Association Between Globular Glial Tauopathies and Frontotemporal Dementia-Expanding the Spectrum of Gliocentric Disorders: A Review

Tau biomarkers for neurodegenerative diseases: Current state and perspectives

Neurodegenerative diseases, particularly tauopathies, pose significant global health challenges, especially in aging populations. Tauopathies are characterized by progressive neuronal damage and intracellular deposits of hyperphosphorylated tau. Early and accurate diagnosis is hindered by overlapping clinical features and reliance on post-mortem analyses, emphasizing the need for reliable in vivo biomarkers to improve early diagnosis and management. Advances in tau biomarkers and imaging have facilitated targeted Alzheimer's disease therapies, but progress for other tauopathies remains inadequate. Future diagnostic frameworks should integrate multiple biomarkers across different tissues within specific timelines. However, challenges such as co-pathologies and limited understanding of pathogenic mechanisms remain significant obstacles. Emerging ultrasensitive technologies, including seeding amplification assays and minimally invasive sources of biomarkers like skin biopsy, hold promise for biomarker discovery. Here, we present the current clinical classification of tau proteinopathies, the challenges that are posed by the actual diagnostic criteria, followed by the most recent advancements in tau biomarker technologies.

Unprecedented Combination of Rare Degenerative Pathologies in an Octogenarian Ex-Football Player

A 79-year-old former professional football player presented with language deficits and cognitive changes. A year later, he had difficulty completing sentences, and 3 years after onset, was reduced to one-word answers. He developed severe apathy and agitation, and became more impulsive. He eventually became mute and had difficulty with walking and balance. The patient had mild repetitive head injury while playing football and three concussions. Magnetic resonance imaging revealed left > right frontotemporal atrophy. Duration of illness was 6 years. Neuropathology revealed an unexpected number and diversity of degenerative pathologies, including chronic traumatic encephalopathy (CTE, high level), high level Alzheimer's disease neuropathologic change (A3B3C3), limbic Lewy body disease, cerebral amyloid angiopathy (type 2), argyrophilic grain disease (Stage 2), and neuronal intranuclear hyaline inclusion body disease. In addition, there was selective and asymmetric involvement of the corticospinal tract with globular oligodendroglial tau pathology corresponding to globular glial tauopathy (Type II). The patchy and irregular accentuation of cortical tau pathology, particularly in the depths of sulci and accumulation around blood vessels, allows the diagnosis of CTE-neuropathologic change. This diagnosis correlated with the past medical history of multiple concussions. In addition, the patient had an unprecedented number and combination of additional degenerative pathologies, including those that are rare, and how they contributed to the clinical symptoms is difficult to interpret. Globular glial tauopathy Type II is a rare disorder that has been mostly reported in association with progressive supranuclear gaze palsy, and these observations support the notion that globular glial tauopathy Type II is an independent entity with isolated corticospinal tract involvement. These observations highlight that rare disorders can occur in the same individual and be overlooked, especially when there is more obvious pathology. It is essential for neuropathologists to consider an extensive array of neuropathological examinations when assessing patients with neurodegenerative disorders.

Traumatic Encephalopathy Syndrome: Head Impact Exposure and Blood Biomarkers in Professional Combat Athletes

OBJECTIVE

This study aimed to (1) determine whether there was an association between a diagnosis of traumatic encephalopathy syndrome (TES) and changes in three specific serum biomarkers, and (2) determine head impact exposure thresholds among both TES+ and TES- groups.

SETTING

Data were collected from Cleveland Clinic's Professional Athletes Brain Health Study (PABHS).

PARTICIPANTS

This study included 192 professional combat athletes, 35 years of age and older. Athletes must be actively fighting or retired with a minimum of 10 professional fights over their careers.

DESIGN/INTERVENTION

This was a retrospective observational study of the PABHS longitudinal cohort.

MAIN MEASURES

The generalized linear model with the generalized estimating equation for repeated measurements was used to compare various biomarkers between both active and retired TES- and TES+ groups.

RESULTS

The odds ratio for TES diagnosis was 5.44 (95% CI = 2.48, 11.94; P < .0001) among active fighters and 10.75 (95% CI = 3.52, 32.85; P < .0001) among retired fighters, indicating the odds for a TES diagnosis were over 5 times greater for active fighters with every fight completed at or beyond 30 professional fights. Retired fighters had 10 times greater odds of TES diagnosis with every fight completed at or beyond 15 professional fights. Likewise, the odds of a TES diagnosis were 2.0% (95% CI = 0.3, 3.1; P = 0.0039) greater with each pg/mL increase of glial fibrillary acidic protein (GFAP). No relationship was observed between a TES diagnosis and neurofilament light chain or P-tau231.

CONCLUSION

This study provides preliminary evidence that progressively elevated levels of the GFAP blood biomarker increase the odds of a TES diagnosis among retired professional fighters. Further evaluation is required to improve clarity and understanding of the relationship between progressive changes in the GFAP blood biomarker and a TES diagnosis, specifically evaluating the duration of chronicity and exposure thresholds.

The interaction between dysfunction of vasculature and tauopathy in Alzheimer's disease and related dementias

Tauopathy is one of the pathological features of Alzheimer's disease and related dementias (ADRD). At present, there have been many studies on the formation, deposition, and intercellular transmission of tau in neurons and immune cells. The vasculature is an important component of the central nervous system. This review discusses the interaction between vasculature and tau in detail from three aspects. (1) The vascular risk factors (VRFs) discussed in this review include diabetes mellitus (DM), abnormal blood pressure (BP), and hypercholesterolemia. (2) In ADRD pathology, the hyperphosphorylation and deposition of tau interact with disrupted vasculature, such as different cells (endothelial cells, smooth muscular cells, and pericytes), the blood-brain barrier (BBB), and the cerebral lymphatic system. (3) The functions of vasculature are regulated by various signaling transductions. Endothelial nitric oxide synthase/nitric oxide, calcium signaling, Rho/Rho-associated coiled-coil containing Kinase, and receptors for advanced glycation end products are discussed in this review. Our findings indicate that the prevention and treatment of vascular health may be a potential target for ADRD combination therapy. HIGHLIGHTS: Persistent VRFs increase early disruption of vascular mechanisms and are strongly associated with tau pathology in ADRD. Cell dysfunction in the vasculature causes BBB leakage and drainage incapacity of the cerebral lymphatic system, which interacts with tau pathology. Signaling molecules in the vasculature regulate vasodilation and contraction, angiogenesis, and CBF. Abnormal signaling transduction is related to tau hyperphosphorylation and deposition.

Non-linear association of liver enzymes with cognitive performance in the elderly: A cross-sectional study

BACKGROUND

Although liver metabolic dysfunction has been found to potentially elevate susceptibility to cognitive impairment and dementia, there is still insufficient evidence to explore the non-linear association of liver enzymes with cognitive performance. Therefore, we aimed to elucidate the non-linear relationship between liver enzymes and cognitive performance.

METHODS

In this cross-sectional study, 2764 individuals aged ≥ 60 who participated in the National Health and Nutrition Survey (NHANES) between 2011 and 2014 were included. The primary data comprised liver enzyme levels (alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), AST/ALT ratio, and gamma-glutamyl transferase (GGT)), and cognitive performance was the major measured outcome. The associations were analyzed using weighted multivariate logistic regression, subgroup analysis, a generalized additive model, smooth fitting curves, and threshold effects.

RESULTS

The results of the fully adjusted model indicated that ALP was negatively associated with the animal fluency test (AFT) score (OR = 1.48, 95% CI: 1.11-1.98), whereas ALT demonstrated a positive association with the consortium to establish a registry for Alzheimer's disease (CERAD) test score (OR = 0.72, 95% CI: 0.53-0.97). Additionally, the AST/ALT ratio was negatively associated with the global cognitive test (OR = 2.39, 95% CI: 1.53-3.73), CERAD (OR = 2.61, 95% CI: 1.77-3.84), and digit symbol substitution test (DSST) scores (OR = 2.51, 95% CI: 1.57-4.02). GGT was also negatively associated with the AFT score (OR = 1.16, 95% CI: 1.01-1.33) in unadjusted model. A non-linear relationship was observed between liver enzymes and the risk of cognitive impairment as assessed by the global cognitive test. Specifically, when ALP > 60 U/L, 0.77 < AST/ALT < 1.76, and 25 < GGT < 94 U/L, higher liver enzyme levels were significantly associated with an elevated cognitive impairment risk, while a lower cognitive impairment risk when ALT level was > 17 U/L.

CONCLUSIONS

There is a non-linear relationship between liver enzymes and cognitive performance, indicating that liver enzyme levels should be maintained within a certain level to mitigate the risk of cognitive impairment.

Distinct involvement of the cranial and spinal nerves in progressive supranuclear palsy

The most frequent neurodegenerative proteinopathies include diseases with deposition of misfolded tau or α-synuclein in the brain. Pathological protein aggregates in the PNS are well-recognized in α-synucleinopathies and have recently attracted attention as a diagnostic biomarker. However, there is a paucity of observations in tauopathies. To characterize the involvement of the PNS in tauopathies, we investigated tau pathology in cranial and spinal nerves (PNS-tau) in 54 tauopathy cases [progressive supranuclear palsy (PSP), n = 15; Alzheimer's disease (AD), n = 18; chronic traumatic encephalopathy (CTE), n = 5; and corticobasal degeneration (CBD), n = 6; Pick's disease, n = 9; limbic-predominant neuronal inclusion body 4-repeat tauopathy (LNT), n = 1] using immunohistochemistry, Gallyas silver staining, biochemistry, and seeding assays. Most PSP cases revealed phosphorylated and 4-repeat tau immunoreactive tau deposits in the PNS as follows: (number of tau-positive cases/available cases) cranial nerves III: 7/8 (88%); IX/X: 10/11 (91%); and XII: 6/6 (100%); anterior spinal roots: 10/10 (100%). The tau-positive inclusions in PSP often showed structures with fibrillary (neurofibrillary tangle-like) morphology in the axon that were also recognized with Gallyas silver staining. CBD cases rarely showed fine granular non-argyrophilic tau deposits. In contrast, tau pathology in the PNS was not evident in AD, CTE and Pick's disease cases. The single LNT case also showed tau pathology in the PNS. In PSP, the severity of PNS-tau involvement correlated with that of the corresponding nuclei, although, occasionally, p-tau deposits were present in the cranial nerves but not in the related brainstem nuclei. Not surprisingly, most of the PSP cases presented with eye movement disorder and bulbar symptoms, and some cases also showed lower-motor neuron signs. Using tau biosensor cells, for the first time we demonstrated seeding capacity of tau in the PNS. In conclusion, prominent PNS-tau distinguishes PSP from other tauopathies. The morphological differences of PNS-tau between PSP and CBD suggest that the tau pathology in PNS could reflect that in the central nervous system. The high frequency and early presence of tau lesions in PSP suggest that PNS-tau may have clinical and biomarker relevance.

Histopathological Correlates of Lobar Microbleeds in False-Positive Cerebral Amyloid Angiopathy Cases

OBJECTIVE

A definite diagnosis of cerebral amyloid angiopathy (CAA), characterized by the accumulation of amyloid β in walls of cerebral small vessels, can only be obtained through pathological examination. A diagnosis of probable CAA during life relies on the presence of hemorrhagic markers, including lobar cerebral microbleeds (CMBs). The aim of this project was to study the histopathological correlates of lobar CMBs in false-positive CAA cases.

METHODS

In 3 patients who met criteria for probable CAA during life, but showed no CAA upon neuropathological examination, lobar CMBs were counted on ex vivo 3T magnetic resonance imaging (MRI) and on ex vivo 7T MRI. Areas with lobar CMBs were next sampled and cut into serial sections, on which the CMBs were then identified.

RESULTS

Collectively, there were 25 lobar CMBs on in vivo MRI and 22 on ex vivo 3T MRI of the analyzed hemispheres. On ex vivo MRI, we targeted 12 CMBs for sampling, and definite histopathological correlates were retrieved for 9 of them, of which 7 were true CMBs. No CAA was found on any of the serial sections. The "culprit vessels" associated with the true CMBs instead showed moderate to severe arteriolosclerosis. Furthermore, CMBs in false-positive CAA cases tended to be located more often in the juxtacortical or subcortical white matter than in the cortical ribbon.

INTERPRETATION

These findings suggest that arteriolosclerosis can generate lobar CMBs and that more detailed investigations into the exact localization of CMBs with respect to the cortical ribbon could potentially aid the diagnosis of CAA during life. ANN NEUROL 2023;94:856-870.

Distribution Patterns of Astrocyte Populations in the Human Cortex

Astrocytes are a major class of glial cell in the central nervous system that have a diverse range of types and functions thought to be based on their anatomical location, morphology and cellular properties. Recent studies highlight that astrocyte dysfunction contributes to the pathogenesis of neurological conditions. However, few studies have described the pattern, distribution and density of astrocytes in the adult human cortex. This study mapped the distribution and density of astrocytes immunolabelled with a range of cytoskeletal and membrane markers in the human frontal cortex. Distinct and overlapping astrocyte populations were determined. The frontal cortex from ten normal control cases (75 ± 9 years) was immunostained with glial fibrillary acidic protein (GFAP), aldehyde dehydrogenase-1 L1 (ALDH1L1), connexin-43 (Cx43), aquaporin-4 (AQP4), and glutamate transporter 1 (GLT-1). All markers labelled populations of astrocytes in the grey and white matter, separate cortical layers, subpial and perivascular regions. All markers were informative for labelling different cellular properties and cellular compartments of astrocytes. ALDH1L1 labelled the largest population of astrocytes, and Cx43-immunopositive astrocytes were found in all cortical layers. AQP4 and GLT-1 labelled distal astrocytic process and end-feet in the same population of astrocytes (98% of GLT-1-immunopositive astrocytes contained AQP4). In contrast, GFAP, the most widely used marker, predominantly labelled astrocytes in superficial cortical layers. This study highlights the diversity of astrocytes in the human cortex, providing a reference map of the distribution of distinct and overlapping astrocyte populations which can be used for comparative purposes in various disease, inflammatory and injury states involving astrocytes.

Globular glial tauopathy type II

The globular glial tauopathies (GGTs) are a rare group of neurodegenerative diseases with fewer than 90 autopsy-confirmed cases reported in the literature. Although there has been some uncertainty about whether GGT is entirely distinct from progressive supranuclear palsy, a recent study of tau filament structures supports the definition of GGT as a separate neuropathological entity. We present a sporadic case of GGT type II presenting with a progressive corticobasal-primary lateral sclerosis overlap syndrome in a 74-year-old woman. Neuropathological examination identified neuronal and glial tau inclusions, including globular astrocytic and oligodendroglial inclusions. We also discuss the clinical features and molecular pathophysiology of GGT. Increased awareness of this condition could become more important as patients with GGT may be candidates for anti-tau therapies currently undergoing clinical evaluation in patients with other tauopathies.

The many faces of globular glial tauopathy: A clinical and imaging study

BACKGROUND

Globular glial tauopathy (GGT) has been associated with frontotemporal dementia syndromes; little is known about the clinical and imaging characteristics of GGT and how they differ from other non-globular glial 4-repeat tauopathies (N4GT) such as progressive supranuclear palsy (PSP) or corticobasal degeneration (CBD).

METHODS

For this case-control study the Mayo Clinic brain banks were queried for all cases with an autopsy-confirmed diagnosis of GGT between 1 January 2011 and 31 October 2021. Fifty patients with N4GT (30 PSP, 20 CBD) were prospectively recruited and followed by the Neurodegenerative Research Group at Mayo Clinic, Minnesota. Magnetic resonance imaging was used to characterize patterns of gray/white matter atrophy, MR-parkinsonism index, midbrain volume, and white matter hyperintensities.¹⁸ F-Fluorodeoxyglucose-, ¹¹ C Pittsburg compound-, and ¹⁸ F-flortaucipir-positron emission tomography scans were reviewed.

RESULTS

Twelve patients with GGT were identified: 83% were women compared to 42% in NG4T (p = 0.02) with median age at death 76.5 years (range: 55-87). The most frequent clinical features were eye movement abnormalities, parkinsonism, behavioral changes followed by pyramidal tract signs and motor speech abnormalities. Lower motor neuron involvement was present in 17% and distinguished GGT from NG4T (p = 0.035). Primary progressive apraxia of speech was the most frequent initial diagnosis (25%); 50% had a Parkinson-plus syndrome before death. Most GGT patients had asymmetric frontotemporal atrophy with matching hypometabolism. GGT patients had more gray matter atrophy in temporal lobes, normal MR-parkinsonism index, and larger midbrain volumes.

CONCLUSIONS

Female sex, lower motor neuron involvement in the context of a frontotemporal dementia syndrome, and asymmetric brain atrophy with preserved midbrain might be suggestive of underlying GGT.

Progressive Supranuclear Palsy Syndrome Associated With a Novel Tauopathy: Case Study

BACKGROUND AND OBJECTIVES

To report a novel tauopathy in a patient with protracted course progressive supranuclear palsy (PC-PSP).

METHODS

This was a clinical follow-up, gene analysis, neuropathologic study.

RESULTS

A 73-year-old man presented with diplopia, slowness, shuffling gait, and falls. Neurologic examination revealed slowed saccades, restricted up-gaze, and mild parkinsonism. Three years after onset, he developed personality changes. Slowly progressive parkinsonism was associated with memory and executive deficits. MRI showed subtle bilateral hippocampal and midbrain tegmentum atrophy and hyperintensity in the brainstem tegmentum and white matter of the medial temporal lobe. The duration of illness was 11 years. There were no pathogenic mutations in 80 genes known to be involved in neurodegeneration, including MAPT (H1/H1 haplotype) and APOE (ε3/ε3 genotype). Neuropathology revealed PSP type pathology together with the pathology described in the novel limbic-predominant neuronal inclusion body 4-repeat tauopathy (LNT) correlating well with the signal alterations seen in MRI.

DISCUSSION

Our observation broadens the spectrum of tau pathology associated with PC-PSP and suggests that memory deficit and hippocampal atrophy may be suggestive of non-Alzheimer disease pathology, including LNT. Understanding the diverse range of tau morphologies may help explain phenotypic heterogeneity seen in PSP.

Populations of Tau Conformers Drive Prion-like Strain Effects in Alzheimer's Disease and Related Dementias

Recent findings of diverse populations of prion-like conformers of misfolded tau protein expand the prion concept to Alzheimer's disease (AD) and monogenic frontotemporal lobar degeneration (FTLD)-MAPT P301L, and suggest that distinct strains of misfolded proteins drive the phenotypes and progression rates in many neurodegenerative diseases. Notable progress in the previous decades has generated many lines of proof arguing that yeast, fungal, and mammalian prions determine heritable as well as infectious traits. The extraordinary phenotypic diversity of human prion diseases arises from structurally distinct prion strains that target, at different progression speeds, variable brain structures and cells. Although human prion research presents beneficial lessons and methods to study the mechanism of strain diversity of protein-only pathogens, the fundamental molecular mechanism by which tau conformers are formed and replicate in diverse tauopathies is still poorly understood. In this review, we summarize up to date advances in identification of diverse tau conformers through biophysical and cellular experimental paradigms, and the impact of heterogeneity of pathological tau strains on personalized structure- and strain-specific therapeutic approaches in major tauopathies.

Clinical, radiologic, and pathologic features of the globular glial tauopathy subtype of frontotemporal lobar degeneration in right temporal variant frontotemporal dementia with salient features of Geschwind syndrome

Globular Glial Tauopathy (GGT) is a rare form of Frontotemporal Lobar Degeneration (FTLD) consisting of 4-repeat tau globular inclusions in astrocytes and oligodendrocytes. We present the pathological findings of GGT in a previously published case of a 73-year-old woman with behavioral symptoms concerning for right temporal variant frontotemporal dementia with initial and salient features of Geschwind syndrome. Clinically, she lacked motor abnormalities otherwise common in previously published GGT cases. Brain MRI showed focal right anterior temporal atrophy (indistinguishable from five FTLD-TDP cases) and subtle ipsilateral white matter signal abnormalities. Brain autopsy showed GGT type III and Alzheimer's neuropathologic changes. .

Clinical Spectrum of Tauopathies

Tauopathies are both clinical and pathological heterogeneous disorders characterized by neuronal and/or glial accumulation of misfolded tau protein. It is now well understood that every pathologic tauopathy may present with various clinical phenotypes based on the primary site of involvement and the spread and distribution of the pathology in the nervous system making clinicopathological correlation more and more challenging. The clinical spectrum of tauopathies includes syndromes with a strong association with an underlying primary tauopathy, including Richardson syndrome (RS), corticobasal syndrome (CBS), non-fluent agrammatic primary progressive aphasia (nfaPPA)/apraxia of speech, pure akinesia with gait freezing (PAGF), and behavioral variant frontotemporal dementia (bvFTD), or weak association with an underlying primary tauopathy, including Parkinsonian syndrome, late-onset cerebellar ataxia, primary lateral sclerosis, semantic variant PPA (svPPA), and amnestic syndrome. Here, we discuss clinical syndromes associated with various primary tauopathies and their distinguishing clinical features and new biomarkers becoming available to improve in vivo diagnosis. Although the typical phenotypic clinical presentations lead us to suspect specific underlying pathologies, it is still challenging to differentiate pathology accurately based on clinical findings due to large phenotypic overlaps. Larger pathology-confirmed studies to validate the use of different biomarkers and prospective longitudinal cohorts evaluating detailed clinical, biofluid, and imaging protocols in subjects presenting with heterogenous phenotypes reflecting a variety of suspected underlying pathologies are fundamental for a better understanding of the clinicopathological correlations.

Tauopathies: new perspectives and challenges

BACKGROUND

Tauopathies are a class of neurodegenerative disorders characterized by neuronal and/or glial tau-positive inclusions.

MAIN BODY

Clinically, tauopathies can present with a range of phenotypes that include cognitive/behavioral-disorders, movement disorders, language disorders and non-specific amnestic symptoms in advanced age. Pathologically, tauopathies can be classified based on the predominant tau isoforms that are present in the inclusion bodies (i.e., 3R, 4R or equal 3R:4R ratio). Imaging, cerebrospinal fluid (CSF) and blood-based tau biomarkers have the potential to be used as a routine diagnostic strategy and in the evaluation of patients with tauopathies. As tauopathies are strongly linked neuropathologically and genetically to tau protein abnormalities, there is a growing interest in pursuing of tau-directed therapeutics for the disorders. Here we synthesize emerging lessons on tauopathies from clinical, pathological, genetic, and experimental studies toward a unified concept of these disorders that may accelerate the therapeutics.

CONCLUSIONS

Since tauopathies are still untreatable diseases, efforts have been made to depict clinical and pathological characteristics, identify biomarkers, elucidate underlying pathogenesis to achieve early diagnosis and develop disease-modifying therapies.

Current concepts of mixed pathologies in neurodegenerative diseases

Neurodegenerative diseases are a pathologically, clinically and genetically diverse group of disorders without effective disease-modifying therapies. Pathologically, these disorders are characterised by disease-specific protein aggregates in neurons and/or glia and referred to as proteinopathies. Many neurodegenerative diseases show pathological overlap with the same abnormally deposited protein occurring in anatomically distinct regions, which give rise to specific patterns of cognitive and motor clinical phenotypes. Sequential distribution patterns of protein inclusions throughout the brain have been described. Rather than occurring in isolation, it is increasingly recognised that combinations of one or more proteinopathies with or without cerebrovascular disease frequently occur in individuals with neurodegenerative diseases. In addition, complex constellations of ageing-related and incidental pathologies associated with tau, TDP-43, Aβ, α-synuclein deposition have been commonly reported in longitudinal ageing studies. This review provides an overview of current classification of neurodegenerative and age-related pathologies and presents the spectrum and complexity of mixed pathologies in community-based, longitudinal ageing studies, in major proteinopathies, and genetic conditions. Mixed pathologies are commonly reported in individuals >65 years with and without cognitive impairment; however, they are increasingly recognised in younger individuals (<65 years). Mixed pathologies are thought to lower the threshold for developing cognitive impairment and dementia. Hereditary neurodegenerative diseases also show a diverse range of mixed pathologies beyond the proteinopathy primarily linked to the genetic abnormality. Cases with mixed pathologies might show a different clinical course, which has prognostic relevance and obvious implications for biomarker and therapy development, and stratifying patients for clinical trials.

Presenilin-1 Mutations Are a Cause of Primary Lateral Sclerosis-Like Syndrome

Background and Purpose

Primary lateral sclerosis (PLS) is a progressive upper motor neuron (UMN) disorder. It is debated whether PLS is part of the amyotrophic lateral sclerosis (ALS) spectrum, or a syndrome encompassing different neurodegenerative diseases. Recently, new diagnostic criteria for PLS have been proposed. We describe four patients of two pedigrees, meeting definite PLS criteria and harboring two different mutations in presenilin 1 (PSEN1).

Methods

Patients underwent neurological and neuropsychological examination, MRI, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), amyloid-related biomarkers, and next-generation sequencing (NGS) testing.

Results

Four patients, aged 25–45 years old, presented with a progressive UMN syndrome meeting clinical criteria of definite PLS. Cognitive symptoms and signs were mild or absent during the first year of the disease but appeared or progressed later in the disease course. Brain MRI showed microbleeds in two siblings, but iron-related hypointensities in the motor cortex were absent. Brain FDG-PET showed variable areas of hypometabolism, including the motor cortex and frontotemporal lobes. Amyloid deposition was confirmed with either cerebrospinal fluid (CSF) or imaging biomarkers. Two heterozygous likely pathogenic mutations in PSEN1 (p.Pro88Leu and p.Leu166Pro) were found in the NGS testing.

Conclusion

Clinically defined PLS is a syndrome encompassing different neurodegenerative diseases. The NGS testing should be part of the diagnostic workup in patients with PLS, at least in those with red flags, such as early-onset, cognitive impairment, and/or family history of neurodegenerative diseases.

Corpus callosum hypersignals and focal atrophy: Neuroimaging findings in globular glial tauopathy type I

Background and purpose

Globular glial tauopathies (GGTs) have heterogeneous presentations; little evidence regarding typical clinical and magnetic resonance imaging (MRI) presentations are available.

Methods

We retrospectively assessed MRIs from three postmortem‐confirmed GGT cases, in two patients with atypical progressive aphasia and one with corticobasal syndrome.

Results

We suggest that four principal concomitant MRI findings characterize GGT type I: a sagittal callosal hyperintense band, marked focal callosal atrophy suggesting white matter degeneration originating in cortical areas responsible for symptoms (anterior atrophy in predominantly language manifestations and posterior atrophy in predominantly apraxia), periventricular white matter lesions, and mild‐to‐moderate brain stem atrophy.

Conclusions

We observed four concomitant MRI abnormalities in patients with atypical dementia, parkinsonism, and late incomplete supranuclear gaze palsy. Two patients had atypical progressive aphasia and one had corticobasal syndrome.