Ross, Owen A.

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 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

ABSTRACTBackgroundPrimary progressive apraxia of speech is a neurodegenerative disorder characterized by early, isolated speech impairment due to impairment of motor speech planning and programming. Patients with PPAOS have varying disease durations from the estimated onset of the first symptom to death. Clinicopathological and neuroimaging features related to disease duration are unknown for PPAOS. We determine whether clinical, neuroimaging, or pathological features are associated with disease duration in primary progressive apraxia of speech (PPAOS).MethodsWe analyzed data from 41 PPAOS participants who were enrolled and longitudinally followed to death in NIH‐funded studies over 15 years. Demographic, clinical, and genetic features were abstracted. Brain volumes of cortical, subcortical, and brainstem regions were calculated. Regional tau lesion count (burden) was assessed histologically. Spearman rank correlations were performed between disease duration and variables of interest, followed by multiple regression analyses.ResultsDisease duration did not correlate with any baseline demographic, clinical, or pathologic features. Shorter disease duration correlated with a faster rate of behavioral change and of apraxia of speech severity over time, smaller baseline volumes of the superior frontal lobe and supplementary motor cortex, and higher tau burden in the locus ceruleus (ρ = −0.5, p = 0.03). Multiple regression analysis identified rate of behavioral change and volume loss in the superior frontal lobe as key clinical and neuroimaging variables, respectively.ConclusionIn patients with PPAOS, we found shorter disease duration to be related to behavioral dyscontrol and involvement of the frontal lobe, as well as a higher burden of 4‐repeat tau lesions in the locus ceruleus.

AbstractINTRODUCTIONIncreasing evidence indicates that α‐synuclein (αSYN) oligomers are toxic. We sought to determine whether αSYN oligomers were associated with faster cognitive decline in prospectively‐followed patients with dementia with Lewy bodies (DLB).METHODSEight autopsy‐confirmed patients with DLB were selected based on rapid or slow cognitive decline determined by the rate of change of Mini‐Mental State Examination (MMSE) scores. Quantitative neuropathologic analysis of αSYN oligomers, Lewy‐related pathology, phosphorylated tau, and amyloid‐β was conducted in hippocampal subfields (CA1‐4 and subiculum) and the entorhinal cortex.RESULTSDLB with rapid cognitive decline showed greater CA1 αSYN oligomer burden (p = 0.029) and tau burden (p = 0.029) than DLB with slow decline. The groups showed comparable burden of Lewy‐related pathology and amyloid‐β pathology in the hippocampal formation and entorhinal cortex.DISCUSSIONHippocampal accumulation of αSYN oligomers and phosphorylated tau is associated with rapid cognitive decline in DLB. Therapeutic strategies targeting αSYN oligomers warrant further investigation.Highlights Proximity ligation assay (PLA) and digital pathology for oligomer quantification. Abundant α‐synuclein (αSYN) oligomers in CA1 of patients with dementia with Lewy bodies (DLB) with rapid decline. First human brain study linking αSYN oligomers to cognitive trajectory. Potential therapeutic implications of targeting αSYN oligomers in DLB.

Abstract Background People with HIV (PWH) are at increased risk of stroke likely due to many factors including antiretroviral therapy (ART). We sought to evaluate the association between ARTand risk of stroke in PWH. Methods We conducted a prospective case-control study at the University Teaching Hospital in Lusaka, Zambia between March 2022 and October 2024 in PWH comparing those with stroke (cases) and without (controls) matched (1:2) for age, sex and race. Standardized data collection instruments were used to collect demographic, clinical, laboratory and imaging information. Comparisons were made between the cases and controls, and subgroup analysis by ART duration was done for the cases. Results We analyzed results for 205 cases and 410 controls. Compared to controls, cases were more likely to have hypertension (71% vs. 18%, p=0.001), lower CD4 counts [293(163-592) cells/µl vs. 533 (376-688) cells/µl, p=0.0001] and to be on second line ART (23% vs. 4%, p=0.001). Hypertension (aOR 19.7, 95% CI 3.1-126.4, p=0.002) and Tenofovir Disoproxil Fumarate (TDF) use (aOR 85.3, 95% CI 5.3-1380.7, p=0.002) were associated with increased odds of stroke, whereas Dolutegravir (aOR 0.03, 95% CI 0.001-0.58, p=0.02) and alcohol use (aOR 0.24, 95% CI 0.06-0.95) were associated with reduced odds of stroke. The majority of stroke patients on long-term ART were using Dolutegravir (80% vs. 35%, p=0.001) and TDF (72% vs. 42%, p=0.01). Conclusion In PWH, TDF associates with higher odds of stroke. Although Dolutegravir associates with reduced odds of stroke, stroke patients on long-term ART are more likely to be on it.

Pick’s disease (PiD) is a rare neurodegenerative disorder defined by dementia, frontotemporal lobe atrophy, and 3-repeat tau inclusions. To elucidate PiD pathobiology, we performed the first bulk transcriptomics study on PiD using short- and long-read sequencing on the parietal cortex of 28 PiD and 15 control samples. We identified several significantly differentially expressed genes, with CCL2 displaying the strongest association with 3-repeat tau pathology and increased burden in PiD compared to those in 4-repeat tau progressive supranuclear palsy (PSP) cases. Investigation of co-expressed genes and pathways suggested the involvement of mRNA processing, mitochondrial function, and immune processes in disease pathobiology. Long-read RNA sequencing on a subset of samples (eight PiD and four control) proposed novel, potentially disease-associated transcripts for AZGP1 , CD44 , HSD11B2 , and WIF1 , predicted to result in truncated proteins. In conclusion, we observed transcriptomic changes in the parietal cortex of patients with PiD that may inform into clinically relevant biomarkers and therapeutic strategies.

AbstractINTRODUCTIONPhosphorylated ubiquitin (p‐S65‐Ub) is generated during PINK1‐PRKN mitophagy as a specific marker of mitochondrial damage. Despite the widespread deposition of p‐S65‐Ub in aged and diseased human brain, the genetic contribution to its accumulation remains unclear.METHODSTo identify novel mitophagy regulators, we performed a genome‐wide association study using p‐S65‐Ub level as a quantitative trait in 1012 autopsy‐confirmed Lewy body disease (LBD) samples.RESULTSWe identified a significant genome‐wide association with p‐S65‐Ub for rs429358 (apolipoprotein E ε4 [APOE4]) and a suggestive association for rs6480922 (ZMIZ1). APOE4 was associated with higher p‐S65‐Ub levels and greater neuropathological burden. Functional validation in mouse and human induced pluripotent stem cell (iPSC) models confirmed APOE4‐mediated mitophagy alterations. Intriguingly, ZMIZ1 rs6480922 was associated with lower p‐S65‐Ub levels, reduced neuropathological load, and increased brain weight, indicating a potential protective role.DISCUSSIONOur findings underscore the importance of mitochondrial quality control in LBD pathogenesis and nominate regulators that may contribute to disease risk or resilience.Highlights p‐S65‐Ub levels were used as a quantitative marker of mitochondrial damage. A GWAS identified two genetic variants that modify mitophagy in LBD autopsy brain. APOE4 was associated with increased p‐S65‐Ub accumulation and neuropathology. APOE4 altered mitophagy via pathology‐dependent and pathology‐independent mechanisms. ZMIZ1 was linked to reduced p‐S65‐Ub and neuropathology indicative of protection.

Abstract Leucine-rich repeat kinase 2 (LRRK2) phosphorylates a subset of Rab GTPases that regulate receptor trafficking; activating mutations in LRRK2 are linked to Parkinson’s disease. Rab phosphorylation is a transient event that can be reversed by phosphatases, including PPM1H, that acts on phosphoRab8A and phosphoRab10. Here we report a phosphatome-wide siRNA screen that identified PPM1M as a phosphoRab12-preferring phosphatase that also acts on phosphoRab8A and phosphoRab10. Upon knockout from cells or mice, PPM1M displays selectivity for phosphoRab12. As shown previously for mice harboring LRRK2 pathway mutations, knockout of Ppm1m leads to primary cilia loss in striatal cholinergic interneurons. We have also identified a rare PPM1M mutation in patients with Parkinson’s disease that is catalytically inactive when tested in vitro and in cells. These findings identify PPM1M as a key player in the LRRK2 signaling pathway and provide a new therapeutic target for the possible benefit of patients with Parkinson’s disease. Teaser Parkinson’s linked Rab phosphorylation is reversed by PPM1M; the inactive D440N variant is implicated in rare patient cases.