Neuroimaging in Dementia

Jointly constrained group sparse connectivity representation improves early diagnosis of Alzheimer's disease on routinely acquired T1-weighted imaging-based brain network

Background

Radiomics-based morphological brain networks (radMBN) constructed from routinely acquired structural MRI (sMRI) data have gained attention in Alzheimer's disease (AD). However, the radMBN suffers from limited characterization of AD because sMRI only characterizes anatomical changes and is not a direct measure of neuronal pathology or brain activity.

Purpose

To establish a group sparse representation of the radMBN under a joint constraint of group-level white matter fiber connectivity and individual-level sMRI regional similarity (JCGS-radMBN).

Methods

Two publicly available datasets were adopted, including 120 subjects from ADNI with both T1-weighted image (T1WI) and diffusion MRI (dMRI) for JCGS-radMBN construction, 818 subjects from ADNI and 200 subjects solely with T1WI from AIBL for validation in early AD diagnosis. Specifically, the JCGS-radMBN was conducted by jointly estimating non-zero connections among subjects, with the regularization term constrained by group-level white matter fiber connectivity and individual-level sMRI regional similarity. Then, a triplet graph convolutional network was adopted for early AD diagnosis. The discriminative brain connections were identified using a two-sample t-test, and the neurobiological interpretation was validated by correlating the discriminative brain connections with cognitive scores.

Results

The JCGS-radMBN exhibited superior classification performance over five brain network construction methods. For the typical NC vs. AD classification, the JCGS-radMBN increased by 1-30% in accuracy over the alternatives on ADNI and AIBL. The discriminative brain connections exhibited a strong connectivity to hippocampus, parahippocampal gyrus, and basal ganglia, and had significant correlation with MMSE scores.

Conclusion

The proposed JCGS-radMBN facilitated the AD characterization of brain network established on routinely acquired imaging modality of sMRI.

Supplementary Information

The online version of this article (10.1007/s13755-023-00269-0) contains supplementary material, which is available to authorized users.

Lipids and lipoproteins may play a role in the neuropathology of Alzheimer's disease

Alzheimer's disease (AD) and other classes of dementia are important public health problems with overwhelming social, physical, and financial effects for patients, society, and their families and caregivers. The pathophysiology of AD is poorly understood despite the extensive number of clinical and experimental studies. The brain's lipid-rich composition is linked to disturbances in lipid homeostasis, often associated with glucose and lipid abnormalities in various neurodegenerative diseases, including AD. Moreover, elevated low-density lipoprotein (LDL) cholesterol levels may be related to a higher probability of AD. Here, we hypothesize that lipids, and electronegative LDL (L5) in particular, may be involved in the pathophysiology of AD. Although changes in cholesterol, triglyceride, LDL, and glucose levels are seen in AD, the cause remains unknown. We believe that L5-the most electronegative subfraction of LDL-may be a crucial factor in understanding the involvement of lipids in AD pathology. LDL and L5 are internalized by cells through different receptors and mechanisms that trigger separate intracellular pathways. One of the receptors involved in L5 internalization, LOX-1, triggers apoptotic pathways. Aging is associated with dysregulation of lipid homeostasis, and it is believed that alterations in lipid metabolism contribute to the pathogenesis of AD. Proposed mechanisms of lipid dysregulation in AD include mitochondrial dysfunction, blood-brain barrier disease, neuronal signaling, inflammation, and oxidative stress, all of which lead ultimately to memory loss through deficiency of synaptic integration. Several lipid species and their receptors have essential functions in AD pathogenesis and may be potential biomarkers.

Preparing Malaysia for Population Aging through the Advanced Memory and Cognitive Service in Hospital Universiti Sains Malaysia

Improving healthcare and living conditions has led to an increase in life expectancies and challenges of population aging in Malaysia. The Advanced Memory and Cognitive Service builds on integrated healthcare among multidisciplinary specialists to provide holistic and patient-centred healthcare. The service treats older adults experiencing neurocognitive impairment as well as young individuals with complex neurocognitive disorders and thoroughly screens asymptomatic individuals at high risk of developing neurocognitive disorders. This early intervention strategy is a preventive effort in the hope of reducing disease burden and improving quality of life to prepare Malaysia for the forthcoming population aging.

The advances in the early and accurate diagnosis of Creutzfeldt-Jakob disease and other prion diseases: where are we today?

INTRODUCTION

Before the introduction of MRI diffusion-weighted images (DWI), the diagnosis of Creutzfeldt-Jakob disease (CJD) relied upon nonspecific findings including clinical symptoms, EEG abnormalities, and elevated levels of cerebrospinal fluid 14-3-3 protein. Subsequently, the use of DWI has improved diagnostic accuracy, but it sometimes remains difficult to differentiate CJD from encephalitis, epilepsy, and other dementing disorders. The revised diagnostic criteria include real-time quaking-induced conversion (RT-QuIC), detecting small amounts of CJD-specific prion protein, and clinically sensitive DWI. Combining these techniques has further improved diagnostic accuracy, enabling earlier diagnosis.

AREAS COVERED

Herein, the authors review the recent advances in diagnostic methods and revised diagnostic criteria for sporadic CJD. They also discuss other prion diseases, such as variant CJD and chronic wasting disease, where the emergence of new types is a concern.

EXPERT OPINION

Despite improvements in diagnostic methods and criteria, some subtypes of prion disease are still difficult to diagnose, and even the diagnosis using the most innovative RT-QuIC test remains a challenge in terms of accuracy and standardization. However, these revised criteria can be adapted to the emergence of new types of prion diseases. It is essential to continue careful surveillance and update information on the latest prion disease phenotypes.

Alzheimer Disease and Related Cognitive Impairment in Older Adults: A Narrative Review of Screening, Prevention, and Management for Manual Therapy Providers

Objective

The aim of this narrative review was to review literature relevant to manual therapists about cognitive impairment, together with screening, potential treatment, and prevention modalities.

Methods

A literature search of AMED (Allied and Complementary Medicine Database), CINAHL (Cumulative Index of Nursing and Allied Health Literature), PubMed, and MEDLINE was conducted with the search terms "cognitive decline," "cognitive impairment," "screening," and "prevention." We reviewed current screening practices, including functional exams, imaging, and laboratory testing. We reviewed current potential preventive measures and treatments being implemented in practice.

Results

We selected 49 resources for this narrative summary. The Montreal Cognitive Assessment and Mini-Mental State Exam are recommended screening tools. Imaging and laboratory testing are not recommended in screening for cognitive decline. Promotion of healthy, active living through physical and mental activities may assist with prevention of cognitive decline.

Conclusion

Cognitive decline affects a large proportion of the US population. Recognizing signs and symptoms of this condition starts with individuals, caretakers, family members, and health care providers. Health care providers should utilize the most appropriate screening tools to assess the presence of cognitive conditions.

Diminished Neuronal ESCRT-0 Function Exacerbates AMPA Receptor Derangement and Accelerates Prion-Induced Neurodegeneration

Endolysosomal defects in neurons are central to the pathogenesis of prion and other neurodegenerative disorders. In prion disease, prion oligomers traffic through the multivesicular body (MVB) and are routed for degradation in lysosomes or for release in exosomes, yet how prions impact proteostatic pathways is unclear. We found that prion-affected human and mouse brain showed a marked reduction in Hrs and STAM1 (ESCRT-0), which route ubiquitinated membrane proteins from early endosomes into MVBs. To determine how the reduction in ESCRT-0 impacts prion conversion and cellular toxicity in vivo, we prion-challenged conditional knockout mice (male and female) having Hrs deleted from neurons, astrocytes, or microglia. The neuronal, but not astrocytic or microglial, Hrs-depleted mice showed a shortened survival and an acceleration in synaptic derangements, including an accumulation of ubiquitinated proteins, deregulation of phosphorylated AMPA and metabotropic glutamate receptors, and profoundly altered synaptic structure, all of which occurred later in the prion-infected control mice. Finally, we found that neuronal Hrs (nHrs) depletion increased surface levels of the cellular prion protein, PrPC, which may contribute to the rapidly advancing disease through neurotoxic signaling. Taken together, the reduced Hrs in the prion-affected brain hampers ubiquitinated protein clearance at the synapse, exacerbates postsynaptic glutamate receptor deregulation, and accelerates neurodegeneration.SIGNIFICANCE STATEMENT Prion diseases are rapidly progressive neurodegenerative disorders characterized by prion aggregate spread through the central nervous system. Early disease features include ubiquitinated protein accumulation and synapse loss. Here, we investigate how prion aggregates alter ubiquitinated protein clearance pathways (ESCRT) in mouse and human prion-infected brain, discovering a marked reduction in Hrs. Using a prion-infection mouse model with neuronal Hrs (nHrs) depleted, we show that low neuronal Hrs is detrimental and markedly shortens survival time while accelerating synaptic derangements, including ubiquitinated protein accumulation, indicating that Hrs loss exacerbates prion disease progression. Additionally, Hrs depletion increases the surface distribution of prion protein (PrPC), linked to aggregate-induced neurotoxic signaling, suggesting that Hrs loss in prion disease accelerates disease through enhancing PrPC-mediated neurotoxic signaling.

PRNP expression predicts imaging findings in sporadic Creutzfeldt-Jakob disease

OBJECTIVE

We explored the relationship between regional PRNP expression from healthy brain tissue and patterns of increased and decreased diffusion and regional brain atrophy in patients with sporadic Creutzfeldt-Jakob disease (sCJD).

METHODS

We used PRNP microarray data from 6 healthy adult brains from Allen Brain Institute and T1-weighted and diffusion-weighted MRIs from 34 patients diagnosed with sCJD and 30 age- and sex-matched healthy controls to construct partial correlation matrices across brain regions for specific measures of interest: PRNP expression, mean diffusivity, volume, cortical thickness, and local gyrification index, a measure of cortical folding.

RESULTS

Regional patterns of PRNP expression in the healthy brain correlated with regional patterns of diffusion signal abnormalities and atrophy in sCJD. Among different measures of cortical morphology, regional patterns of local gyrification index in sCJD most strongly correlated with regional patterns of PRNP expression. At the vertex-wise level, different molecular subtypes of sCJD showed distinct regional correlations in local gyrification index across the cortex. Local gyrification index correlation patterns most closely matched patterns of PRNP expression in sCJD subtypes known to have greatest pathologic involvement of the cerebral cortex.

INTERPRETATION

These results suggest that the specific genetic and molecular environment in which the prion protein is expressed confer variable vulnerability to misfolding across different brain regions that is reflected in patterns of imaging findings in sCJD. Further work in larger samples will be needed to determine whether these regional imaging patterns can serve as reliable markers of distinct disease subtypes to improve diagnosis and treatment targeting.

Distinguishing Curable from Progressive Dementias for Defining Cancer Care Options

The likelihood of a diagnosis of dementia increases with a person's age, as is also the case for many cancers, including melanoma and multiple myeloma, where the median age of diagnosis is above 60 years. However, patients diagnosed with dementia are less likely to be offered invasive curative therapies for cancer. Together with analysis of diet and medication history, advanced imaging methods and genetic profiling can now indicate more about syndromes causing the neurological symptoms. Cachexia, malnutrition, dehydration, alcohol consumption, and even loneliness can all accentuate or cause the "3Ds" of dementia, delirium and depression. Many common drugs, especially in the context of polypharmacy, can cause cognitive difficulties resembling neurodegenerative disease. These syndromes may be reversed by diet, social and caregiver changes, and stopping potentially inappropriate medications (PIMs). More insidious are immune reactions to many different autoantigens, some of which are related to cancers and tumors. These can induce movement and cognitive difficulties that mimic Alzheimer's and Parkinson's diseases and other ataxias associated with aging. Paraneoplastic neurological syndromes may be reversed by directed immunotherapies if detected in their early stages but are best treated by removal of the causative tumor. A full genetic workup should be done for all individuals as soon as possible after diagnosis, to guide less invasive treatments suitable for frail individuals. While surgical interventions may be contraindicated, genetic profile guided immunotherapies, oral treatments, and radiation may be equally curative in a significant number of cancers.

Brain Networks, Clinical Manifestations, and Neuroimaging of Cognitive Disorders: The Role of Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), and Other Advanced Neuroimaging Tests

In this article, we briefly discuss imaging modalities used in clinical settings for neuroanatomical characterization and for diagnosis of the underlying disease. We then discuss how each neuroimaging tool can be used in the context of clinical syndromes. The major underlying causes relevant to our discussion include Alzheimer disease, Lewy body disease, cerebrovascular disease, frontotemporal degeneration, autoimmune diseases, and systemic or metabolic derangements.

An Association Between Large Optic Cupping and Total and Regional Brain Volume: The Women's Health Initiative

PURPOSE

To investigate the relationships between optic nerve cupping and total and regional brain volumes.

DESIGN

Secondary analysis of randomized clinical trial data.

METHODS

Women 65 to 79 years of age without glaucoma with cup-to-disc ratio (CDR) measurements from the Women's Health Initiative (WHI) Sight Examination study and magnetic resonance imaging (MRI)-based total and regional brain volumes from the WHI Memory Study MRI-1 were included. Large CDR was defined as 0.6 or greater in either eye. Generalized estimating equation models were used to account for intra-brain correlations between the right and left sides. The final analysis was adjusted for demographic and clinical characteristics and for total brain volume (for regional analyses).

RESULTS

Final analyses included 471 women, with the mean age ± SD was 69.2 ± 3.6 years; 92.8% of the subjects were white. Of 471 women, 34 (7.2%) had large CDR. Controlling for total brain volume and for demographic and clinical characteristics, lateral ventricle volume was 3.01 cc larger for subjects with large CDR compared to those without large CDR (95% CI = 0.02 to 5.99; P = .048). Furthermore, frontal lobe volume was 4.78 cc lower for subjects with large CDR compared to those without (95% CI = -8.71, -0.84; P = 0.02), and occipital lobe volume was 1.86 cc lower for those with large CDR compared to those without (95% CI = -3.39, -0.3; P =.02).

CONCLUSIONS

Our analysis suggests that in women aged 65 years or more, large CDR is associated with lower relative total brain volume and absolute regional volume in the frontal and occipital lobes. Enlarged CDR in individuals without glaucoma may represent a sign of optic nerve and brain aging, although more longitudinal data are needed.

Oral environment and cerebral blood flow in patients with neurodegenerative dementia: comparison of Alzheimer type dementia and dementia with Lewy bodies

BACKGROUND

The number of patients with dementia is increasing worldwide. Modifying risk factors may significantly reduce the prevalence and cost of dementia. The number of remaining teeth, occlusal force, denture use, and periodontal disease status are associated with the risk of developing dementia. The oral environment may be a risk factor for dementia. This study aimed to investigate the association between the oral environment and cerebral blood flow in patients with mild cognitive impairment and dementia (either Alzheimer type dementia (ATD) or dementia with Lewy bodies (DLB)). We aimed to identify differences in the oral environment according to the underlying neurodegenerative disease.

METHODS

The participants were 25 patients with ATD and 25 patients with DLB who visited the Department of Dementia and Geriatric Medicine, Kanagawa Dental University Hospital. Patients were diagnosed with ATD and DLB by well-trained specialists certified by the Japanese Dementia Society and categorised as Level 3 or 4 by the Functional Assessment Staging of Alzheimer Disease scale. The correlation between oral environment (number of teeth, periodontal tissue, and oral function) and cerebral blood flow in each brain area calculated by single photon emission computed tomography was examined.

RESULTS

The DLB group showed a significant correlation between masticatory performance and cerebral blood flow in some areas, while no such correlation was observed in the ATD group. Significant correlations were found between periodontal pocket depth and bleeding on probing and cerebral blood flow in some areas in both groups, although the correlation was considerable in the ATD group.

CONCLUSIONS

The results of this study suggest that the association between changes in the oral environment and cerebral blood flow may differ among patients with ATD and DLB, depending on the underlying causative disease.

Cognitive Impairment in Older Adults: Epidemiology, Diagnosis, and Treatment

Cognitive impairment and dementia affect dozens of millions of people worldwide and cause significant distress to patients and caregivers and a financial burden to families and health care systems. Careful history-taking, cognitive and physical examination, and supplemental neuroimaging and fluid-based biomarkers can accurately diagnose neurocognitive disorders. Management includes non-pharmacological and pharmacological treatments tailored to the etiology and to the individual.

Adapting UK Biobank imaging for use in a routine memory clinic setting: The Oxford Brain Health Clinic

The Oxford Brain Health Clinic (BHC) is a joint clinical-research service that provides memory clinic patients and clinicians access to high-quality assessments not routinely available, including brain MRI aligned with the UK Biobank imaging study (UKB). In this work we present how we 1) adapted the UKB MRI acquisition protocol to be suitable for memory clinic patients, 2) modified the imaging analysis pipeline to extract measures that are in line with radiology reports and 3) explored the alignment of measures from BHC patients to the largest brain MRI study in the world (ultimately 100,000 participants). Adaptations of the UKB acquisition protocol for BHC patients include dividing the scan into core and optional sequences (i.e., additional imaging modalities) to improve patients' tolerance for the MRI assessment. We adapted the UKB structural MRI analysis pipeline to take into account the characteristics of a memory clinic population (e.g., high amount of white matter hyperintensities and hippocampal atrophy). We then compared the imaging derived phenotypes (IDPs) extracted from the structural scans to visual ratings from radiology reports, non-imaging factors (age, cognition) and to reference distributions derived from UKB data. Of the first 108 BHC attendees (August 2020-November 2021), 92.5 % completed the clinical scans, 88.0 % consented to use of data for research, and 43.5 % completed the additional research sequences, demonstrating that the protocol is well tolerated. The high rates of consent to research makes this a valuable real-world quality research dataset routinely captured in a clinical service. Modified tissue-type segmentation with lesion masking greatly improved grey matter volume estimation. CSF-masking marginally improved hippocampal segmentation. The IDPs were in line with radiology reports and showed significant associations with age and cognitive performance, in line with the literature. Due to the age difference between memory clinic patients of the BHC (age range 65-101 years, average 78.3 years) and UKB participants (44-82 years, average 64 years), additional scans on elderly healthy controls are needed to improve reference distributions. Current and future work aims to integrate automated quantitative measures in the radiology reports and evaluate their clinical utility.

Blood Analytes as Biomarkers of Mechanisms Involved in Alzheimer’s Disease Progression

Alzheimer’s disease (AD) is the leading cause of dementia, but the pathogenetic factors are not yet well known, and the relationships between brain and systemic biochemical derangements and disease onset and progression are unclear. We aim to focus on blood biomarkers for an accurate prognosis of the disease. We used a dataset characterized by longitudinal findings collected over the past 10 years from 90 AD patients. The dataset included 277 observations (both clinical and biochemical ones, encompassing blood analytes encompassing routine profiles for different organs, together with immunoinflammatory and oxidative markers). Subjects were grouped into four severity classes according to the Clinical Dementia Rating (CDR) Scale: mild (CDR = 0.5 and CDR = 1), moderate (CDR = 2), severe (CDR = 3) and very severe (CDR = 4 and CDR = 5). Statistical models were used for the identification of potential blood markers of AD progression. Moreover, we employed the Pathfinder tool of the Reactome database to investigate the biological pathways in which the analytes of interest could be involved. Statistical results reveal an inverse significant relation between four analytes (high-density cholesterol, total cholesterol, iron and ferritin) with AD severity. In addition, the Reactome database suggests that such analytes could be involved in pathways that are altered in AD progression. Indeed, the identified blood markers include molecules that reflect the heterogeneous pathogenetic mechanisms of AD. The combination of such blood analytes might be an early indicator of AD progression and constitute useful therapeutic targets.

A case report and literature review of cognitive malingering and psychopathology

Malingering of cognitive difficulties constitutes a major issue in psychiatric forensic settings. Here, we present a selective literature review related to the topic of cognitive malingering, psychopathology and their possible connections. Furthermore, we report a single case study of a 60-year-old man with a long and ongoing judicial history who exhibits a suspicious multi-domain neurocognitive disorder with significant reduction of autonomy in daily living, alongside a longtime history of depressive symptoms. Building on this, we suggest the importance of evaluating malingering conditions through both psychiatric and neuropsychological assessment tools. More specifically, the use of Performance Validity Tests (PVTs)-commonly but not quite correctly considered as tests of "malingering"-alongside the collection of clinical history and the use of routine psychometric testing, seems to be crucial in order to detect discrepancies between self-reported patient's symptoms, embedded validity indicators and psychometric results.

Default Mode Network quantitative diffusion and resting-state functional magnetic resonance imaging correlates in sporadic Creutzfeldt-Jakob disease

Grey matter involvement is a well-known feature in sporadic Creutzfeldt-Jakob disease (sCJD), yet precise anatomy-based quantification of reduced diffusivity is still not fully understood. Default Mode Network (DMN) areas have been recently demonstrated as selectively involved in sCJD, and functional connectivity has never been investigated in prion diseases. We analyzed the grey matter involvement using a quantitatively multi-parametric MRI approach. Specifically, grey matter mean diffusivity of 37 subjects with sCJD was compared with that of 30 age-matched healthy controls with a group-wise approach. Differences in mean diffusivity were also examined between the cortical (MM(V)1, MM(V)2C, and VV1) and subcortical (VV2 and MV2K) subgroups of sCJD for those with autopsy data available (n = 27, 73%). We also assessed resting-state functional connectivity of both ventral and dorsal components of DMN in a subset of subject with a rs-fMRI dataset available (n = 17). Decreased diffusivity was predominantly present in posterior cortical regions of the DMN, but also outside of the DMN in temporal areas and in a few limbic and frontal areas, in addition to extensive deep nuclei involvement. Both subcortical and cortical sCJD subgroups showed decreased diffusivity subcortically, whereas only the cortical type expressed significantly decreased diffusivity cortically, mainly in parietal, occipital, and medial-inferior temporal cortices bilaterally. Interestingly, we found abnormally increased connectivity in both dorsal and ventral components of the DMN in sCJD subjects compared with healthy controls. The significance and possible utility of functional imaging as a biomarker for tracking disease progression in prion disease needs to be explored further.

The Correlation Between White Matter Hyperintensity Burden and Regional Brain Volumetry in Patients With Alzheimer's Disease

Background

White matter hyperintensities (WMHs) and regional brain lobe atrophy coexist in the brain of patients with Alzheimer's disease (AD), but the association between them in patients with AD still lacks comprehensive investigation and solid imaging data support.

Objective

We explored whether WMHs can promote the pathological process of AD by aggravating atrophy in specific brain regions and tried to explain the regional specificity of these relationships.

Methods

A sample of 240 adults including 180 normal controls (NCs) and 80 cases with AD were drawn from the ADNI database. T1-weighted magnetic resonance imaging (MRI) and T2-weighted fluid-attenuated MRI of the participants were downloaded and were analyzed using AccuBrain^® to generate the quantitative ratio of WMHs (WMHr, WMH volumes corrected by intracranial volume) and regional brain atrophy. We also divided WMHr into periventricular WMHr (PVWMHr) and deep WMHr (DWMHr) for the purpose of this study. The Cholinergic Pathways Hyperintensities Scale (CHIPS) scores were conducted by two evaluators. Independent t-test, Mann–Whitney U test, or χ² test were used to compare the demographic characteristics, and Spearman correlation coefficient values were used to determine the association between WMHs and different regions of brain atrophy.

Results

Positive association between WMHr and quantitative medial temporal lobe atrophy (QMTA) (r_s = 0.281, p = 0.011), temporal lobe atrophy (r_s = 0.285, p = 0.011), and insular atrophy (r_s = 0.406, p < 0.001) was found in the AD group before Bonferroni correction. PVWMHr contributed to these correlations. By separately analyzing the relationship between PVWMHr and brain atrophy, we found that there were still positive correlations after correction in QMTA (r_s = 0.325, p = 0.003), temporal lobe atrophy (r_s = 0.298, p = 0.007), and insular atrophy (r_s = 0.429, p < 0.001) in AD group.

Conclusion

WMH severity tends to be associated with regional brain atrophy in patients with AD, especially with medial temporal lobe, temporal lobe, and insular lobe atrophy. PVWMHs were devoted to these correlations.

Mixed Reality Prototype of Multimodal Screening for Early Detection of Cognitive Impairments in Elderly Individuals: Protocol Development and Usability Study (Preprint)

Background

The early diagnosis of cognitive impairments is an important step in the adequate management of dementia. The project “Smart Cognition & Behaviour Screening powered by Augmented Reality” (SCOBES-AR) aims to develop a multimodal screening tool (MST) for the early detection of cognitive impairments using augmented and virtual reality. The first project phase selected validated assessments for combination with the MST and tested it in 300 healthy older adults.

Objective

This study established a protocol for the implementation and usability of a mixed reality (MR)–enhanced multidisciplinary screening tool for the early detection of cognitive impairments in older adults. The developed MST will be partially enhanced by MR, which is a combination of augmented reality (AR) and virtual reality (VR). This MR-enhanced prototype of the screening tool (MR-MST) will be tested and compared to the previously developed MST. The usability of the prototype will also be examined.

Methods

This single-center observational crossover design study screens 100 healthy participants (aged 60-75 years) for cognitive decline using a specially developed MST (assessment of cognitive functions, olfactory sensitivity, nutritional preferences, gait parameters, reaction times, and activities of daily living) and an MR-enhanced MST in which the assessments of cognitive functions, reaction time, activities of daily living, and gait will be performed using tailor-made software and AR and VR hardware. The results of the MR-enhanced MST will be compared to those without MR. The usability of the developed MR-enhanced MST will be tested on 10 investigators and 10 test participants using observed summative evaluation and the codiscovery method, and on 2 usability experts using the codiscovery and cognitive walkthrough methods.

Results

This study was funded by the Austrian Research Promotion Agency (grant 866873) and received approval from the ethics committee of the Medical University of Graz. The MR-MST and the experimental protocol for this study were developed. All participants gave written informed consent. As of July 15, 2022, a total of 70 participants have been screened. Data analysis and dissemination are scheduled for completion by September 2023.

Conclusions

The development and testing of the MR-MST is an important step toward the establishment of the best practice procedure for the implementation of AR and VR in the screening of cognitive declines in older adults. It will help improve our knowledge of the usability and applicability of the developed prototype and promote further advancement in AR and VR technologies to be used in therapeutic settings.

International Registered Report Identifier (IRRID)

DERR1-10.2196/39513

Imaging Aspects of the Hippocampus

The hippocampus is one of the most sophisticated structures in the brain, owing to its complex anatomy, intriguing functions, relationship with other structures, and relevant associated symptoms. Despite being a structure analyzed for centuries, its anatomy and physiology in the human body are still being extensively studied, as well as associated pathologic conditions and potential biomarkers. It can be affected by a broad group of diseases that can be classified as congenital, degenerative, infectious or inflammatory, neoplastic, vascular, or toxic-metabolic disease. The authors present the anatomy and close structures, function, and development of the hippocampus, as well as an original algorithm for imaging diagnosis. The algorithm includes pathologic conditions that typically affect the hippocampus and groups them into nodular (space occupying) and nonnodular pathologic conditions, serving as a guide to narrow the differential diagnosis. MRI is the imaging modality of choice for evaluation of the hippocampus, and CT and nuclear medicine also improve the analysis. The MRI differential diagnosis depends on anatomic recognition and careful characterization of associated imaging findings such as volumetric changes, diffusion restriction, cystic appearance, hyperintensity at T1-weighted imaging, enhancement, or calcification, which play a central role in diagnosis along with clinical findings. Some pathologic conditions arising from surrounding structures such as the amygdala are also important to recognize. Pathologic conditions of the hippocampus can be a challenge to diagnose because they usually manifest as similar clinical syndromes, so the imaging findings play a potential role in guiding the final diagnosis. Online supplemental material is available for this article. ^©RSNA, 2022.

Altruistic Social Activity, Depressive Symptoms, and Brain Regional Gray Matter Volume: Voxel-Based Morphometry Analysis from 8695 Old Adults

Altruistic social activity, such as giving support to others, has shown protective benefits on dementia risk and cognitive decline. However, the pathological mechanism is unclear. In the present study, we investigated the association between altruistic social activity and brain regional gray matter. Furthermore, to explore the psychological interplay in altruistic social activity, we tested mediating effect of depressive symptoms on brain regional gray matter. We performed a cross-sectional Voxel-Based Morphology (VBM) analysis including 8695 old adults (72.9±6.1 years) from Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD) Cohort. We measured altruistic social activities by self-report questionnaire, depressive symptoms by Geriatric Depression Scale (GDS)-short version. We employed the whole-brain VBM method to detect relevant structural properties related to altruistic social activity. We then performed multiple regression models to detect the mediating effect of depressive symptoms on particular brain regional gray matter volume while adjusting possible physical and social lifestyle covariables. We found that altruistic social activity is associated with larger gray matter volume in posterior insula, middle cingulate gyrus, hippocampus, thalamus, superior temporal gyrus, anterior orbital gyrus, and middle occipital gyrus. Depressive symptoms mediated over 10% on altruistic social activity and hippocampus volume, over 20% on altruistic social activity and cingulate gyrus volume. Our results indicated that altruistic social activity might preserve brain regional gray matter where are sensitive to aging and cognitive decline. Meanwhile, this association may be explained by indirect effect on depressive symptoms, suggesting that altruistic social activity may mitigate the neuropathology of dementia.

COVID-19-associated encephalitis or Creutzfeldt-Jakob disease: a case report

Background: Accurate diagnosis and management of patients with rapidly progressive dementia may be challenging during the COVID-19 pandemic, which has negatively influenced the diagnostic performances, medical resource allocation and routine care for all non-COVID-19 diseases. Case Presentation: We herein present a case of a 57‐year‐old male with rapidly progressive cognitive decline, headache, diplopia, myalgia, unsteady gait, aggression, depression, insomnia, hallucinations and delusions of persecution. COVID-19-associated encephalitis was briefly considered as a differential diagnosis. However, this hypothesis was rejected upon further investigation. A final diagnosis of sporadic Creutzfeldt–Jakob disease was made. Conclusion: A timely and accurate diagnosis of Creutzfeldt–Jakob disease gives patients and their families the chance to receive a good standard of healthcare and avoid extensive evaluations for other conditions.

A Deep Neural Network-Based Method for Prediction of Dementia Using Big Data

The rise in dementia among the aging Korean population will quickly create a financial burden on society, but timely recognition of early warning for dementia and proper responses to the occurrence of dementia can enhance medical treatment. Health behavior and medical service usage data are relatively more accessible than clinical data, and a prescreening tool with easily accessible data could be a good solution for dementia-related problems. In this paper, we apply a deep neural network (DNN) to prediction of dementia using health behavior and medical service usage data, using data from 7031 subjects aged over 65 collected from the Korea National Health and Nutrition Examination Survey (KNHANES) in 2001 and 2005. In the proposed model, principal component analysis (PCA) featuring and min/max scaling are used to preprocess and extract relevant background features. We compared our proposed methodology, a DNN/scaled PCA, with five well-known machine learning algorithms. The proposed methodology shows 85.5% of the area under the curve (AUC), a better result than that using other algorithms. The proposed early prescreening method for possible dementia can be used by both patients and doctors.

KALPANA: Advanced Spectroscopic Signal Processing Platform for Improved Accuracy to Aid in Early Diagnosis of Brain Disorders in Clinical Setting

Magnetic resonance spectroscopy (MRS) plays a substantial role in the non-invasive detection of brain neurochemicals, antioxidants, and neurotransmitters. Quantitative monitoring of these neurochemicals and neurotransmitters in the brain has a profound application for the understanding of brain disorders. Significant progress in the MR scanner as well as MR pulse sequence development to detect in vivo neurochemicals has been accomplished. The processing of MR signal from these low abundant neurochemicals/neurotransmitters should be very robust and sensitive in order to provide distinctive observations of disease-related neurochemical alterations and their absolute quantitation to aid in early clinical diagnosis. We highlight the diversity in currently available MRS processing tools, and recently introduced, KALPANA, a promising package integrating the end-to-end processing as well as robust quantitation of neurochemicals in a user-friendly approach through a graphical user interface. This further necessitates the futuristic need for advanced MRS processing pipeline and the respective readout that can help in early diagnosis and prognosis of diseases in the clinical environment.

Biomarkers and diagnostic guidelines for sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease is a fatal neurodegenerative disease caused by misfolded prion proteins (PrP^Sc). Effective therapeutics are currently not available and accurate diagnosis can be challenging. Clinical diagnostic criteria use a combination of characteristic neuropsychiatric symptoms, CSF proteins 14-3-3, MRI, and EEG. Supportive biomarkers, such as high CSF total tau, could aid the diagnostic process. However, discordant studies have led to controversies about the clinical value of some established surrogate biomarkers. Development and clinical application of disease-specific protein aggregation and amplification assays, such as real-time quaking induced conversion (RT-QuIC), have constituted major breakthroughs for the confident pre-mortem diagnosis of sporadic Creutzfeldt-Jakob disease. Updated criteria for the diagnosis of sporadic Creutzfeldt-Jakob disease, including application of RT-QuIC, should improve early clinical confirmation, surveillance, assessment of PrP^Sc seeding activity in different tissues, and trial monitoring. Moreover, emerging blood-based, prognostic, and potentially pre-symptomatic biomarker candidates are under investigation.

Improved Segmentation of the Intracranial and Ventricular Volumes in Populations with Cerebrovascular Lesions and Atrophy Using 3D CNNs

Successful segmentation of the total intracranial vault (ICV) and ventricles is of critical importance when studying neurodegeneration through neuroimaging. We present iCVMapper and VentMapper, robust algorithms that use a convolutional neural network (CNN) to segment the ICV and ventricles from both single and multi-contrast MRI data. Our models were trained on a large dataset from two multi-site studies (N = 528 subjects for ICV, N = 501 for ventricular segmentation) consisting of older adults with varying degrees of cerebrovascular lesions and atrophy, which pose significant challenges for most segmentation approaches. The models were tested on 238 participants, including subjects with vascular cognitive impairment and high white matter hyperintensity burden. Two of the three test sets came from studies not used in the training dataset. We assessed our algorithms relative to four state-of-the-art ICV extraction methods (MONSTR, BET, Deep Extraction, FreeSurfer, DeepMedic), as well as two ventricular segmentation tools (FreeSurfer, DeepMedic). Our multi-contrast models outperformed other methods across many of the evaluation metrics, with average Dice coefficients of 0.98 and 0.96 for ICV and ventricular segmentation respectively. Both models were also the most time efficient, segmenting the structures in orders of magnitude faster than some of the other available methods. Our networks showed an increased accuracy with the use of a conditional random field (CRF) as a post-processing step. We further validated both segmentation models, highlighting their robustness to images with lower resolution and signal-to-noise ratio, compared to tested techniques. The pipeline and models are available at: https://icvmapp3r.readthedocs.io and https://ventmapp3r.readthedocs.io to enable further investigation of the roles of ICV and ventricles in relation to normal aging and neurodegeneration in large multi-site studies.

Anti-gamma-aminobutyric acid receptor type A encephalitis: a review

PURPOSE OF REVIEW

To systematically review the clinical features, diagnosis, and management of anti-gamma-aminobutyric acid receptor Type A (GABAA) autoimmune encephalitis with a focus on recent data.

RECENT FINDINGS

In a review of published reports, we identified 50 cases of anti-GABAA receptor encephalitis with clinical features reported. The median age at presentation was 47 years old (range, 2.5 months-88 years old), 64% were adults, 36% were children and it occurred in both males and females. Eight-two percent (41/50) presented with seizures, 72% (36/50) with encephalopathy, and 58% (29/50) with both. Of those presenting with seizures, 42% developed status epilepticus during their disease course. Ninety-six percent (48/50) had MRI results reported, with 83% of these cases having abnormal findings, most commonly multifocal/diffuse cortical and subcortical T2/FLAIR hyperintense lesions without associated gadolinium enhancement. Almost one-third, 28% (14/50), had an associated malignancy detected by the time of diagnosis, 64% (9/14) of which was thymoma. Of 44 patients with outcomes reported, 80% had partial or complete recovery, whereas 20% had poor outcomes including 11% (5/44) who died. Of the 42 patients with type of treatment(s) and outcomes reported, 54% (23/42) received only first-line immunotherapy and 31% (13/42) received first-line and second-line immunotherapy. Receiving a combination of first-line and second-line immunotherapy may be associated with higher likelihood of complete recovery. When follow-up MRIs were reported, all showed improvement, and sometimes complete resolution, of T2/FLAIR hyperintensities.

SUMMARY

Anti-GABAA receptor encephalitis can present across the age spectrum and should be considered in patients who present with rapidly progressive encephalopathy and/or seizures. Brain MRI often shows a distinctive pattern of multifocal cortical and subcortical T2/FLAIR hyperintense lesions, generally not typical of other known central nervous system autoantibody associated encephalitis syndromes. High clinical suspicion and early diagnosis are important given the potential for clinical improvement with immunotherapy.

High-quality brain perfusion SPECT images may be achieved with a high-speed recording using 360° CZT camera

Objective

The aim of this study was to compare brain perfusion SPECT obtained from a 360° CZT and a conventional Anger camera.

Methods

The 360° CZT camera utilizing a brain configuration, with 12 detectors surrounding the head, was compared to a 2-head Anger camera for count sensitivity and image quality on 30-min SPECT recordings from a brain phantom and from ^99mTc-HMPAO brain perfusion in 2 groups of 21 patients investigated with the CZT and Anger cameras, respectively. Image reconstruction was adjusted according to image contrast for each camera.

Results

The CZT camera provided more than 2-fold increase in count sensitivity, as compared with the Anger camera, as well as (1) lower sharpness indexes, giving evidence of higher spatial resolution, for both peripheral/central brain structures, with respective median values of 5.2%/3.7% versus 2.4%/1.9% for CZT and Anger camera respectively in patients (p < 0.01), and 8.0%/6.9% versus 6.2%/3.7% on phantom; and (2) higher gray/white matter contrast on peripheral/central structures, with respective ratio median values of 1.56/1.35 versus 1.11/1.20 for CZT and Anger camera respectively in patients (p < 0.05), and 2.57/2.17 versus 1.40/1.12 on phantom; and (3) no change in noise level. Image quality, scored visually by experienced physicians, was also significantly higher on CZT than on the Anger camera (+ 80%, p < 0.01), and all these results were unchanged on the CZT images obtained with only a 15 min recording time.

Conclusion

The 360° CZT camera provides brain perfusion images of much higher quality than a conventional Anger camera, even with high-speed recordings, thus demonstrating the potential for repositioning brain perfusion SPECT to the forefront of brain imaging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-020-00334-7.

"The Dichotic Digit Test" as an Index Indicator for Hearing Problem in Dementia: Systematic Review and Meta-Analysis

BACKGROUND

Patients with dementia commonly have problems processing speech in the presence of competing background speech or noise. This difficulty can be present from the very early stages of dementia, and may be a preclinical feature of Alzheimer's disease.

PURPOSE

This study investigates whether people with dementia perform worse on the dichotic digit test (DDT), an experimental probe of speech processing in the presence of competing speech, and whether test performance may predict dementia onset.

RESEARCH DESIGN

Systematic review and meta-analysis.

DATA COLLECTION AND ANALYSIS

A literature search was conducted in Medline, Embase, Scopus, and Psycinfo. We included (1) studies that included people with a diagnosis of dementia and a healthy control group with no cognitive impairment; (2) studies that reported results from a DDT in a free-recall response task; and (3) studies that had the dichotic digit mean correct percentage score or right-ear advantage, as outcome measurements.

RESULTS

People with dementia had a lower DDT total score, with a pooled mean difference of 18.6% (95% confidence interval [CI]: 21.2-15.9). Patients with dementia had an increased right-ear advantage relative to controls with a pooled difference of 24.4% (95% CI: 21.8-27.0).

CONCLUSION

The DDT total scores are lower and the right-ear advantage increased in cognitively impaired versus normal control participants. The findings also suggest that the reduction of dichotic digit total score and increase of right-ear advantage progress as cognitive impairment increases. Whether abnormalities in dichotic digit scores could predict subsequent dementia onset should be examined in further longitudinal studies.

Cognitive Impairment Evaluation and Management

Clinicians should use a systematic approach to evaluating patients presenting with a concern for cognitive impairment. This approach includes interviewing a knowledgeable informant and performing a thorough mental status examination in order to determine the presence of functional impairments and the domains of cognition that are impaired. The results of this interview and examination determine the next steps of the diagnostic work-up. The pattern of cognitive impairment shapes the differential diagnosis. Treatment should address symptoms, and environmental, psychological, and behavioral interventions are essential.

Roles of glutamate receptors in a novel in vitro model of early, comorbid cerebrovascular, and Alzheimer's diseases

Systemic multimorbidity is highly prevalent in the elderly and, remarkably, coexisting neuropathological markers of Alzheimer's (AD) and cerebrovascular (CVD) diseases are found at autopsy in most brains of patients clinically diagnosed as AD. Little is known on neurodegeneration peculiar to comorbidities, especially at early stages when pathogenesis may propagate at subclinical levels. We developed a novel in vitro model of comorbid CVD/AD in organotypic hippocampal cultures, by combining oxygen-glucose deprivation (OGD) and exposure to amyloid-Aβ oligomers (AβOs), both applied at levels subtoxic to neurons when used in isolation. We focused on synaptic proteins and the roles of glutamate receptors, which have been implicated in many basic and clinical approaches to either CVD or AD. Subtoxic insults by OGD and AβOs synergized to reduce levels of synaptophysin (SYP) and PSD-95 without cell death, while effects of antagonists of either metabotropic or ionotropic glutamate receptors were distinct from reports in models of isolated CVD or AD. In particular, modulation of glutamate receptors differentially impacted SYP and PSD-95, and antagonists of a single receptor subtype had distinct effects when either isolated or combined. Our findings highlight the complexity of CVD/AD comorbidity, help understand variable responses to glutamate receptor antagonists in patients diagnosed with AD and may contribute to future development of therapeutics based on investigation of the pattern of progressive comorbidity.

Neuropsychological autopsy of testamentary capacity: Methodology and issues in the elderly

The forensic assessment of testamentary capacity is a topical issue given the prevalence of dementia illnesses and the increase in the complexity of modern financial and family structures. Although a contemporaneous assessment would be desirable, the majority of situations require a retrospective assessment of the mental state a deceased individual. Neuropsychologists, independently or as part of a board of consultants, are, therefore, frequently requested to give an expert opinion of the competence of cognitively impaired elderly testators.This paper offers a guide for carrying out a neuropsychological autopsy, namely the process of posthumous evaluation, for determining testamentary capacity. Taking into account the recent literature on the assessment of testamentary capacity, we propose a three-phase procedure for carrying out the neuropsychological autopsy in the forensic context. The neuropsychological autopsy of testamentary capacity is based on the meticulous, chronologically structured evaluation of any medical documents, available psychometric data, along with the critical examination of any source of information about the cognitive level of functioning of the deceased person at the time of the will.

Shortening heparan sulfate chains prolongs survival and reduces parenchymal plaques in prion disease caused by mobile, ADAM10-cleaved prions

Cofactors are essential for driving recombinant prion protein into pathogenic conformers. Polyanions promote prion aggregation in vitro, yet the cofactors that modulate prion assembly in vivo remain largely unknown. Here we report that the endogenous glycosaminoglycan, heparan sulfate (HS), impacts prion propagation kinetics and deposition sites in the brain. Exostosin-1 haploinsufficient (Ext1^+/-) mice, which produce short HS chains, show a prolonged survival and a redistribution of plaques from the parenchyma to vessels when infected with fibrillar prions, and a modest delay when infected with subfibrillar prions. Notably, the fibrillar, plaque-forming prions are composed of ADAM10-cleaved prion protein lacking a glycosylphosphatidylinositol anchor, indicating that these prions are mobile and assemble extracellularly. By analyzing the prion-bound HS using liquid chromatography-mass spectrometry (LC-MS), we identified the disaccharide signature of HS differentially bound to fibrillar compared to subfibrillar prions, and found approximately 20-fold more HS bound to the fibrils. Finally, LC-MS of prion-bound HS from human patients with familial and sporadic prion disease also showed distinct HS signatures and higher HS levels associated with fibrillar prions. This study provides the first in vivo evidence of an endogenous cofactor that accelerates prion disease progression and enhances parenchymal deposition of ADAM10-cleaved, mobile prions.

Longitudinal multimodal imaging and clinical endpoints for frontotemporal dementia clinical trials

Frontotemporal dementia refers to a group of progressive neurodegenerative syndromes usually caused by the accumulation of pathological tau or TDP-43 proteins. The effects of these proteins in the brain are complex, and each can present with several different clinical syndromes. Clinical efficacy trials of drugs targeting these proteins must use endpoints that are meaningful to all participants despite the variability in symptoms across patients. There are many candidate clinical measures, including neuropsychological scores and functional measures. Brain imaging is another potentially attractive outcome that can be precisely quantified and provides evidence of disease modification. Most imaging studies in frontotemporal dementia have been cross-sectional, and few have compared longitudinal changes in cortical volume with changes in other measures such as perfusion and white matter integrity. The current study characterized longitudinal changes in 161 patients with three frontotemporal dementia syndromes: behavioural variant frontotemporal dementia (n = 77) and the semantic (n = 45) and non-fluent (n = 39) variants of primary progressive aphasia. Visits included comprehensive neuropsychological and functional assessment, structural MRI (3 T), diffusion tensor imaging, and arterial spin labelled perfusion imaging. The goal was to identify measures that are appropriate as clinical trial outcomes for each group, as well as those that might be appropriate for trials that would include more than one of these groups. Linear mixed effects models were used to estimate changes in each measure, and to examine the correlation between imaging and clinical changes. Sample sizes were estimated based on the observed effects for theoretical clinical trials using bootstrapping techniques to provide 95% confidence intervals for these estimates. Declines in functional and neuropsychological measures, as well as frontal and temporal cortical volumes and white matter microstructure were detected in all groups. Imaging changes were statistically significantly correlated with, and explained a substantial portion of variance in, the change in most clinical measures. Perfusion and diffusion tensor imaging accounted for variation in clinical decline beyond volume alone. Sample size estimates for atrophy and diffusion imaging were comparable to clinical measures. Corpus callosal fractional anisotropy led to the lowest sample size estimates for all three syndromes. These findings provide further guidance on selection of trial endpoints for studies in frontotemporal dementia and support the use of neuroimaging, particularly structural and diffusion weighted imaging, as biomarkers. Diffusion and perfusion imaging appear to offer additional utility for explaining clinical change beyond the variance explained by volume alone, arguing for considering multimodal imaging in treatment trials.

Prion Diseases

Prions diseases are uniformly fatal neurodegenerative diseases that occur in sporadic, genetic, and acquired forms. Acquired prion diseases, caused by infectious transmission, are least common. Most prion diseases are not infectious, but occur spontaneously through misfolding of normal prion proteins or genetic mutations in the prion protein gene. Although most prion diseases are not caused by infection, they can be transmitted accidentally. Certain infection control protocols should be applied when handling central nervous system and other high-risk tissues. New diagnostic methods are improving premortem and earlier diagnosis. Treatment trials have not shown improved survival, but therapies may be available soon.

The quantitative neuroradiology initiative framework: application to dementia

There are numerous challenges to identifying, developing and implementing quantitative techniques for use in clinical radiology, suggesting the need for a common translational pathway. We developed the quantitative neuroradiology initiative (QNI), as a model framework for the technical and clinical validation necessary to embed automated segmentation and other image quantification software into the clinical neuroradiology workflow. We hypothesize that quantification will support reporters with clinically relevant measures contextualized with normative data, increase the precision of longitudinal comparisons, and generate more consistent reporting across levels of radiologists' experience. The QNI framework comprises the following steps: (1) establishing an area of clinical need and identifying the appropriate proven imaging biomarker(s) for the disease in question; (2) developing a method for automated analysis of these biomarkers, by designing an algorithm and compiling reference data; (3) communicating the results via an intuitive and accessible quantitative report; (4) technically and clinically validating the proposed tool pre-use; (5) integrating the developed analysis pipeline into the clinical reporting workflow; and (6) performing in-use evaluation. We will use current radiology practice in dementia as an example, where radiologists have established visual rating scales to describe the degree and pattern of atrophy they detect. These can be helpful, but are somewhat subjective and coarse classifiers, suffering from floor and ceiling limitations. Meanwhile, several imaging biomarkers relevant to dementia diagnosis and management have been proposed in the literature; some clinically approved radiology software tools exist but in general, these have not undergone rigorous clinical validation in high volume or in tertiary dementia centres. The QNI framework aims to address this need. Quantitative image analysis is developing apace within the research domain. Translating quantitative techniques into the clinical setting presents significant challenges, which must be addressed to meet the increasing demand for accurate, timely and impactful clinical imaging services.

Test-retest reliability in an fMRI study of naming in dementia

fMRI has been used as an outcome measure in dementia treatment studies, with many previous studies comparing only single pre- and post-treatment fMRI scans to determine treatment-induced neural changes, while utilizing single subject experimental designs. The purpose of the current study was to evaluate fMRI test-retest reliability in dementia patients and typical older adults using noun and verb confrontation naming to evaluate the validity of using a single pre/post-treatment scan comparison. Seven individuals with dementia and 9 control participants were tested three times over two months using the same fMRI procedures. Differences in individual and group level activation patterns were observed that varied across time. Additionally, the extent of variability fluctuated across individuals, groups, and the grammatical category of target words. Our findings suggested that one time fMRI scanning may inadequately represent an individual's typical brain activation pattern, particularly an individual with dementia. Thus, multiple imaging baselines are recommended.

Dissecting the genetic relationship between cardiovascular risk factors and Alzheimer's disease

Cardiovascular (CV)- and lifestyle-associated risk factors (RFs) are increasingly recognized as important for Alzheimer's disease (AD) pathogenesis. Beyond the ε4 allele of apolipoprotein E (APOE), comparatively little is known about whether CV-associated genes also increase risk for AD. Using large genome-wide association studies and validated tools to quantify genetic overlap, we systematically identified single nucleotide polymorphisms (SNPs) jointly associated with AD and one or more CV-associated RFs, namely body mass index (BMI), type 2 diabetes (T2D), coronary artery disease (CAD), waist hip ratio (WHR), total cholesterol (TC), triglycerides (TG), low-density (LDL) and high-density lipoprotein (HDL). In fold enrichment plots, we observed robust genetic enrichment in AD as a function of plasma lipids (TG, TC, LDL, and HDL); we found minimal AD genetic enrichment conditional on BMI, T2D, CAD, and WHR. Beyond APOE, at conjunction FDR < 0.05 we identified 90 SNPs on 19 different chromosomes that were jointly associated with AD and CV-associated outcomes. In meta-analyses across three independent cohorts, we found four novel loci within MBLAC1 (chromosome 7, meta-p = 1.44 × 10^-9), MINK1 (chromosome 17, meta-p = 1.98 × 10^-7) and two chromosome 11 SNPs within the MTCH2/SPI1 region (closest gene = DDB2, meta-p = 7.01 × 10^-7 and closest gene = MYBPC3, meta-p = 5.62 × 10^-8). In a large 'AD-by-proxy' cohort from the UK Biobank, we replicated three of the four novel AD/CV pleiotropic SNPs, namely variants within MINK1, MBLAC1, and DDB2. Expression of MBLAC1, SPI1, MINK1 and DDB2 was differentially altered within postmortem AD brains. Beyond APOE, we show that the polygenic component of AD is enriched for lipid-associated RFs. We pinpoint a subset of cardiovascular-associated genes that strongly increase the risk for AD. Our collective findings support a disease model in which cardiovascular biology is integral to the development of clinical AD in a subset of individuals.

Prion Seeds Distribute throughout the Eyes of Sporadic Creutzfeldt-Jakob Disease Patients

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common prion disease in humans and has been iatrogenically transmitted through corneal graft transplantation. Approximately 40% of sCJD patients develop visual or oculomotor symptoms and may seek ophthalmological consultation. Here we used the highly sensitive real-time quaking-induced conversion (RT-QuIC) assay to measure postmortem prion seeding activities in cornea, lens, ocular fluid, retina, choroid, sclera, optic nerve, and extraocular muscle in the largest series of sCJD patient eyes studied by any assay to date. We detected prion seeding activity in 100% of sCJD eyes, representing three common sCJD subtypes, with levels varying by up to 4 log-fold among individuals. The retina consistently showed the highest seed levels, which in some cases were only slightly lower than brain. Within the retina, prion deposits were detected by immunohistochemistry (IHC) in the retinal outer plexiform layer in most sCJD cases, and in some eyes the inner plexiform layer, consistent with synaptic prion deposition. Prions were not detected by IHC in any other eye region. With RT-QuIC, prion seed levels generally declined in eye tissues with increased distance from the brain, and yet all corneas had prion seeds detectable. Prion seeds were also present in the optic nerve, extraocular muscle, choroid, lens, vitreous, and sclera. Collectively, these results reveal that sCJD patients accumulate prion seeds throughout the eye, indicating the potential diagnostic utility as well as a possible biohazard.IMPORTANCE Cases of iatrogenic prion disease have been reported from corneal transplants, yet the distribution and levels of prions throughout the eye remain unknown. This study probes the occurrence, level, and distribution of prions in the eyes of patients with sporadic Creutzfeldt-Jakob disease (sCJD). We tested the largest series of prion-infected eyes reported to date using an ultrasensitive technique to establish the prion seed levels in eight regions of the eye. All 11 cases had detectable prion seeds in the eye, and in some cases, the seed levels in the retina approached those in brain. In most cases, prion deposits could also be seen by immunohistochemical staining of retinal tissue; other ocular tissues were negative. Our results have implications for estimating the risk for iatrogenic transmission of sCJD as well as for the development of antemortem diagnostic tests for prion diseases.

Differential diagnosis with other rapid progressive dementias in human prion diseases

Prion diseases are unique in medicine as in humans they occur in sporadic, genetic, and acquired forms. The most common human prion disease is sporadic Creutzfeldt-Jakob disease (CJD), which commonly presents as a rapidly progressive dementia (RPD) with behavioral, cerebellar, extrapyramidal, and some pyramidal features, with the median survival from symptom onset to death of just a few months. Because human prion diseases, as well as other RPDs, are relatively rare, they can be difficult to diagnose, as most clinicians have seen few, if any, cases. Not only can prion diseases mimic many other conditions that present as RPD, but some of those conditions can present similarly to prion disease. In this article, the authors discuss the different etiologic categories of conditions that often present as RPD and also present RPDs that had been misdiagnosed clinically as CJD. Etiologic categories of conditions are presented in order of the mnemonic used for remembering the various categories of RPDs: VITAMINS-D, for vascular, infectious, toxic-metabolic, autoimmune, mitochondrial/metastases, iatrogenic, neurodegenerative, system/seizures/sarcoid, and demyelinating. When relevant, clinical, imaging, or other features of an RPD that overlap with those of CJD are presented.