Progressive supranuclear palsy (PSP) is a 4R-tauopathy predominated by subcortical pathology in neurons, astrocytes, and oligodendroglia associated with various clinical phenotypes. In the present international study, we addressed the question of whether or not sequential distribution patterns can be recognized for PSP pathology. We evaluated heat maps and distribution patterns of neuronal, astroglial, and oligodendroglial tau pathologies and their combinations in different clinical subtypes of PSP in postmortem brains. We used conditional probability and logistic regression to model the sequential distribution of tau pathologies across different brain regions. Tau pathology uniformly predominates in the neurons of the pallido-nigroluysian axis in different clinical subtypes. However, clinical subtypes are distinguished not only by total tau load but rather cell-type (neuronal versus glial) specific vulnerability patterns of brain regions suggesting distinct dynamics or circuitspecific segregation of propagation of tau pathologies. For Richardson syndrome (n = 81) we recognize six sequential steps of involvement of brain regions by the combination of cellular tau pathologies. This is translated to six stages for the practical neuropathological diagnosis by the evaluation of the subthalamic nucleus, globus pallidus, striatum, cerebellum with dentate nucleus, and frontal and occipital cortices. This system can be applied to further clinical subtypes by emphasizing whether they show caudal (cerebellum/dentate nucleus) or rostral (cortical) predominant, or both types of pattern. Defining cell-specific stages of tau pathology helps to identify preclinical or early-stage cases for the better understanding of early pathogenic events, has implications for understanding the clinical subtype-specific dynamics of disease-propagation, and informs tau-neuroimaging on distribution patterns.

Objective: To use digital histology in a large autopsy cohort of Lewy Body Disorder (LBD) patients with dementia to test the hypotheses that co-occurring Alzheimer’s disease (AD) pathology impacts the anatomic distribution of α-synuclein (SYN) pathology and that co-occurring neocortical tau pathology in LBD associates with worse cognitive performance and occurs in a pattern differing from AD. Methods: Fifty-five autopsy-confirmed LBD (PDD: 36, DLB:19) patients and 25 AD patients were studied. LBD patients were categorized as having moderate/severe AD co-pathology (SYN+AD=20) or little/no AD co-pathology (SYN-AD=35). Digital measures of tau, Aβ, and SYN histopathology in neocortical and subcortical/limbic regions were compared between groups and related to antemortem cognitive testing. Results: SYN burden was higher in SYN+AD than SYN-AD in each neocortical region (F(1,54)=5.6–6.0,p<0.02) but was equivalent in entorhinal cortex and putamen (F(1,43–49)=0.7–1.7,p>0.2). SYN+AD performed worse than SYN-AD on a temporal-lobe mediated naming task (t(27)=2.1,p=0.04). Antemortem cognitive test scores inversely correlated with tau burden (r=−0.39 to −0.68,p<0.05). AD had higher tau than SYN+AD in all regions (F(1,43)=12.8–97.2,p<.001); however, SYN+AD had a greater proportion of tau in the temporal neocortex than AD, (t(41)=2.0,p<.05) whereas AD had a greater proportion of tau in the frontal neocortex than SYN+AD (t(41)=3.3,p<0.002). SYN+AD had similar severity and distribution of neocortical Aβ compared to AD (F(1,40–43)=1.6–2.0,p>.1). Interpretation: LBD patients with AD co-pathology harbor greater neocortical SYN pathology. Regional tau pathology relates to cognitive performance in LBD dementia, and its distribution may diverge from pure AD. Tau co-pathology contributes uniquely to the heterogeneity of cognitive impairment in LBD.

Higher antemortem CSF t-tau/Aβ and lower Aβ levels are predictive of increasing cerebral AD and SYN pathology. These biomarkers may identify patients with LBD vulnerable to cortical SYN pathology who may benefit from both SYN and AD-targeted disease-modifying therapies.

Summary Mammalian target of rapamycin (mTOR) is a key protein kinase that regulates basic cellular processes, including development and growth. Mutations in mTOR cause tuberous sclerosis complex (TSC), a condition that is characterized by developmental brain malformations (cortical tubers) and epilepsy. Although considerable insight has been gained recently into the pathologic dysfunction of mTOR in tubers in TSC‐related epilepsy, data on the mTOR cascade in mesial temporal lobe epilepsy (MTLE) are lacking. Immunohistochemical investigation with confocal microscopy was performed to evaluate mTOR cascade and to correlate its activity with cellular alterations observed in surgically resected samples of human neocortex and hippocampus in MTLE. We compared results in human tissue to findings in the rat pilocarpine model of sclerotic MTLE. In nonsclerotic and control hippocampus, many neurons in the CA1 subfield expressed high levels of phospho‐S6 (p‐S6), a reliable marker of mTOR activation. In nonsclerotic and control hippocampus, as well as in magnetic resonance imaging (MRI) normal human neocortex, protoplasmic astrocytes did not express p‐S6. In contrast, in sclerotic hippocampus, prominent p‐S6 immunostaining was observed mainly in astrocytes and microglia located in the areas of neuronal loss and astrogliosis, whereas neurons in preserved areas of CA1 expressed significantly lower levels of p‐S6 immunopositivity than neurons in nonsclerotic or control CA1 subfields. In surgically resected neocortex with chronic astroglial scar tissue, only microglia revealed moderate p‐S6 immunoreactivity. Different from human sclerotic epileptic hippocampus, astrogliosis in the chronic rat pilocarpine model of epilepsy was not characterized by glial cells with mTOR activation. The mTOR cascade is activated in astroglial cells in sclerotic MTLE, but not in astrocytes in chronic neocortical scarring or in the pilocarpine model of MTLE. These findings suggest that the astroglial “scar” in sclerotic MTLE has active, ongoing cellular changes. Targeting mTOR in MTLE may provide new pathways for the medical therapy of epilepsy.

PD, PD with dementia, and dementia with Lewy bodies are clinical syndromes characterized by the neuropathological accumulation of alpha‐synuclein in the CNS that represent a clinicopathological spectrum known as Lewy body disorders. These clinical entities have marked heterogeneity of motor and nonmotor symptoms with highly variable disease progression. The biological basis for this clinical heterogeneity remains poorly understood. Previous attempts to subtype patients within the spectrum of Lewy body disorders have centered on clinical features, but converging evidence from studies of neuropathology and ante mortem biomarkers, including CSF, neuroimaging, and genetic studies, suggest that Alzheimer's disease beta‐amyloid and tau copathology strongly influence clinical heterogeneity and prognosis in Lewy body disorders. Here, we review previous clinical biomarker and autopsy studies of Lewy body disorders and propose that Alzheimer's disease copathology is one of several likely pathological contributors to clinical heterogeneity of Lewy body disorders, and that such pathology can be assessed in vivo. Future work integrating harmonized assessments and genetics in PD, PD with dementia, and dementia with Lewy bodies patients followed to autopsy will be critical to further refine the classification of Lewy body disorders into biologically distinct endophenotypes. This approach will help facilitate clinical trial design for both symptomatic and disease‐modifying therapies to target more homogenous subsets of Lewy body disorders patients with similar prognosis and underlying biology. © 2019 International Parkinson and Movement Disorder Society

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IntroductionSex differences in dementia with Lewy bodies (DLB) have been reported in clinically defined cohorts; however, clinical diagnostic accuracy in DLB is suboptimal and phenotypic differences have not been assessed in pathologically confirmed participants.MethodsCore DLB features were compared across 55 women and 156 men with pathologically defined DLB in the National Alzheimer’s Coordinating Center. These analyses were repeated for 55 women and 55 men matched for age, education and tau burden.ResultsIn the total sample, women died older, had fewer years of education, had higher tau burden but were less likely to be diagnosed with dementia and clinical DLB. In the matched sample, visual hallucinations continued to be less common in women, and fewer women met clinical DLB criteria.DiscussionSex impacts clinical manifestations of underlying pathologies in DLB. Despite similar underlying Lewy body pathology, women are less likely to manifest core DLB features and may be clinically underdiagnosed.

IntroductionRecent evidence has implicated perituberal, MRI-normal brain tissue as a possible source of seizures in tuberous sclerosis complex (TSC). Data on aberrant structural features in this area that may predispose to the initiation or progression of seizures are very limited. We used immunohistochemistry and confocal microscopy to compare epileptogenic, perituberal, MRI-normal tissue with cortical tubers.ResultsIn every sample of epileptogenic, perituberal tissue, we found many abnormal cell types, including giant cells and cytomegalic neurons. The majority of giant cells were surrounded by morphologically abnormal astrocytes with long processes typical of interlaminar astrocytes. Perituberal giant cells and astrocytes together formed characteristic “microtubers”. A parallel analysis of tubers showed that many contained astrocytes with features of both protoplasmic and gliotic cells.ConclusionsMicrotubers represent a novel pathognomonic finding in TSC and may represent an elementary unit of cortical tubers. Microtubers and cytomegalic neurons in perituberal parenchyma may serve as the source of seizures in TSC and provide potential targets for therapeutic and surgical interventions in TSC.