Alzheimer's Drug Discovery Foundation Research Articles

Molecular and structural insight into the differences among common and rare Alzheimer's disease-associated apoE variants.

Alzheimer's Disease (AD) is the leading cause of dementia worldwide with multiple risk modifying factors identified through GWAS including common apoE variants (apoE2, apoE3, apoE4). Additionally, rare apoE variants including apoE3-R136S (Christchurch), apoE3-V236E (Jacksonville), and apoE4-R251G may alter AD risk. ApoE interacts with AD-associated proteins TREM2 and amyloid-beta (Aβ), holding interactions at the hinge and LDL receptor binding domain (LDLRBD) for TREM2 and the N-terminal helices and lipid binding domain (LBD) for Aβ. The structure, conformation, and dynamics differences among these apoE variants that may alter apoE interactions with TREM2 and Aβ are unknown. In this study, we investigated how these apoE isoforms differ in secondary structure, conformation, and dynamics using molecular dynamics (MD) simulations. The apoE variants’ structures were obtained by mutating the known NMR structure of lipid-free apoE3 (PDBID: 2L7B). We performed 500 ns MD simulations for the six apoE variants with the last 250 ns of equilibrated trajectories used for analysis. The apoE variants differed primarily in the conformational stability of the N-terminal, hinge, and LBD regions. Further, apoE variants differed in secondary structure, and specifically in the length, occupancy, and type of helices that make up the N-terminal, hinge, and LBD regions. Our dynamic cross-correlated motion analysis revealed variations in the correlated motions between the hinge, LDLRBD, and LBD regions of apoE variants. The conformational stability, secondary structure, and dynamic motion differences among the apoE variants provide important insight into how these common and rare apoE variants may alter interactions with TREM2, Aβ, and other AD-associated proteins to affect the risk of developing AD. Acknowledgements: This work was supported by the NIH 1R01AG068395-01A1, NIH 5T32EB023872-04, and Alzheimer's Drug Discovery Foundation.

Interactions between apolipoprotein E, sex, and amyloid-beta on cerebrospinal fluid p-tau levels in the European prevention of Alzheimer's dementia longitudinal cohort study (EPAD LCS).

SummaryBackgroundAlzheimer's Disease, the leading cause of dementia, is over-represented in females. The apolipoprotein E (APOE)ε4 allele is the strongest genetic risk factor for late-onset AD and is associated with aberrant cerebrospinal fluid levels (CSF) of total tau (t-tau), phosphorylated tau (p-tau), and amyloid-β (Aβ). There is some evidence that sex may mediate the relationship between APOE status and CSF tau, however, evidence is mixed.MethodsWe aimed to examine the interaction between sex, APOE ε4 status, CSF Aβ on t-tau and p-tau in 1599 mid-to-late life individuals without a diagnosis of dementia in the European Prevention of Alzheimer's Dementia (EPAD) longitudinal cohort study.FindingsWe found a significant interaction between APOE status, sex, and CSF Aβ on CSF p-tau levels (β = 0·18, p = 0·04). Specifically, there was a stronger association between APOE status and CSF Aβ42 on CSF p-tau in males compared to females. Further, in females with high Aβ levels (reflecting less cortical deposition), ε4 carriers had significantly elevated p-tau levels relative to non-carriers (W = 39663, p = 0·01). However, there were no significant differences in p-tau between male ε4 carriers and non-carriers with high Aβ (W = 23523, p = 0·64).InterpretationAn interaction between sex and cerebrospinal fluid Aβ may mediate the relationship between APOE status and CSF p-tau. These data suggest tau accumulation may be independent of Aβ in females, but not males.FundingInnovative Medicines Initiative, Swedish Research Council, Alzheimer Drug Discovery Foundation, Swedish Alzheimer Foundation, the Swedish state under the agreement between the Swedish government and the County Councils: the ALF-agreement, and the Alzheimer's Association 2021 Zenith Award.

The iterative process of fluid biomarker development and validation in Alzheimer's disease

The iterative process of fluid biomarker development and validation in Alzheimer's disease

2021 marks a new era for Alzheimer's therapeutics

2021 marks a new era for Alzheimer's therapeutics

Antiphospholipid antibodies and neurological manifestations in acute COVID-19: A single-centre cross-sectional study.

BackgroundA high prevalence of antiphospholipid antibodies has been reported in case series of patients with neurological manifestations and COVID-19; however, the pathogenicity of antiphospholipid antibodies in COVID-19 neurology remains unclear.MethodsThis single-centre cross-sectional study included 106 adult patients: 30 hospitalised COVID-neurological cases, 47 non-neurological COVID-hospitalised controls, and 29 COVID-non-hospitalised controls, recruited between March and July 2020. We evaluated nine antiphospholipid antibodies: anticardiolipin antibodies [aCL] IgA, IgM, IgG; anti-beta-2 glycoprotein-1 [aβ2GPI] IgA, IgM, IgG; anti-phosphatidylserine/prothrombin [aPS/PT] IgM, IgG; and anti-domain I β2GPI (aD1β2GPI) IgG.FindingsThere was a high prevalence of antiphospholipid antibodies in the COVID-neurological (73.3%) and non-neurological COVID-hospitalised controls (76.6%) in contrast to the COVID-non-hospitalised controls (48.2%). aPS/PT IgG titres were significantly higher in the COVID-neurological group compared to both control groups (p < 0.001). Moderate-high titre of aPS/PT IgG was found in 2 out of 3 (67%) patients with acute disseminated encephalomyelitis [ADEM]. aPS/PT IgG titres negatively correlated with oxygen requirement (FiO2R=-0.15 p = 0.040) and was associated with venous thromboembolism (p = 0.043). In contrast, aCL IgA (p < 0.001) and IgG (p < 0.001) was associated with non-neurological COVID-hospitalised controls compared to the other groups and correlated positively with d-dimer and creatinine but negatively with FiO2.InterpretationOur findings show that aPS/PT IgG is associated with COVID-19-associated ADEM. In contrast, aCL IgA and IgG are seen much more frequently in non-neurological hospitalised patients with COVID-19. Characterisation of antiphospholipid antibody persistence and potential longitudinal clinical impact are required to guide appropriate management.FundingThis work is supported by UCL Queen Square Biomedical Research Centre (BRC) and Moorfields BRC grants (#560441 and #557595). LB is supported by a Wellcome Trust Fellowship (222102/Z/20/Z). RWP is supported by an Alzheimer's Association Clinician Scientist Fellowship (AACSF-20-685780) and the UK Dementia Research Institute. KB is supported by the Swedish Research Council (#2017-00915) and the Swedish state under the agreement between the Swedish government and the County Councils, the ALF-agreement (#ALFGBG-715986). HZ is a Wallenberg Scholar supported by grants from the Swedish Research Council (#2018-02532), the European Research Council (#681712), Swedish State Support for Clinical Research (#ALFGBG-720931), the Alzheimer Drug Discovery Foundation (ADDF), USA (#201809-2016862), and theUK Dementia Research Institute at UCL. BDM is supported by grants from the MRC/UKRI (MR/V007181/1), MRC (MR/T028750/1) and Wellcome (ISSF201902/3). MSZ, MH and RS are supported by the UCL/UCLH NIHR Biomedical Research Centre and MSZ is supported by Queen Square National Brain Appeal.

Value-Generating Exploratory Trials in Neurodegenerative Dementias.

Drug development for Alzheimer disease and other neurodegenerative dementias, including frontotemporal dementia, has experienced a long history of phase 2 and phase 3 clinical trials that failed to show efficacy of investigational drugs. Despite differences in clinical and behavioral characteristics, these disorders have shared pathologies and face common challenges in designing early-phase trials that are predictive of late-stage success. Here, we discuss exploratory clinical trials in neurodegenerative dementias. These are generally phase 1b or phase 2a trials that are designed to assess pharmacologic effects and rely on biomarker outcomes, with shorter treatment durations and fewer patients than traditional phase 2 studies. Exploratory trials can establish go/no-go decision points, support proof of concept and dose selection, and terminate drugs that fail to show target engagement with suitable exposure and acceptable safety profiles. Early failure saves valuable resources including opportunity costs. This is especially important for programs in academia and small biotechnology companies but may be applied to high-risk projects in large pharmaceutical companies to achieve proof of concept more rapidly at lower costs than traditional approaches. Exploratory studies in a staged clinical development program may provide promising data to warrant the substantial resources needed to advance compounds through late-stage development. To optimize the design and application of exploratory trials, the Alzheimer's Drug Discovery Foundation and the Association for Frontotemporal Degeneration convened an advisory panel to provide recommendations on outcome measures and statistical considerations for these types of studies and study designs that can improve efficiency in clinical development.

Quantification of the Trans-Synaptic Partners Neuroligin-Neurexin in CSF of Neurodegenerative Diseases by Parallel Reaction Monitoring Mass Spectrometry

Background: Synaptic proteins are increasingly studied as biomarkers for synaptic dysfunction and loss, which are early and central events in Alzheimer’s disease (AD) and strongly correlate with the degree of cognitive decline. In this study, we specifically investigated the synaptic binding partners neurexins (NRXN) and neuroligins (Nlgn), to assess their biomarker’s potential. Methods: We developed a parallel reaction monitoring mass spectrometric method for the simultaneous quantification of NRXNs and Nlgns in cerebrospinal fluid (CSF) of neurodegenerative diseases, focusing on AD. Specifically, NRXN-1α, NRXN-1β, NRXN-2α, NRXN-3α and Nlgn1, Nlgn2, Nlgn3 and Nlgn4 proteins were targeted. Findings: The proteins were investigated in a clinical cohort including CSF from controls (n=22), mild cognitive impairment (MCI) due to AD (n=44), MCI due to other conditions (n=46), AD (n=77) and a group of non-AD dementia (n=28). No difference in levels of NRXNs and Nlgns was found between AD (both at dementia and MCI stages) or controls or the non-AD dementia group for any of the targeted proteins. NRXN and Nlgn proteins correlated strongly with each other, but only a weak correlation with the AD core biomarkers and the synaptic biomarkers neurogranin and growth-associated protein 43, was found, possibly reflecting different pathogenic processing at the synapse. Interpretation: We conclude that NRXN and Nlgn proteins do not represent suitable biomarkers for synaptic pathology in AD. The panel developed here could aid in future investigations of the potential involvement of Nlgns and NRXNs in synaptic dysfunction in other disorders of the central nervous system. Funding: HZ is a Wallenberg Scholar supported by grants from the Swedish Research Council (#2018-02532), the European Research Council (#681712), Swedish State Support for Clinical Research (#ALFGBG- 720931), the Alzheimer Drug Discovery Foundation (ADDF), USA (#201809-2016862), the AD Strategic Fund and the Alzheimer's Association (#ADSF-21-831376-C, #ADSF-21-831381-C and #ADSF-21-831377-C), the Olav Thon Foundation, the Erling-Persson Family Foundation, Stiftelsen for Gamla Tjanarinnor, Hjarnfonden, Sweden (#FO2019-0228), the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 860197 (MIRIADE), and the UK Dementia Research Institute at UCL. KB is supported by the Swedish Research Council (#2017-00915), the Alzheimer Drug Discovery Foundation (ADDF), USA (#RDAPB- 201809- 2016615), the Swedish Alzheimer Foundation (#AF-742881), Hjarnfonden, Sweden (#FO2017-0243), the Swedish state under the agreement between the Swedish government and the County Councils, the ALF-agreement (#ALFGBG-715986), and European Union Joint Program for Neurodegenerative Disorders (JPND2019-466-236). The funders had no role in data collection, analysis, or decision to publish. EC received support from Gamla tjanarinnor, Stohnes stiftelse, Demensfonden and Emil och Maria Palms stiftelse. AV is supported by Fondation Ophtalmologique Adolphe de Rothschild, Fondation Chatrier and AAIHP association. Declaration of Interest: HZ has served at scientific advisory boards for Eisai, Denali, Roche Diagnostics, Wave, Samumed, Siemens Healthineers, Pinteon Therapeutics, Nervgen, AZTherapies and CogRx, has given lectures in symposia sponsored by Cellectricon, Fujirebio, Alzecure and Biogen, and is a co-founder of Brain Biomarker Solutions in Gothenburg AB (BBS), which is a part of the GU Ventures Incubator Program. KB has served as a consultant or at advisory board for Axon, Biogen, CogRx, Lilly, MegQu, Novartis and Roche Diagnostics. OH has acquired research support (for the institution) from Roche, Pfizer, GE Healthcare, Biogen, Eli Lilly and AVID Radiopharmaceuticals. In the past 2 years, he has received consultancy/speaker fees (paid to the institution) from Biogen and Roche. All other authors have nothing to declare. Ethical Approval: The use of these patient samples was approved by the Ethics Committee at the University of Gothenburg (EPN 140811).

Blood phosphorylated tau 181 as a biomarker for Alzheimer's disease: a diagnostic performance and prediction modelling study using data from four prospective cohorts.

CSF and PET biomarkers of amyloid β and tau accurately detect Alzheimer's disease pathology, but the invasiveness, high cost, and poor availability of these detection methods restrict their widespread use as clinical diagnostic tools. CSF tau phosphorylated at threonine 181 (p-tau181) is a highly specific biomarker for Alzheimer's disease pathology. We aimed to assess whether blood p-tau181 could be used as a biomarker for Alzheimer's disease and for prediction of cognitive decline and hippocampal atrophy. We developed and validated an ultrasensitive blood immunoassay for p-tau181. Assay performance was evaluated in four clinic-based prospective cohorts. The discovery cohort comprised patients with Alzheimer's disease and age-matched controls. Two validation cohorts (TRIAD and BioFINDER-2) included cognitively unimpaired older adults (mean age 63-69 years), participants with mild cognitive impairment (MCI), Alzheimer's disease, and frontotemporal dementia. In addition, TRIAD included healthy young adults (mean age 23 years) and BioFINDER-2 included patients with other neurodegenerative disorders. The primary care cohort, which recruited participants in Montreal, Canada, comprised control participants from the community without a diagnosis of a neurological condition and patients referred from primary care physicians of the Canadian National Health Service for specialist care. Concentrations of plasma p-tau181 were compared with established CSF and PET biomarkers and longitudinal measurements using Spearman correlation, area under the curve (AUC), and linear regression analyses. We studied 37 individuals in the discovery cohort, 226 in the first validation cohort (TRIAD), 763 in the second validation cohort (BioFINDER-2), and 105 in the primary care cohort (n=1131 individuals). In all cohorts, plasma p-tau181 showed gradual increases along the Alzheimer's disease continuum, from the lowest concentrations in amyloid β-negative young adults and cognitively unimpaired older adults, through higher concentrations in the amyloid β-positive cognitively unimpaired older adults and MCI groups, to the highest concentrations in the amyloid β-positive MCI and Alzheimer's disease groups (p<0·001, Alzheimer's disease vs all other groups). Plasma p-tau181 distinguished Alzheimer's disease dementia from amyloid β-negative young adults (AUC=99·40%) and cognitively unimpaired older adults (AUC=90·21-98·24% across cohorts), as well as other neurodegenerative disorders, including frontotemporal dementia (AUC=82·76-100% across cohorts), vascular dementia (AUC=92·13%), progressive supranuclear palsy or corticobasal syndrome (AUC=88·47%), and Parkinson's disease or multiple systems atrophy (AUC=81·90%). Plasma p-tau181 was associated with PET-measured cerebral tau (AUC=83·08-93·11% across cohorts) and amyloid β (AUC=76·14-88·09% across cohorts) pathologies, and 1-year cognitive decline (p=0·0015) and hippocampal atrophy (p=0·015). In the primary care cohort, plasma p-tau181 discriminated Alzheimer's disease from young adults (AUC=100%) and cognitively unimpaired older adults (AUC=84·44%), but not from MCI (AUC=55·00%). Blood p-tau181 can predict tau and amyloid β pathologies, differentiate Alzheimer's disease from other neurodegenerative disorders, and identify Alzheimer's disease across the clinical continuum. Blood p-tau181 could be used as a simple, accessible, and scalable test for screening and diagnosis of Alzheimer's disease. Alzheimer Drug Discovery Foundation, European Research Council, Swedish Research Council, Swedish Alzheimer Foundation, Swedish Dementia Foundation, Alzheimer Society Research Program.

The Effects of Rasagiline on Glucose Metabolism and Cognition and Their Relationship to Tau Burden in a Double-Blind, Placebo-Controlled Phase Ii Clinical Trial of Participants with Alzheimer's Dementia

Background: A Phase II proof of concept (POC) randomized clinical trial was conducted to evaluate the effects of rasagiline, a MAO-B inhibitor, in mild to moderate Alzheimer’s disease. The primary objective was to determine if 1 mg of rasagiline daily for 24 weeks is associated with improved regional brain metabolism (FDG PET) compared to placebo. Secondary objectives included use of flortaucipir PET to assess effects on tau pathology and determination of directional consistency of clinical endpoints with FDG PET. Methods: This was a double-blind, parallel group, placebo-controlled, community-based, three-site trial of 50 participants randomized 1:1 to receive oral rasagiline or placebo (NCT02359552). FDG PET was analyzed at screening for the presence of an AD-like pattern as an inclusion criterion and longitudinally using prespecified regions of interest and image classification. Participants who completed baseline and 24-week FDG PET scans and passed quality control were included in the primary analysis; secondary clinical outcomes were analyzed using an ITT model. Findings: Between May 19, 2015 and January 26, 2018, 96 participants were screened, 50 randomized, and 43 completed treatment. The study met its primary endpoint, demonstrating favorable change in FDG PET differences in rasagiline vs. placebo in middle frontal (2·5%,95%CI 0·3–4·7%,p<0·025), anterior cingulate (2·2%,0·1–4·3%,p<0·041), and striatal (2·4%,0·2–4·3%,p<0·023) regions. Tau PET cortical region secondary endpoints did not differ between study arms. Clinical secondary endpoint measures of Quality of Life (p<0·04) and COWAT favored rasagiline. Rasagiline was generally well tolerated with low rates of both serious and other adverse events and notably less neuropsychiatric symptoms reported with rasagiine. Interpretation: These study outcomes illustrate the potential benefits of rasagiline on clinical and neuroimaging measures in AD, with positive effects on frontostriatal pathways. Strengths are the FDG PET results coupled with the directional consistency of clinical outcomes. This data adds important converging evidence for POC of rasagiline in patients well characterized using FDG and tau PET. Limitations include the study size and duration. Further investigation of rasagiline in AD is warranted. Funding: Alzheimer’s Drug Discovery Foundation (ADDF) Declaration of Interest: Dawn Matthews is an employee of ADM Diagnostics, Inc., which was compensated to provide image analysis for the study. Dr. Aaron Ritter has nothing to disclose. Dr. Ronald Thomas has nothing to disclose. Randolph Andrews is an employee of ADM Diagnostics, Inc., which was compensated to provide image analysis for the study. Dr. Ana Lukic is an employee of ADM Diagnostics, Inc., which was compensated to provide image analysis for the study. Carolyn Revta has received grants from Toyama Pharmaceuticals, Biohaven Pharmaceuticals, and Vivoryon (Probiodrug) during the conduct of the study. Dr. Babak Tousi has received a grant from the Alzheimer’s Drug Discovery Foundation during the study. Dr. James Leverenz has received research support from the Alzheimer’s Association, Avid Radiopharmaceuticals, Department of Defense, GE Healthcare, Lewy Body Dementia Association, Michael J Fox Foundation, National Institute of Health and Sanofi/Genzyme. Dr. Howard Fillit is founding Executive Director and Chief Science Officer of the Alzheimer’s Drug Discovery Foundation which funded the rasagiline clinical trial, and has provided consulting to the following pharmaceutical companies: Axovant, vTv, Lundbeck, Otsuka, Lilly, Biogen (RTI), Roche, Genentech, Merck, Samus, Pfizer, and Alector. Dr. Kate Zhong has nothing to disclose. Dr. Howard Feldman reports a service agreement through UCSD with the Cleveland Clinic for data management and biostatistics during the conduct of this study; grants from Toyama Pharmaceuticals , Biohaven Pharmaceuticals , and Vivoryon (Probiodrug). Dr. Feldman also reports service agreements through UCSD for consulting with Eisai Pharmaceuticals, Merck Pharmaceuticals, Tau RX , Samus Therapeutics, Arkuda Therapeutics, Samumed, Axon Neurosciences Roche/Genentech Pharmaceuticals for DMC and DSMB activities; Tau Consortium for Scientific Advisory Board; Novo Nordisk for Advisory Board. He reports travel expenses Samus, Samumed, Axox and Alion Pharmaceuticals and speaker fees to UCSD from World Events Forum, Optum Health, and Medscape. Dr. Jeffrey Cummings reports grants from National Institute of General Medical Sciences (NIGMS) COBRE grant #P20GM109025, during the conduct of the study; personal fees from Acadia, Actinogen, AgenBio, Alkahest, Alzheon, Avanir, Axsome, Biogen, Cassava, Cerecin, Cerevel, Cognoptix, Cortexyme, EIP, Eisai, Foresight, Green Valley, Grifols, Idorsia, Karuna, Nutricia, Orion, Otsuka, Probiodrug, QR Pharma, ReMYND, Resverlogix, Roche, Samumed, Samus Therapeutics, Third Rock, Signant Health, Sunovion, Suven, and United Neuroscience pharmaceutical and assessment companies;other from Alzheimer Drug Discovery Foundation; other from ADAMAS, BioAsis, MedAvante, QR Pharma, and United Neuroscience,;personal fees from Neuropsychiatric Inventory (NPI), outside the submitted work; and Dr. Cummings is the Chief Scientific Advisor for CNS Innovations. Ethical Approval: The study was conducted under Institutional Review Board approval.

Antihypertensive medications and risk for incident dementia and Alzheimer's disease: a meta-analysis of individual participant data from prospective cohort studies

Dementia is a major health concern for which prevention and treatment strategies remain elusive. Lowering high blood pressure with specific antihypertensive medications (AHMs) could reduce the burden of disease. We investigated whether specific AHM classes reduced the risk for dementia. We did a meta-analysis of individual participant data from eligible observational studies published between Jan 1, 1980, and Jan 1, 2019. Cohorts were eligible for inclusion if they prospectively recruited community-dwelling adults; included more than 2000 participants; collected data for dementia events over at least 5 years; had measured blood pressure and verified use of AHMs; included in-person exams, supplemented with additional data, to capture dementia events; and had followed up cases for mortality. We assessed the association of incident dementia and clinical Alzheimer's disease with use of five AHM classes, within strata of baseline high (systolic blood pressure [SBP] ≥140 mm Hg or diastolic blood pressure [DBP] ≥90 mm Hg) and normal (SBP <140 mm Hg and DBP <90 mm Hg) blood pressure. We used a propensity score to control for confounding factors related to the probability of receiving AHM. Study-specific effect estimates were pooled using random-effects meta-analyses. Six prospective community-based studies (n=31 090 well phenotyped dementia-free adults older than 55 years) with median follow-ups across cohorts of 7-22 years were eligible for analysis. There were 3728 incident cases of dementia and 1741 incident Alzheimer's disease diagnoses. In the high blood pressure stratum (n=15 537), those using any AHM had a reduced risk for developing dementia (hazard ratio [HR] 0·88, 95% CI 0·79-0·98; p=0·019) and Alzheimer's disease (HR 0·84, 0·73-0·97; p=0·021) compared with those not using AHM. We did not find any significant differences between one drug class versus all others on risk of dementia. In the normal blood pressure stratum (n=15 553), there was no association between AHM use and incident dementia or Alzheimer's disease. Over a long period of observation, no evidence was found that a specific AHM drug class was more effective than others in lowering risk of dementia. Among people with hypertensive levels of blood pressure, use of any AHM with efficacy to lower blood pressure might reduce the risk for dementia. These findings suggest future clinical guidelines for hypertension management should also consider the beneficial effect of AHM on the risk for dementia. The Alzheimer's Drug Discovery Foundation and the National Institute on Aging Intramural Research Program.

Upregulation of Mitofusin2 in neurons slows down skeletal muscles atrophy in ALS disease and aging model

Skeletal muscles undergo atrophy in response to diseases and aging. Mitochondria, the source of cellular energy, were found to be fragmented in experimental models of ALS disease and aging. However, whether and how mitochondrial fragmentation plays a role in the progression of disease and aging is not clear. Mitofusin2 (Mfn2) is a key regulator of mitochondrial fusion which is crucial for the maintenance of mitochondrial morphology. To test whether Mfn2 reduction in motor neurons contributed to the disease progression in SOD1G93A mice or aged mice, we generated transgenic mice overexpressing Mfn2 specifically in neurons under the control of the Thy1.2 promoter (TMFN mice). Mfn2 overexpression was confirmed in spinal cords but not skeletal muscles. By crossing Mfn2 overexpressed mice with SOD1G93A mice, we obtained double transgenic Mfn2/SOD1G93A mice. Interestingly, mitochondrial fragmentation was abolished in motor neurons of Mfn2/SOD1G93A mice even in the disease endstage. Strikingly, characteristic neuromuscular junction (NMJ) denervation, collapse, and dysfunction in SOD1G93A mice were also greatly alleviated in Mfn2/SOD1G93A mice. The dramatic protective effect of neuronal Mfn2 in SOD1G93A mice was further indicated by the greatly delayed symptom onset of more than 60 days and the complete prevention of behavioral deficits at 120 days old, a very late stage immediately before endstage onset.A similar protective effect was observed in aged mice. The Mfn2 neuronal overexpression mice suffered less neuromuscular synaptic dysfunction and skeletal muscle atrophy than their non‐transgenic litter mates even at 22 months old, which in human years is equivalent to the 70s. Taken together, our study provides evidence suggesting that Mfn2 deficiency induced mitochondrial fragmentation in motor neurons is likely an important mechanism leading to NMJ dysfunction and skeletal muscle atrophy in ALS and aging, and that Mfn2 could be a common therapeutic target for skeletal muscle atrophy.Support or Funding InformationThis study is supported by grants from the US NIH (1R01NS097679 and 1R01NS089604), US Alzheimer's Association (AARG‐17‐499682), and US Association for Frontotemporal Degeneration and Alzheimer's Drug Discovery Foundation (20161206).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

THE USE OF COGNITIVE AND ERP BIOMARKERS OF CHOLINERGIC FUNCTION IN NOVEL TESTS OF MUSCARINIC POSITIVE ALLOSTERIC MODULATORS

Introduction The decline of cholinergic functioning is associated with increased cognitive decline and the development of Alzheimer's disease (AD) pathology. At present, there is no pharmacological agent that slows the progression the disease. Muscarinic post positive allosteric modulators (PAMs) are a new class of compounds aiming to restore cholinergic functioning in patients suffering from AD pathology. PAMs of the M1 receptor can potentiate the response of the M1 receptor to acetylcholine, without inducing the harmful side-effects. This is due to the fact that PAMs do not bind at the target site, rather they boost the signal of acetylcholine when is engaged at the orthosteric receptor. The downside of using PAMs is that they have low affinity to radioactive ligands, so this reduces the utility of PET imaging. This creates a challenge in how to establish functional efficacy of the compound in both preclinical and clinical trials. Methods To address this challenge, we plan on using cognitive tasks and electroencephalography (qEEG) to identify dose-depended changes in cholinergic functioning. These functional biomarkers allow us to develop more detailed models of how M1PAMs may influence downstream cognitive processing. The cognitive and EEG measures presented have been shown to modulate cholinergic tone, therefore we should be able to identify effective target engagement. Results Cognitive tasks tested spatial and sustained attention, episodic and working memory, perceptual vigilance and psychomotor speed. Tasks recorded by EEG tested auditory and visual discrimination using oddball tasks, and incidental memory. Conclusions These cognitive and electrophysiological results will assist in establishing functional targets for future studies using M1PAMs. This research was funded by Funding for this research comes from an Alzheimer's Association and the Alzheimer's Drug Discovery Foundation.

Neuronal Pentraxin 2 Predicts Medial Temporal Atrophy and Memory Decline across the Alzheimer's Disease Spectrum

PURPOSEChronic neuro‐inflammation is an important mechanism underlying normal aging and Alzheimer's disease (AD) that is thought to potentiate medial temporal lobe (MTL) atrophy and memory decline. Currently, there are not enough prognostic biomarkers that can track the development and progression of normal aging versus AD, as well as differing effects on the brain. Our study examined which pro‐ or anti‐inflammatory cerebrospinal fluid (CSF) biomarkers best predicted AD neuropathology over 24 months.METHODSBaseline mass spectrometry data from two hundred and eighty‐five adults was obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Our focus was on examining biomarkers directly associated with inflammatory processes. For our study, we utilized T1‐weighted medial temporal gray matter volumes at baseline and months 6, 12, and 24 after baseline. Statistical analyses were conducted using SPSS 23.0 software. We used linear mixed models as well as least significant differences (LSD) post‐hoc tests to analyze how variables differed by baseline diagnosis (normal aging, pre‐AD, AD) or pre‐AD patients that did or did not convert to AD. We used stepwise regression analyses to analyze which inflammatory biomarkers best predicted atrophy and memory decline over 24 months. We specifically focused on CSF levels of Neuronal Pentraxin 2 (NPTX2) and Chitinase‐3‐like‐protein‐1 (C3LP1), as they are the inflammatory biomarkers that significantly predicted MTL atrophy and memory decline. NPTX2 is a biomarker of synaptic plasticity. C3LP1 is a biomarker of microglial activation and chronic neuro‐inflammation. We also analyzed relative risk ratios for diagnosis with NPTX2 and C3LP1 with multinomial logistic regression analyses. Preliminary results for memory indicate that, regardless of baseline diagnosis, higher NPTX2 levels strongly predict higher memory scores by month 24 (Figure 1).RESULTSNPTX2 and C3LP1, respectively beneficial and adverse biomarkers of synaptic plasticity and microglial activation, loaded significantly. By month 24, higher baseline NPTX2 corresponded to less MTL atrophy [R2= .287] and less memory decline [R2= .560]. Conversely, higher C3LP1 modestly predicted more MTL atrophy [R2=.083].CONCLUSIONSOur study suggests that NPTX2 is a promising biomarker for predicting longitudinal changes in medial temporal volume, especially memory performance across the AD spectrum. Baseline NPTX2 performs better than C3LP1 in predicting MTL atrophy and memory decline over time. C3LP1 was a comparatively modest predictor of medial temporal atrophy and memory decline. For future directions, studies should investigate if clinical trials using anti‐inflammatory drugs/nutritional therapy increase or inhibit NPTX2 and/or C3LP1.Support or Funding InformationThis study was funded by Iowa State University and NIH K99 AG047282. Data collection and sharing for this project were funded by the ADNI (National Institutes of Health Grant U01‐AG‐024904) and Department of Defense ADNI (award number W81XWH‐12‐2‐0012). ADNI is funded by the National Institute on Aging, the National Institute of Biomedical Imaging and Bioengineering, and through generous contributions from the Alzheimer's Association and the Alzheimer's Drug Discovery Foundation. The Canadian Institutes of Health Research is providing funds to support ADNI clinical sites in Canada. Private‐sector contributions are facilitated by the Foundation for the National Institutes of Health (www.fnih.org). The grantee organization is the Northern California Institute for Research and Education, and the study is coordinated by the Alzheimer's Disease Cooperative Study at the University of California, San Diego. ADNI data are disseminated by the Laboratory for Neuro Imaging at the University of Southern California. The data used in the preparation of this article were obtained from the ADNI database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report.

Novel CSF Biomarker of Metabolic Dysfunction Predicts AD‐like Associations across the Alzheimer's Spectrum

Obesity and insulin resistance(IR) are associated with brain atrophy and cognitive decline, particularly in Alzheimer's disease (AD). IR is correlated with temporal and frontal amyloid deposition and brain atrophy in late middle‐aged participants at risk for AD, as well as less glucose metabolism in cognitively normal elders and AD participants. Because insulin‐degrading enzyme complicates the measurement of insulin levels in cerebrospinal fluid (CSF), an alternative biomarker for metabolic dysregulation in CSF should be used to draw conclusions between central hyper insulinemia and associations with brain atrophy and hypometabolism. Ecto‐nucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2), also known as autotaxin, is studied in tumor cell mobility and is produced by beige adipose tissue. ENPP2 regulates energy metabolism, and is higher in AD prefrontal cortex (PFC). Additionally, ENPP2 stimulates the formation of lysophosphatidic acid, which promotes the generation of tissue fibrosis in vivo and in vitro. We studied Alzheimer's Disease Neuroimaging Initiative(ADNI) participants who were cognitively normal (CN; n=86) or had Mild Cognitive impairment (MCI; n=135) or AD (n=66). Statistical analyses were conducted using SPSS software. Multinomial regression analyses tested if higher ENPP2 was associated with higher relative risk ratios for MCI or AD diagnosis, relative to the CN reference group. Mixed model analyses were used to regress ENPP2 against metabolic, MRI, FDG‐PET and cognitive outcomes. Then on‐parametric Spearman's statistic was used to correlate ENPP2 and CSF biomarker values. T1‐weighted MRI images were preprocessed using FreeSurfer 4.3, and cortical thickness was examined in8 bilateral regions of interest. CSF ENPP2 levels strongly corresponded with CSF insulin‐like growth factor binding protein 2, an established biomarker of glucoregulatory function, and systemic fasting glucose. ENPP2 levels were higher in MCI and AD, and each point increase in log‐based ENPP2 values corresponded to a 3.5 to 5 times increase in the odds of having some degree of clinically relevant memory impairment. Higher ENPP2 predicted thinner PFC cortical thickness in most regions of interest in AD such as medialorbitofrontal cortex, and pars orbital is in MCI. In addition, less bilateral prefrontal cortex glucose metabolism was seen in AD. ENPP2 was also positively correlated with levels of total tau, p‐Tau181, total tau/Aβ1‐42, as well as pTau‐181/Aβ1‐42 to a marginal degree. This pattern suggests that CSF ENPP2 predicts AD neuropathology in a manner similar to dysmetabolism. Future studies should examine the potential benefit of decreasing ENPP2 levels in individuals with MCI or AD.Support or Funding InformationThis study was funded by Iowa State University and NIH K99 AG047282. Neither funding source had any involvement in the report. Data collection and sharing for this project were funded by the ADNI (National Institutes of Health Grant U01‐AG‐024904) and Department of Defense ADNI (award number W81XWH‐12‐2‐0012). ADNI is funded by the National Institute on Aging, the National Institute of Biomedical Imaging and Bioengineering, and through generous contributions from the Alzheimer's Association and the Alzheimer's Drug Discovery Foundation. The Canadian Institutes of Health Research is providing funds to support ADNI clinical sites in Canada. Private‐sector contributions are facilitated by the Foundation for the National Institutes of Health (www.fnih.org). The grantee organization is the Northern California Institute for Research and Education, and the study is coordinated by the Alzheimer's Disease Cooperative Study at the University of California, San Diego. ADNI data are disseminated by the Laboratory for Neuro Imaging at the University of Southern California. The data used in the preparation of this article were obtained from the ADNI database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report.

Overcoming obstacles to repurposing for neurodegenerative disease.

Repurposing Food and Drug Administration (FDA)-approved drugs for a new indication may offer an accelerated pathway for new treatments to patients but is also fraught with significant commercial, regulatory, and reimbursement challenges. The Alzheimer’s Drug Discovery Foundation (ADDF) and the Michael J. Fox Foundation for Parkinson’s Research (MJFF) convened an advisory panel in October 2013 to understand stakeholder perspectives related to repurposing FDA-approved drugs for neurodegenerative diseases. Here, we present opportunities on how philanthropy, industry, and government can begin to address these challenges, promote policy changes, and develop targeted funding strategies to accelerate the potential of FDA-approved repurposed drugs.

Interactions of APOE genotype and RXR agonists on soluble Aβ and oAβ levels (LB624)

Interactions of APOE genotype and RXR agonists on soluble Aβ and oAβ levels Kevin Koster1, Jia Luo2, Sue Lee2, Varsha Shete2, Gregory RJ Thatcher2, Mary Jo LaDu1, Leon M Tai1 There is a critical need to develop novel Alzheimer’s disease (AD) therapeutics that lower amyloid beta (Aβ) levels, as current therapeutics are failing in clinical trials. APOE4 (encodes apolipoprotein E; apoE) is the greatest AD genetic risk factor compared to APOE3. ApoE represents a promising target for modulating A levels, as it has been shown to have genotype‐specific effects on Aβ pathology in humans and mice. Recently, bexarotene (Bex), a retinoid X receptor (RXR) agonist, was shown to reduce soluble and insoluble levels of Aβ via increasing mouse apoE levels. However, subsequent data have raised concerns over the activity and mechanism of action of Bex. A major issue is that the effect of modulating human apoE on Aβ levels is unclear. Further, the levels of Aβ pathology at time of treatment may determine RXR agonist activity i.e. treatment vs prevention paradigms. Therefore, novel EFAD mice (overexpress Aβ42 and express human apoE3 or apoE4) were treated with Bex and LG268, a more selective RXR agonist. RXR agonist treatment of E3FAD and E4FAD mice with intermediate Aβ levels resulted in increased soluble Aβ42 and oligomeric Aβ levels (oAβ), with a trend to increase insoluble Aβ levels. RXR agonist treatment of E4FAD mice with high Aβ levels decreased soluble Aβ42 and oAβ levels, with no effect on insoluble Aβ. Further, our data indicate that the beneficial effects of RXR agonists are mediated through: increased ABCA1 and ABCG1 expression, increased lipidation of apoE‐containing lipoproteins, and thus increased apoE/A complex levels. Collectively these data suggest that RXR agonists may increase neurotoxic Aβ levels in prevention paradigms. However, RXR agonists may be effective for AD patients expressing APOE4 at a more advanced stage of the disease via a novel mechanism of action: enhanced apoE4 lipidation.Grant Funding Source: Supported by Alzheimer's Disease Drug Discovery Foundation

Developing novel blood-based biomarkers for Alzheimer's disease

Alzheimer's disease is the public health crisis of the 21st century. There is a clear need for a widely available, inexpensive and reliable method to diagnosis Alzheimer's disease in the earliest stages, track disease progression, and accelerate clinical development of new therapeutics. One avenue of research being explored is blood based biomarkers. In April 2012, the Alzheimer's Association and the Alzheimer's Drug Discovery Foundation convened top scientists from around the world to discuss the state of blood based biomarker development. This manuscript summarizes the meeting and the resultant discussion, including potential next steps to move this area of research forward.

Amyloid β deposition, neurodegeneration, and cognitive decline in sporadic Alzheimer's disease: a prospective cohort study

Similar to most chronic diseases, Alzheimer's disease (AD) develops slowly from a preclinical phase into a fully expressed clinical syndrome. We aimed to use longitudinal data to calculate the rates of amyloid β (Aβ) deposition, cerebral atrophy, and cognitive decline. In this prospective cohort study, healthy controls, patients with mild cognitive impairment (MCI), and patients with AD were assessed at enrolment and every 18 months. At every visit, participants underwent neuropsychological examination, MRI, and a carbon-11-labelled Pittsburgh compound B ((11)C-PiB) PET scan. We included participants with three or more (11)C-PiB PET follow-up assessments. Aβ burden was expressed as (11)C-PiB standardised uptake value ratio (SUVR) with the cerebellar cortex as reference region. An SUVR of 1·5 was used to discriminate high from low Aβ burdens. The slope of the regression plots over 3-5 years was used to estimate rates of change for Aβ deposition, MRI volumetrics, and cognition. We included those participants with a positive rate of Aβ deposition to calculate the trajectory of each variable over time. 200 participants (145 healthy controls, 36 participants with MCI, and 19 participants with AD) were assessed at enrolment and every 18 months for a mean follow-up of 3·8 (95% CI CI 3·6-3·9) years. At baseline, significantly higher Aβ burdens were noted in patients with AD (2·27, SD 0·43) and those with MCI (1·94, 0·64) than in healthy controls (1·38, 0·39). At follow-up, 163 (82%) of the 200 participants showed positive rates of Aβ accumulation. Aβ deposition was estimated to take 19·2 (95% CI 16·8-22·5) years in an almost linear fashion-with a mean increase of 0·043 (95% CI 0·037-0·049) SUVR per year-to go from the threshold of (11)C-PiB positivity (1·5 SUVR) to the levels observed in AD. It was estimated to take 12·0 (95% CI 10·1-14·9) years from the levels observed in healthy controls with low Aβ deposition (1·2 [SD 0·1] SUVR) to the threshold of (11)C-PiB positivity. As AD progressed, the rate of Aβ deposition slowed towards a plateau. Our projections suggest a prolonged preclinical phase of AD in which Aβ deposition reaches our threshold of positivity at 17·0 (95% CI 14·9-19·9) years, hippocampal atrophy at 4·2 (3·6-5·1) years, and memory impairment at 3·3 (2·5-4·5) years before the onset of dementia (clinical dementia rating score 1). Aβ deposition is slow and protracted, likely to extend for more than two decades. Such predictions of the rate of preclinical changes and the onset of the clinical phase of AD will facilitate the design and timing of therapeutic interventions aimed at modifying the course of this illness. Science and Industry Endowment Fund (Australia), The Commonwealth Scientific and Industrial Research Organisation (Australia), The National Health and Medical Research Council of Australia Program and Project Grants, the Austin Hospital Medical Research Foundation, Victorian State Government, The Alzheimer's Drug Discovery Foundation, and the Alzheimer's Association.

Improving dementia care: The role of screening and detection of cognitive impairment

The value of screening for cognitive impairment, including dementia and Alzheimer's disease, has been debated for decades. Recent research on causes of and treatments for cognitive impairment has converged to challenge previous thinking about screening for cognitive impairment. Consequently, changes have occurred in health care policies and priorities, including the establishment of the annual wellness visit, which requires detection of any cognitive impairment for Medicare enrollees. In response to these changes, the Alzheimer's Foundation of America and the Alzheimer's Drug Discovery Foundation convened a workgroup to review evidence for screening implementation and to evaluate the implications of routine dementia detection for health care redesign. The primary domains reviewed were consideration of the benefits, harms, and impact of cognitive screening on health care quality. In conference, the workgroup developed 10 recommendations for realizing the national policy goals of early detection as the first step in improving clinical care and ensuring proactive, patient-centered management of dementia.

Diverse therapeutic targets and biomarkers for Alzheimer's disease and related dementias: report on the Alzheimer's Drug Discovery Foundation 2012 International Conference on Alzheimer's Drug Discovery

The Alzheimer's Drug Discovery Foundation's 13th International Conference on Alzheimer's Drug Discovery was held on 10-11 September 2012 in Jersey City, NJ, USA. This meeting report provides an overview of Alzheimer's Drug Discovery Foundation-funded programs, ranging from novel biomarkers to accelerate clinical development to drug-discovery programs with a focus on targets related to neuroprotection, mitochondrial function, apolipoprotein E and vascular biology.