was 10.5 ± 4.2 years. The association between symptoms duration and HS and TDP-43 was examined with logistic regression analyses controlling for age at death, atherosclerosis in the Circle of Willis (CW), cerebral infarcts, gender, baseline Mini Mental State Examination scores, APOE-4 allele, and presence of Lewy bodies (LB).

RESULTS

HS was present in 18% (n = 64) and TDP-43 in 51.5% (n = 185) of the patients. HS and TDP-43 were more frequent in patients whose symptoms lasted more than 10 years. LBs were present in 72% of the patients with HS and in 64% of the patients with TDP-43. Age at onset was not associated with TDP-43 or HS. HS was associated with duration of symptoms and LB, TDP-43, and atherosclerosis in the CW. TDP-43 was associated with duration of symptoms, LB, and HS.

INTERPRETATION

HS and TDP-43 are present in early and late onset AD. However, their presence is mainly driven by the duration of symptoms and the presence of LB. This suggests that HS and TDP-43 are part of the later neuropathological changes in AD.

Psychosis-associated DNA methylomic variation in Alzheimer's disease cortex

Psychotic symptoms are a common and debilitating feature of Alzheimer's disease (AD) and are associated with a more rapid course of decline. Current evidence from postmortem and neuroimaging studies implicates frontal, temporal, and parietal lobes, with reported disruptions in monoaminergic pathways. However, the molecular mechanisms underlying this remain unclear. In the present study, we investigated methylomic variation associated with AD psychosis in 3 key brain regions implicated in the etiology of psychosis (prefrontal cortex, entorhinal cortex, and superior temporal gyrus) in postmortem brain samples from 29 AD donors with psychosis and 18 matched AD donors without psychosis. We identified psychosis-associated methylomic changes in a number of loci, with these genes being enriched in known schizophrenia-associated genetic and epigenetic variants. One of these known loci resided in the AS3MT gene-previously implicated in schizophrenia in a large GWAS meta-analysis. We used bisulfite-pyrosequencing to confirm hypomethylation across 4 neighboring CpG sites in the ASM3T gene. Finally, our regional analysis nominated multiple CpG sites in TBX15 and WT1, which are genes that have been previously implicated in AD. Thus one potential implication from our study is whether psychosis-associated variation drives reported associations in AD case-control studies.

Animal Models of Psychosis in Alzheimer Disease

Psychosis in Alzheimer Disease (AD) represents a distinct clinicopathologic variant associated with increased cognitive and functional morbidity and an accelerated disease course. To date, extant treatments offer modest benefits with significant risks. The development of new pharmacologic treatments for psychosis in AD would be facilitated by validated preclinical models with which to test candidate interventions. The current review provides a brief summary of the process of validating animal models of human disease together with a critical analysis of the challenges posed in attempting to apply those standards to AD-related behavioral models. An overview of phenotypic analogues of human cognitive and behavioral impairments, with an emphasis on those relevant to psychosis, in AD-related mouse models is provided, followed by an update on recent progress in efforts to translate findings in the pathophysiology of psychotic AD into novel models. Finally, some future directions are suggested to expand the catalogue of psychosis-relevant phenotypes that may provide a sturdier framework for model development and targets for preclinical treatment outcomes.

Psychosis in neurodegenerative disorders: recent developments

PURPOSE OF REVIEW

This review presents the latest developments covered in the literature regarding psychosis in neurodegenerative disorders and discusses possible future research directions.

RECENT FINDINGS

Recent findings in the field of psychosis and neurodegenerative disorders revolve around four main themes. The first theme is the impact of sex on the expression of psychosis in neurodegenerative disorders. The second theme focuses on the relationship between psychosis and neurodegenerative disease biomarkers. The third concerns how psychotic symptoms in neurodegenerative disorders may share common mechanisms with other primary psychotic disorders such as schizophrenia. Finally, there have been some promising developments in the area of therapeutics to treat dementia-related psychosis involving both established and novel treatments.

SUMMARY

New findings in the field of neurodegeneration and psychosis parallel new directions in the field of neurodegeneration in general. More specifically, we have seen a shift in focus to issues highlighting the role of sex, biomarkers, translation to other disorders, and therapeutics.

Panaxadiol inhibits synaptic dysfunction in Alzheimer's disease and targets the Fyn protein in APP/PS1 mice and APP-SH-SY5Y cells

AIM

Alzheimer's disease (AD), a neurodegenerative disease, is characterized by memory loss and synaptic damage. Up to now, there are limited drugs to cure or delay the state of this illness. Recently, the Fyn tyrosine kinase is implicated in AD pathology triggered by synaptic damage. Thus, Fyn inhibition may prevent or delay the AD progression. Therefore, in this paper, we investigated whether Panaxadiol could decrease synaptic damage in AD and the underlying mechanism.

MAIN METHODS

The ability of learning and memory of mice has detected by Morris Water Maze. The pathological changes detected by H&E staining and Nissl staining. The percentage of cell apoptosis and the calcium concentration were detected by Flow Cytometry in vitro. The amount of synaptic protein and related proteins in the Fyn/GluN2B/CaMKIIα signaling pathway were detected by Western Blot.

KEY FINDINGS

In the present article, Panaxadiol could significantly improve the ability of learning and memory of mice and reduce its synaptic dysfunction. Panaxadiol could down-regulate GluN2B's phosphorylation level by inhibition Fyn kinase activity, Subsequently, decrease Ca²⁺-mediated synaptic damage, reducing LDH leakage, inhibiting apoptosis in AD, resulting in facilitating the cells survival. For the underlying molecular mechanism, we used PP2 to block the Fyn/GluN2B/CaMKIIα signaling pathway. The results from WB showed that the expression of related proteins in the Fyn signaling pathway decreased with PP2 treated.

SIGNIFICANCE

Our results indicate that Panaxadiol could decrease synaptic damage, which will cause AD via inhibition of the Fyn/GluN2B/CaMKIIα signaling pathway. Thus, the Panaxadiol is a best promising candidate to test as a potential therapy for AD.