Sebastian Roemer-Cassiano

Verified

Sebastian verified their affiliation via an institutional email.

Learn more

Verified

Sebastian verified their affiliation via an institutional email.

Learn more

• MD
• Medical Doctor at Ludwig-Maximilians-Universität in Munich

Purpose Off-target binding remains a significant challenge in tau-PET neuroimaging. While off-targets including monoamine oxidase enzymes and neuromelanin-containing cells have been identified, recent studies indicated a relevant binding of novel tau tracers to melanin-containing structures. To date, little is known about the effect of melanocytes...

In Alzheimer’s disease (AD), amyloid-β (Aβ) triggers the aggregation and spreading of tau pathology, which drives neurodegeneration and cognitive decline. However, the pathophysiological link between Aβ and tau remains unclear, which hinders therapeutic efforts to attenuate Aβ-related tau accumulation. Aβ has been found to trigger neuronal hyperact...

Patients with Alzheimer’s disease (AD) and clinically overlapping neurodegenerative diseases are classified molecularly using the A/T/N classification system. Apart from fluid biomarkers and structural MRI, the three-dimensional A/T/N system incorporates characteristic features from β-amyloid-PET (A), tau-PET (T), and FDG-PET (N). We evaluated if d...

In Alzheimer’s disease (AD), Aβ triggers p-tau secretion, which drives tau aggregation. Therefore, it is critical to characterize modulators of Aβ-related p-tau increases which may alter AD trajectories. Here, we assessed whether factors known to alter tau levels in AD modulate the association between fibrillar Aβ and secreted p-tau 181 determined...

Background Memory clinic patients typically present with Alzheimer’s disease (AD) and cerebral small vessel disease (SVD) to varying degrees. Therefore, it is crucial to determine the etiology of cognitive deficits for facilitating patient‐centered treatment in memory clinics. Plasma biomarkers (ptau217, Glial Fibrillary Acidic Protein [GFAP], Neur...

Background Lewy body pathology consisting of aggregated alpha‐Synuclein (a‐Syn) is the hallmark pathology in Parkinson’s disease, yet a‐Syn aggregates are also commonly observed post‐mortem as a co‐pathology in Alzheimer’s disease (AD) patients. Preclinical research has shown that a‐Syn can amplify Ab‐associated tau seeding and aggregation, hence a...

Background Understanding modulators of Alzheimer's disease’s (AD) progression is crucial for determining optimal treatment windows and targets. Apolipoprotein E e4 (ApoE4), i.e. a key AD risk factor, is associated with earlier tau accumulation at lower Aß levels (Steward et al. 2023), yet, the mechanisms driving this connection remain unclear. Thus...

Background Neuroimaging studies have revealed age and sex‐specific differences in Alzheimer’s disease (AD) trajectories. However, how age and sex modulate tau spreading remains unclear. Thus, we investigated how age and sex modulate the amyloid‐beta (Aß)‐induced accumulation and spreading of tau pathology from local epicenters across connected brai...

Background In Alzheimer’s disease (AD), cortical tau aggregation is a strong predictor of cortical brain atrophy as shown by MRI and PET studies, particularly driving the degeneration of neuronal somata in the grey matter. However, tau’s physiological role is to stabilize microtubules within axons in the brain’s white matter (WM) pathways. Therefor...

Background In Alzheimer’s disease, Aß triggers tau spreading which drives neurodegeneration and cognitive decline. However, the mechanistic link between Aß and tau remains unclear, which hinders therapeutic efforts to attenuate Aß‐related tau accumulation. Preclinical research could show that tau spreads across connected neurons in an activity‐depe...

Background Memory clinic patients typically present with Alzheimer’s disease (AD) and cerebral small vessel disease (SVD) to varying degrees. Therefore, it is crucial to determine the etiology of cognitive deficits for facilitating patient‐centered treatment in memory clinics. Plasma biomarkers (ptau217, Glial Fibrillary Acidic Protein [GFAP], Neur...

Background Understanding modulators of Alzheimer's disease’s (AD) progression is crucial for determining optimal treatment windows and targets. Apolipoprotein E ε4 (ApoE4), i.e. a key AD risk factor, is associated with earlier tau accumulation at lower Aβ levels (Steward et al. 2023), yet, the mechanisms driving this connection remain unclear. Thus...

Background Lewy body pathology consisting of aggregated alpha‐Synuclein (a‐Syn) is the hallmark pathology in Parkinson’s disease, yet a‐Syn aggregates are also commonly observed post‐mortem as a co‐pathology in Alzheimer’s disease (AD) patients. Preclinical research has shown that a‐Syn can amplify Ab‐associated tau seeding and aggregation, hence a...

Background In Alzheimer’s disease, Aβ triggers tau spreading which drives neurodegeneration and cognitive decline. However, the mechanistic link between Aβ and tau remains unclear, which hinders therapeutic efforts to attenuate Aβ‐related tau accumulation. Preclinical research could show that tau spreads across connected neurons in an activity‐depe...

Background In Alzheimer’s disease (AD), cortical tau aggregation is a strong predictor of cortical brain atrophy as shown by MRI and PET studies, particularly driving the degeneration of neuronal somata in the grey matter. However, tau’s physiological role is to stabilize microtubules within axons in the brain’s white matter (WM) pathways. Therefor...

Background Neuroimaging studies have revealed age and sex‐specific differences in Alzheimer’s disease (AD) trajectories. However, how age and sex modulate tau spreading remains unclear. Thus, we investigated how age and sex modulate the amyloid‐beta (Aβ)‐induced accumulation and spreading of tau pathology from local epicenters across connected brai...

Tau PET has attracted increasing interest as an imaging biomarker for 4-repeat (4R)-tauopathy progressive supranuclear palsy (PSP). However, the translation of in vitro 4R-tau binding to in vivo tau PET signals is still unclear. Therefore, we performed a translational study using a broad spectrum of advanced methodologies to investigate the sources...

Background Preclinical, postmortem, and positron emission tomography (PET) imaging studies have pointed to neuroinflammation as a key pathophysiological hallmark in primary 4‐repeat (4R) tauopathies and its role in accelerating disease progression. Objective We tested whether microglial activation (1) progresses in similar spatial patterns as the...

Four-repeat (4R) tauopathies are neurodegenerative diseases characterized by cerebral accumulation of 4R tau pathology. The most prominent 4R tauopathies are progressive supranuclear palsy (PSP) and corticobasal degeneration characterized by subcortical tau accumulation and cortical neuronal dysfunction, as shown by PET-assessed hypoperfusion and g...

Background Several magnetic resonance imaging (MRI) measures have been suggested as progression biomarkers in progressive supranuclear palsy (PSP), and some PSP staging systems have been recently proposed. Objective Comparing structural MRI measures and staging systems in tracking atrophy progression in PSP and estimating the sample size to use th...

Purpose [¹⁸F]PI-2620 positron emission tomography (PET) detects misfolded tau in progressive supranuclear palsy (PSP) and Alzheimer’s disease (AD). We questioned the feasibility and value of absolute [¹⁸F]PI-2620 PET quantification for assessing tau by regional distribution volumes (VT). Here, arterial input functions (AIF) represent the gold stand...

In Alzheimer’s disease, amyloid-beta (Aβ) triggers the trans-synaptic spread of tau pathology, and aberrant synaptic activity has been shown to promote tau spreading. Aβ induces aberrant synaptic activity, manifesting in increases in the presynaptic growth-associated protein 43 (GAP-43), which is closely involved in synaptic activity and plasticity...

Background Recent post‐mortem studies suggest that cerebrovascular disease contributes to Alzheimer’s disease (AD) pathophysiology and clinical progression. In particular, cerebral amyloid angiopathy is highly common in AD and has been linked to faster cognitive decline. Yet, in‐vivo evidence on the contribution of cerebrovascular disease to pathob...

Background In Alzheimer’s disease (AD), Amyloid‐beta deposition (Ab) is associated with tau spreading from epicenters to connected regions. Yet, Ab and tau accumulate in strikingly different patterns, and it is unclear how Abdrives tau spreading. We envision two mechanisms, i.e. i) that cortical Ab exerts remote effects and “pulls” tau out of conne...

Background Targeting amyloid (Aß) may show highest clinical efficacy when preventing downstream tau spreading and subsequent neurodegeneration. Thus, it’s critical to establish Aß‐PET thresholds at which tau spreading is triggered, which may depend on ApoE4, i.e. a key genetic risk factor for Aß, tau and cognitive decline. Yet, ApoE4’s impact on Aß...

Background Animal and in vitro studies of Alzheimer’s disease (AD) found that tau spreads trans‐synaptically in an activity‐dependent manner, suggesting that synapses are key routes for tau spread. Importantly, amyloid‐beta (Ab) induces synaptic remodeling and aberrant synaptic activity, which may accelerate trans‐synaptic tau spread. In AD patient...

Background State‐of‐the‐art preprocessing of MRI and PET data is crucial for Alzheimer’s disease (AD) neuroimaging research. Therefore, standardization and harmonization of neuroimaging preprocessing across sites is key to generate comparable and sharable datasets and to reduce potential bias introduced by different preprocessing strategies. Furthe...

Background State‐of‐the‐art preprocessing of MRI and PET data is crucial for Alzheimer’s disease (AD) neuroimaging research. Therefore, standardization and harmonization of neuroimaging preprocessing across sites is key to generate comparable and sharable datasets and to reduce potential bias introduced by different preprocessing strategies. Furthe...

Background Recent post‐mortem studies suggest that cerebrovascular disease contributes to Alzheimer’s disease (AD) pathophysiology and clinical progression. In particular, cerebral amyloid angiopathy is highly common in AD and has been linked to faster cognitive decline. Yet, in‐vivo evidence on the contribution of cerebrovascular disease to pathob...

Background Animal and in vitro studies of Alzheimer’s disease (AD) found that tau spreads trans‐synaptically in an activity‐dependent manner, suggesting that synapses are key routes for tau spread. Importantly, amyloid‐beta (Ab) induces synaptic remodeling and aberrant synaptic activity, which may accelerate trans‐synaptic tau spread. In AD patient...

Background Targeting amyloid (Aß) may show highest clinical efficacy when preventing downstream tau spreading and subsequent neurodegeneration. Thus, it’s critical to establish Aß‐PET thresholds at which tau spreading is triggered, which may depend on ApoE4, i.e. a key genetic risk factor for Aß, tau and cognitive decline. Yet, ApoE4’s impact on Aß...

Background In Alzheimer’s disease (AD), Amyloid‐beta deposition (Ab) is associated with tau spreading from epicenters to connected regions. Yet, Ab and tau accumulate in strikingly different patterns, and it is unclear how Abdrives tau spreading. We envision two mechanisms, i.e. i) that cortical Ab exerts remote effects and “pulls” tau out of conne...

Importance For the Alzheimer disease (AD) therapies to effectively attenuate clinical progression, it may be critical to intervene before the onset of amyloid-associated tau spreading, which drives neurodegeneration and cognitive decline. Time points at which amyloid-associated tau spreading accelerates may depend on individual risk factors, such a...

Background and Purpose The purpose of this study was to evaluate the performance of magnetic resonance imaging (MRI) in measuring the optic nerve sheath diameter (ONSD) compared to the established method transorbital sonography (TOS) in patients with idiopathic intracranial hypertension (IIH). Methods Twenty-three patients with IIH were prospectiv...

Microglial activation occurs early in Alzheimer's disease (AD) and previous studies reported both detrimental and protective effects of microglia on AD progression. Here, we used CSF sTREM2 to investigate disease stage-dependent drivers of microglial activation and to determine downstream consequences on AD progression. We included 402 patients wit...

Alzheimer’s disease (AD) is characterized by Aβ and tau accumulation, microglial activation, metabolic brain changes, neurodegeneration, and cognitive decline. Studies found both detrimental and protective effects of microglial activation on AD progression, hence neuroinflammation may be a double‐edged sword in AD, which is critical for clinical tr...

In Alzheimer’s disease (AD), the functional connectome plays a key role in the trans‐neuronal spreading of tau pathology, a key driver of cognitive decline. The functional connectome is comprised of segregated, but communicating networks which lose segregation with age, resulting in an overall more diffuse connectome. Prior neuroimaging studies hav...

4‐repeat (4R) tauopathies are neurodegenerative diseases characterized by cerebral accumulation of 4R tau pathology. The most prominent 4R‐tauopathies are progressive‐supranuclear‐palsy (PSP) and corticobasal‐syndrome (CBS) characterized by tau accumulation in subcortical nuclei as well as cortical neuronal dysfunction, as shown by PET‐assessed hyp...

In Alzheimer’s disease (AD), the functional connectome plays a key role in the trans‐neuronal spreading of tau pathology, a key driver of cognitive decline. The functional connectome is comprised of segregated, but communicating networks which lose segregation with age, resulting in an overall more diffuse connectome. Prior neuroimaging studies hav...

4‐repeat (4R) tauopathies are neurodegenerative diseases characterized by cerebral accumulation of 4R tau pathology. The most prominent 4R‐tauopathies are progressive‐supranuclear‐palsy (PSP) and corticobasal‐syndrome (CBS) characterized by tau accumulation in subcortical nuclei as well as cortical neuronal dysfunction, as shown by PET‐assessed hyp...

Introduction: Lower network segregation is associated with accelerated cognitive decline in Alzheimer's disease (AD), yet it is unclear whether less segregated brain networks facilitate connectivity-mediated tau spreading. Methods: We combined resting state functional magnetic resonance imaging (fMRI) with longitudinal tau positron emission tomo...

Background Tau-PET is a prognostic marker for cognitive decline in Alzheimer’s disease, and the heterogeneity of tau-PET patterns matches cognitive symptom heterogeneity. Thus, tau-PET may allow precision-medicine prediction of individual tau-related cognitive trajectories, which can be important for determining patient-specific cognitive endpoints...

Temporalis muscle (TM) atrophy has emerged as a potential biomarker for muscle wasting. However, its diagnostic utility as a monitoring tool in intensive care remains uncertain. Hence, the objective of this study was to evaluate the diagnostic value of sequential ultrasound- and computed tomography (CT)-based measurements of TM thickness (TMT). Wit...

Background Microglial activation occurs early in Alzheimer’s disease (AD) and previous studies reported both detrimental and protective effects of microglia on AD progression. Therefore, it is critical to investigate at which AD stages microglial activation could be protective or detrimental to evaluate microglia as a treatment target. To address t...

In Alzheimer’s disease (AD), younger symptom onset is associated with accelerated disease progression and tau spreading, yet the mechanisms underlying faster disease manifestation are unknown. To address this, we combined resting-state fMRI and longitudinal tau-PET in two independent samples of controls and biomarker-confirmed AD patients (ADNI/Bio...

Background To assess the validity of neurosonological parameters (transorbital sonography (TOS)) for detection and monitoring of patients with idiopathic intracranial hypertension (IIH). Methods Prospective, single-center, case-controlled study in 25 patients with IIH and 19 controls. Visual parameters of papilledema, visual acuity, computerized s...