Functional Outcomes of a Comprehensive, Individualized, Person-Centered Management Program in Advanced Alzheimer"™s Disease(AD): Results from a 52-Week Randomized Controlled Trial
Background: We conducted a 28-week, single-blind, randomized, controlled trial of the efficacy of Comprehensive, Individualized, Person-Centered Management (CI-PCM) and memantine treatment (Reisberg et al., Dement Geriatr Cogn Disord, 2017) in advanced AD persons. CI-PCM and memantine was approximately 7.5 times more beneficial to AD persons on the Functional Assessment Staging Tool (FAST) (Kenowsky et. al., Alzheimer"™s and Dementia, 2017) than to AD persons who received memantine alone in the memantine FDA approval pivotal trial conducted by Reisberg et. al., (NEJM 2003). We also conducted a 24-week extension study. Herein, we report the difference in functional outcomes between the CI-PCM and Usual Community Care (UCC+FC) groups at 52-weeks on the FAST and the ADCS-ADLSev-Abv. See Figures 1 and 2. Method: After screening, 20 eligible subject-carepartner dyads were randomized equally to the CI-PCM and UCC+FC groups. All 20 dyads completed the 28-week study and entered the 24-week extension study. One subject in the UCC+FC group died during the extension study. The FAST and ADCS-ADLsev-abv were conducted at baseline, and weeks 4, 12, 28, and 52. P values were calculated using the Wilcoxon Mann Whitney test. Result: The mean FAST total score from baseline (6.6±0.1SE) to week 52 (6.5±0.01SE) showed an improvement of functional limitations in the CI-PCM group. The mean FAST total score for the UCC+FC group showed a functional decline from baseline (6.6±0.1SE) to week 52 (6.8±0.1SE), displaying a robustly significant difference between the two groups (p<0.0014). The mean ADCS-ADL-sev-abv total score for the CI-PCM group demonstrated a 20.9% improvement in functioning from baseline (15.3±2.0SE) to week 52 (18.5±2.5SE). The mean ADCS-ADL-sev-abv total score for the UCC+FC group showed a decline of 48.6% from baseline (14.8±2.1SE) to week 52 (7.6±2.3SE), indicating a significant difference between the two groups (p<0.009). Conclusion: The CI-PCM program is the only evidenced-based treatment to date that can significantly improve and reverse functional deterioration in advanced AD persons. The functional success of the CI-PCM program may primarily be attributed to care partners learning to memory coach AD persons to perform daily activities such as bathing, dressing, feeding and toileting themselves, and to become/maintain urinary and fecal continence.
Apolipoprotein E4 Effects a Distinct Transcriptomic Profile and Dendritic Arbor Characteristics in Hippocampal Neurons Cultured in vitro
The APOE gene is diversified by three alleles Îµ2, Îµ3, and Îµ4 encoding corresponding apolipoprotein (apo) E isoforms. Possession of the Îµ4 allele is signified by increased risks of age-related cognitive decline, Alzheimer's disease (AD), and the rate of AD dementia progression. ApoE is secreted by astrocytes as high-density lipoprotein-like particles and these are internalized by neurons upon binding to neuron-expressed apoE receptors. ApoE isoforms differentially engage neuronal plasticity through poorly understood mechanisms. We examined here the effects of native apoE lipoproteins produced by immortalized astrocytes homozygous for Îµ2, Îµ3, and Îµ4 alleles on the maturation and the transcriptomic profile of primary hippocampal neurons. Control neurons were grown in the presence of conditioned media from Apoe -/- astrocytes. ApoE2 and apoE3 significantly increase the dendritic arbor branching, the combined neurite length, and the total arbor surface of the hippocampal neurons, while apoE4 fails to produce similar effects and even significantly reduces the combined neurite length compared to the control. ApoE lipoproteins show no systemic effect on dendritic spine density, yet apoE2 and apoE3 increase the mature spines fraction, while apoE4 increases the immature spine fraction. This is associated with opposing effects of apoE2 or apoE3 and apoE4 on the expression of NR1 NMDA receptor subunit and PSD95. There are 1,062 genes differentially expressed across neurons cultured in the presence of apoE lipoproteins compared to the control. KEGG enrichment and gene ontology analyses show apoE2 and apoE3 commonly activate expression of genes involved in neurite branching, and synaptic signaling. In contrast, apoE4 cultured neurons show upregulation of genes related to the glycolipid metabolism, which are involved in dendritic spine turnover, and those which are usually silent in neurons and are related to cell cycle and DNA repair. In conclusion, our work reveals that lipoprotein particles comprised of various apoE isoforms differentially regulate various neuronal arbor characteristics through interaction with neuronal transcriptome. ApoE4 produces a functionally distinct transcriptomic profile, which is associated with attenuated neuronal development. Differential regulation of neuronal transcriptome by apoE isoforms is a newly identified biological mechanism, which has both implication in the development and aging of the CNS.
Absence of Apolipoprotein E is associated with exacerbation of prion pathology and promotes microglial neurodegenerative phenotype
Prion diseases or prionoses are a group of rapidly progressing and invariably fatal neurodegenerative diseases. The pathogenesis of prionoses is associated with self-replication and connectomal spread of PrPSc, a disease specific conformer of the prion protein. Microglia undergo activation early in the course of prion pathogenesis and exert opposing roles in PrPSc mediated neurodegeneration. While clearance of PrPSc and apoptotic neurons have disease-limiting effect, microglia-driven neuroinflammation bears deleterious consequences to neuronal networks. Apolipoprotein (apo) E is a lipid transporting protein with pleiotropic functions, which include controlling of the phagocytic and inflammatory characteristics of activated microglia in neurodegenerative diseases. Despite the significance of microglia in prion pathogenesis, the role of apoE in prionoses has not been established. We showed here that infection of wild type mice with 22L mouse adapted scrapie strain is associated with significant increase in the total brain apoE protein and mRNA levels and also with a conspicuous cell-type shift in the apoE expression. There is reduced expression of apoE in activated astrocytes and marked upregulation of apoE expression by activated microglia. We also showed apoE ablation exaggerates PrPSc mediated neurodegeneration. Apoe-/- mice have shorter disease incubation period, increased load of spongiform lesion, pronounced neuronal loss, and exaggerated astro and microgliosis. Astrocytes of Apoe-/- mice display salient upregulation of transcriptomic markers defining A1 neurotoxic astrocytes while microglia show upregulation of transcriptomic markers characteristic for microglial neurodegenerative phenotype. There is impaired clearance of PrPSc and dying neurons by microglia in Apoe-/- mice along with increased level of proinflammatory cytokines. Our work indicates that apoE absence renders clearance of PrPSc and dying neurons by microglia inefficient, while the excess of neuronal debris promotes microglial neurodegenerative phenotype aggravating the vicious cycle of neuronal death and neuroinflammation.
Segmented Linear Mixed Model Analysis Reveals Association of the APOEÉ›4 Allele with Faster Rate of Alzheimer's Disease Dementia Progression
BACKGROUND:APOEÉ›4 allele carriers present with increased risk for late-onset Alzheimer's disease (AD), show cognitive symptoms at earlier age, and are more likely to transition from mild cognitive impairment (MCI) to dementia but despite this, it remains unclear whether or not the É›4 allele controls the rate of disease progression. OBJECTIVE:To determine effects of the É›4 allele on rates of cognitive decline and brain atrophy during MCI and dementia stages of AD. METHODS:A segmented linear mixed model was chosen for longitudinal modeling of cognitive and brain volumetric data of 73 É›3/É›3, 99 É›3/É›4, and 39 É›4/É›4 Alzheimer's Disease Neuroimaging Initiative participants who transitioned during the study from MCI to AD dementia. RESULTS:É›4 carriers showed faster decline on MMSE, ADAS-11, CDR-SB, and MoCA scales, with the last two measures showing significant É›4 allele-dose effects after dementia transition but not during MCI. The É›4 effect was more prevalent in younger participants and in females. É›4 carriers also demonstrated faster rates of atrophy of the whole brain, the hippocampus, the entorhinal cortex, the middle temporal gyrus, and expansion of the ventricles after transitioning to dementia but not during MCI. CONCLUSION/CONCLUSIONS:Possession of the É›4 allele is associated with a faster progression of dementia due to AD. Our observations support the notion that APOE genotype not only controls AD risk but also differentially regulates mechanisms of neurodegeneration underlying disease advancement. Furthermore, our findings carry significance for AD clinical trial design.
Peroxiredoxin 6 mediates protective function of astrocytes in AÎ² proteostasis
BACKGROUND:) activities involved in repair of oxidatively damaged cell membrane lipids and cellular signaling. In the CNS, PRDX6 is uniquely expressed by astrocytes and its exact function remains unexplored. METHODS:AD transgenic mice were once crossed to mice overexpressing wild-type Prdx6 allele or to Prdx6 knock out mice. AÎ² pathology and associated neuritic degeneration were assessed in mice aged 10â€‰months. Laser scanning confocal microscopy was used to characterize AÎ² plaque morphology and activation of plaque-associated astrocytes and microglia. Effect of Prdx6 gene dose on plaque seeding was assessed in mice aged six months. RESULTS:AD transgenic mice promotes selective enticement of astrocytes to AÎ² plaques and penetration of plaques by astrocytic processes along with increased number and phagocytic activation of periplaque microglia. This effects suppression of nascent plaque seeding and remodeling of mature plaques consequently curtailing brain AÎ² load and AÎ²-associated neuritic degeneration. Conversely, Prdx6 haplodeficiency attenuates astro- and microglia activation around AÎ² plaques promoting AÎ² deposition and neuritic degeneration. CONCLUSIONS:We identify here PRDX6 as an important factor regulating response of astrocytes toward AÎ² plaques. Demonstration that phagocytic activation of periplaque microglia vary directly with astrocytic PRDX6 expression level implies previously unappreciated astrocyte-guided microglia effect in AÎ² proteostasis. Our showing that upregulation of PRDX6 attenuates AÎ² pathology may be of therapeutic relevance for AD.
FAM222A encodes a protein which accumulates in plaques in Alzheimer's disease
Alzheimer's disease (AD) is characterized by amyloid plaques and progressive cerebral atrophy. Here, we report FAM222A as a putative brain atrophy susceptibility gene. Our cross-phenotype association analysis of imaging genetics indicates a potential link between FAM222A and AD-related regional brain atrophy. The protein encoded by FAM222A is predominantly expressed in the CNS and is increased in brains of patients with AD and in an AD mouse model. It accumulates within amyloid deposits, physically interacts with amyloid-ÃŽÂ² (AÃŽÂ²) via its N-terminal AÃŽÂ² binding domain, and facilitates AÃŽÂ² aggregation. Intracerebroventricular infusion or forced expression of this protein exacerbates neuroinflammation and cognitive dysfunction in an AD mouse model whereas ablation of this protein suppresses the formation of amyloid deposits, neuroinflammation and cognitive deficits in the AD mouse model. Our data support the pathological relevance of protein encoded by FAM222A in AD.
Detection of Cerebrovascular Loss in the Normal Aging C57BL/6 Mouse Brain Using in vivo Contrast-Enhanced Magnetic Resonance Angiography
Microvascular rarefaction, or the decrease in vascular density, has been described in the cerebrovasculature of aging humans, rats, and, more recently, mice in the presence and absence of age-dependent diseases. Given the wide use of mice in modeling age-dependent human diseases of the cerebrovasculature, visualization, and quantification of the global murine cerebrovasculature is necessary for establishing the baseline changes that occur with aging. To provide in vivo whole-brain imaging of the cerebrovasculature in aging C57BL/6 mice longitudinally, contrast-enhanced magnetic resonance angiography (CE-MRA) was employed using a house-made gadolinium-bearing micellar blood pool agent. Enhancement in the vascular space permitted quantification of the detectable, or apparent, cerebral blood volume (aCBV), which was analyzed over 2 years of aging and compared to histological analysis of the cerebrovascular density. A significant loss in the aCBV was detected by CE-MRA over the aging period. Histological analysis via vessel-probing immunohistochemistry confirmed a significant loss in the cerebrovascular density over the same 2-year aging period, validating the CE-MRA findings. While these techniques use widely different methods of assessment and spatial resolutions, their comparable findings in detected vascular loss corroborate the growing body of literature describing vascular rarefaction aging. These findings suggest that such age-dependent changes can contribute to cerebrovascular and neurodegenerative diseases, which are modeled using wild-type and transgenic laboratory rodents.
Anti-prion Protein Antibody 6D11 Restores Cellular Proteostasis of Prion Protein Through Disrupting Recycling Propagation of PrPSc and Targeting PrPSc for Lysosomal Degradation
PrPSc is an infectious and disease-specific conformer of the prion protein, which accumulation in the CNS underlies the pathology of prion diseases. PrPSc replicates by binding to the cellular conformer of the prion protein (PrPC) expressed by host cells and rendering its secondary structure a likeness of itself. PrPC is a plasma membrane anchored protein, which constitutively recirculates between the cell surface and the endocytic compartment. Since PrPSc engages PrPC along this trafficking pathway, its replication process is often referred to as "recycling propagation." Certain monoclonal antibodies (mAbs) directed against prion protein can abrogate the presence of PrPSc from prion-infected cells. However, the precise mechanism(s) underlying their therapeutic propensities remains obscure. Using N2A murine neuroblastoma cell line stably infected with 22L mouse-adapted scrapie strain (N2A/22L), we investigated here the modus operandi of the 6D11 clone, which was raised against the PrPSc conformer and has been shown to permanently clear prion-infected cells from PrPSc presence. We determined that 6D11 mAb engages and sequesters PrPC and PrPSc at the cell surface. PrPC/6D11 and PrPSc/6D11 complexes are then endocytosed from the plasma membrane and are directed to lysosomes, therefore precluding recirculation of nascent PrPSc back to the cell surface. Targeting PrPSc by 6D11 mAb to the lysosomal compartment facilitates its proteolysis and eventually shifts the balance between PrPSc formation and degradation. Ongoing translation of PrPC allows maintaining the steady-state level of prion protein within the cells, which was not depleted under 6D11 mAb treatment. Our findings demonstrate that through disrupting recycling propagation of PrPSc and promoting its degradation, 6D11 mAb restores cellular proteostasis of prion protein.
A Review of Statistical Methods in Imaging Genetics
With the rapid growth of modern technology, many biomedical studies are being conducted to collect massive datasets with volumes of multi-modality imaging, genetic, neurocognitive, and clinical information from increasingly large cohorts. Simultaneously extracting and integrating rich and diverse heterogeneous information in neuroimaging and/or genomics from these big datasets could transform our understanding of how genetic variants impact brain structure and function, cognitive function, and brain-related disease risk across the lifespan. Such understanding is critical for diagnosis, prevention, and treatment of numerous complex brain-related disorders (e.g., schizophrenia and Alzheimer's disease). However, the development of analytical methods for the joint analysis of both high-dimensional imaging phenotypes and high-dimensional genetic data, a big data squared (BD2) problem, presents major computational and theoretical challenges for existing analytical methods. Besides the high-dimensional nature of BD2, various neuroimaging measures often exhibit strong spatial smoothness and dependence and genetic markers may have a natural dependence structure arising from linkage disequilibrium. We review some recent developments of various statistical techniques for imaging genetics, including massive univariate and voxel-wise approaches, reduced rank regression, mixture models, and group sparse multi-task regression. By doing so, we hope that this review may encourage others in the statistical community to enter into this new and exciting field of research.
A concise and persistent feature to study brain resting-state network dynamics: Findings from the Alzheimer's Disease Neuroimaging Initiative
Alzheimer's disease (AD) is the most common type of dementia in the elderly with no effective treatment currently. Recent studies of noninvasive neuroimaging, resting-state functional magnetic resonance imaging (rs-fMRI) with graph theoretical analysis have shown that patients with AD and mild cognitive impairment (MCI) exhibit disrupted topological organization in large-scale brain networks. In previous work, it is a common practice to threshold such networks. However, it is not only difficult to make a principled choice of threshold values, but also worse is the discard of potential important information. To address this issue, we propose a threshold-free feature by integrating a prior persistent homology-based topological feature (the zeroth Betti number) and a newly defined connected component aggregation cost feature to model brain networks over all possible scales. We show that the induced topological feature (Integrated Persistent Feature) follows a monotonically decreasing convergence function and further propose to use its slope as a concise and persistent brain network topological measure. We apply this measure to study rs-fMRI data from the Alzheimer's Disease Neuroimaging Initiative and compare our approach with five other widely used graph measures across five parcellation schemes ranging from 90 to 1,024 region-of-interests. The experimental results demonstrate that the proposed network measure shows more statistical power and stronger robustness in group difference studies in that the absolute values of the proposed measure of AD are lower than MCI and much lower than normal controls, providing empirical evidence for decreased functional integration in AD dementia and MCI.