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Varlow C, Vasdev N. Evaluation of Tau Radiotracers in Chronic Traumatic Encephalopathy. J Nucl Med 2023; 64:460-465. [PMID: 36109185 PMCID: PMC10071800 DOI: 10.2967/jnumed.122.264404] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/06/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Chronic traumatic encephalopathy (CTE) is a neurologic disorder associated with head injuries, diagnosed by the perivascular accumulation of hyperphosphorylated tau protein (phospho-tau) identified at autopsy. Tau PET radiopharmaceuticals developed for imaging Alzheimer disease are under evaluation for brain injuries. The goal of this study was to conduct a head-to-head in vitro evaluation of 5 tau PET radiotracers in subjects pathologically diagnosed with CTE. Methods: Autoradiography was used to assess the specific binding and distribution of 3H-flortaucipir (also known as Tauvid, AV-1451, and T807), 3H-MK-6240 (also known as florquinitau), 3H-PI-2620, 3H-APN-1607 (also known as PM-PBB3 and florzolotau), and 3H-CBD-2115 (also known as 3H-OXD-2115) in fresh-frozen human postmortem CTE brain tissue (stages I-IV). Immunohistochemistry was performed for phospho-tau with AT8, 3R tau with RD3, 4R tau with RD4 and amyloid-β with 6F/3D antibodies. Tau target density (maximum specific binding) was quantified by saturation analysis with 3H-flortaucipir in tissue sections. Results: 3H-flortaucipir demonstrated a positive signal in all CTE cases examined, with varying degrees of specific binding (68.7% ± 10.5%; n = 12) defined by homologous blockade and to a lesser extent by heterologous blockade with MK-6240 (27.3% ± 13.6%; n = 12). The 3H-flortaucipir signal was also displaced by the monoamine oxidase (MAO)-A inhibitor clorgyline (43.9% ± 4.6%; n = 3), indicating off-target binding to MAO-A. 3H-APN-1607 was moderately displaced in homologous blocking studies and was not displaced by 3H-flortaucipir; however, substantial displacement was observed when blocking with the β-amyloid-targeting compound NAV-4694. 3H-MK-6240 and 3H-PI-2620 had negligible binding in all but 2 CTE IV cases, and binding may be attributed to pathology severity or mixed Alzheimer disease/CTE pathology. 3H-CBD-2115 showed moderate binding, displaced under homologous blockade, and aligned with 4R-tau immunostaining. Conclusion: In human CTE tissues, 3H-flortaucipir and 3H-APN-1607 revealed off-target binding to MAO-A and amyloid-β, respectively, and should be considered if these radiotracers are used in PET imaging studies of patients with brain injuries. 3H-MK-6240 and 3H-PI-2620 bind to CTE tau in severe- or mixed-pathology cases, and their respective 18F PET radiotracers warrant further evaluation in patients with severe suspected CTE.
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Affiliation(s)
- Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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Liang B, Alosco ML, Armañanzas R, Martin BM, Tripodis Y, Stern RA, Prichep LS. Long-Term Changes in Brain Connectivity Reflected in Quantitative Electrophysiology of Symptomatic Former National Football League Players. J Neurotrauma 2023; 40:309-317. [PMID: 36324216 PMCID: PMC9902050 DOI: 10.1089/neu.2022.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exposure to repetitive head impacts (RHI) has been associated with long-term disturbances in cognition, mood, and neurobehavioral dysregulation, and reflected in neuroimaging. Distinct patterns of changes in quantitative features of the brain electrical activity (quantitative electroencephalogram [qEEG]) have been demonstrated to be sensitive to brain changes seen in neurodegenerative disorders and in traumatic brain injuries (TBI). While these qEEG biomarkers are highly sensitive at time of injury, the long-term effects of exposure to RHI on brain electrical activity are relatively unexplored. Ten minutes of eyes closed resting EEG data were collected from a frontal and frontotemporal electrode montage (BrainScope Food and Drug Administration-cleared EEG acquisition device), as well as assessments of neuropsychiatric function and age of first exposure (AFE) to American football. A machine learning methodology was used to derive a qEEG-based algorithm to discriminate former National Football League (NFL) players (n = 87, 55.40 ± 7.98 years old) from same-age men without history of RHI (n = 68, 54.94 ± 7.63 years old), and a second algorithm to discriminate former players with AFE <12 years (n = 33) from AFE ≥12 years (n = 54). The algorithm separating NFL retirees from controls had a specificity = 80%, a sensitivity = 60%, and an area under curve (AUC) = 0.75. Within the NFL population, the algorithm separating AFE <12 from AFE ≥12 resulted in a sensitivity = 76%, a specificity = 52%, and an AUC = 0.72. The presence of a profile of EEG abnormalities in the NFL retirees and in those with younger AFE includes features associated with neurodegeneration and the disruption of neuronal transmission between regions. These results support the long-term consequences of RHI and the potential of EEG as a biomarker of persistent changes in brain function.
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Affiliation(s)
- Bo Liang
- BrainScope Company, Chevy Chase, Maryland, USA
| | - Michael L. Alosco
- Boston University CTE Center, Boston University, Boston, Massachusetts, USA
- Department of Neurology, Boston University, Boston, Massachusetts, USA
| | - Ruben Armañanzas
- BrainScope Company, Chevy Chase, Maryland, USA
- Institute for Data Science and Artificial Intelligence, Universidad de Navarra, Pamplona, Spain
- Tecnun School of Engineering, Universidad de Navarra, Donostia-San Sebastian, Spain
| | - Brett M. Martin
- Boston University CTE Center, Boston University, Boston, Massachusetts, USA
| | - Yorghos Tripodis
- Boston University CTE Center, Boston University, Boston, Massachusetts, USA
- Department of Biostatistics, Boston University, Boston, Massachusetts, USA
| | - Robert A. Stern
- Boston University CTE Center, Boston University, Boston, Massachusetts, USA
- Department of Neurology, Boston University, Boston, Massachusetts, USA
- Departments of Neurosurgery and Anatomy & Neurobiology, Boston University, Boston, Massachusetts, USA
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Abstract
Imaging of mild traumatic brain injury (TBI) using conventional techniques such as CT or MRI often results in no specific imaging correlation that would explain cognitive and clinical symptoms. Molecular imaging of mild TBI suggests that secondary events after injury can be detected using PET. However, no single specific pattern emerges that can aid in diagnosing the injury or determining the prognosis of the long-term behavioral profiles, indicating the heterogeneous and diffuse nature of TBI. Chronic traumatic encephalopathy, a primary tauopathy, has been shown to be strongly associated with repetitive TBI. In vivo data on the available tau PET tracers, however, have produced mixed results and overall low retention profiles in athletes with a history of repetitive mild TBI. Here, we emphasize that the lack of a mechanistic understanding of chronic TBI has posed a challenge when interpreting the results of molecular imaging biomarkers. We advocate for better target identification, improved analysis techniques such as machine learning or artificial intelligence, and novel tracer development.
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Affiliation(s)
- Gérard N. Bischof
- Department of Nuclear Medicine, University of Cologne, Cologne, Germany;,Institute for Neuroscience and Medicine II–Molecular Organization of the Brain, Research Center Juelich, Juelich, Germany; and
| | - Donna J. Cross
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah
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Alosco ML, Su Y, Stein TD, Protas H, Cherry JD, Adler CH, Balcer LJ, Bernick C, Pulukuri SV, Abdolmohammadi B, Coleman MJ, Palmisano JN, Tripodis Y, Mez J, Rabinovici GD, Marek KL, Beach TG, Johnson KA, Huber BR, Koerte I, Lin AP, Bouix S, Cummings JL, Shenton ME, Reiman EM, McKee AC, Stern RA. Associations between near end-of-life flortaucipir PET and postmortem CTE-related tau neuropathology in six former American football players. Eur J Nucl Med Mol Imaging 2023; 50:435-452. [PMID: 36152064 PMCID: PMC9816291 DOI: 10.1007/s00259-022-05963-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/01/2022] [Indexed: 01/11/2023]
Abstract
PURPOSE Flourine-18-flortaucipir tau positron emission tomography (PET) was developed for the detection for Alzheimer's disease. Human imaging studies have begun to investigate its use in chronic traumatic encephalopathy (CTE). Flortaucipir-PET to autopsy correlation studies in CTE are needed for diagnostic validation. We examined the association between end-of-life flortaucipir PET and postmortem neuropathological measurements of CTE-related tau in six former American football players. METHODS Three former National Football League players and three former college football players who were part of the DIAGNOSE CTE Research Project died and agreed to have their brains donated. The six players had flortaucipir (tau) and florbetapir (amyloid) PET prior to death. All brains from the deceased participants were neuropathologically evaluated for the presence of CTE. On average, the participants were 59.0 (SD = 9.32) years of age at time of PET. PET scans were acquired 20.33 (SD = 13.08) months before their death. Using Spearman correlation analyses, we compared flortaucipir standard uptake value ratios (SUVRs) to digital slide-based AT8 phosphorylated tau (p-tau) density in a priori selected composite cortical, composite limbic, and thalamic regions-of-interest (ROIs). RESULTS Four brain donors had autopsy-confirmed CTE, all with high stage disease (n = 3 stage III, n = 1 stage IV). Three of these four met criteria for the clinical syndrome of CTE, known as traumatic encephalopathy syndrome (TES). Two did not have CTE at autopsy and one of these met criteria for TES. Concomitant pathology was only present in one of the non-CTE cases (Lewy body) and one of the CTE cases (motor neuron disease). There was a strong association between flortaucipir SUVRs and p-tau density in the composite cortical (ρ = 0.71) and limbic (ρ = 0.77) ROIs. Although there was a strong association in the thalamic ROI (ρ = 0.83), this is a region with known off-target binding. SUVRs were modest and CTE and non-CTE cases had overlapping SUVRs and discordant p-tau density for some regions. CONCLUSIONS Flortaucipir-PET could be useful for detecting high stage CTE neuropathology, but specificity to CTE p-tau is uncertain. Off-target flortaucipir binding in the hippocampus and thalamus complicates interpretation of these associations. In vivo biomarkers that can detect the specific p-tau of CTE across the disease continuum are needed.
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Affiliation(s)
- Michael L Alosco
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Yi Su
- Banner Alzheimer's Institute, Arizona State University, and Arizona Alzheimer's Consortium, Phoenix, AZ, USA
| | - Thor D Stein
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
- Framingham Heart Study, Framingham, MA, USA
- VA Bedford Healthcare System, Bedford, MA, USA
| | - Hillary Protas
- Banner Alzheimer's Institute, Arizona Alzheimer's Consortium, Phoenix, AZ, USA
| | - Jonathan D Cherry
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
| | - Charles H Adler
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Laura J Balcer
- Departments of Neurology, Population Health and Ophthalmology, NYU Grossman School of Medicine, New York, NY, USA
| | - Charles Bernick
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
- Department of Neurology, University of Washington, Seattle, WA, USA
| | - Surya Vamsi Pulukuri
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Bobak Abdolmohammadi
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Michael J Coleman
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Boston, MA, USA
| | - Joseph N Palmisano
- Biostatistics and Epidemiology Data Analytics Center (BEDAC), Boston University School of Public Health, Boston, MA, USA
| | - Yorghos Tripodis
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Jesse Mez
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Framingham Heart Study, Framingham, MA, USA
| | - Gil D Rabinovici
- Memory & Aging Center, Departments of Neurology, Radiology & Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - Kenneth L Marek
- Institute for Neurodegenerative Disorders, Invicro, LLC, New Haven, CT, USA
| | - Thomas G Beach
- Banner Sun Health Research Institute, Sun City, Arizona, USA
| | - Keith A Johnson
- Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Gordon Center for Medical Imaging, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
| | - Bertrand Russell Huber
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
- VA Bedford Healthcare System, Bedford, MA, USA
- National Center for PTSD, VA Boston Healthcare, Jamaica Plain, MA, USA
| | - Inga Koerte
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Boston, MA, USA
- Massachusetts General Hospital, Boston, MA, USA
- cBRAIN, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Ludwig Maximilians University, Munich, Germany
- Graduate School of Systemic Neurosciences, Ludwig Maximilians University, Munich, Germany
- NICUM (NeuroImaging Core Unit Munich), Ludwig Maximilians University, Munich, Germany
| | - Alexander P Lin
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Boston, MA, USA
- Center for Clinical Spectroscopy, Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Sylvain Bouix
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Boston, MA, USA
| | - Jeffrey L Cummings
- Chambers-Grundy Center for Transformative Neuroscience, Department of Brain Health, School of Integrated Health Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Martha E Shenton
- VA Boston Healthcare System, Boston, MA, USA
- Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Eric M Reiman
- Banner Alzheimer's Institute, University of Arizona, Arizona State University, Translational Genomics Research Institute, and Arizona Alzheimer's Consortium, Phoenix, AZ, USA
| | - Ann C McKee
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- VA Boston Healthcare System, Boston, MA, USA
- Framingham Heart Study, Framingham, MA, USA
- VA Bedford Healthcare System, Bedford, MA, USA
| | - Robert A Stern
- Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
- Departments of Neurosurgery, and Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA, USA.
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Fesharaki-Zadeh A. A Case of Possible Chronic Traumatic Encephalopathy and Alzheimer's Disease in an Ex-Football Player. Neurologist 2022; 27:249-252. [PMID: 34879014 PMCID: PMC9439689 DOI: 10.1097/nrl.0000000000000391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Chronic traumatic encephalopathy (CTE) is a debilitating neurodegenerative disease, which is often the sequelae of repetitive head trauma. Although the definitive diagnosis of CTE is made postmortem, there are proposed clinical algorithms aimed at identifying characteristic features of CTE, based on a combination of clinical history, serum, cerebrospinal fluid and neuroimaging biomarkers. There are promising new advances in positron emission tomography neuroimaging, including tau specific ligands, which will potentially provide a robust assessment as well as an exploratory tool of the disease semiology and progression. CASE REPORT Here is a unique case of an ex-football player, who suffered multiple prior traumatic brain injuries throughout his career, and presented to our clinic with significant episodic memory, visuospatial and executive functioning deficits, as well as comorbid mood and behavioral changes in the absence of prior psychiatric history or substance use. His clinical presentation and biomarkers were consistent with a suspected diagnosis of CTE comorbid with Alzheimer disease, which comprises a significant portion of overall CTE cases. CONCLUSION This case report presents a patient with a subtle case of dementia, which could be easily mistaken for behavioral variant frontotemporal dementia or primary progressive aphasia. This in turn highlights the importance of detailed longitudinal history taking, as well as rigorous biomarker studies.
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Buckland ME, Affleck AJ, Pearce AJ, Suter CM. Chronic Traumatic Encephalopathy as a Preventable Environmental Disease. Front Neurol 2022; 13:880905. [PMID: 35769361 PMCID: PMC9234108 DOI: 10.3389/fneur.2022.880905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/06/2022] [Indexed: 11/29/2022] Open
Abstract
In this Perspective we explore the evolution of our understanding of chronic traumatic encephalopathy (CTE) and its relationship with repetitive head injury. As with many neurodegenerative conditions, there is an imperfect correspondence between neuropathology and clinical phenotype, but unlike other neurodegenerative diseases, CTE has a discrete and easily modifiable risk factor: exposure to repetitive head injury. Consequently, evaluation of the evidence regarding exposure to repetitive head injury and CTE risk should be undertaken using public or occupational health frameworks of medical knowledge. The current debate over the existence of CTE as a disease of concern is fuelled in part by immediate medico-legal considerations, and the involvement of high-profile athletes, with inevitable media interest. Moving beyond this debate has significant potential to address and reduce disease impact in the near future, and provide novel insights into mechanisms underlying abnormal protein accumulation in CTE and other neurodegenerative diseases.
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Affiliation(s)
- Michael E. Buckland
- Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
- *Correspondence: Michael E. Buckland
| | - Andrew J. Affleck
- Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Alan J. Pearce
- College of Science, Health and Engineering, La Trobe University, Bundoora, VIC, Australia
| | - Catherine M. Suter
- Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
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Varlow C, Knight AC, McQuade P, Vasdev N. Characterization of neuroinflammatory positron emission tomography biomarkers in chronic traumatic encephalopathy. Brain Commun 2022; 4:fcac019. [PMID: 35198978 PMCID: PMC8856182 DOI: 10.1093/braincomms/fcac019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/10/2021] [Accepted: 02/01/2022] [Indexed: 11/12/2022] Open
Abstract
Chronic traumatic encephalopathy is a neurological disorder associated with head trauma and is confirmed upon autopsy. PET imaging of chronic traumatic encephalopathy may provide a means to move towards ante-mortem diagnosis and therapeutic intervention following brain injuries. Characterization of the neuroinflammatory PET biomarkers, 18 kDa translocator protein and monoamine oxidase-B was conducted using [3H]PBR-28 and [3H]L-deprenyl, respectively, in post-mortem chronic traumatic encephalopathy brain tissue. [3H]PBR-28 displayed high specific binding in both chronic traumatic encephalopathy (95.40 ± 1.87%; n = 11 cases) and healthy controls (89.89 ± 8.52%, n = 3 cases). Cell-type expression of the 18 kDa translocator protein was confirmed by immunofluorescence to microglia, astrocyte and macrophage markers. [3H]L-deprenyl also displayed high specific binding in chronic traumatic encephalopathy (96.95 ± 1.43%; n = 12 cases) and healthy controls (93.24 ± 0.43%; n = 2 cases), with the distribution co-localized to astrocytes by immunofluorescence. Saturation analysis was performed to quantify the target density of the 18 kDa translocator protein and monoamine oxidase-B in both chronic traumatic encephalopathy and healthy control tissue. Using [3H]PBR-28, the target density of the 18 kDa translocator protein in healthy controls was 177.91 ± 56.96 nM (n = 7 cases; mean ± standard deviation); however, a highly variable target density (345.84 ± 372.42 nM; n = 11 cases; mean ± standard deviation) was measured in chronic traumatic encephalopathy. [3H]L-deprenyl quantified a monoamine oxidase-B target density of 304.23 ± 115.93 nM (n = 8 cases; mean ± standard deviation) in healthy control tissue and is similar to the target density in chronic traumatic encephalopathy tissues (365.80 ± 128.55 nM; n = 12 cases; mean ± standard deviation). A two-sample t-test determined no significant difference in the target density values of the 18 kDa translocator protein and monoamine oxidase-B between healthy controls and chronic traumatic encephalopathy (P > 0.05), albeit a trend towards increased expression of both targets was observed in chronic traumatic encephalopathy. To our knowledge, this work represents the first in vitro characterization of 18 kDa translocator protein and monoamine oxidase-B in chronic traumatic encephalopathy and reveals the variability in neuroinflammatory pathology following brain injuries. These preliminary findings will be considered when designing PET imaging studies after brain injury and for the ultimate goal of imaging chronic traumatic encephalopathy in vivo.
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Affiliation(s)
- Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada M5T 1R8
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Ashley C. Knight
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada M5T 1R8
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Paul McQuade
- Takeda Pharmaceutical Company, Cambridge, MA 02139, USA
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada M5T 1R8
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8
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Morgan R, Prosapio J, Kara S, Sonty S, Youssef P, Nedd K. Preliminary clinical diagnostic criteria for chronic traumatic encephalopathy: A case report and literature review. INTERDISCIPLINARY NEUROSURGERY 2021. [DOI: 10.1016/j.inat.2021.101290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Ricci M, Cimini A, Camedda R, Chiaravalloti A, Schillaci O. Tau Biomarkers in Dementia: Positron Emission Tomography Radiopharmaceuticals in Tauopathy Assessment and Future Perspective. Int J Mol Sci 2021; 22:ijms222313002. [PMID: 34884804 PMCID: PMC8657996 DOI: 10.3390/ijms222313002] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/14/2021] [Accepted: 11/25/2021] [Indexed: 01/20/2023] Open
Abstract
Abnormal accumulation of Tau protein is closely associated with neurodegeneration and cognitive impairment and it is a biomarker of neurodegeneration in the dementia field, especially in Alzheimer’s disease (AD); therefore, it is crucial to be able to assess the Tau deposits in vivo. Beyond the fluid biomarkers of tauopathy described in this review in relationship with the brain glucose metabolic patterns, this review aims to focus on tauopathy assessment by using Tau PET imaging. In recent years, several first-generation Tau PET tracers have been developed and applied in the dementia field. Common limitations of first-generation tracers include off-target binding and subcortical white-matter uptake; therefore, several institutions are working on developing second-generation Tau tracers. The increasing knowledge about the distribution of first- and second-generation Tau PET tracers in the brain may support physicians with Tau PET data interpretation, both in the research and in the clinical field, but an updated description of differences in distribution patterns among different Tau tracers, and in different clinical conditions, has not been reported yet. We provide an overview of first- and second-generation tracers used in ongoing clinical trials, also describing the differences and the properties of novel tracers, with a special focus on the distribution patterns of different Tau tracers. We also describe the distribution patterns of Tau tracers in AD, in atypical AD, and further neurodegenerative diseases in the dementia field.
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Affiliation(s)
- Maria Ricci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (A.C.); (R.C.); (A.C.); (O.S.)
- Correspondence:
| | - Andrea Cimini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (A.C.); (R.C.); (A.C.); (O.S.)
| | - Riccardo Camedda
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (A.C.); (R.C.); (A.C.); (O.S.)
| | - Agostino Chiaravalloti
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (A.C.); (R.C.); (A.C.); (O.S.)
- Nuclear Medicine Section, IRCCS Neuromed, 86077 Pozzilli, Italy
| | - Orazio Schillaci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy; (A.C.); (R.C.); (A.C.); (O.S.)
- Nuclear Medicine Section, IRCCS Neuromed, 86077 Pozzilli, Italy
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Asken BM, Rabinovici GD. Identifying degenerative effects of repetitive head trauma with neuroimaging: a clinically-oriented review. Acta Neuropathol Commun 2021; 9:96. [PMID: 34022959 PMCID: PMC8141132 DOI: 10.1186/s40478-021-01197-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/07/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND AND SCOPE OF REVIEW Varying severities and frequencies of head trauma may result in dynamic acute and chronic pathophysiologic responses in the brain. Heightened attention to long-term effects of head trauma, particularly repetitive head trauma, has sparked recent efforts to identify neuroimaging biomarkers of underlying disease processes. Imaging modalities like structural magnetic resonance imaging (MRI) and positron emission tomography (PET) are the most clinically applicable given their use in neurodegenerative disease diagnosis and differentiation. In recent years, researchers have targeted repetitive head trauma cohorts in hopes of identifying in vivo biomarkers for underlying biologic changes that might ultimately improve diagnosis of chronic traumatic encephalopathy (CTE) in living persons. These populations most often include collision sport athletes (e.g., American football, boxing) and military veterans with repetitive low-level blast exposure. We provide a clinically-oriented review of neuroimaging data from repetitive head trauma cohorts based on structural MRI, FDG-PET, Aβ-PET, and tau-PET. We supplement the review with two patient reports of neuropathology-confirmed, clinically impaired adults with prior repetitive head trauma who underwent structural MRI, FDG-PET, Aβ-PET, and tau-PET in addition to comprehensive clinical examinations before death. REVIEW CONCLUSIONS Group-level comparisons to controls without known head trauma have revealed inconsistent regional volume differences, with possible propensity for medial temporal, limbic, and subcortical (thalamus, corpus callosum) structures. Greater frequency and severity (i.e., length) of cavum septum pellucidum (CSP) is observed in repetitive head trauma cohorts compared to unexposed controls. It remains unclear whether CSP predicts a particular neurodegenerative process, but CSP presence should increase suspicion that clinical impairment is at least partly attributable to the individual's head trauma exposure (regardless of underlying disease). PET imaging similarly has not revealed a prototypical metabolic or molecular pattern associated with repetitive head trauma or predictive of CTE based on the most widely studied radiotracers. Given the range of clinical syndromes and neurodegenerative pathologies observed in a subset of adults with prior repetitive head trauma, structural MRI and PET imaging may still be useful for differential diagnosis (e.g., assessing suspected Alzheimer's disease).
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Affiliation(s)
- Breton M. Asken
- Department of Neurology, Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, 675 Nelson Rising Lane, Suite 190, San Francisco, CA 94143 USA
| | - Gil D. Rabinovici
- Departments of Neurology, Radiology & Biomedical Imaging, Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco, 675 Nelson Rising Lane, Suite 190, San Francisco, CA 94143 USA
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Alosco ML, Culhane J, Mez J. Neuroimaging Biomarkers of Chronic Traumatic Encephalopathy: Targets for the Academic Memory Disorders Clinic. Neurotherapeutics 2021; 18:772-791. [PMID: 33847906 PMCID: PMC8423967 DOI: 10.1007/s13311-021-01028-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2021] [Indexed: 12/14/2022] Open
Abstract
Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts, such as those from contact sports. The pathognomonic lesion for CTE is the perivascular accumulation of hyper-phosphorylated tau in neurons and other cell process at the depths of sulci. CTE cannot be diagnosed during life at this time, limiting research on risk factors, mechanisms, epidemiology, and treatment. There is an urgent need for in vivo biomarkers that can accurately detect CTE and differentiate it from other neurological disorders. Neuroimaging is an integral component of the clinical evaluation of neurodegenerative diseases and will likely aid in diagnosing CTE during life. In this qualitative review, we present the current evidence on neuroimaging biomarkers for CTE with a focus on molecular, structural, and functional modalities routinely used as part of a dementia evaluation. Supporting imaging-pathological correlation studies are also presented. We targeted neuroimaging studies of living participants at high risk for CTE (e.g., aging former elite American football players, fighters). We conclude that an optimal tau PET radiotracer with high affinity for the 3R/4R neurofibrillary tangles in CTE has not yet been identified. Amyloid PET scans have tended to be negative. Converging structural and functional imaging evidence together with neuropathological evidence show frontotemporal and medial temporal lobe neurodegeneration, and increased likelihood for a cavum septum pellucidum. The literature offers promising neuroimaging biomarker targets of CTE, but it is limited by cross-sectional studies of small samples where the presence of underlying CTE is unknown. Imaging-pathological correlation studies will be important for the development and validation of neuroimaging biomarkers of CTE.
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Affiliation(s)
- Michael L Alosco
- Department of Neurology, Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Boston University School of Medicine, 72 E Concord St, Suite B7800, MA, 02118, Boston, USA.
| | - Julia Culhane
- Department of Neurology, Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Boston University School of Medicine, 72 E Concord St, Suite B7800, MA, 02118, Boston, USA
| | - Jesse Mez
- Department of Neurology, Boston University Alzheimer's Disease Research Center, Boston University CTE Center, Boston University School of Medicine, 72 E Concord St, Suite B7800, MA, 02118, Boston, USA
- Framingham Heart Study, Boston University School of Medicine, MA, Boston, USA
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