Primary age-related tauopathy (PART) is characterized by the presence of tau neurofibrillary tangles (NFTs) which are typically observed in Alzheimer's disease (AD) brains, with few or without β-amyloid (Aβ) plaques. The diagnosis of PART can be categorized into "definite" or "possible" depending on the amount of Aβ plaques. Definite PART is diagnosed when NFTs are observed and the Braak stage is ≤IV, with Thal Aβ Phase 0 (Crary et al., 2014). According to the neuropathological diagnostic criteria, we reported that PART was frequently observed in the Chinese population according to our findings from specimens in our brain bank, with 47% of brain bank subjects meeting the criteria for PART. There is no consensus on the nature of PART. It remains to be elucidated whether PART is an early form of AD or a novel tauopathy (Duyckaerts et al., 2015; Jellinger et al., 2015).
Aged ; Aged, 80 and over ; Aging/pathology* ; Alzheimer Disease/pathology* ; Brain/pathology* ; Cohort Studies ; Female ; Humans ; Male ; Middle Aged ; Neurofibrillary Tangles/pathology* ; Tauopathies/pathology*

Primary age-related tauopathy (PART) is characterized by tau neurofibrillary tangles (NFTs) in the absence of amyloid plaque pathology. In the present study, we analyzed the distribution patterns of phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43) in the brains of patients with PART. Immunohistochemistry and immunofluorescence double-labeling in multiple brain regions was performed on brain tissues from PART, Alzheimer's disease (AD), and aging control cases. We examined the regional distribution patterns of pTDP-43 intraneuronal inclusions in PART with Braak NFT stages > 0 and ≤ IV, and a Thal phase of 0 (no beta-amyloid present). We found four stages which indicated potentially sequential dissemination of pTDP-43 in PART. Stage I was characterized by the presence of pTDP-43 lesions in the amygdala, stage II by such lesions in the hippocampus, stage III by spread of pTDP-43 to the neocortex, and stage IV by pTDP-43 lesions in the putamen, pallidum, and insular cortex. In general, the distribution pattern of pTDP-43 pathology in PART cases was similar to the early TDP-43 stages reported in AD, but tended to be more restricted to the limbic system. However, there were some differences in the distribution patterns of pTDP-43 between PART and AD, especially in the dentate gyrus of the hippocampus. Positive correlations were found in PART between the Braak NFT stage and the pTDP-43 stage and density.
Aged ; Aged, 80 and over ; Aging ; metabolism ; pathology ; Brain ; metabolism ; pathology ; DNA-Binding Proteins ; metabolism ; Disease Progression ; Female ; Humans ; Immunohistochemistry ; Inclusion Bodies ; pathology ; Male ; Middle Aged ; Neurofibrillary Tangles ; metabolism ; pathology ; Neurons ; metabolism ; pathology ; Severity of Illness Index ; Tauopathies ; metabolism ; pathology

Cognitive impairments and motor dysfunction are commonly observed behavioral phenotypes in genetic animal models of neurodegenerative diseases. JNPL3 transgenic mice expressing human P301L-mutant tau display motor disturbances with age- and gene dose-dependent development of neurofibrillary tangles, suggesting that tau pathology causes neurodegeneration associated with motor behavioral abnormalities. Although gait ignition failure (GIF), a syndrome marked by difficulty in initiating locomotion, has been described in patients with certain forms of tauopathies, transgenic mouse models mirroring human GIF syndrome have yet to be reported. Using the open field and balance beam tests, here we discovered that JNPL3 homozygous mice exhibit a marked delay of movement initiation. The elevated plus maze excluded the possibility that hesitation to start in JNPL3 mice was caused by enhanced levels of anxiety. Considering the normal gait ignition in rTg4510 mice expressing the same mutant tau in the forebrain, GIF in JNPL3 mice seems to arise from abnormal tau deposition in the hindbrain areas involved in locomotor initiation. Accordingly, immunohistochemistry revealed highly phosphorylated paired helical filament tau in JNPL3 brainstem areas associated with gait initiation. Together, these findings demonstrate a novel behavioral phenotype of impaired gait initiation in JNPL3 mice and underscore the value of this mouse line as a tool to study the neural mechanisms and potential treatments for human GIF syndrome.
Animals ; Anxiety ; Brain Stem ; Cognition Disorders ; Gait ; Humans ; Immunohistochemistry ; Locomotion ; Mice ; Mice, Transgenic ; Models, Animal ; Neurodegenerative Diseases ; Neurofibrillary Tangles ; Pathology ; Phenotype ; Prosencephalon ; Rhombencephalon ; Tauopathies

BACKGROUND AND PURPOSE: Conflicting results about vestibular function in progressive supranuclear palsy (PSP) prompted a systematic examination of the semicircular canal function, otolith function, and postural stability. METHODS: Sixteen patients with probable PSP [9 females, age=72±6 years (mean±SD), mean disease duration=3.6 years, and mean PSP Rating Scale score=31] and 17 age-matched controls were examined using the video head impulse test, caloric testing, ocular and cervical vestibular evoked myogenic potentials (o- and cVEMPs), video-oculography, and posturography. RESULTS: There was no evidence of impaired function of the angular vestibulo-ocular reflex (gain=1.0±0.1), and caloric testing also produced normal findings. In terms of otolith function, there was no significant difference between PSP patients and controls in the absolute peakto-peak amplitude of the oVEMP (13.5±7.2 µV and 12.5±5.6 µV, respectively; p=0.8) or the corrected peak-to-peak amplitude of the cVEMP (0.6±0.3 µV and 0.5±0.2 µV, p=0.3). The total root-mean-square body sway was significantly increased in patients with PSP compared to controls (eyes open/head straight/hard platform: 9.3±3.7 m/min and 6.9±2.1 m/min, respectively; p=0.032). As expected, the saccade velocities were significantly lower in PSP patients than in controls: horizontal, 234±92°/sec and 442±66°/sec, respectively; downward, 109±105°/sec and 344±72°/sec; and upward, 121±110°/sec and 348±78°/sec (all p<0.01). CONCLUSIONS: We found no evidence of impairment of either high- or low-frequency semicircular function or otolith organ function in the examined PSP patients. It therefore appears that other causes such as degeneration of supratentorial pathways lead to postural imbalance and falls in patients with PSP.
Accidental Falls ; Caloric Tests ; Female ; Head Impulse Test ; Humans ; Movement Disorders ; Otolithic Membrane ; Reflex, Vestibulo-Ocular ; Saccades ; Semicircular Canals ; Supranuclear Palsy, Progressive ; Tauopathies ; Vestibular Evoked Myogenic Potentials

BACKGROUND: Tauopathies, a class of neurodegenerative diseases that includes Alzheimer's disease (AD), are characterized by the deposition of neurofibrillary tangles composed of hyperphosphorylated tau protein in the human brain. As abnormal alterations in histone acetylation and methylation show a cause and effect relationship with AD, we investigated the role of several Jumonji domain-containing histone demethylase (JHDM) genes, which have yet to be studied in AD pathology. METHODS: To examine alterations of several JHDM genes in AD pathology, we performed bioinformatics analyses of JHDM gene expression profiles in brain tissue samples from deceased AD patients. Furthermore, to investigate the possible relationship between alterations in JHDM gene expression profiles and AD pathology in vivo, we examined whether tissue-specific downregulation of JHDM Drosophila homologs (kdm) can affect tauR406W-induced neurotoxicity using transgenic flies containing the UAS-Gal4 binary system. RESULTS: The expression levels of JHDM1A, JHDM2A/2B, and JHDM3A/3B were significantly higher in postmortem brain tissue from patients with AD than from non-demented controls, whereas JHDM1B mRNA levels were downregulated in the brains of patients with AD. Using transgenic flies, we revealed that knockdown of kdm2 (homolog to human JHDM1), kdm3 (homolog to human JHDM2), kdm4a (homolog to human JHDM3A), or kdm4b (homolog to human JHDM3B) genes in the eye ameliorated the tauR406W-engendered defects, resulting in less severe phenotypes. However, kdm4a knockdown in the central nervous system uniquely ameliorated tauR406W-induced locomotion defects by restoring heterochromatin. CONCLUSION: Our results suggest that downregulation of kdm4a expression may be a potential therapeutic target in AD.
Acetylation ; Alzheimer Disease ; Brain ; Central Nervous System ; Computational Biology ; Diptera ; Down-Regulation ; Drosophila melanogaster ; Drosophila ; Heterochromatin ; Histones ; Humans ; Locomotion ; Methylation ; Neurodegenerative Diseases ; Neurofibrillary Tangles ; Pathology ; Phenotype ; RNA, Messenger ; tau Proteins ; Tauopathies ; Transcriptome

Accumulated evidence suggests that sporadic cases of Alzheimer's disease (AD) make up more than 95% of total AD patients, and diabetes has been implicated as a strong risk factor for the development of AD. Diabetes shares pathological features of AD, such as impaired insulin signaling, increased oxidative stress, increased amyloid-beta (Aβ) production, tauopathy and cerebrovascular complication. Due to shared pathologies between the two diseases, anti-diabetic drugs may be a suitable therapeutic option for AD treatment. In this article, we will discuss the well-known pathologies of AD, including Aβ plaques and tau tangles, as well as other mechanisms shared in AD and diabetes including reactive glia and the breakdown of blood brain barrier in order to evaluate the presence of any potential, indirect or direct links of pre-diabetic conditions to AD pathology. In addition, clinical evidence of high incidence of diabetic patients to the development of AD are described together with application of anti-diabetic medications to AD patients.
Alzheimer Disease ; Blood-Brain Barrier ; Encephalitis ; Humans ; Incidence ; Insulin ; Neuroglia ; Oxidative Stress ; Pathology ; Risk Factors ; Tauopathies

Due to the progressive aging of Korean society and the introduction of brain banks to the Korean medical system, the possibility that pathologists will have access to healthy elderly brains has increased. The histopathological analysis of an elderly brain from a subject with relatively well-preserved cognition is quite different from that of a brain from a demented subject. Additionally, the histology of elderly brains differs from that of young brains. This brief review discusses primary age-related tauopathy; this term was coined to describe elderly brains with Alzheimer’s diseasetype neurofibrillary tangles mainly confined to medial temporal structures, and no β-amyloid pathology.
Aged ; Aging ; Amyloid beta-Peptides ; Autopsy ; Brain ; Cognition ; Dementia ; Humans ; Neurofibrillary Tangles ; Numismatics ; Pathology ; Tauopathies

BACKGROUND AND PURPOSE: Behavioral variant frontotemporal dementia (bvFTD) is a subtype of frontotemporal dementia, which has clinical symptoms of progressive personality and behavioral changes with deterioration of social cognition and executive functions. The pathology of bvFTD is known to be tauopathy or TDP-43 equally. We analyzed the 18F-THK5351 positron emission tomography (PET) scans, which were recently developed tau PET, in patients with clinically-diagnosed bvFTD. METHODS: Forty-eight participants, including participants with behavioral variant frontotemporal dementia (bvFTD, n=3), Alzheimer's disease (AD, n=21) and normal cognition (NC, n=24) who completed 3T magnetic resonance images, 18F-THK5351 PET scans, and detailed neuropsychological tests were included in the study. Voxel-wise statistical analysis and region of interest (ROI)-based analyses were performed to evaluate the retention of THK in bvFTD patients. RESULTS: In the voxel-based and ROI-based analyses, patients with bvFTD showed greater THK retention in the prefrontal, medial frontal, orbitofrontal, anterior cingulate, insula, anterior inferior temporal and striatum regions compared to NC participants. Left-right asymmetry was noted in the bvFTD patients. A patient with extrapyramidal symptoms showed much greater THK retention in the brainstem. CONCLUSIONS: The distribution of THK retention in the bvFTD patients was mainly in the frontal, insula, anterior temporal, and striatum regions which are known to be the brain regions corresponding to the clinical symptoms of bvFTD. Our study suggests that 18F-THK5351 PET imaging could be a supportive tool for diagnosis of bvFTD.
Alzheimer Disease ; Brain ; Brain Stem ; Cognition ; Diagnosis ; Executive Function ; Frontotemporal Dementia* ; Gyrus Cinguli ; Humans ; Neuropsychological Tests ; Pathology ; Positron-Emission Tomography ; Tauopathies

The pathological features of Alzheimer's disease are senile plaques which are aggregates of β-amyloid peptides and neurofibrillary tangles in the brain. Neurofibrillary tangles are aggregates of hyperphosphorylated tau proteins, and these induce various other neurodegenerative diseases, such as progressive supranuclear palsy, corticobasal degeneration, frontotemporal lobar degeneration, frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and chronic traumatic encephalopathy. In the case of Alzheimer's disease, the measurement of neurofibrillary tangles associated with cognitive decline is suitable for differential diagnosis, disease progression assessment, and to monitor the effects of therapeutic treatment. This review discusses considerations for the development of tau ligands for imaging and summarizes the results of the first-in-human and preclinical studies of the tau tracers that have been developed thus far. The development of tau ligands for imaging studies will be helpful for differential diagnosis and for the development of therapeutic treatments for tauopathies including Alzheimer's disease.
Alzheimer Disease ; Brain ; Brain Injury, Chronic ; Chromosomes, Human, Pair 17 ; Diagnosis, Differential ; Disease Progression ; Frontotemporal Dementia ; Frontotemporal Lobar Degeneration ; Ligands ; Neurodegenerative Diseases ; Neurofibrillary Tangles ; Parkinsonian Disorders ; Peptides ; Plaque, Amyloid ; Supranuclear Palsy, Progressive ; tau Proteins ; Tauopathies

Alzheimer's disease (AD) is the most common form of dementia. Although uncountable clinical trials have been done to develop the treatment of AD, there are a couple of drugs that can be used only for symptomatic treatment. Therefore, many studies based on the amyloid cascade hypothesis and the tauopathy hypothesis are still ongoing. After the failure of numerous huge Phase III clinical trials, arguments on those hypotheses have arisen and efforts to establish other possible therapeutic strategies based on diverse plausible mechanisms associated with AD have been done as well. One of the new therapeutic targets for AD is the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. In this review, questions on the two hypotheses, the definition of the PI3K/AKT pathway, the relationship between the pathway and AD, and the possibility of the modulation of the pathway as a new therapeutic strategy for AD will be discussed briefly.
Alzheimer Disease* ; Amyloid ; Dementia ; Phosphatidylinositol 3-Kinase ; Tauopathies