Locus coeruleus integrity and neuropsychiatric symptoms in a cohort of early- and late-onset Alzheimer's disease.

INTRODUCTION: Early-onset Alzheimer's disease (EOAD) shows a higher burden of neuropsychiatric symptoms than late-onset Alzheimer's disease (LOAD). We aim to determine the differences in the severity of neuropsychiatric symptoms and locus coeruleus (LC) integrity between EOAD and LOAD accounting for disease stage. METHODS: One hundred four subjects with AD diagnosis and 32 healthy controls were included. Participants underwent magnetic resonance imaging (MRI) to measure LC integrity, measures of noradrenaline levels in cerebrospinal fluid (CSF) and Neuropsychiatric Inventory (NPI). We analyzed LC-noradrenaline measurements and clinical and Alzheimer's disease (AD) biomarker associations. RESULTS: EOAD showed higher NPI scores, lower LC integrity, and similar levels of CSF noradrenaline compared to LOAD. Notably, EOAD exhibited lower LC integrity independently of disease stage. LC integrity negatively correlated with neuropsychiatric symptoms. Noradrenaline levels were increased in AD correlating with AD biomarkers. DISCUSSION: Decreased LC integrity negatively contributes to neuropsychiatric symptoms. The higher LC degeneration in EOAD compared to LOAD could explain the more severe neuropsychiatric symptoms in EOAD. HIGHLIGHTS: LC degeneration is greater in early-onset AD (EOAD) compared to late-onset AD. Tau-derived LC degeneration drives a higher severity of neuropsychiatric symptoms. EOAD harbors a more profound selective vulnerability of the LC system. LC degeneration is associated with an increase of cerebrospinal fluid noradrenaline levels in AD.

Misfolded α-Synuclein in Autosomal Dominant Alzheimer's Disease.

We analyzed Lewy body (LB) pathology in 18 autosomal dominant Alzheimer's disease (ADAD) brains via immunohistochemistry. Real-time quaking induced conversion was used to detect misfolded α-synuclein (α-syn) in 18 living ADAD cerebrospinal fluid (CSF) samples. Concomitant LB pathology was present in 44% ADAD brains. Only 6% CSF samples were positive for misfolded α-syn. In an additional AD sample, all patients with confirmed LB presented misfolded α-syn in postmortem CSF regardless of the LB staging. In conclusion, misfolded α-syn in CSF was scarce in symptomatic living ADAD individuals, in contrast to postmortem brain tissue. These results suggest late appearance of LB pathology in ADAD.

Muscle magnetic resonance imaging of a large cohort of distal hereditary motor neuropathies reveals characteristic features useful for diagnosis.

Distal motor neuropathies (dHMN) are an heterogenous group of diseases characterized by progressive muscle weakness affecting predominantly the distal muscles of the lower and upper limbs. Our aim was to study the imaging features and pattern of muscle involvement in muscle magnetic resonance imaging (MRI) in dHMN patients of suspected genetic origin (dHMN). We conducted a retrospective study collecting clinical, genetic and muscle imaging data. Muscle MRI included T1-weighted and T2 weighted Short Tau Inversion Recovery images (STIR-T2w) sequences. Muscle replacement by fat was quantified using the Mercuri score. Identification of selective patterns of involvement was performed using hierarchical clustering. Eighty-four patients with diagnosis of dHMN were studied. Fat replacement was predominant in the distal lower leg muscles (82/84 cases), although also affected thigh and pelvis muscles. Asymmetric involvement was present in 29% of patients. The superficial posterior compartment of the leg, including the soleus and gastrocnemius muscles, was the most affected area (77/84). We observed a reticular pattern of fatty replacement progressing towards what is commonly known as "muscle islands" in 79.8%. Hyperintensities in STIR-T2w were observed in 78.6% patients mainly in distal leg muscles. Besides features common to all individuals, we identified and describe a pattern of muscle fat replacement characteristic of BICD2, HSPB1 and DYNC1H1 patients. We conclude that muscle MRI of patients with suspected dHMN reveals common features helpful in diagnosis process.

Analysis of muscle magnetic resonance imaging of a large cohort of patient with VCP-mediated disease reveals characteristic features useful for diagnosis.

BACKGROUND: The diagnosis of patients with mutations in the VCP gene can be complicated due to their broad phenotypic spectrum including myopathy, motor neuron disease and peripheral neuropathy. Muscle MRI guides the diagnosis in neuromuscular diseases (NMDs); however, comprehensive muscle MRI features for VCP patients have not been reported so far. METHODS: We collected muscle MRIs of 80 of the 255 patients who participated in the "VCP International Study" and reviewed the T1-weighted (T1w) and short tau inversion recovery (STIR) sequences. We identified a series of potential diagnostic MRI based characteristics useful for the diagnosis of VCP disease and validated them in 1089 MRIs from patients with other genetically confirmed NMDs. RESULTS: Fat replacement of at least one muscle was identified in all symptomatic patients. The most common finding was the existence of patchy areas of fat replacement. Although there was a wide variability of muscles affected, we observed a common pattern characterized by the involvement of periscapular, paraspinal, gluteal and quadriceps muscles. STIR signal was enhanced in 67% of the patients, either in the muscle itself or in the surrounding fascia. We identified 10 diagnostic characteristics based on the pattern identified that allowed us to distinguish VCP disease from other neuromuscular diseases with high accuracy. CONCLUSIONS: Patients with mutations in the VCP gene had common features on muscle MRI that are helpful for diagnosis purposes, including the presence of patchy fat replacement and a prominent involvement of the periscapular, paraspinal, abdominal and thigh muscles.

Diagnostic Performance and Clinical Applicability of Blood-Based Biomarkers in a Prospective Memory Clinic Cohort.

BACKGROUND AND OBJECTIVES: Blood-based biomarkers have emerged as minimally invasive options for evaluating cognitive impairment. Most studies to date have assessed them in research cohorts, limiting their generalization to everyday clinical practice. We evaluated their diagnostic performance and clinical applicability in a prospective, real-world, memory clinic cohort. METHODS: All patients referred with suspected cognitive impairment between July 2019 and June 2021 were prospectively invited to participate. Five plasma biomarkers (tau phosphorylated at threonine 181 [p-tau181], glial fibrillary acidic protein [GFAP], neurofilament light chain [NfL], total tau [t-tau], and ubiquitin C-terminal hydrolase L1 [UCH-L1]) were determined with single-molecule array. Performance was assessed in comparison to clinical diagnosis (blinded to plasma results) and amyloid status (CSF/PET). A group of cognitively unimpaired (CU) controls was also included. RESULTS: Three hundred forty-nine participants (mean age 68, SD 8.3 years) and 36 CU controls (mean age 61.7, SD 8.2 years) were included. In the subcohort with available Alzheimer disease (AD) biomarkers (n = 268), plasma p-tau181 and GFAP had a high diagnostic accuracy to differentiate AD from non-neurodegenerative causes (area under the receiver operating characteristic curve 0.94 and 0.92, respectively), with p-tau181 systematically outperforming GFAP. Plasma p-tau181 levels predicted amyloid status (85% sensitivity and specificity) with accurate individual prediction in approximately 60% of the patients. Plasma NfL differentiated frontotemporal dementia (FTD) syndromes from CU (0.90) and non-neurodegenerative causes (0.93), whereas the discriminative capacity with AD and between all neurodegenerative and non-neurodegenerative causes was less accurate. A combination of p-tau181 and NfL identified FTD with 82% sensitivity and 85% specificity and had a negative predictive value for neurodegenerative diagnosis of 86%, ruling out half of the non-neurodegenerative diagnoses. In the subcohort without AD biomarkers, similar results were obtained. T-tau and UCH-L1 did not offer added diagnostic value. DISCUSSION: Plasma p-tau181 predicted amyloid status with high accuracy and could have potentially avoided CSF/amyloid PET testing in approximately 60% of subjects in a memory clinic setting. NfL was useful for identifying FTD from non-neurodegenerative causes but behaved worse than p-tau181 in all other comparisons. Combining p-tau181 and NfL improved diagnostic performance for FTD and non-neurodegenerative diagnoses. However, the 14% false-negative results suggest that further improvement is needed before implementation outside memory clinics. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that plasma p-tau181 correlates with the presence or absence of AD and a combination of plasma p-tau181 and NfL correlates moderately well with a diagnosis of FTD.

Higher Cerebral Small Vessel Disease Burden in Patients with White Matter Recent Small Subcortical Infarcts.

INTRODUCTION: Recent small subcortical infarcts (RSSI) are considered an acute manifestation of cerebral small vessel disease (CSVD). We assessed whether the topography of RSSI was related to CSVD markers on magnetic resonance imaging (MRI). MATERIAL AND METHODS: We screened the local registries of two independent stroke centers in Catalonia and selected patients with a symptomatic RSSI on MRI performed during admission. RSSI location was classified into brainstem, supratentorial subcortical structures (SSS), and centrum semiovale (CSO) regions. Clinical variables, including vascular risk factors, were collected. Radiological markers of CSVD on MRI were evaluated individually and by means of the global CSVD burden score. The associations between each RSSI location and CSVD markers were studied in uni- and multivariate logistic regression analysis. RESULTS: Among 475 patients with RSSI, 152 (32%) had an infarct in the brainstem, 227 (48%) in SSS, and 96 (20%) in CSO region. The median CSVD burden score was 2 (IQR, 1-3). After adjusting for confounding factors, a RSSI in CSO was associated with higher periventricular and deep white matter hyperintensity scores [OR 1.64 (95% CI, 1.16-2.33), and OR 1.44 (95% CI, 1.07-1.93), respectively]. Higher CSVD burden score was positively associated with CSO [OR 1.48 (95% CI, 1.22-1.81)] and inversely associated with SSS [0.85 (95% CI, 0.72-0.99)] location after adjusting for relevant confounders. CONCLUSIONS: CSO RSSI were related to a higher burden of CSVD, particularly to white matter hyperintensities, compared to other RSSI locations. The pathophysiological significance of such findings should be investigated in the future with advanced neuroimaging techniques.

Susceptibility Vessel Sign in Deep Perforating Arteries in Patients with Recent Small Subcortical Infarcts.

OBJECTIVES: Recent small subcortical infarcts (RSSI) are considered an acute manifestation of cerebral small vessel disease. Paramagnetic signals in perforating arteries supplying RSSI may be detected on T2*-relaxation derived sequences on MRI and is defined as susceptibility vessel sign (SVS). We aimed to study the prevalence of SVS in patients with RSSI, and explore whether its identification is related to cerebral small vessel disease markers. MATERIALS AND METHODS: We selected patients with RSSI identified on MRI during admission from a single-center stroke registry. The main demographic and clinical features, including vascular risk factors, were collected. Radiological features of RSSI and cerebral small vessel disease [white matter hyperintensities in deep and periventricular regions, enlarged perivascular spaces, lacunae, microbleeds, and brain atrophy] were described using validated qualitative scores. The presence of SVS was assessed on T2*gradient-echo or other susceptibility-weighted imaging. We compared the clinical and radiological features of patients with or without SVS in uni- and multivariate models. RESULTS: Out of 210 patients with an RSSI on an MRI, 35 (17%) showed SVS. The proportion of SVS+ patients was similar in different susceptibility imaging modalities (p=.64). Risk factor profiles and clinical course were similar in SVS+ and SVS- patients. SVS+ patients had a higher grade of deep white matter hyperintensities and brain atrophy, more lacunae (p=.001, p=.034, p=.022, respectively), and a similar degree of the rest of radiological variables, compared to SVS- patients. In the multivariate analysis, the grade of deep white matter hyperintensities was the only independent factor associated with SVS [OR 3.1 (95% CI, 1.5-6.4)]. CONCLUSIONS: SVS in patients with RSSI is uncommon and related to a higher grade of deep white matter hyperintensities. Pathophysiological mechanisms underlying the deposition of hemosiderin in the path of occluded perforating arteries are uncertain and might include endothelial dysfunction or embolic mechanisms.

Thalamic perforating artery stroke on computed tomography perfusion in a patient with coronavirus disease 2019.

Emerging evidence suggests that patients with coronavirus disease 2019 (COVID-19) are at risk of thromboembolic complications, including ischemic strokes. We present a case illustrating the value of CT perfusion to identify acute small subcortical infarcts in a patient with COVID-19 admitted to an intensive care unit for bilateral pneumonia and pulmonary embolism presenting with sudden right limb weakness.