Dickson, Dennis W.

Abstract Background Cerebral amyloid angiopathy (CAA), characterized by the accumulation of amyloid‐beta in the cerebrovasculature, affects blood vessel integrity leading to brain hemorrhages and an accelerated cognitive decline in Alzheimer’s Disease (AD) patients. Our previous genome‐wide association study (GWAS) identified a LINC‐PINT splice variant associated with lower CAA levels in individuals without the APOE e4 allele and higher levels of LINC‐PINT expression in the brain of AD donors. In this study, we expand our GWAS to include additional donors with AD and those lacking significant AD neuropathology (non‐AD), with available CAA scores. Method In our prior study we assessed 853 AD donors. We expanded this by addition of genetic data from 550 AD and 502 non‐AD donors from the Mayo Clinic Brain Bank, scored for CAA. We performed QC and imputation (TOPMED) of all datasets. We conducted GWAS in AD only ( N = 1,363), non‐AD only, and all donors ( N = 1,865) by testing imputed variant dosages for association with square root transformed CAA using linear regression, adjusting for relevant covariates. To assess associations in the context of major CAA risk factors, we performed interaction analysis with APOEe4 presence and sex; and pursued stratified analyses. Result Variants at the APOE locus were identified as the most significant in our study. In addition, several other variants approached genome‐wide significance after adjusting for AD neuropathology (Braak stage and Thal phase). T he LINC‐PINT splice variant remained associated with lower CAA scores in AD donors without the APOEe4 risk allele. To enhance the robustness of our findings, we are pursuing further expansion of our study cohort to include other available datasets. To explore putative functional consequences of key variants we are collecting peripheral gene expression measures in participants from Mayo Clinic with neuroimaging measures including microhemorrhages. Conclusion We expect this study will provide further insights into the genetic architecture underlying risk for CAA, both in the context of significant AD pathology, and without. Characterization of genetic variants and their functional outcomes may lead to new avenues of research aimed at identifying biomarkers and therapies to treat CAA, a common co‐pathology in those with and without AD.

Abstract Background Alzheimer's disease (AD) is pathologically characterized by the presence of extracellular amyloid beta plaques and intracellular tau tangles. Related disorders share aspects of AD pathology including progressive supranuclear palsy (PSP), a tauopathy, and pathologic aging (PA) defined by presence of amyloid but not tau. We hypothesize that there are shared, and distinct, brain molecular changes associated with amyloid and tau protein levels in AD and related disorders and that identifying these will provide novel insights into disease pathogenesis. Methods We collected brain multiomics measures (genetic, transcriptomic, epigenomic, proteomic and metabolomic) from donors diagnosed with AD, PSP, PA and controls. Following quality control and normalization, omics measures were tested for association with disease diagnosis and amyloid and tau neuropathology using regression models adjusting for relevant covariates. Association with biochemical measures of core AD proteins were also assessed in a subset of AD cases. Gene sets were evaluated for enrichment of cellular pathways and cell type signatures. Results We found remarkably conserved transcriptomic changes associated with AD and PSP, and downregulation of myelination pathway genes in both diseases. Among PSP cases, we found divergent patterns of transcriptional associations with distinct tau lesions. In a cohort of AD cases, we found broad transcriptional and epigenetic dysregulation associated with levels of tau protein, but not amyloid beta. Conversely a genetic analysis implicated more variants associated with amyloid levels than tau. Conclusion Multi‐omics studies across various proteinopathies can identify convergent and divergent molecular signatures that are candidates for shared therapeutic targets and disease differentiating biomarkers.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative diseases that share clinical and pathological features, as well as genetic causes. A G4C2 repeat expansion in chromosome 9 open reading frame 72 (C9orf72) is the most common genetic cause of ALS and FTD, collectively referred to as c9ALS/FTD. Assembly modulation is a new therapeutic approach which appears to target allosteric sites on aberrant forms of multi-protein complexes and restore them to the healthy state. Recent findings demonstrate that tetrahydroisoquinolone (THIQ)-based protein assembly modulators can ameliorate ALS/FTD-associated phenotypes in cellular and animal models. In the present study, we investigated the effects of PAV-615, a novel and advanced THIQ-based modulator, in a c9ALS/FTD mouse model expressing 149 G4C2 repeat expansions (referred to as 149R mouse model). Specifically, PAV-615 was administered to 5-month-old 149R mice via intraperitoneal injection for one month. Motor function was evaluated using the hang wire test, while anxiety-like behavior and hyperactivity were assessed using the open-field test. Pathological markers, including dipeptide repeat (DPR) proteins, phosphorylated TAR DNA-binding protein 43 (pTDP-43) and ataxin 2-positive stress granules, were quantified by Meso Scale Discovery and immunohistochemistry assays. Compared with vehicle-treated controls, PAV-615 significantly improved motor performance and modestly reduced anxiety-like behavior and hyperactivity in 149R mice. Moreover, PAV-615 treatment significantly decreased cortical DPR, pTDP-43 and ataxin 2-positive stress granule burdens. These results support assembly modulation as a promising therapeutic approach treatment of ALS/FTD.

Abstract INTRODUCTION Visual hallucinations (VHs) represent one of the core clinical features of dementia with Lewy bodies (DLB); however, their underlying pathology remains unclear. METHODS We employed proximity ligation assay (PLA) and phosphorylated α‐synuclein (αSYN) immunohistochemistry to compare αSYN oligomers and Lewy‐related pathology across brain regions along the ventral visual pathway in patients with and without VHs (five patients each). RESULTS Greater αSYN oligomer burden in the parahippocampal cortex was observed in patients with VHs compared to those without ( p = 0.041), whereas the burden of Lewy‐related pathology was similar between groups. DISCUSSION Our findings suggest that αSYN oligomers, rather than conventional Lewy‐related pathology, may be more closely associated with VHs in DLB. This provides novel evidence linking αSYN oligomers to a core clinical feature in DLB and suggests potential therapeutic targets for managing VH in these patients. Highlights Visualization of αSYN oligomers by PLA and quantitative neuropathologic analysis. Abundant αSYN oligomers in parahippocampal cortex of DLB with VHs. First human brain study linking αSYN oligomers to VHs. Potential oligomer‐targeted therapy for managing VH in DLB.

Objective Colony-stimulating factor-1 receptor (<i>CSF1R</i>)-related disorder (CSF1R-RD) is a rapidly progressive neurodegenerative disease with a median onset of 43 years. More than 200 <i>CSF1R</i> pathogenic variants have been identified. Patients develop rapidly progressive dementia and motor symptoms, with a median disease duration of 6.8 years. The p.R777Q variant causes CSF1R-RD; it is deleterious to protein function. We describe the clinical and pathological features of CSF1R-RD associated with p.R777Q and report a new family carrying this variant. We compare the neuropathological findings of an index patient (with short-duration disease) with those of a patient with long-duration CSF1R-RD.Methods We present clinical and imaging data from a new family with p.R777Q. We also describe the neuropathology of an index patient and contrast these findings with features of a patient with CSF1R-RD with an 11-year disease course caused by the c.2656_2657insC variant.Results We reviewed the literature on 13 individuals from 8 families with the p.R777Q variant from Asia, Europe, and North America. The mean age at onset was 41±14 years, ranging from 22 to 63 years, and the mean survival was 3.3±2.5 years. Neuropathologic studies of our index patient (10-month disease duration) revealed features consistent with CSF1R-RD. Axonal and myelin pathology was severe in the periventricular white matter. Compared with the patient with an 11-year disease duration, the index patient had less severe white matter lesions.Conclusion Compared with CSF1R-RD associated with other variants, the p.R777Q variant has an aggressive course. Compared with the patient with a long disease duration, the index patient had milder neuropathological findings. These differences may be specific to p.R777Q or associated with rapid clinical progression.

Objective Lewy body disease (LBD) is a complex neurodegenerative disorder characterized by the accumulation of misfolded α‐synuclein in the brain. Neuroinflammation has long been implicated in LBD pathogenesis, and recent genetic studies in Parkinson's disease (a clinical manifestation of LBD) have shown consistent association with the human leukocyte antigen (HLA) gene complex. Here, we assessed whether variation in HLA alleles influences neuropathological burden in a neuropathologically‐defined series of LBD cases. Methods We conducted a comprehensive analysis of HLA allelic variants in a cohort of 539 LBD cases of European descent from the Mayo Clinic brain bank. High‐resolution whole‐genome sequencing was used, and the HLA alleles of each sample were called using the HLA*LA tool and assessed for association with neuropathological outcomes. Results Our analysis identified 1 significant ( P < 3.43 × 10 −5 ) and 4 suggestive ( P < 0.001) associations between certain HLA alleles and specific neuropathological outcomes in LBD, suggesting a potential role for HLA‐mediated immune mechanisms in disease progression and subtype differentiation. Specifically, HLA‐DPB1*06:01 was significantly associated with lower Lewy body counts in the parahippocampal gyrus ( P = 3.30 × 10 −5 ), with weaker and suggestive associations observed in the middle frontal ( P = 1.80 × 10 −4 ) and inferior parietal gyrus ( P = 6.33 × 10 −4 ). Additionally, although only suggestive, HLA‐DRB1*11:01 correlated with a lower Thal amyloid phase ( P = 1.56 x 10 −4 ), and HLA‐B*15:01 correlated with an increased risk of diffuse LBD ( P = 7.58 x 10 −4 ). Interpretation This study provides a detailed evaluation of the relationship between HLA alleles and LBD pathology, highlighting the importance of immune‐related genetic factors in the etiology of LBD. ANN NEUROL 2026;99:492–501

Objective: Progressive apraxia of speech (PAOS) is a neurodegenerative syndrome characterized by impaired motor speech planning and programming, whereas behavioral variant frontotemporal dementia (bvFTD) is characterized by deviant behavioral (e.g., personality and social) features. Clinical and anatomic characteristics of bvFTD in the context of PAOS are understudied. Methods: We identified 12 participants with PAOS and features that were consistent with bvFTD at baseline or follow-up. Eleven completed a head MRI scan. We compared clinical features and anatomical patterns of atrophy in these 11 PAOS-bvFTD participants to 11 matched PAOS participants without bvFTD and 22 age- and sex-matched healthy controls. Statistical Parametric Mapping (SPM) was applied to visualize gray matter volume across both groups compared to controls and each other. Medians and 25th and 75th percentiles were assessed in patients and across groups; Fisher’s Exact Test and Mann–Whitney U tests were applied using BlueSky software, version 10.3.1-Pro. Results: As expected, PAOS-bvFTD participants performed worse on the Frontal Behavioral Inventory (median: 33/72 vs. 10/72), 20-item behavioral assessment scale (4.5/20 vs. 1.0/20), and the Neuropsychiatry inventory (4/36 vs. 1.5/36) compared to the PAOS group (p < 0.01 for all), with no differences in other demographic, neurological, or language tests. Seven of the eleven PAOS-bvFTD participants had bvFTD features develop within three years of symptom onset. The PAOS-bvFTD and PAOS groups showed volume loss in frontal lobe regions compared to controls, with PAOS-bvFTD participants having more prefrontal volume loss than PAOS participants. Conclusions: Behavioral features consistent with bvFTD can co-occur in patients with PAOS and are related to greater atrophy of the prefrontal cortex.

Abstract Our understanding of Alzheimer's disease (AD) and related dementias (ADRD) has grown exponentially, thanks to significant investments by the National Institute on Aging (NIA). This article celebrates the 40th anniversary of the NIA's Alzheimer's Disease Research Centers, highlighting the pivotal role of neuropathology as the bedrock for neurodegeneration research. Neuropathology has championed the key principles of proteinopathy, selective vulnerability, and stereotypic spread. Furthermore, neuropathologic studies advanced our understanding of ADRD prevalence, heterogeneity, clinical–pathological correlations, and genetic underpinnings, spurring biomarker development for target engagement and disease monitoring. Disease‐modifying therapies for AD were inspired and informed by neuropathology. The neuropathology community is poised to refine diagnostics, leveraging digital pathology and integrating genetics and pathomics to enhance subtyping for novel precision medicine approaches. Despite some common misconceptions and logistical challenges, neuropathology continues to be a critical component of the ADRD research infrastructure, serving as a key bridge between allied basic and clinical sciences. Highlights We celebrate 40 years of NIA‐funded ADRCs and their contributions through neuropathology studies that have significantly advanced our understanding and treatment of ADRD. Neuropathology uncovers principles of neurodegenerative disease: proteinopathy, selective vulnerability, and stereotypic spread, informing diagnostics and therapies. Development of AD biomarkers with reference to neuropathology enhances accuracy in diagnosis and monitoring, paving the way for targeted disease‐modifying therapies. Integration of digital pathology, genetics, and novel tools in neurodegeneration research promises advanced precision medicine approaches and refined diagnostics. Misconceptions and logistical challenges to neuropathological research are addressed to improve understanding and collaboration.

Background The purpose of this study was to clarify the usefulness of the ‘hot cross bun’ sign (HCBS) as a diagnostic imaging marker in a large cohort of patients with multiple system atrophy (MSA) and spinocerebellar ataxia (SCA). Methods This multicentre study included 97 patients with neuropathologically confirmed MSA, and 105 patients with genetically confirmed SCA. Neuroimaging features, including HCBS and middle cerebellar peduncle (MCP) hyperintensities, were assessed. HCBS was graded from 0 to 2: 0, none; 1, only a vertical hyperintense line; and 2, a cruciform hyperintense line. The neuropathological correlates of HCBS were evaluated in 15 patients with MSA with ≤3 months between MRI and autopsy. Results In patients with a disease duration <3 years, grade 1 or 2 HCBS was detected in 100% patients with MSA with predominant cerebellar ataxia (MSA-C) and 39.0% with SCA; whereas grade 2 HCBS was observed in 50% with MSA-C and 2.4% with SCA. Moreover, the coexistence of grade 2 HCBS and MCP hyperintensities exhibited a specificity of 100%. A neuropathological assessment revealed myelin loss, alpha-synuclein aggregates and astrocytic reaction in the MCP, transverse fibres, central zone between longitudinal fasciculi and raphe nucleus, with relative preservation in the longitudinal fasciculi and medial lemniscus in patients with MSA and grade 2 HCBS. Conclusions Grade 1 or 2 HCBS is a highly sensitive finding in patients with MSA-C, and the observation of grade 2 HCBS within 3 years of motor symptom onset has excellent specificity for discriminating MSA-C from SCA, especially when accompanied by MCP hyperintensities.