Citations

AbstractINTRODUCTIONCorticobasal syndrome (CBS) can result from underlying Alzheimer's disease (AD) pathologies. Little is known about the utility of blood plasma metrics to predict positron emission tomography (PET) biomarker‐confirmed AD in CBS.METHODSA cohort of eighteen CBS patients (8 amyloid beta [Aβ]+; 10 Aβ−) and 8 cognitively unimpaired (CU) individuals underwent PET imaging and plasma analysis. Plasma concentrations were compared using a Kruskal–Wallis test. Spearman correlations assessed relationships between plasma concentrations and PET uptake.RESULTSCBS Aβ+ group showed a reduced Aβ42/40 ratio, with elevated phosphorylated tau (p‐tau)181, glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) concentrations, while CBS Aβ− group only showed elevated NfL concentration compared to CU. Both p‐tau181 and GFAP were able to differentiate CBS Aβ− from CBS Aβ+ and showed positive associations with Aβ and tau PET uptake.DISCUSSIONThis study supports use of plasma p‐tau181 and GFAP to detect AD in CBS. NfL shows potential as a non‐specific disease biomarker of CBS regardless of underlying pathology.Highlights Plasma phosphorylated tau (p‐tau)181 and glial fibrillary acidic protein (GFAP) concentrations differentiate corticobasal syndrome (CBS) amyloid beta (Aβ)− from CBS Aβ+. Plasma neurofilament light concentrations are elevated in CBS Aβ− and Aβ+ compared to controls. Plasma p‐tau181 and GFAP concentrations were associated with Aβ and tau positron emission tomography (PET) uptake. Aβ42/40 ratio showed a negative correlation with Aβ PET uptake.

Abstract Background Stepwise functional connectivity (SFC) detects whole‐brain functional couplings of a selected region of interest at increasing link‐step topological distances. Objective This study applied SFC to test the hypothesis that stepwise architecture propagating from the disease epicenter would shape patterns of brain atrophy in patients with progressive supranuclear palsy–Richardson's syndrome (PSP‐RS). Methods Thirty‐six patients with PSP‐RS and 44 age‐matched healthy control subjects underwent brain magnetic resonance imaging on a 3‐T scanner. The disease epicenter was defined as the peak of atrophy observed in an independent cohort of 13 cases with postmortem confirmation of PSP pathology and used as seed region for SFC analysis. First, we explored SFC rearrangements in patients with PSP‐RS, as compared with age‐matched control subjects. Subsequently, we tested SFC architecture propagating from the disease epicenter as a determinant of brain atrophy distribution. Results The disease epicenter was identified in the left midbrain tegmental region. Compared with age‐matched control subjects, patients with PSP‐RS showed progressively widespread decreased SFC of the midbrain with striatal and cerebellar regions through direct connections and sensorimotor cortical regions through indirect connections. A correlation was found between average link‐step distance from the left midbrain in healthy subjects and brain volumes in patients with PSP‐RS ( r = 0.38, P < 0.001). Conclusions This study provides comprehensive insights into the topology of functional network rearrangements in PSP‐RS and demonstrates that the brain architectural topology, as described by SFC propagating from the disease epicenter, shapes the pattern of atrophic changes in PSP‐RS. Our findings support the view of a network‐based pathology propagation in this primary tauopathy. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Purpose: We describe the communication challenges of four patients with a neurodegenerative disorder consistent with behavioral variant frontotemporal dementia (bvFTD), characterized by early behavioral and personality changes. By describing their clinical profiles, we identify common barriers to functional communication in this population and provide recommendations for how speech-language pathologists (SLPs) might contribute to minimizing them. Method: Four patients with bvFTD were selected from a cohort of patients with progressive communication impairments. Three of them returned for at least one follow-up visit. Case histories are presented along with the results of comprehensive speech and language, neuropsychological, and neurological testing. Results: At the time of initial evaluation, patients were between the ages of 54 and 66 years and had been experiencing symptoms for 1.5–6 years. Consistent with their bvFTD diagnoses, all patients had prominent behavioral and personality changes that impacted communication. Patients 1 and 2 also had mild aphasia at enrollment, primarily characterized by anomia and loss of word meaning. Patients 3 and 4 both had apraxia of speech and moderate-to-severe aphasia at enrollment with prominent anomia and agrammatism. All four patients had impaired executive functioning and relative sparing of visuospatial skills; episodic memory was also impaired for Patients 2 and 4. Even though functional communication was progressively limited for all patients, none of them received regular support from an SLP. Conclusions: This case series adds to a scant, but growing, literature demonstrating that patients with bvFTD have communication impairments. SLPs are uniquely positioned to identify barriers to functional communication and to provide tailored strategy training to the patients and their care partners over the course of their disease. Systematic evaluation of the efficacy of treatment in this population would be valuable. Supplemental Material: https://doi.org/10.23641/asha.25933762

AbstractProgressive apraxia of speech (PAOS) is a 4R tauopathy characterized by difficulties with motor speech planning. Neurodegeneration in PAOS targets the premotor cortex, particularly the supplementary motor area (SMA), with degeneration of white matter (WM) tracts connecting premotor and motor cortices and Broca's area observed on diffusion tensor imaging (DTI). We aimed to assess flortaucipir uptake across speech‐language‐related WM tracts identified using DTI tractography in PAOS. Twenty‐two patients with PAOS and 26 matched healthy controls were recruited by the Neurodegenerative Research Group (NRG) and underwent MRI and flortaucipir‐PET. The patient population included patients with primary progressive apraxia of speech (PPAOS) and non‐fluent variant/agrammatic primary progressive aphasia (agPPA). Flortaucipir PET scans and DTI were coregistered using rigid registration with a mutual information cost function in subject space. Alignments between DTI and flortaucipir PET were inspected in all cases. Whole‐brain tractography was calculated using deterministic algorithms by a tractography reconstruction tool (DSI‐studio) and specific tracts were identified using an automatic fiber tracking atlas‐based method. Fractional anisotropy (FA) and flortaucipir standardized uptake value ratios (SUVRs) were averaged across the frontal aslant tract, arcuate fasciculi, inferior frontal‐occipital fasciculus, inferior and middle longitudinal fasciculi, as well as the SMA commissural fibers. Reduced FA (p < .0001) and elevated flortaucipir SUVR (p = .0012) were observed in PAOS cases compared to controls across all combined WM tracts. For flortaucipir SUVR, the greatest differentiation of PAOS from controls was achieved with the SMA commissural fibers (area under the receiver operator characteristic curve [AUROC] = 0.83), followed by the left arcuate fasciculus (AUROC = 0.75) and left frontal aslant tract (AUROC = 0.71). Our findings demonstrate that flortaucipir uptake is increased across WM tracts related to speech/language difficulties in PAOS.

Background: TAR DNA binding protein 43 (TDP-43) has been shown to be associated with whole hippocampal atrophy in primary age-related tauopathy (PART). It is currently unknown which subregions of the hippocampus are contributing to TDP-43 associated whole hippocampal atrophy in PART. Objective: To identify which specific hippocampal subfield regions are contributing to TDP-43-associated whole hippocampal atrophy in PART. Methods: A total of 115 autopsied cases from the Mayo Clinic Alzheimer Disease Research Center, Neurodegenerative Research Group, and the Mayo Clinic Study of Aging were analyzed. All cases underwent antemortem brain volumetric MRI, neuropathological assessment of the distribution of Aβ (Thal phase), and neurofibrillary tangle (Braak stage) to diagnose PART, as well as assessment of TDP-43 presence/absence in the amygdala, hippocampus and beyond. Hippocampal subfield segmentation was performed using FreeSurfer version 7.4.1. Statistical analyses using logistic regression were performed to assess for associations between TDP-43 and hippocampal subfield volumes, accounting for potential confounders. Results: TDP-43 positive patients ( n = 37, 32%), of which 15/15 were type-α, had significantly smaller whole hippocampal volumes, and smaller volumes of the body and tail of the hippocampus compared to TDP-43 negative patients. Subfield analyses revealed an association between TDP-43 and the molecular layer of hippocampal body and the body of cornu ammonis 1 (CA1), subiculum, and presubiculum regions. There was no association between TDP-43 stage and subfield volumes. Conclusions: Whole hippocampal volume loss linked to TDP-43 in PART is mainly due to volume loss occurring in the molecular layer, CA1, subiculum and presubiculum of the hippocampal body.

AbstractBackground and purposePrimary lateral sclerosis (PLS) is a neurodegenerative disorder that primarily affects the central motor system. In rare cases, clinical features of PLS may overlap with those of progressive supranuclear palsy (PSP). We investigate neuroimaging features that can help distinguish PLS with overlapping features of PSP (PLS‐PSP) from PSP.MethodsSix patients with PLS‐PSP were enrolled between 2019 and 2023. We compared their clinical and neuroimaging characteristics with 18 PSP–Richardson syndrome (PSP‐RS) patients and 20 healthy controls. Magnetic resonance imaging, 18F‐flortaucipir positron emission tomography (PET), quantitative susceptibility mapping, and diffusion tensor imaging tractography (DTI) were performed to evaluate eight brain regions of interest. Area under the receiver operating characteristic curve (AUROC) was calculated.ResultsFive of the six PLS‐PSP patients (83.3%) were male. Median age at symptom onset was 61.5 (52.5–63) years, and all had mixed features of PLS and PSP. Volumes of the pallidum, caudate, midbrain, and cerebellar dentate were smaller in PSP‐RS than PLS‐PSP, providing good discrimination (AUROC = 0.75 for all). The susceptibilities in pallidum, midbrain, and cerebellar dentate were greater in PSP‐RS compared to PLS‐PSP, providing excellent discrimination (AUROC ≥ 0.90 for all). On DTI, fractional anisotropy (FA) in the posterior limb of the internal capsule from the corticospinal tract was lower in PLS‐PSP compared to PSP‐RS (AUROC = 0.86), but FA in the superior cerebellar peduncle was lower in PSP‐RS (AUROC = 0.95). Pallidum flortaucipir PET uptake was greater in PSP‐RS compared to PLS‐PSP (AUROC = 0.74).ConclusionsRegional brain volume, tractography, and magnetic susceptibility, but not tau‐PET, are useful in distinguishing PLS‐PSP from PSP.