Neurofibrillary Tangles In Hippocampus Research Articles

Heterogenous Tau Pathology in the Hippocampus of Progressive Supranuclear Palsy

AbstractBackgroundGlobose neurofibrillary tangles (NFTs) are found in subcortical areas of post‐mortem brain from individuals with the second most common primary tauopathy, progressive supranuclear palsy (PSP). The degree of cognitive impairment in secondary tauopathies such as Alzheimer’s disease (AD) correlates with the presence of NFTs, which originally appear in the entorhinal cortex before spreading throughout the hippocampus. In contrast, the degree of hippocampal tau pathology in PSP is thought to be limited, consistent with the view that cognitive impairment in PSP is predominantly subcortical. To better define the extent and variability of tau pathology in subregions of the hippocampus (dentate gyrus, CA4, CA3, CA2, CA1, subiculum, and parahippocampal gyrus), we examined PSP brains available through the Michigan Brain Bank.MethodWe identified 33 brains collected since 2011 where the primary neuropathology was PSP. For further analysis, we selected 15 brains (10 male), 14 of which lacked beta amyloid pathology. In 12 cases, clinical and neuropathological diagnoses of PSP were concordant (three other cases had been clinically identified as corticobasal degeneration or “other cognitive disorder”). Immunofluorescence microscopy and western blot analysis were performed with an antibody specific for phosphorylated tau, TaupS202/pT205. A semi‐quantitative scale was used to determine the degree of NFT pathology (0 = negative, 1 = sparse, 2 = intermediate, and 3 = robust) in hippocampal regions of PSP.ResultImmunofluorescence demonstrated wide variability in the degree and range of tau pathology within the hippocampus. Five of 15 PSP brains demonstrated robust NFT pathology in at least one hippocampal subregion. Within the hippocampus, the CA1 and subiculum most commonly displayed denser NFT pathology whereas the dentate gyrus typically was spared. Western blot analysis likewise demonstrated marked heterogeneity in TaupS202/pT205 signal, ranging from 0 to 161 arbitrary units.ConclusionThese findings support the view that hippocampal NFT pathology is not uncommon in PSP and may contribute to cognitive impairment in a subset of patients. Furthermore, the high variability in hippocampal NFTs nominates this region in PSP as a compelling brain area in which to assess correlations between tau accumulation and perturbations in neuronal cytoarchitecture.

Association of Neurofibrillary Tangle Distribution With Age at Onset-Related Clinical Heterogeneity in Alzheimer Disease: An Autopsy Study.

Patients with earlier age at onset of sporadic Alzheimer disease (AD) are more likely than those with later onset to present with atypical clinical and cognitive features. We sought to determine whether this age-related clinical and cognitive heterogeneity is mediated by different topographic distributions of tau-aggregate neurofibrillary tangles (NFTs) or by variable amounts of concomitant non-AD neuropathology. The relative distribution of NFT density in hippocampus and midfrontal neocortex was calculated, and α-synuclein, TAR DNA binding protein 43 (TDP-43), and microvascular copathologies were staged, in patients with severe AD and age at onset of 51-60 (n = 40), 61-70 (n = 41), and >70 (n = 40) years. Regression, mediation, and mixed effects models examined relationships of pathologic findings with clinical features and longitudinal cognitive decline. Patients with later age at onset of AD were less likely to present with nonmemory complaints (odds ratio [OR] 0.46 per decade, 95% confidence interval [CI] 0.22-0.88), psychiatric symptoms (β = -0.66, 95% CI -1.15 to -0.17), and functional impairment (β = -1.25, 95% CI -2.34 to -0.16). TDP-43 (OR 2.00, 95% CI 1.23-3.35) and microvascular copathology (OR 2.02, 95% CI 1.24-3.40) were more common in later onset AD, and α-synuclein copathology was not related to age at onset. NFT density in midfrontal cortex (β = -0.51, 95% CI -0.72 to -0.31) and midfrontal/hippocampal NFT ratio (β = -0.18, 95% CI -0.26 to -0.10) were lower in those with later age at onset. Executive function (β = 0.48, 95% CI 0.09-0.90) and visuospatial cognitive deficits (β = 0.97, 95% CI 0.46-1.46) were less impaired in patients with later age at onset. Mediation analyses showed that the effect of age at onset on severity of executive function deficits was mediated by midfrontal/hippocampal NFT ratio (β = 0.21, 95% CI 0.08-0.38) and not by concomitant non-AD pathologies. Midfrontal/hippocampal NFT ratio also mediated an association between earlier age at onset and faster decline on tests of global cognition, executive function, and visuospatial abilities. Worse executive dysfunction and faster cognitive decline in people with sporadic AD with earlier rather than later age at onset is mediated by greater relative midfrontal neocortical to hippocampal NFT burden and not by concomitant non-AD neuropathology.

Methionine Sulfoxide Reductase-B3 (MsrB3) Protein Associates with Synaptic Vesicles and its Expression Changes in the Hippocampi of Alzheimer's Disease Patients.

Genome-wide association studies (GWAS) identified susceptibility loci associated with decreased hippocampal volume, and found hippocampal subfield-specific effects at MSRB3 (methionine sulfoxide reductase-B3). The MSRB3 locus was also linked to increased risk for late onset Alzheimer's disease (AD). In this study, we uncovered novel sites of MsrB3 expression in CA pyramidal layer and arteriolar walls by using automated immunohistochemistry on hippocampal sections from 23 individuals accompanied by neuropathology reports and clinical dementia rating scores. Controls, cognitively intact subjects with no hippocampal neurofibrillary tangles, exhibited MsrB3 signal as distinct but rare puncta in CA1 pyramidal neuronal somata. In CA3, however, MsrB3-immunoreactivity was strongest in the neuropil of the pyramidal layer. These patterns were replicated in rodent hippocampi where ultrastructural and immunohistofluorescence analysis revealed MsrB3 signal associated with synaptic vesicles and colocalized with mossy fiber terminals. In AD subjects, the number of CA1 pyramidal neurons with frequent, rather than rare, MsrB3-immunoreactive somatic puncta increased in comparison to controls. This change in CA1 phenotype correlated with the occurrence of AD pathological hallmarks. Moreover, the intensity of MsrB3 signal in the neuropil of CA3 pyramidal layer correlated with the signal pattern in neurons of CA1 pyramidal layer that was characteristic of cognitively intact individuals. Finally, MsrB3 signal in the arteriolar walls in the hippocampal white matter decreased in AD patients. This characterization of GWAS-implicated MSRB3 protein expression in human hippocampus suggests that patterns of neuronal and vascular MsrB3 protein expression reflect or underlie pathology associated with AD.

Brain pathologies in extreme old age

With an emphasis on evolving concepts in the field, we evaluated neuropathologic data from very old research volunteers whose brain autopsies were performed at the University of Kentucky Alzheimer's Disease Center, incorporating data from the Georgia Centenarian Study (n = 49 cases included), Nun Study (n = 17), and University of Kentucky Alzheimer's Disease Center (n = 11) cohorts. Average age of death was 102.0 (range: 98–107) years overall. Alzheimer's disease pathology was not universal (62% with “moderate” or “frequent” neuritic amyloid plaque densities), whereas frontotemporal lobar degeneration was absent. By contrast, some hippocampal neurofibrillary tangles (including primary age-related tauopathy) were observed in every case. Lewy body pathology was seen in 16.9% of subjects and hippocampal sclerosis of aging in 20.8%. We describe anatomic distributions of pigment-laden macrophages, expanded Virchow-Robin spaces, and arteriolosclerosis among Georgia Centenarians. Moderate or severe arteriolosclerosis pathology, throughout the brain, was associated with both hippocampal sclerosis of aging pathology and an ABCC9 gene variant. These results provide fresh insights into the complex cerebral multimorbidity, and a novel genetic risk factor, at the far end of the human aging spectrum.

P4‐043: Progranulin capillary length density is reduced in Alzheimer's disease and correlates with early hippocampal neurofibrillary tangles and diffuse neocortical plaques

P4‐043: Progranulin capillary length density is reduced in Alzheimer's disease and correlates with early hippocampal neurofibrillary tangles and diffuse neocortical plaques

Preclinical AD Workgroup staging: pathological correlates and potential challenges

The National Institute on Aging Preclinical Alzheimer's disease Workgroup (PADW) has issued a preliminary report with recommendations for classifying preclinical Alzheimer's disease (pAD) according to 3 early disease stages. Here we examine the PADW recommendations in relation to neuropathological features in a large, consecutive series of cognitively intact elderly persons, autopsied within a year after cognitive testing (n = 126 cognitively intact patients with mean age 83.7 years at death). Subjects were grouped based on a hypothetical construct correlating pathological features with PADW stages. Many cognitively intact individuals were classifiable as pAD (53/126 or 43%), as expected based on epidemiological and biomarker studies. Of these, most (48%) were in “stage 3”, which corresponds to amyloid pathology with early neurodegeneration. As with prior studies, our data indicate that the development of neocortical neurofibrillary tangles is the key pathological event that is not observed in pAD cases: Braak stages III or IV pathology are hence not truly a substrate for “intermediate likelihood” that cognitive impairment is due to Alzheimer's disease (AD). We also stress the importance of comorbid non-Alzheimer's disease brain pathologies (hippocampal sclerosis, neocortical alpha-synucleinopathy, cerebrovascular disease, and brains with hippocampal neurofibrillary tangles but no cortical amyloid plaques) that can contribute to the development of cognitive impairment, or which may serve as confounds in the application of the PADW recommendations. While the final recommendations from the PADW working group have not yet been released, this preliminary analysis provides a perspective on those recommendations from a neuropathological point of view.

Cortical neuritic plaques and hippocampal neurofibrillary tangles are related to dementia severity in elderly schizophrenia patients

Cognitive decline has been described in elderly patients with schizophrenia, but the underlying pathology remains unknown. Some studies report increases in plaques and neurofibrillary tangles, but there is no evidence for an increased risk for Alzheimer's disease (AD) in elderly schizophrenics. Models of a decreased cerebral reserve suggest that increases in AD-related neuropathology below the threshold for a neuropathological diagnosis could be related to dementia severity in elderly schizophrenia patients. We tested this hypothesis in 110 autopsy specimens of schizophrenia patients, without a neuropathological diagnosis of AD or other neurodegenerative disorders. Furthermore, we assessed the effects of apolipoprotein E (ApoE) status, a known genetic risk factor for AD. Measures of density of neuritic plaques were obtained in five cortical regions, and the degree of hippocampal neurofibrillary tangles was rated. Dementia severity was measured prior to postmortem using the Clinical Dementia Rating (CDR) scale. multivariate analyses of variance were conducted with the factors dementia severity, by ApoE4 carrier status. Hippocampal neurofibrillary tangles correlated with increased dementia severity ( p < .05). Neuritic plaque density increased with greater dementia severity ( p < .005), and ApoE4 carrier status ( p < .005), and these differences were magnified by the ApoE4 carrier status ( p < .01). Even below the threshold for a neuropathological diagnosis of AD, neuritic plaques and hippocampal neurofibrillary tangles are associated with dementia severity in schizophrenia patients, even more so in the presence of genetic risk factors, suggesting that a decreased cerebral reserve in elderly schizophrenics may increase susceptibility for dementia.

O2-02-05: Amyloid causes tauopathy by activating GSK3

Accumulation of amyloid peptides is the earliest molecular defect in Alzheimer's disease (AD), due to increased production or diminished clearance. Integral to pathology of AD is, by definition, accumulation of protein tau, due to over-phosphorylation resulting in conformational changes and aggregation. The hypothesis that amyloid precedes and induces tau pathology in AD is experimentally supported here, while GSK3 is essential in the underlying mechanisms. We generated two new bigenic mouse models: (i) APP-V717I × Tau-P301L mice (biAT) with combined amyloid and tau-pathology: (ii) GSK3β × Tau-P301L mice (biGT) with tauopathy only. Comparative analysis, including the parental APP-V717I and Tau-P301L strains, yielded important data on pivotal roles of GSK3 in AD pathology. The biAT mice present with progressive, synergistic amyloid and tau pathology most dramatic in CA1/2 and cortex, similar in all aspects to the pathology in AD patients. Remarkably, biAT mice survive longer than parental tau-P301L mice (dead before age 1 year) in close correlation with lesser brain-stem tauopathy (Terwel et al, Am J Pathol, 2008). In biGT mice, the neuronal co-expression of Tau-P301L and GSK3β yields a dramatic forebrain tauopathy, with in older biGT mice “tangles in most forebrain neurons”. Remarkably, no major neuron-loss is observed, demonstrating that tangles are not neurotoxic per se. The biGT mice survive even longer than biAT mice, paralleling their more strongly reduced brainstem tauopathy. The close parallels between biAT and biGT mice, comprises (i) similar pathological phospho-epitopes of protein tau, (ii) similar aggravation of tauopathy by amyloid as by GSK3β with neurofibrillary tangles in hippocampus and cortex; (iii) similar defects in behaviour and cognition. Finally but significantly, GSK3 isozymes are activated in the parental APP-V717I amyloid mice, even at young age, when defects in cognition and LTP occur, but before amyloid deposition. The combined data corroborate that neurofibrillary tangles are not neurotoxic per se, and position GSK3 as major signalling link from amyloid to tauopathy in AD. The models offer wide pre-pathology windows to define molecular signals that act up- and downstream or in parallel with GSK3 isozymes: activation by amyloid, contribution to tau-phosphorylation, and role in cognition defects.

Aberrant accentuation of neurofibrillary degeneration in the hippocampus of Alzheimer's disease with amyloid precursor protein 717 and presenilin-1 gene mutations

This study reports correlation of the hippocampal neurofibrillary tangles (NFT) density with beta-amyloid (Aβ) precursor protein (APP) 717 mutation, presenilin (PS)-1 mutation and apolipoprotein E (Apo-E) e4 alleles (E4), being graded as 3 forms (no-E4, one-E4 and two-E4) in autopsied brains from patients with familial and non-familial Alzheimer's disease (AD). We studied the density of NFT-free neurons, intracellular NFT (I-NFT), extracellular NFT (E-NFT) and total NFT (I-NFT plus E-NFT) in the six hippocampal subdivisions: cornu ammonis (CA) 1–CA4, subiculum and entorhinal cortex. The APP mutation cases showed significantly higher total NFT density in the CA1–CA2 region, and the PS-1 mutation cases also showed higher density of total NFT in the CA1–CA3 than non-familial cases. Moreover, high densities of the E-NFT contributed to these high total NFT densities. Non-familial AD cases showed a stereotypical NFT distribution with entorhinal accentuation in the hippocampus irrespective of E4 frequency. Thus, APP and PS-1 mutations predominantly affect the CA regions with profound neurodegeneration, which contributes early and severe clinical features of familial AD.

Tau epitope display in progressive supranuclear palsy and corticobasal degeneration.

Filamentous aggregates of the protein tau are a prominent feature of Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). However, the extent to which the molecular structure of the tau in these aggregates is similar or differs between these diseases is unclear. We approached this question by examining these disorders with a panel of antibodies that represent different structural, conformational, and cleavage-specific tau epitopes. Although each of these antibodies reveals AD pathology, they resolved into three classes with respect to PSP and CBD: AD2 and Tau-46.1 stained the most tau pathology in all cases; Tau-1, 2, 5, and 12 exhibited variable reactivity; and Tau-66 and MN423 did not reveal any tau pathology. In addition, hippocampal neurofibrillary tangles in these cases showed a predominantly PSP/CBD-like, rather than AD-like, staining pattern. These results indicate that the patterns of the tau epitopes represented by this panel that reside in the pathological aggregates of PSP and CBD are similar to each other but distinct from that of AD.

Midlife blood pressure and neuritic plaques, neurofibrillary tangles, and brain weight at death: the HAAS ☆

Midlife hypertension is associated with later development of cognitive impairment, vascular dementia (VsD), and possibly Alzheimer’s disease (AD). Neuropathic cerebrovascular lesions and brain atrophy have been associated with elevated blood pressure (BP), however, to our knowledge there have been no prospective investigations of an association of blood pressure levels measured in midlife with the microscopic lesions of AD. We investigated the relationship of BP level in midlife to development of neurofibrillary tangles (NFT), neuritic plaques (NP), and low brain weight at autopsy among Japanese-American men who were members of the Honolulu Heart Program/Honolulu-Asia aging Study (HHP/HAAS) cohort. The HHP/HAAS is a population-based, longitudinal study of cognitive function and dementia with 36 years of follow-up. Neocortical and hippocampal NFT and NP were counted per mm 2, and fixed brain weight was measured for 243 decedents. Elevated systolic BP, (≥160 mm Hg) in midlife was associated with low brain weight and greater numbers of NP in both neocortex and hippocampus. Diastolic BP elevation, (≥95 mm Hg) was associated with greater numbers of NFT in hippocampus. Results indicate that in addition to the accepted association of high BP with neuropathic cerebrovascular lesions, there is a direct relationship with brain atrophy, NP and NFT.

Clinicopathological study of dementia in the elderly who died at home: A comparison of SDAT and non‐demented subjects with SDAT changes

Forty‐eight elderly persons who resided and died at home are reported. Eight of the subjects (17%) were nondemented but had pathological changes of senile dementia of the Alzheimer type (SDAT). Each of these subjects showed numerous hippocampal neurofibrillary tangles (NFT). Five of the eight subjects demonstrated neocortical senile plaques (SP), such as typical plaques and primitive plaques with diffuse plaques, and one had NFT. The other three subjects did not have SP. The density of SP in hippocampal CA2, midbrain, pons, and cerebellum in SDAT were significantly higher than that of non‐demented subjects with SDAT changes. The density of SP and NFT in SDAT did not exceed that in non‐demented subjects with SDAT changes in the other areas. The distribution of SP in the hippocampal CA2, brainstem, and cerebellum will be useful for the histopathologic diagnosis of SDAT.

Neuronal Localization of Presenilin-1 and Association with Amyloid Plaques and Neurofibrillary Tangles in Alzheimer’s Disease

Mutations in the presenilin-1 (PS1) gene is a cause of early- onset familial Alzheimer's disease (AD). Endogenous PS1 is associated with the endoplasmic reticulum in the cell body of undifferentiated SH-SY5Y neuroblastoma cells. At early stages of neuronal differentiation in rat hippocampal culture, PS1 appears in all neuritic processes and in growth cones. In mature differentiated neurons, PS1 is concentrated in the somatodendritic compartment but is also present at lower levels in axons. A similar localization of PS1 is observed in vivo in neurons of the adult human cerebral cortex. In sporadic AD, PS1 appears in the dystrophic neurites of mature amyloid plaques and co-localizes with a subset of intraneuronal neurofibrillary tangles (NFTs). About 30% of hippocampal NFTs are labeled with a highly specific antibody to the PS1 C-terminal loop domain but not with an antibody to the PS1 N terminus. This observation is consistent with a potential association of the PS1 C-terminal fragment with NFTs, because PS1 is constitutively cleaved to N- and C-terminal fragments in neurons. These results suggest that PS1 is highly expressed and broadly distributed during early stages of neuronal differentiation, consistent with a role for PS1 in neuronal differentiation. Furthermore, the co-localization of PS1 with NFTs and plaque dystrophic neurites implicates a role for PS1 in the diverse pathological manifestations of AD.

Dementia of the Alzheimer type and related dementias in the aged: DAT subgroups and senile dementia of the neurofibrillary tangle type

The aims of this study are to elucidate variations in the neuropathology of dementia of the Alzheimer's type (DAT) and related dementias in the elderly, and to delineate a senile dementia characterized by abundant neurofibrillary tangles (NFT) in the hippocampal region and by a scarcity of senile plaques (SP) throghout the brain (senile dementia of the NFT type; SD‐NFT) in comparison with usual DAT cases. One hundred and five autopsied patients who developed dementia at age 70–100 years were investigated. The autopsy series included 57 cases of DAT, five of diffuse Lewy body disease (DLBD) with Alzheimer‐tyupe neuropathological changes, and five of SD‐NFT. The 57 DAT patients were classified into three subgroups depending onthe severity of the neocotical neuronal degeneration (NFT and neuronal loss): the diffuse, severe type (DAT‐DS, extensive and severe involvement of the neocortex; n= 18); the diffuse, mild type (DAT‐DM, mild involvement of the neocortex; n= 29); and the localized type (DAT‐L, neuronal degeneration almost localized to the hippocampal region; DAT without neocortical NFT; n= 10). The frequencies of the DAT subgroups, DLBD, and SD‐NFT in each age group at the onset were DAT‐DS (41%) &gt; DAT‐DM (38%) &gt; DLBD (16%) &gt; DAT‐L (6%) of patients in their 70s, DAT‐DM (52%) &gt; DAT‐L (24%) &gt; DAT‐DS (16%) &gt; SD‐NFT (8%) of those in their 80s, and DAT‐DS (40%) &gt; SD‐NFT (30%) &gt; DAT‐L (20%) &gt; DAT‐DS (10%) of those in their 90s and older. In a morphometric comparison with age‐mathced DAT cases, the SD‐NFT showed a significantly higher density of hippocampal NFT and a significant scarcity of SP and cerebral amyloid angiopathy in the brain. Analysis of genotypes of apolipoprotein E gene revealed that no patient with the SD‐NFT had ε4 allele which was shown to be frequently associated with DAT. Our results have indicated (i) that the later onset of DAT and related dementias is linked with the milder neuronal degeneration in the neocortex, and (ii) that the SD‐NFT is a common neuropathological condition that causes dementia in the very aged, in which the pathogenetic process may be different from that in DAT.

Substantia Nigra Lesions in Alzheimer Disease and Normal Aging

Clinical and pathological overlap between Alzheimer disease (AD) and Parkinson's disease (PD) has been well described; however, the mechanisms of overlap between these two disorders remain unknown. We retrospectively examined clinical and neuropathological features from 66 individuals participating in the Rochester Alzheimer Disease Center to determine the association of AD with substantia nigra (SN) pathology. SN pathology, identified by a loss of pigmented neurons and the presence of gliosis, pigment-laden macrophages, and Lewy bodies, was blindly scored in 48 AD cases and 18 normal elderly controls. We found moderate or severe pathology in the SN in 2 control brains (11%) and 29 AD brains (60%). The numbers of neocortical and hippocampal neurofibrillary tangles (NFTs) and senile plaques (SPs) were not associated with nigral pathology. There was also no significant association of SN pathology with NFTs or SPs in the striatum, the site to which these neurons project. There was no significant association of increasing SN pathology with aging among AD patients, nor with increasing severity and duration of AD. The signs and symptoms of an extrapyramidal movement disorder were, however, associated with increasing SN pathology. We confirm that pathological lesions in the SN are a common feature of AD and an uncommon feature in normal aging. AD is a significant risk factor for SN lesions and PD, but the pathologic severity of AD, as measured by NFTs and SPs, was not associated with SN lesions.

Immunoreactive changes resulting from dopaminergic denervation of the dentate gyrus of the rat hippocampal formation

The hypothesis that dopaminergic denervation is a factor in the development of hippocampal neurofibrillary tangles was tested in the rat with bilateral stereotaxic 6-hydroxydopamine (6-OHDA) lesions of the ventral tegmental area (VTA). This led to the postsynaptic appearance of cytoplasmic immunoreactivity to ubiquitin in neurons of the dentate gyrus. An additional postsynaptic morphologic abnormality was seen when the animals were pretreated with the D 1 dopaminergic antagonist SCH 23390 and the VTA lesions were combined with septal lesions affecting cholinergic and GABAergic neurons projecting to the dentate gyrus. These changes consisted of a loss of dendritic microtubule associated protein (MAP-2) and tau immunoreactivity and a prominence of remaining dendrites in the molecular layer of the dentate gyrus. Additional investigation will be needed to determine if these transynaptic changes in dentate neurons, resulting from denervation, represent a precursor stage to neurofibrillary tangle development.