hiPSC-derived GRN-deficient astrocytes delay spiking activity of developing neurons.

Frontotemporal dementia (FTD) refers to a group of neurodegenerative disorders that are characterized by pathology predominantly localized to the frontal and temporal lobes. Approximately 40% of FTD cases are familial, and up to 20% of these are caused by heterozygous loss of function mutations in the gene encoding for progranulin (PGRN), GRN. The mechanisms by which loss of PGRN leads to FTD remain incompletely understood. While astrocytes and microglia have long been linked to the neuropathology of FTD due to mutations in GRN (FTD-GRN), a primary mechanistic role of these supporting cells have not been thoroughly addressed. In contrast, mutations in MAPT, another leading cause of familial FTD, greatly alters astrocyte gene expression leading to subsequent non-cell autonomous effects on neurons, suggesting similar mechanisms may be present in FTD-GRN. Here, we utilized human induced pluripotent stem cell (hiPSC)-derived neural tissue carrying a homozygous GRN R493X-/- knock-in mutation to investigate in vitro whether GRN mutant astrocytes have a non-cell autonomous effect on neurons. Using microelectrode array (MEA) analysis, we demonstrate that the development of spiking activity of neurons cultured with GRN R493X-/- astrocytes was significantly delayed compared to cultures with WT astrocytes. Histological analysis of synaptic markers in these cultures showed an increase in GABAergic synaptic markers and a decrease in glutamatergic synaptic markers during this period when activity was delayed. We also demonstrate that this effect may be due in-part to soluble factors. Overall, this work represents one of the first studies investigating astrocyte-induced neuronal pathology in GRN mutant hiPSCs, and supports the hypothesis of astrocyte involvement in the early pathophysiology of FTD.

A Model Predicting Healthcare Capacity Gaps For Alzheimer's Disease-Modifying Treatment in Canada.

BACKGROUND: Alzheimer's disease (AD) is experienced by > 600,000 Canadians. Disease-modifying therapies (DMTs) for earlier stages of disease are in development. Existing health system capacity constraints and the need for biomarker-driven diagnostics to confirm DMT eligibility are concerning. This study aimed to characterize the capacity gap related to early AD (eAD) treatment with DMTs in Canada. METHODS: A capacity model was developed to simulate the flow of a patient from screening to treatment for eAD to quantify the gap between available and required healthcare resources and qualify the bottlenecks restricting the patient journey at a provincial and national level. The model inputs (epidemiological, human resource, and clinical) were evidence-based, healthcare professional-, and patient advocate-informed. RESULTS: The model estimated that nationally < 2% of patients would have access to the required healthcare resources for treatment with a DMT. Eligibility assessment represented the step with the largest capacity gap across all provinces, with a wait list of about 382,000 Canadians one year following DMT introduction. The top three resource gaps included AD specialist time and positron emission tomography and magnetic resonance imaging exam slots. Sensitivity analysis showed that full reliance on cerebrospinal fluid for eligibility testing increased capacity for assessment by about 47,000 patients. CONCLUSION: This model highlights that the Canadian health system is critically under-resourced to diagnose, assess, and treat patients with eAD with DMT. It underscores an urgent need for national policy and provincial resource allocation to close the gap.

A Deep Learning Strategy for Automatic Sleep Staging Based on Two-Channel EEG Headband Data.

Sleep disturbances are common in Alzheimer's disease and other neurodegenerative disorders, and together represent a potential therapeutic target for disease modification. A major barrier for studying sleep in patients with dementia is the requirement for overnight polysomnography (PSG) to achieve formal sleep staging. This is not only costly, but also spending a night in a hospital setting is not always advisable in this patient group. As an alternative to PSG, portable electroencephalography (EEG) headbands (HB) have been developed, which reduce cost, increase patient comfort, and allow sleep recordings in a person's home environment. However, naïve applications of current automated sleep staging systems tend to perform inadequately with HB data, due to their relatively lower quality. Here we present a deep learning (DL) model for automated sleep staging of HB EEG data to overcome these critical limitations. The solution includes a simple band-pass filtering, a data augmentation step, and a model using convolutional (CNN) and long short-term memory (LSTM) layers. With this model, we have achieved 74% (±10%) validation accuracy on low-quality two-channel EEG headband data and 77% (±10%) on gold-standard PSG. Our results suggest that DL approaches achieve robust sleep staging of both portable and in-hospital EEG recordings, and may allow for more widespread use of ambulatory sleep assessments across clinical conditions, including neurodegenerative disorders.

World-Wide FINGERS Network: A global approach to risk reduction and prevention of dementia.

Reducing the risk of dementia can halt the worldwide increase of affected people. The multifactorial and heterogeneous nature of late-onset dementia, including Alzheimer's disease (AD), indicates a potential impact of multidomain lifestyle interventions on risk reduction. The positive results of the landmark multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) support such an approach. The World-Wide FINGERS (WW-FINGERS), launched in 2017 and including over 25 countries, is the first global network of multidomain lifestyle intervention trials for dementia risk reduction and prevention. WW-FINGERS aims to adapt, test, and optimize the FINGER model to reduce risk across the spectrum of cognitive decline-from at-risk asymptomatic states to early symptomatic stages-in different geographical, cultural, and economic settings. WW-FINGERS aims to harmonize and adapt multidomain interventions across various countries and settings, to facilitate data sharing and analysis across studies, and to promote international joint initiatives to identify globally implementable and effective preventive strategies.

Prion-Protein-interacting Amyloid-ß Oligomers of High Molecular Weight Are Tightly Correlated with Memory Impairment in Multiple Alzheimer Mouse Models.

Alzheimer disease (AD) is characterized by amyloid-ß accumulation, with soluble oligomers (Aßo) being the most synaptotoxic. However, the multivalent and unstable nature of Aßo limits molecular characterization and hinders research reproducibility. Here, we characterized multiple Aßo forms throughout the life span of various AD mice and in post-mortem human brain. Aßo exists in several populations, where prion protein (PrP(C))-interacting Aßo is a high molecular weight Aß assembly present in multiple mice and humans with AD. Levels of PrP(C)-interacting Aßo match closely with mouse memory and are equal or superior to other Aß measures in predicting behavioral impairment. However, Aßo metrics vary considerably between mouse strains. Deleting PrP(C) expression in mice with relatively low PrP(C)-interacting Aßo (Tg2576) results in partial rescue of cognitive performance as opposed to complete recovery in animals with a high percentage of PrP(C)-interacting Aßo (APP/PSEN1). These findings highlight the relative contributions and interplay of Aßo forms in AD.

Fyn inhibition rescues established memory and synapse loss in Alzheimer mice.

OBJECTIVE: Currently no effective disease-modifying agents exist for the treatment of Alzheimer disease (AD). The Fyn tyrosine kinase is implicated in AD pathology triggered by amyloid-ß oligomers (Aßo) and propagated by Tau. Thus, Fyn inhibition may prevent or delay disease progression. Here, we sought to repurpose the Src family kinase inhibitor oncology compound, AZD0530, for AD. METHODS: The pharmacokinetics and distribution of AZD0530 were evaluated in mice. Inhibition of Aßo signaling to Fyn, Pyk2, and Glu receptors by AZD0530 was tested by brain slice assays. After AZD0530 or vehicle treatment of wild-type and AD transgenic mice, memory was assessed by Morris water maze and novel object recognition. For these cohorts, amyloid precursor protein (APP) metabolism, synaptic markers (SV2 and PSD-95), and targets of Fyn (Pyk2 and Tau) were studied by immunohistochemistry and by immunoblotting. RESULTS: AZD0530 potently inhibits Fyn and prevents both Aßo-induced Fyn signaling and downstream phosphorylation of the AD risk gene product Pyk2, and of NR2B Glu receptors in brain slices. After 4 weeks of treatment, AZD0530 dosing of APP/PS1 transgenic mice fully rescues spatial memory deficits and synaptic depletion, without altering APP or Aß metabolism. AZD0530 treatment also reduces microglial activation in APP/PS1 mice, and rescues Tau phosphorylation and deposition abnormalities in APP/PS1/Tau transgenic mice. There is no evidence of AZD0530 chronic toxicity. INTERPRETATION: Targeting Fyn can reverse memory deficits found in AD mouse models, and rescue synapse density loss characteristic of the disease. Thus, AZD0530 is a promising candidate to test as a potential therapy for AD.

Cellular prion protein mediates impairment of synaptic plasticity by amyloid-beta oligomers.

A pathological hallmark of Alzheimer's disease is an accumulation of insoluble plaque containing the amyloid-beta peptide of 40-42 amino acid residues. Prefibrillar, soluble oligomers of amyloid-beta have been recognized to be early and key intermediates in Alzheimer's-disease-related synaptic dysfunction. At nanomolar concentrations, soluble amyloid-beta oligomers block hippocampal long-term potentiation, cause dendritic spine retraction from pyramidal cells and impair rodent spatial memory. Soluble amyloid-beta oligomers have been prepared from chemical syntheses, transfected cell culture supernatants, transgenic mouse brain and human Alzheimer's disease brain. Together, these data imply a high-affinity cell-surface receptor for soluble amyloid-beta oligomers on neurons-one that is central to the pathophysiological process in Alzheimer's disease. Here we identify the cellular prion protein (PrP(C)) as an amyloid-beta-oligomer receptor by expression cloning. Amyloid-beta oligomers bind with nanomolar affinity to PrP(C), but the interaction does not require the infectious PrP(Sc) conformation. Synaptic responsiveness in hippocampal slices from young adult PrP null mice is normal, but the amyloid-beta oligomer blockade of long-term potentiation is absent. Anti-PrP antibodies prevent amyloid-beta-oligomer binding to PrP(C) and rescue synaptic plasticity in hippocampal slices from oligomeric amyloid-beta. Thus, PrP(C) is a mediator of amyloid-beta-oligomer-induced synaptic dysfunction, and PrP(C)-specific pharmaceuticals may have therapeutic potential for Alzheimer's disease.

A microglia-containing cerebral organoid model to study early life immune challenges.

Prenatal infections and activation of the maternal immune system have been proposed to contribute to causing neurodevelopmental disorders (NDDs), chronic conditions often linked to brain abnormalities. Microglia are the resident immune cells of the brain and play a key role in neurodevelopment. Disruption of microglial functions can lead to brain abnormalities and increase the risk of developing NDDs. How the maternal as well as the fetal immune system affect human neurodevelopment and contribute to NDDs remains unclear. An important reason for this knowledge gap is the fact that the impact of exposure to prenatal risk factors has been challenging to study in the human context. Here, we characterized a model of cerebral organoids (CO) with integrated microglia (COiMg). These organoids express typical microglial markers and respond to inflammatory stimuli. The presence of microglia influences cerebral organoid development, including cell density and neural differentiation, and regulates the expression of several ciliated mesenchymal cell markers. Moreover, COiMg and organoids without microglia show similar but also distinct responses to inflammatory stimuli. Additionally, IFN-γ induced significant transcriptional and structural changes in the cerebral organoids, that appear to be regulated by the presence of microglia. Specifically, interferon-gamma (IFN-γ) was found to alter the expression of genes linked to autism. This model provides a valuable tool to study how inflammatory perturbations and microglial presence affect neurodevelopmental processes.

Clinical value of Alzheimer's disease biomarker testing.

INTRODUCTION: In the Investigating the Impact of Alzheimer's Disease Diagnostics in British Columbia (IMPACT-AD BC) study, we aimed to understand how Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarker testing-used in medical care-impacted medical decision-making (medical utility), personal decision-making (personal utility), and health system economics. METHODS: The study was designed as an observational, longitudinal cohort study. A total of 149 patients were enrolled between February 2019 and July 2021. Patients referred to memory clinics were approached to participate if their dementia specialist ordered AD CSF biomarker testing as part of their routine medical care, and the clinical scenario met the appropriate use criteria for lumbar puncture and AD CSF biomarker testing. For the medical utility pillar, detailed clinical management plans were collected via physician questionnaires pre- and post-biomarker disclosure. RESULTS: Patients with completed management questionnaires (n = 142) had a median age of 64 (interquartile range: 59-69) years, 48% were female, and 60% had CSF biomarker profiles on the AD continuum. Clinical management changed in 89.4% of cases. AD biomarker testing was associated with decreased need for other diagnostic procedures, including brain imaging (-52.0%) and detailed neuropsychological assessments (-63.2%), increased referrals and counseling (57.0%), and guided AD-related drug prescriptions (+88.4% and -50.0% in biomarker-positive and -negative cases, respectively). DISCUSSION: AD biomarker testing was associated with significant and positive changes in clinical management, including decreased health care resource use, therapy optimization, and increased patient and family member counseling. While certain changes in management were linked to the AD biomarker profile (e.g., referral to clinical trials), the majority of changes were independent of baseline clinical presentation and level of cognitive impairment, demonstrating a broad value for AD biomarker testing in individuals meeting the appropriate use criteria for testing.

Personal value of Alzheimer's disease biomarker testing and result disclosure from the patient and care partner perspective.

INTRODUCTION: We described patients' and care partners' experiences with Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarker testing and result disclosure in routine care. METHODS: IMPACT-AD BC is an observational study of clinic patients who underwent AD CSF biomarker testing as part of their routine medical care (n = 142). In the personal utility arm of the study, semi-structured phone interviews were conducted with a subset of patients (n = 34), and separately with their care partners (n = 31). Post-disclosure interviews were conducted ∼1 month and ∼6 months after biomarker result disclosure and investigated the patients' decision-making process around testing, impact of receiving results, wellness and lifestyle changes, and future planning. RESULTS: A majority of patients (90%) rated their decision to undergo testing as "easy." Post-disclosure, the majority (82%) reported overall positive feelings from having greater certainty and the ability to plan ahead, and results spurred them to adopt/continue healthy behaviors such as exercise (84%) and cognitive activities (54%). Care partners expressed relief from having more diagnostic certainty, increased appreciation of future caregiving responsibilities, and a desire to connect with support resources. DISCUSSION: Perspectives of persons with lived experience in dementia provide new insight into the value of biomarker testing and should be included as part of evidence-guided considerations for pre-test counseling and result disclosure. Moreover, study findings identify an interval when patients and care partners are highly receptive to positive lifestyle and medical interventions.

Genetic reduction of striatal-enriched tyrosine phosphatase (STEP) reverses cognitive and cellular deficits in an Alzheimer's disease mouse model.

Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder. Early in the pathophysiology of AD, synaptic function is disrupted by soluble Aß oligomers, possibly through Aß-mediated internalization of NMDA receptors. Striatal-enriched phosphatase (STEP) is a tyrosine phosphatase that regulates the internalization of NMDA receptors. Recent work shows that STEP is elevated in the prefrontal cortex of human AD patients and in animal models of AD. Here, we use genetic manipulations to reduce STEP activity in a triple transgenic AD mouse model and show that a decrease in STEP levels reverses cognitive and cellular deficits observed in these mice. Our results suggest that STEP inhibitors may prove therapeutic for this devastating disorder.

Recommendations for Preclinical Testing of Treatments Against Alzheimer's Disease-Related Epileptiform Spikes in Transgenic Rodent Models.

Recent evidence suggests that about 30%of patients with mild to moderate Alzheimer's disease (AD) without a known diagnosis of epilepsy may display epileptiform spikes during electroencephalographic (EEG) recordings. These abnormal discharges occur predominantly during sleep and may be associated with accelerated disease progression. Subclinical spikes may represent a relevant target for clinical drug interventions, and there is a clear unmet need for preclinical testing of novel disease modifying agents in suitable animal models. Transgenic rodent models of AD pathology exhibit various forms of epileptiform EEG activity related to the abnormal levels of amyloid species in the brain. Among them, large-amplitude cortical and hippocampal EEG spikes in mouse and rat AD models may be reminiscent of the subclinical epileptiform EEG spikes recorded in some AD patients. This article reports the recommendations of a multidisciplinary panel of experts on optimal EEG markers and experimental designs to measure and report epileptiform activities and their response to symptomatic and disease-modifying drugs in transgenic AD model rodents. These recommendations may harmonize future preclinical EEG studies in the drug discovery research and may increase the comparability of experimental outcomes and their translational clinical value.

Multidomain trials to prevent dementia: addressing methodological challenges.

BACKGROUND: Multidomain trials to prevent dementia by simultaneously targeting multiple risk factors with non-pharmacological lifestyle interventions show promise. Designing trials to evaluate the efficacy of individual interventions and their combinations is methodologically challenging. Determining the efficacy is, nevertheless, important to individuals, payers, and for resource allocations to support intervention implementation. MAIN BODY: The central rationale for seminal trials improving cardiovascular health or reducing falls risk in older adults is that multifactorial conditions may be amenable to improvement by simultaneously targeting multiple modifiable risk factors. Similar reasoning underlies lifestyle interventions to reduce dementia risk using combinations of physical exercise, cognitive training, diet, amelioration of vascular-metabolic risk factors, and improving sleep quality. Randomizing individuals with at least two modifiable risk factors to "standardly tailored" interventions to mitigate their risk factors, versus a comparator arm, will yield an unbiased estimate of the cumulative average effect of modifying more versus fewer risk factors. The between-group difference in the cognitive primary outcome will reflect both the main effects of the mitigated risk factors, as well as their synergistic effects. However, given the positive trial results, there are inherent challenges in quantifying post hoc which components, or combination of components, were responsible for improvements in cognition. Here, we elaborate on these methodological challenges and important considerations in using a standardly tailored design with two arms (one consisting of multidomain interventions tailored to participants' risk profiles and another consisting of active control conditions). We compare this approach to fully factorial designs and highlight the disadvantages and advantages of each. We discuss partial solutions, including analytical strategies such as risk reduction scores that measure reductions in the number or severity of risk factors in each study arm. Positive results can support the causal inference that between-group differences in the primary cognitive outcome were due to risk factor modification. CONCLUSION: Standardly tailored designs are pragmatic and feasible evaluations of multidomain interventions to reduce dementia risk. We propose sensitivity and exploratory analyses of between-group reductions in the severity of risk factors, as a methodology to bolster causal inferences that between-group differences in the primary cognitive outcome are due to the risk factors modified.

Home EEG sleep assessment shows reduced slow-wave sleep in mild-moderate Alzheimer's disease.

Introduction: Sleep disturbances are common in Alzheimer's disease (AD), with estimates of prevalence as high as 65%. Recent work suggests that specific sleep stages, such as slow-wave sleep (SWS) and rapid eye movement (REM), may directly impact AD pathophysiology. A major limitation to sleep staging is the requirement for clinical polysomnography (PSG), which is often not well tolerated in patients with dementia. We have recently developed a deep learning model to reliably analyze lower quality electroencephalogram (EEG) data obtained from a simple, two-lead EEG headband. Here we assessed whether this methodology would allow for home EEG sleep staging in patients with mild-moderate AD. Methods: A total of 26 mild-moderate AD patients and 24 age-matched, healthy control participants underwent home EEG sleep recordings as well as actigraphy and subjective sleep measures through the Pittsburgh Sleep Quality Index (PSQI). Each participant wore the EEG headband for up to three nights. Sleep was staged using a deep learning model previously developed by our group, and sleep stages were correlated with actigraphy measures as well as PSQI scores. Results: We show that home EEG with a headband is feasible and well tolerated in patients with AD. Patients with mild-moderate AD were found to spend less time in SWS compared to healthy control participants. Other sleep stages were not different between the two groups. Actigraphy or the PSQI were not found to predict home EEG sleep stages. Discussion: Our data show that home EEG is well tolerated, and can ascertain reduced SWS in patients with mild-moderate AD. Similar findings have previously been reported, but using clinical PSG not suitable for the home environment. Home EEG will be particularly useful in future clinical trials assessing potential interventions that may target specific sleep stages to alter the pathogenesis of AD. Highlights: Home electroencephalogram (EEG) sleep assessments are important for measuring sleep in patients with dementia because polysomnography is a limited resource not well tolerated in this patient population.Simplified at-home EEG for sleep assessment is feasible in patients with mild-moderate Alzheimer's disease (AD).Patients with mild-moderate AD exhibit less time spent in slow-wave sleep in the home environment, compared to healthy control participants.Compared to healthy control participants, patients with mild-moderate AD spend more time in bed, with decreased sleep efficiency, and more awakenings as measured by actigraphy, but these measures do not correlate with EEG sleep stages.

Simultaneous imaging of redox states in dystrophic neurites and microglia at Aß plaques indicate lysosome accumulation not microglia correlate with increased oxidative stress.

The inter-relationship between microglia dynamics and oxidative stress (Ox-stress) in dystrophic neurites (DNs) at Alzheimer's Disease (AD) plaques may contribute to the pathological changes in neurons. We developed new in vivo imaging strategies to combine EGFP expression in microglia with neuronal expression of genetically encoded ratiometric redox sensors (rogRFP2 or roGFP1), and immunohistochemistry to investigate how microglia influence Ox-stress at amyloid plaques in 5xFAD AD mice. By simultaneously imaging microglia morphology and neuronal Ox-stress over time in vivo and in fixed brains we found that microglia preferentially enwrapped DNs exhibiting the greatest degree of Ox-stress. After microglia were partially depleted with the CSF1 receptor antagonist PLX3397, Ox-stress in DNs increased in a manner that was inversely correlated to the extent of coverage of the adjacent Aß plaques by the remaining microglia. These data suggest that microglia do not create Ox-stress at Aß plaques but instead create protective barriers around Aß plaques possibly reducing the spread of Aß. Intracranial injection of Aß was sufficient to induce neuronal Ox-stress suggesting it to be the initial trigger of Ox-stress generation. Although Ox-stress is increased in DNs, neuronal survival is enhanced following microglia depletion indicating complex and multifactorial roles of microglia with both neurotoxic and neuroprotective components. Increased Ox-stress of DNs was correlated with higher LAMP1 and ubiquitin immunoreactivity supporting proposed mechanistic links between lysosomal accumulation in DNs and their intrinsic generation of Ox-stress. Our results suggest protective as well as neurotoxic roles for microglia at plaques and that the generation of Ox-stress of DNs could intrinsically be generated via lysosomal disruption rather than by microglia. In Brief: Simultaneous imaging of microglia and neuronal Ox-stress revealed a double-edged role for microglia in 5xFAD mice. Plaque associated microglia were attracted to and enwrapped Aß plaques as well as the most highly oxidized DNs. After partial depletion of microglia, DNs were larger with greater levels of Ox-stress. Despite increased Ox-stress after microglia removal neuronal survival improved. Greater Ox-stress was correlated with increased levels of LAMP1 and ubiquitin thereby linking lysosome accumulation and Ox-stress in DNs.

Memory impairment in transgenic Alzheimer mice requires cellular prion protein.

Soluble oligomers of the amyloid-beta (Abeta) peptide are thought to play a key role in the pathophysiology of Alzheimer's disease (AD). Recently, we reported that synthetic Abeta oligomers bind to cellular prion protein (PrP(C)) and that this interaction is required for suppression of synaptic plasticity in hippocampal slices by oligomeric Abeta peptide. We hypothesized that PrP(C) is essential for the ability of brain-derived Abeta to suppress cognitive function. Here, we crossed familial AD transgenes encoding APPswe and PSen1DeltaE9 into Prnp-/- mice to examine the necessity of PrP(C) for AD-related phenotypes. Neither APP expression nor Abeta level is altered by PrP(C) absence in this transgenic AD model, and astrogliosis is unchanged. However, deletion of PrP(C) expression rescues 5-HT axonal degeneration, loss of synaptic markers, and early death in APPswe/PSen1DeltaE9 transgenic mice. The AD transgenic mice with intact PrP(C) expression exhibit deficits in spatial learning and memory. Mice lacking PrP(C), but containing Abeta plaque derived from APPswe/PSen1DeltaE9 transgenes, show no detectable impairment of spatial learning and memory. Thus, deletion of PrP(C) expression dissociates Abeta accumulation from behavioral impairment in these AD mice, with the cognitive deficits selectively requiring PrP(C).

Community participation in activities and places among older adults with and without dementia.

Availability of community-based destinations and amenities can facilitate healthy aging by supporting older adults' functional abilities and enabling their participation in society, especially for those experiencing declining cognitive abilities. This study used a survey tool called participation in ACTivities and places OUTside the Home for older adults, specifically designed to examine the out-of-home participation of older adults living with or without dementia, to collect data on specific places and activities that individuals participate in over time. Thirty cognitively intact participants and 29 participants living with dementia were recruited. The past/present net participation figures indicate that all destinations are likely to be abandoned by persons with dementia over time. The findings indicate that both groups of participants were most likely to abandon recreation and physical activity places, although a higher number of persons with dementia reported that they would likely abandon these places in the future than the cognitively intact participants. Participants with dementia indicated multiple en route and at destination challenges, as well as their coping strategies. This study adds to our understanding of the out-of-home places visited by persons living with and without dementia and the patterns of changes in those visits over time. The findings are useful for health and social care professionals, including occupational therapists, social workers, as well as family caregivers, in recognizing the relative importance of certain out-of-home places and activities over others and the challenges faced by persons with dementia in getting to those places. This knowledge can inform programme and service providers to develop targeted interventions to support continued engagement by older adults with dementia and cognitively intact older adults.

Sleep and its regulation: An emerging pathogenic and treatment frontier in Alzheimer's disease.

A majority of patients with Alzheimer's disease (AD) experience some form of sleep disruption, including nocturnal sleep fragmentation, increased daytime napping, decreased slow-wave sleep (SWS, stage N3), and decreased rapid-eye-movement sleep (REM). Clinical studies are investigating whether such sleep disturbances are a consequence of the underlying disease, and whether they also contribute to the clinical and pathological manifestations of AD. Emerging research has provided a direct link between several of these sleep disruptions and AD pathophysiology, suggesting that treating sleep disorders in this population may target basic mechanisms of the disease. Here, we provide a comprehensive review of sleep disturbances associated with the spectrum of AD, ranging from the preclinical stages through dementia. We discuss how sleep interacts with AD pathophysiology and, critically, whether sleep impairments can be targeted to modify the disease course in a subgroup of affected AD patients. Ultimately, larger studies that fully utilize new diagnostic and experimental tools will be required to better define the most relevant sleep disturbance to target in AD, the interventions that best modulate this target symptom, and whether successful early intervention can modify AD risk and prevent dementia.

The Use of Patient-Derived Induced Pluripotent Stem Cells for Alzheimer's Disease Modeling.

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by a progressive deterioration in multiple facets of cognitive function. As the average age of the population rises, AD poses a massive current and future healthcare threat. Today, there is no cure for AD nor well-established interventions to slow progression, and treatment is largely symptomatic. The failure rate for new drugs in clinical trials has remained high, pointing out a critical need for better disease modeling that can enhance our understanding of basic disease pathophysiology, leading to better drug discovery and preclinical validation. The advent of induced pluripotent stem cells (iPSCs) has allowed researchers access to an unlimited supply of patient cells that can be differentiated into a neural fate, allowing for modeling of neurological disorders such as AD. This development has propelled AD research and presents opportunities to produce more accurate AD models to facilitate research into pathophysiology as well as drug screening and development. In this review, we conduct an in-depth assessment of the literature to identify the majority of work to date on patient-derived iPSCs. We outline research into both the familial and sporadic forms of the disease, as well as modern methods of modeling the disease three-dimensionally. Finally, we identify challenges to be addressed and areas of further research for iPSC modeling of AD.

Premature termination codon readthrough upregulates progranulin expression and improves lysosomal function in preclinical models of GRN deficiency.

BACKGROUND: Frontotemporal lobar degeneration (FTLD) is a devastating and progressive disorder, and a common cause of early onset dementia. Progranulin (PGRN) haploinsufficiency due to autosomal dominant mutations in the progranulin gene (GRN) is an important cause of FTLD (FTLD-GRN), and nearly a quarter of these genetic cases are due to a nonsense mutation. Premature termination codons (PTC) can be therapeutically targeted by compounds allowing readthrough, and aminoglycoside antibiotics are known to be potent PTC readthrough drugs. Restoring endogenous PGRN through PTC readthrough has not previously been explored as a therapeutic intervention in FTLD. METHODS: We studied whether the aminoglycoside G418 could increase PGRN expression in HEK293 and human induced pluripotent stem cell (hiPSC)-derived neurons bearing the heterozygous S116X, R418X, and R493X pathogenic GRN nonsense mutations. We further tested a novel substituted phthalimide PTC readthrough enhancer in combination with G418 in our cellular models. We next generated a homozygous R493X knock-in hiPSC isogenic line (R493X-/- KI), assessing whether combination treatment in hiPSC-derived neurons and astrocytes could increase PGRN and ameliorate lysosomal dysfunction relevant to FTLD-GRN. To provide in vivo proof-of-concept of our approach, we measured brain PGRN after intracerebroventricular administration of G418 in mice expressing the V5-tagged GRN nonsense mutation R493X. RESULTS: The R418X and R493X mutant GRN cell lines responded to PTC readthrough with G418, and treatments increased PGRN levels in R493X-/- KI hiPSC-derived neurons and astrocytes. Combining G418 with a PTC readthrough enhancer increased PGRN levels over G418 treatment alone in vitro. PGRN deficiency has been shown to impair lysosomal function, and the mature form of the lysosomal protease cathepsin D is overexpressed in R493X-/- KI neurons. Increasing PGRN through G418-mediated PTC readthrough normalized this abnormal lysosomal phenotype in R493X-/- KI neuronal cultures. A single intracerebroventricular injection of G418 induced GRN PTC readthrough in 6-week-old AAV-GRN-R493X-V5 mice. CONCLUSIONS: Taken together, our findings suggest that PTC readthrough may be a potential therapeutic strategy for FTLD caused by GRN nonsense mutations.