Citations

AbstractINTRODUCTIONParkinsonism in patients with Alzheimer's disease (AD) is often attributed to Lewy‐related pathology, given its high comorbidity. In the era of anti‐amyloid therapy, recognizing parkinsonism caused by AD pathology is needed to optimize the treatment.METHODSThis study aimed to quantitatively characterize parkinsonism and nigral neuropathology in AD without Lewy bodies (LB). Nigral neurons were counted automatically. Fine‐tuned ChatGPT collected structured clinical data.RESULTSAmong 635 AD patients without LB, 62 (9.7%) presented parkinsonism, which correlated with reduced nigral neuron density (p < 0.01). Tau burden did not explain the nigral neuronal loss. TAR DNA‐binding protein 43 (TDP‐43) pathology correlated with reduced nigral pigmented neuron density (p = 0.03).DISCUSSIONOur findings suggest that parkinsonism in AD without LB is related to nigral neuronal loss in association with TDP‐43 pathology. Recognition of parkinsonism in AD without LB is crucial for appropriate therapy.Highlights One in 10 Alzheimer's disease (AD) patients without Lewy bodies had parkinsonism. Parkinsonism in AD was correlated with reduced nigral neuron density. TAR DNA‐binding protein 43 pathology was associated with nigral degeneration in AD. AD should be included in the differential diagnosis of dementia with parkinsonism.

AbstractBackgroundThe aggregation of α‐synuclein protein, encoded by the SNCA gene, forms Lewy bodies (LBs) in neurons and is a key pathological feature of Lewy body dementia (LBD). Interestingly, the apolipoprotein E gene (APOE), primarily expressed in glial cells, is the strongest genetic modifier for LBD. The ε4 allele of this gene (APOE4) notably increases the risk of LBD. However, the specific mechanisms through which APOE‐regulated glial cells affect α‐synuclein aggregation in neurons are not yet fully understood.MethodTo explore this, we conducted spatial transcriptomics using the 10X Genomics Visium CytAssist platform on Formalin‐Fixed Paraffin‐Embedded tissue slides from the temporal cortex of human LBD brains (N = 4 brains in controls and N = 6 brains in LBD group, with an equal ratio of APOE3/3 and APOE3/4 genotypes). We defined the neuronal layers of the gray matter (Layers 1 to 6, L1‐6) and white matter in each brain based on the gene signature of each spot. We also identified LBs from hematoxylin and eosin (H&E) staining on the same slides, and annotated LB‐positive (LB+), LB‐surrounding and LB‐negative (LB‐) spots in each brain using Loupe Browser. We evaluated SNCA and APOE gene expression in each layer and analyzed cell‐cell communication using the CellChat tool across the layers.ResultWe observed that the SNCA gene was highly expressed in L5, which corresponded to the areas where most LBs were found. Notably, within LB+ spots across all layers, both SNCA and APOE gene expression levels were elevated in APOE3/4 cases compared to APOE3/3 cases. Furthermore, we identified cell‐cell communication networks between LB+ and LB‐surrounding spots, particularly in L4 and L5. These networks were enriched by microglia‐related signaling pathways, including APOE signaling, migration inhibitory factor (MIF) signaling, and colony stimulating factor 1 (CSF1) signaling. Interestingly, APOE3/4 brains exhibited significantly reduced interactions and lower interaction strength in these networks compared to APOE3/3 samples.ConclusionOur findings indicate that impaired cell‐cell communication, such as microglia‐mediated immune responses around LB regions, may be associated with the increased risk presented by the APOE4 allele in LBD brains.

Abstract Purpose This study examined occupational histories in neuropathologically confirmed cases of multiple system atrophy to identify environmental associations of potential relevance to disease causation. Methods 270 neuropathologically confirmed cases of multiple system atrophy obtained from the Mayo Clinic brain bank for neurodegenerative disorders in Jacksonville, Florida, were included in this case-control study. Demographic and disease information was collected from medical records. Information regarding occupational history was collected retrospectively from medical records and published obituaries. Proportions of employment by occupational sector were compared to United States census data. Results The most common prior occupations in patients were healthcare (15.2%), education (15.2%), administration (14.8%), clerical (10.7%), petroleum industry (8.9%), business ownership (8.5%), and metal industry (7.8%). When comparing patients to United States census data, significant differences were identified for electrical (5.6% vs. 0.4%, P < 0.001), education (15.2% vs. 2.3%, P < 0.001), real estate (4.4% vs. 0.7%, P < 0.001), metal industry (7.8% vs. 3.0%, P < 0.001), information technology (4.1% vs. 1.8%, P = 0.011), clerical (10.7% vs. 5.5%, P = 0.001), and petroleum industry (8.9% vs. 5.6%, P = 0.024). Conclusions Electrical engineers and electricians, educators, real estate agents, workers in the metal industry, information technologists, clerical staff, and workers in the petroleum industry were significantly overrepresented in our series of multiple system atrophy patients as compared to population data. We hypothesize that these occupational associations may signify environmental exposures increasing disease risk in genetically susceptible individuals. We cannot exclude a potential selection bias in patients willing to donate their brains to an academic center in order to contribute to scientific knowledge.

We report a patient who presented clinically with progressive supranuclear palsy (PSP) but was pathologically diagnosed as having primary lateral sclerosis (PLS) with magnetic resonance imaging (MRI) with a quantitative susceptibility mapping (QSM) protocol. A 70‐year‐old man was clinically diagnosed with PSP due to early falls and unresponsiveness to levodopa therapy. Postmortem pathological examination revealed mild loss of Betz cells, gliosis, and transactive response DNA binding protein of 43 kDa (TDP‐43)‐positive inclusions in the motor cortex, leading to the pathological diagnosis of PLS. To explore methods for differentiating PLS from PSP, ante‐mortem QSM images were visually and quantitatively assessed for abnormal increases in magnetic susceptibility in the motor cortex. Prussian blue and Luxol fast blue combined with periodic acid‐Schiff staining were also performed to understand the source of the susceptibility increases. QSM showed clear hyperintense signals in the motor cortex. Magnetic susceptibility in the motor cortex was higher in the PLS patient (Z = 4.7, p < 0.001) compared to normal controls and pathologically diagnosed PSP patients. Pathological examination of the region showed intracortical myelin loss, as well as iron deposition. Underlying pathological processes for the increased magnetic susceptibility include not only iron deposition but also intracortical myelin. Our case suggests that QSM is a potential tool to differentiate PLS from PSP, providing insights for accurate diagnosis and enhancing clinical decision‐making.

AbstractAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by upper and lower motor neuron signs. There are, however, cases where upper motor neurons (UMNs) are predominantly affected, leading to clinical presentations of UMN‐dominant ALS or primary lateral sclerosis. Furthermore, cases exhibiting an UMN‐predominant pattern of motor neuron disease (MND) presenting with corticobasal syndrome (CBS) have been sparsely reported. This study aims to clarify the clinicopathological features of patients with UMN‐predominant MND. We reviewed 24 patients with UMN‐predominant MND with TDP‐43 pathology in the presence or absence of frontotemporal lobar degeneration. Additionally, we reviewed the medical records of patients with pathologically‐confirmed corticobasal degeneration (CBD) who received a final clinical diagnosis of CBS (n = 10) and patients with pathologically‐confirmed progressive supranuclear palsy (PSP) who received a final clinical diagnosis of PSP syndrome (n = 10). Of 24 UMN‐predominant MND patients, 20 had a clinical diagnosis of an atypical parkinsonian disorder, including CBS (n = 11) and PSP syndrome (n = 8). Only two patients had antemortem diagnoses of motor neuron disease. UMN‐predominant MND patients with CBS less frequently exhibited apraxia than those with CBD, and they were less likely to meet clinical criteria for possible or probable CBS. Similarly, UMN‐predominant MND patients with PSP syndrome less often met clinical criteria for probable PSP than PSP patients with PSP syndrome. Our findings suggest that UMN‐predominant MND can mimic atypical parkinsonism, and should be considered in the differential diagnosis of CBS and PSP syndrome, in particular when criteria are not met.

Abstract Transactive response DNA-binding protein 43 (TDP-43) pathology is categorized as type A-E in frontotemporal lobar degeneration and as type α-β in Alzheimer disease (AD) based on inclusion type. We screened amygdala slides of 131 cases with varying ages at death, clinical/neuroimaging findings, and AD neuropathologic changes for TDP-43 pathology using anti-phospho-TDP-43 antibodies. Seven cases (5%) only showed atypical TDP-43 inclusions that could not be typed. Immunohistochemistry and immunofluorescence assessed the atypical star-shaped TDP-43 pathology including its distribution, species, cellular localization, and colocalization with tau. All 7 had died at an extremely old age (median: 100 years [IQR: 94–101]) from nonneurological causes and none had dementia (4 cognitively unimpaired, 3 with amnestic mild cognitive impairment). Neuroimaging showed mild medial temporal involvement. Pathologically, the star-shaped TDP-43-positive inclusions were found in medial (subpial) amygdala and, occasionally, in basolateral regions. Hippocampus only showed TDP-43-positive neurites in the fimbria and subiculum while the frontal lobe was free of TDP-43 inclusions. The star-shaped inclusions were better detected with antibodies against N-terminal than C-terminal TDP-43. Double-labeling studies confirmed deposition of TDP-43 within astrocytes and colocalization with tau. We have identified a novel TDP-43 pathology with star-shaped morphology associated with superaging, with a homogeneous clinicopathologic picture, possibly representing a novel, true aging-related TDP-43 pathology.