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

A 62-year-old man presented with a one-year history of word finding difficulty, impaired single word comprehension and personality changes including aggression, apathy and eating change. Brain MRIs showed severe atrophy in the left anterior temporal lobe. The clinical syndromic diagnosis was semantic variant primary progressive aphasia. He died at age 70 of pneumonia. At autopsy, transactive response DNA-binding protein (TDP) immunoreactive long dystrophic neurites were predominantly found in the cerebral cortices, which were compatible with frontotemporal lobar degeneration-TDP type C pathology.
Aggression ; Apathy ; Aphasia, Primary Progressive ; Atrophy ; Autopsy ; Brain ; Cerebral Cortex ; Comprehension ; Diagnosis ; Eating ; Frontotemporal Dementia ; Frontotemporal Lobar Degeneration ; Humans ; Magnetic Resonance Imaging ; Middle Aged ; Neurites ; Pathology ; Pneumonia ; Semantics ; TDP-43 Proteinopathies ; Temporal Lobe

BACKGROUND AND PURPOSE: Only a few studies have investigated the relationship between different subtypes and disease progression or prognosis in patients with behavioral variant frontotemporal dementia (bvFTD). Since a localized injury often produces more focal signs than a diffuse injury, we hypothesized that the clinical characteristics differ between patients with bvFTD who show diffuse frontal lobe atrophy (D-type) on axial magnetic resonance imaging (MRI) scans versus those with focal or circumscribed frontal lobe atrophy (F-type). METHODS: In total, 94 MRI scans (74 scans from bvFTD and 20 scans from age-matched normal controls) were classified into 35 D- and 39 F-type bvFTD cases based on an axial MRI visual rating scale. We compared baseline clinical characteristics, progression in motor and cognitive symptoms, and survival times between D- and F-types. Survival analyses were performed for 62 of the 74 patients. RESULTS: While D-type performed better on neuropsychological tests than F-type at baseline, D-type had higher baseline scores on the Unified Parkinson's Disease Rating Scale (UPDRS) Part III. Evaluations of motor progression showed that the disease duration with motor symptoms was shorter in D-type than F-type. Moreover, the survival time was shorter in D-type (6.9 years) than F-type (9.4 years). Cox regression analyses revealed that a high UPDRS Part III score at baseline contributed to an increased risk of mortality, regardless of the pattern of atrophy. CONCLUSIONS: The prognosis is worse for D-type than for those with F-type. Shorter survival in D-type may be associated with the earlier appearance of motor symptoms.
Atrophy* ; Disease Progression ; Frontal Lobe ; Frontotemporal Dementia* ; Frontotemporal Lobar Degeneration ; Humans ; Magnetic Resonance Imaging ; Mortality ; Neurobehavioral Manifestations ; Neuropsychological Tests ; Parkinson Disease ; Prognosis*

Aged ; Agraphia ; etiology ; Amyotrophic Lateral Sclerosis ; complications ; pathology ; Female ; Frontotemporal Lobar Degeneration ; complications ; pathology ; Humans ; Magnetic Resonance Imaging

Primary progressive aphasia (PPA) is a clinical syndrome diagnosed when three core criteria are met. First, there should be a language impairment (i.e., aphasia) that interferes with the usage or comprehension of words. Second, the neurological work-up should determine that the disease is neurodegenerative, and therefore progressive. Third, the aphasia should arise in relative isolation, without equivalent deficits of comportment or episodic memory. The language impairment can be fluent or non-fluent and may or may not interfere with word comprehension. Memory for recent events is preserved although memory scores obtained in verbally mediated tests may be abnormal. This distinctive clinical pattern is most conspicuous in the initial stages of the disease, and reflects a relatively selective atrophy of the language network, usually located in the left hemisphere. There are different clinical variants of PPA, each with a characteristic pattern of atrophy. Clinicoanatomical correlations in patient with these variants have led to new insights on the organization of the large-scale language network in the human brain. For example, the left anterior temporal lobe, which was not part of the classic language network, has been shown to play a critical role in word comprehension and object naming. Furthermore, patients with PPA have shown that fluency can be dissociated from grammaticality. The underlying neuropathological diseases are heterogeneous and can include Alzheimer's disease as well as frontotemporal lobar degeneration. The clinician's task is to recognize PPA and differentiate it from other neurodegenerative phenotypes, use biomarkers to surmise the nature of the underlying neuropathology, and institute the most fitting multimodal interventions.
Alzheimer Disease ; Aphasia ; Aphasia, Primary Progressive* ; Atrophy ; Biomarkers ; Brain ; Comprehension ; Dementia ; Frontotemporal Lobar Degeneration ; Humans ; Memory ; Memory, Episodic ; Neuropathology ; Phenotype ; Temporal Lobe

Approximately 15% of patients with frontotemporal dementia (FTD) have co-occurring motor neuron disease (MND). FTD-MND cases have frontotemporal lobar degeneration (FTLD)-transactive response DNA-binding protein (TDP) pathology, which is divided into four subtypes (types A, B, C, and D) based on the morphological appearance, cellular location, and distribution of the abnormal TDP inclusions and dystrophic neurites. We report a patient with FTD-MND whose pathological diagnosis was FTLD-TDP type B. This is the first documented autopsy-confirmed case of FTD-MND in Korea.
Autopsy* ; Diagnosis ; Frontotemporal Dementia* ; Frontotemporal Lobar Degeneration ; Humans ; Korea ; Motor Neuron Disease* ; Motor Neurons* ; Neurites ; Pathology

Approximately 15% of patients with frontotemporal dementia (FTD) have co-occurring motor neuron disease (MND). FTD-MND cases have frontotemporal lobar degeneration (FTLD)-transactive response DNA-binding protein (TDP) pathology, which is divided into four subtypes (types A, B, C, and D) based on the morphological appearance, cellular location, and distribution of the abnormal TDP inclusions and dystrophic neurites. We report a patient with FTD-MND whose pathological diagnosis was FTLD-TDP type B. This is the first documented autopsy-confirmed case of FTD-MND in Korea.
Autopsy* ; Diagnosis ; Frontotemporal Dementia* ; Frontotemporal Lobar Degeneration ; Humans ; Korea ; Motor Neuron Disease* ; Motor Neurons* ; Neurites ; Pathology

Frontotemporal dementia (FTD), formerly called Pick's disease, is a progressive dementia that is associated with focal atrophy of the frontal and/or temporal lobes. FTD has three major clinical subtypes ; 1) a frontal variant of frontotemporal dementia (fvFTD), 2) semantic dementia (SD), and 3) progressive nonfluent aphasia (PNFA). These different variants differ in their clinical symptoms, cognitive deficits, and affected brain regions. The insidious onset of personality changes and behavioral abnormalities is the most prominent feature of fvFTD. Poor insight, loss of personal and social awareness, and blunting of affect are common behavioral changes in fvFTD. The most common presenting complaint in SD involves language, and is often described as a loss of memory for words or a loss of word meaning. Patients with PNFA present with changes in fluency, pronunciation, or word finding difficulty. An accumulating body of evidence suggests that FTD overlaps with three other neurodegenerative diseases: motor neuron disease (MND), corticobasal degeneration (CBD), and progressive supranuclear palsy (PSP). Treatment for FTD consists of behavioral and pharmacological approaches. Medications such as selective serotonin reuptake inhibitors, antipsychotics have used in FTD. Cholinesterase inhibitors do not consistently improve cognitive and behavioral symptoms of FTD. Further research should be directed at developing new therapeutic methods to improve the patients' symptoms.
Antipsychotic Agents ; Atrophy ; Behavioral Symptoms ; Brain ; Cholinesterase Inhibitors ; Dementia ; Frontotemporal Dementia ; Frontotemporal Lobar Degeneration ; Humans ; Memory ; Motor Neuron Disease ; Neurobehavioral Manifestations ; Pick Disease of the Brain ; Primary Progressive Nonfluent Aphasia ; Serotonin Uptake Inhibitors ; Supranuclear Palsy, Progressive ; Temporal Lobe

The recent identification of the transactive response DNA binding protein with a molecular weight of 43 kDa (TDP-43) as the major pathological protein, in both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin positive inclusions (FTLD-U), provides the new insight into understanding disease processes. The pathogenesis of both diseases is unclear, although they are related by having some overlap of symptoms and now by the shared histopathology of TDP-43 deposition. The number of degenerative diseases associated with TDP-43 has increased, leading to the new designation "TDP-43 proteinopathy". TDP-43 is a highly conserved protein ubiquitously expressed in many tissues including the central nervous system where it is present in neuronal and glial nuclei and to a lesser extent in the cytoplasm. Currently, TDP-43 has been implicated in regulating gene transcription and alternative splicing, in addition to maintaining mRNA stability. However, we still need to investigate the effects of posttranslational modifications of TDP-43, including phosphorylation, ubiquitination, and cleavage, on its regulation of various cellular processes. We review recently published studies of TDP-43 and its relationship to human disease with a special focus on ALS and FTLD-U. We conclude that the TDP-43 proteinopathies represent a novel class of neurodegenerative disorders and both ALS and FTLD-U are closely related conditions linked to similar mechanism of neurodegeneration.
Alternative Splicing ; Amyotrophic Lateral Sclerosis ; Central Nervous System ; Cytoplasm ; DNA ; DNA-Binding Proteins ; Frontotemporal Dementia ; Frontotemporal Lobar Degeneration ; Humans ; Molecular Weight ; Neurodegenerative Diseases ; Neurons ; Phosphorylation ; Protein Processing, Post-Translational ; RNA Stability ; TDP-43 Proteinopathies ; Ubiquitin ; Ubiquitination

Frontotemporal lobar degeneration (FTLD) is a progressive dementia with prominent neuropsychiatric features, aphasia or both. FTLD predominantly affects the frontal and anterior part of temporal cortex. FTLD is classified into frontotemporal dementia (FTD), progressive nonfluent aphasia (PA), and semantic dementia (SD). FTLD is estimated to account for 20% of cases of degenerative dementia with presenile onset. This disease typically has onset in the mid- or early fifties. FTD is characterized by behavioral change and executive dysfunction, PA features a progressive nonfluent aphasia. SD is characterized by a progressive semantic aphasia and associative agnosia. Structural imaging shows atrophy of the frontal lobe and the anterior portion of the temporal lobe, bilaterally symmetric or asymmetric. Pathologically, FTLD can be classified into tau-positive pathology, tau-negative, ubiquitin positive pathology, dementia lacking distinctive histology. At present, there are no specific pharmacological therapies approved for use in any of the FTLD syndrome.
Agnosia ; Aphasia ; Atrophy ; Dementia ; Frontal Lobe ; Frontotemporal Dementia ; Frontotemporal Lobar Degeneration* ; Pathology ; Primary Progressive Nonfluent Aphasia ; Temporal Lobe ; Ubiquitin