Publications by authors named "Bobak Abdolmohammadi"

11 Publications

  • Page 1 of 1

Validity of the 2014 traumatic encephalopathy syndrome criteria for CTE pathology.

Alzheimers Dement 2021 Apr 7. Epub 2021 Apr 7.

Boston University Alzheimer's Disease and CTE Centers, Boston University School of Medicine, Boston, Massachusetts, USA.

Introduction: Validity of the 2014 traumatic encephalopathy syndrome (TES) criteria, proposed to diagnose chronic traumatic encephalopathy (CTE) in life, has not been assessed.

Methods: A total of 336 consecutive brain donors exposed to repetitive head impacts from contact sports, military service, and/or physical violence were included. Blinded to clinical information, neuropathologists applied National Institute on Neurological Disorders and Stroke/National Institute of Biomedical Imaging and Bioengineering CTE criteria. Blinded to neuropathological information, clinicians interviewed informants and reviewed medical records. An expert panel adjudicated TES diagnoses.

Results: A total of 309 donors were diagnosed with TES; 244 donors had CTE pathology. TES criteria demonstrated sensitivity and specificity of 0.97 and 0.21, respectively. Cognitive (odds ratio [OR] = 3.6; 95% confidence interval [CI]: 1.2-5.1), but not mood/behavior or motor symptoms, were significantly associated with CTE pathology. Having Alzheimer's disease (AD) pathology was significantly associated with reduced TES accuracy (OR = 0.27; 95% CI: 0.12-0.59).

Discussion: TES criteria provided good evidence to rule out, but limited evidence to rule in, CTE pathology. Requiring cognitive symptoms in revised criteria and using AD biomarkers may improve CTE pathology prediction.
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http://dx.doi.org/10.1002/alz.12338DOI Listing
April 2021

Genetics of Chronic Traumatic Encephalopathy.

Semin Neurol 2020 08 26;40(4):420-429. Epub 2020 Jul 26.

Boston University Alzheimer's Disease Center, Boston University School of Medicine, Boston, MA.

Although chronic traumatic encephalopathy (CTE) garners substantial attention in the media and there have been marked scientific advances in the last few years, much remains unclear about the role of genetic risk in CTE. Two athletes with comparable contact-sport exposure may have varying amounts of CTE neuropathology, suggesting that other factors, including genetics, may contribute to CTE risk and severity. In this review, we explore reasons why genetics may be important for CTE, concepts in genetic study design for CTE (including choosing controls, endophenotypes, gene by environment interaction, and epigenetics), implicated genes in CTE (including , , and ), and whether predictive genetic testing for CTE should be considered.
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http://dx.doi.org/10.1055/s-0040-1713631DOI Listing
August 2020

Duration of American Football Play and Chronic Traumatic Encephalopathy.

Ann Neurol 2020 01 23;87(1):116-131. Epub 2019 Nov 23.

Boston University Alzheimer's Disease and Chronic Traumatic Encephalopathy Center, Boston University School of Medicine, Boston, MA.

Objective: Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to contact and collision sports, including American football. We hypothesized a dose-response relationship between duration of football played and CTE risk and severity.

Methods: In a convenience sample of 266 deceased American football players from the Veterans Affairs-Boston University-Concussion Legacy Foundation and Framingham Heart Study Brain Banks, we estimated the association of years of football played with CTE pathological status and severity. We evaluated the ability of years played to classify CTE status using receiver operating characteristic curve analysis. Simulation analyses quantified conditions that might lead to selection bias.

Results: In total, 223 of 266 participants met neuropathological diagnostic criteria for CTE. More years of football played were associated with having CTE (odds ratio [OR] = 1.30 per year played, 95% confidence interval [CI] = 1.19-1.41; p = 3.8 × 10 ) and with CTE severity (severe vs mild; OR = 1.14 per year played, 95% CI = 1.07-1.22; p = 3.1 × 10 ). Participants with CTE were 1/10th as likely to have played <4.5 years (negative likelihood ratio [LR] = 0.102, 95% CI = 0.100-0.105) and were 10 times as likely to have played >14.5 years (positive LR = 10.2, 95% CI = 9.8-10.7) compared with participants without CTE. Sensitivity and specificity were maximized at 11 years played. Simulation demonstrated that years played remained adversely associated with CTE status when years played and CTE status were both related to brain bank selection across widely ranging scenarios.

Interpretation: The odds of CTE double every 2.6 years of football played. After accounting for brain bank selection, the magnitude of the relationship between years played and CTE status remained consistent. ANN NEUROL 2020;87:116-131.
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http://dx.doi.org/10.1002/ana.25611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6973077PMC
January 2020

The neuropathology of chronic traumatic encephalopathy.

Handb Clin Neurol 2018 ;158:297-307

VA Boston Healthcare System, Boston, MA, United States; Departments of Neurology and Pathology, Boston University School of Medicine, and Boston University CTE Center, Boston, MA, United States.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head trauma, including concussion and subconcussion. CTE was first recognized in boxers nearly a century ago as "dementia pugilistica" or "punch drunk," but has been recently identified in contact sports athletes (including American football, ice hockey, soccer, baseball, rugby, boxing, and wrestling) and military veterans exposed to blast. Similar to many other neurodegenerative diseases, CTE is diagnosed conclusively only by neuropathologic examination of brain tissue. CTE is characterized by the buildup of hyperphosphorylated tau as neurofibrillary tangles, abnormal neurites, and inclusions in astrocytes around small blood vessels with a tendency to occur in clusters at the sulcal depths of the cortex. Using the McKee criteria, a consensus panel of expert neuropathologists confirmed CTE as a unique neurodegenerative disease with a pathognomonic CTE lesion that has only been found in individuals exposed to brain trauma. Recently, 177 instances of CTE were reported in a convenience sample of 202 former American football players, including 110 of 111 former National Football League players (99%), 48 of 53 former college football players (91%), and 3 of 14 former high school players (21%), by far the largest case series ever reported. Significant increases in active microglia and inflammation also occur after repetitive head impact injury and in CTE. A preliminary study showed that inflammatory cytokines were elevated in the brain tissue and cerebrospinal fluid of individuals with pathologically confirmed CTE compared to controls and individuals with Alzheimer disease, which may some day be useful in diagnosis of CTE during life. Although many fundamental questions remain to be answered regarding CTE, postmortem analysis of tissue from brain donors and tissue-based research have accelerated and expanded our current understanding of CTE and its pathogenesis. Guided by the neuropathologic findings, current research efforts are underway to develop biomarkers to diagnose CTE and effective ways to treat the disorder during life.
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http://dx.doi.org/10.1016/B978-0-444-63954-7.00028-8DOI Listing
March 2019

Variation in TMEM106B in chronic traumatic encephalopathy.

Acta Neuropathol Commun 2018 11 4;6(1):115. Epub 2018 Nov 4.

Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, 72 E Concord Street, B7800, Boston, MA, 02118, USA.

The genetic basis of chronic traumatic encephalopathy (CTE) is poorly understood. Variation in transmembrane protein 106B (TMEM106B) has been associated with enhanced neuroinflammation during aging and with TDP-43-related neurodegenerative disease, and rs3173615, a missense coding SNP in TMEM106B, has been implicated as a functional variant in these processes. Neuroinflammation and TDP-43 pathology are prominent features in CTE. The purpose of this study was to determine whether genetic variation in TMEM106B is associated with CTE risk, pathological features, and ante-mortem dementia. Eighty-six deceased male athletes with a history of participation in American football, informant-reported Caucasian, and a positive postmortem diagnosis of CTE without comorbid neurodegenerative disease were genotyped for rs3173615. The minor allele frequency (MAF = 0.42) in participants with CTE did not differ from previously reported neurologically normal controls (MAF = 0.43). However, in a case-only analysis among CTE cases, the minor allele was associated with reduced phosphorylated tau (ptau) pathology in the dorsolateral frontal cortex (DLFC) (AT8 density, odds ratio [OR] of increasing one quartile = 0.42, 95% confidence interval [CI] 0.22-0.79, p = 0.008), reduced neuroinflammation in the DLFC (CD68 density, OR of increasing one quartile = 0.53, 95% CI 0.29-0.98, p = 0.043), and increased synaptic protein density (β = 0.306, 95% CI 0.065-0.546, p = 0.014). Among CTE cases, TMEM106B minor allele was also associated with reduced ante-mortem dementia (OR = 0.40, 95% CI 0.16-0.99, p = 0.048), but was not associated with TDP-43 pathology. All case-only models were adjusted for age at death and duration of football play. Taken together, variation in TMEM106B may have a protective effect on CTE-related outcomes.
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http://dx.doi.org/10.1186/s40478-018-0619-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6215686PMC
November 2018

Lewy Body Pathology and Chronic Traumatic Encephalopathy Associated With Contact Sports.

J Neuropathol Exp Neurol 2018 09;77(9):757-768

Department of Neurology.

Traumatic brain injury has been associated with increased risk of Parkinson disease and parkinsonism, and parkinsonism and Lewy body disease (LBD) can occur with chronic traumatic encephalopathy (CTE). To test whether contact sports and CTE are associated with LBD, we compared deceased contact sports athletes (n = 269) to cohorts from the community (n = 164) and the Boston University Alzheimer disease (AD) Center (n = 261). Participants with CTE and LBD were more likely to have β-amyloid deposition, dementia, and parkinsonism than CTE alone (p < 0.05). Traditional and hierarchical clustering showed a similar pattern of LBD distribution in CTE compared to LBD alone that was most frequently neocortical, limbic, or brainstem. In the community-based cohort, years of contact sports play were associated with neocortical LBD (OR = 1.30 per year, p = 0.012), and in a pooled analysis a threshold of >8 years of play best predicted neocortical LBD (ROC analysis, OR = 6.24, 95% CI = 1.5-25, p = 0.011), adjusting for age, sex, and APOE ɛ4 allele status. Clinically, dementia was significantly associated with neocortical LBD, CTE stage, and AD; parkinsonism was associated with LBD pathology but not CTE stage. Contact sports participation may increase risk of developing neocortical LBD, and increased LBD frequency may partially explain extrapyramidal motor symptoms sometimes observed in CTE.
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http://dx.doi.org/10.1093/jnen/nly065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6097837PMC
September 2018

Age of first exposure to tackle football and chronic traumatic encephalopathy.

Ann Neurol 2018 05;83(5):886-901

Boston University Alzheimer's Disease and CTE Center, Department of Neurology, Boston University School of Medicine, Boston, MA.

Objective: To examine the effect of age of first exposure to tackle football on chronic traumatic encephalopathy (CTE) pathological severity and age of neurobehavioral symptom onset in tackle football players with neuropathologically confirmed CTE.

Methods: The sample included 246 tackle football players who donated their brains for neuropathological examination. Two hundred eleven were diagnosed with CTE (126 of 211 were without comorbid neurodegenerative diseases), and 35 were without CTE. Informant interviews ascertained age of first exposure and age of cognitive and behavioral/mood symptom onset.

Results: Analyses accounted for decade and duration of play. Age of exposure was not associated with CTE pathological severity, or Alzheimer's disease or Lewy body pathology. In the 211 participants with CTE, every 1 year younger participants began to play tackle football predicted earlier reported cognitive symptom onset by 2.44 years (p < 0.0001) and behavioral/mood symptoms by 2.50 years (p < 0.0001). Age of exposure before 12 predicted earlier cognitive (p < 0.0001) and behavioral/mood (p < 0.0001) symptom onset by 13.39 and 13.28 years, respectively. In participants with dementia, younger age of exposure corresponded to earlier functional impairment onset. Similar effects were observed in the 126 CTE-only participants. Effect sizes were comparable in participants without CTE.

Interpretation: In this sample of deceased tackle football players, younger age of exposure to tackle football was not associated with CTE pathological severity, but predicted earlier neurobehavioral symptom onset. Youth exposure to tackle football may reduce resiliency to late-life neuropathology. These findings may not generalize to the broader tackle football population, and informant-report may have affected the accuracy of the estimated effects. Ann Neurol 2018;83:886-901.
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http://dx.doi.org/10.1002/ana.25245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367933PMC
May 2018

Chronic Traumatic Encephalopathy in Football Players-Reply.

JAMA 2017 12;318(23):2353

Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts.

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http://dx.doi.org/10.1001/jama.2017.16687DOI Listing
December 2017

Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.

JAMA 2017 07;318(4):360-370

Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts2Department of Neurology, Boston University School of Medicine, Boston, Massachusetts4VA Boston Healthcare System, US Department of Veteran Affairs, Boston, Massachusetts5Department of Veterans Affairs Medical Center, Bedford, Massachusetts12Department of Pathology, Boston University School of Medicine, Boston, Massachusetts23Boston University School of Medicine, Boston, Massachusetts.

Importance: Players of American football may be at increased risk of long-term neurological conditions, particularly chronic traumatic encephalopathy (CTE).

Objective: To determine the neuropathological and clinical features of deceased football players with CTE.

Design, Setting, And Participants: Case series of 202 football players whose brains were donated for research. Neuropathological evaluations and retrospective telephone clinical assessments (including head trauma history) with informants were performed blinded. Online questionnaires ascertained athletic and military history.

Exposures: Participation in American football at any level of play.

Main Outcomes And Measures: Neuropathological diagnoses of neurodegenerative diseases, including CTE, based on defined diagnostic criteria; CTE neuropathological severity (stages I to IV or dichotomized into mild [stages I and II] and severe [stages III and IV]); informant-reported athletic history and, for players who died in 2014 or later, clinical presentation, including behavior, mood, and cognitive symptoms and dementia.

Results: Among 202 deceased former football players (median age at death, 66 years [interquartile range, 47-76 years]), CTE was neuropathologically diagnosed in 177 players (87%; median age at death, 67 years [interquartile range, 52-77 years]; mean years of football participation, 15.1 [SD, 5.2]), including 0 of 2 pre-high school, 3 of 14 high school (21%), 48 of 53 college (91%), 9 of 14 semiprofessional (64%), 7 of 8 Canadian Football League (88%), and 110 of 111 National Football League (99%) players. Neuropathological severity of CTE was distributed across the highest level of play, with all 3 former high school players having mild pathology and the majority of former college (27 [56%]), semiprofessional (5 [56%]), and professional (101 [86%]) players having severe pathology. Among 27 participants with mild CTE pathology, 26 (96%) had behavioral or mood symptoms or both, 23 (85%) had cognitive symptoms, and 9 (33%) had signs of dementia. Among 84 participants with severe CTE pathology, 75 (89%) had behavioral or mood symptoms or both, 80 (95%) had cognitive symptoms, and 71 (85%) had signs of dementia.

Conclusions And Relevance: In a convenience sample of deceased football players who donated their brains for research, a high proportion had neuropathological evidence of CTE, suggesting that CTE may be related to prior participation in football.
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http://dx.doi.org/10.1001/jama.2017.8334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5807097PMC
July 2017

Cognitive Reserve as a Modifier of Clinical Expression in Chronic Traumatic Encephalopathy: A Preliminary Examination.

J Neuropsychiatry Clin Neurosci 2017 19;29(1):6-12. Epub 2016 Aug 19.

From Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston (MLA, JM, NWK, TDS, LEG, RCC, TMS, PTK, LM, BA, DD, PHM, CJN, RAS, ACM); the Department of Neurology, Boston University School of Medicine, Boston (MLA, JM, NWK, TDS, LEG, DIK, TMS, PTK, LM, BA, DD, PHM, RAS, ACM); Internal Medicine Department, North Shore Medical Center (DD); the VA Boston Healthcare System, U.S. Department of Veteran Affairs, Boston (NWK, TDS, ACM); the Departments of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston (NWK, TDS, ACM); the Department of Veterans Affairs Medical Center, Bedford, Mass. (TDS, ACM); the Departments of Psychiatry and Ophthalmology, Boston University School of Medicine, Boston (LEG); the Departments of Biomedical, Electrical & Computer Engineering, Boston University College of Engineering, Boston (LEG); the Concussion Legacy Foundation (RCC, CJN); the Department of Neurosurgery, Boston University School of Medicine, Boston (RAS); the Department of Neurosurgery, Emerson Hospital, Concord, Mass. (RCC); Braintree Rehabilitation Hospital, Braintree, Mass. (DIK); and the Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston (PHM, RAS).

This study conducted a preliminary examination on cognitive reserve (CR) as a modifier of symptom expression in subjects with autopsy-confirmed chronic traumatic encephalopathy (CTE). The sample included 25 former professional football players neuropathologically diagnosed with CTE stage III or IV. Next of kin interviews ascertained age at cognitive and behavioral/mood symptom onset and demographic/athletic characteristics. Years of education and occupational attainment defined CR. High occupational achievement predicted later age at cognitive (p=0.02) and behavioral/mood (p=0.02) onset. Education was not an individual predictor. These preliminary findings suggest that CR may forestall the clinical manifestation of CTE.
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http://dx.doi.org/10.1176/appi.neuropsych.16030043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5288278PMC
April 2017

Assessing clinicopathological correlation in chronic traumatic encephalopathy: rationale and methods for the UNITE study.

Alzheimers Res Ther 2015 Oct 12;7(1):62. Epub 2015 Oct 12.

Alzheimer's Disease Center, Boston University School of Medicine, 72 East Concord Street, B-7800, Boston, MA, 02118, USA.

Introduction: Chronic traumatic encephalopathy (CTE) is a progressive neurodegeneration associated with repetitive head impacts. Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) is a U01 project recently funded by the National Institute of Neurological Disorders and Stroke and the National Institute of Biomedical Imaging and Bioengineering. The goal of the UNITE project is to examine the neuropathology and clinical presentation of brain donors designated as "at risk" for the development of CTE based on prior athletic or military exposure. Here, we present the rationale and methodology for UNITE.

Methods: Over the course of 4 years, we will analyze the brains and spinal cords of 300 deceased subjects who had a history of repetitive head impacts sustained during participation in contact sports at the professional or collegiate level or during military service. Clinical data are collected through medical record review and retrospective structured and unstructured family interviews conducted by a behavioral neurologist or neuropsychologist. Blinded to the clinical data, a neuropathologist conducts a comprehensive assessment for neurodegenerative disease, including CTE, using published criteria. At a clinicopathological conference, a panel of physicians and neuropsychologists, blinded to the neuropathological data, reaches a clinical consensus diagnosis using published criteria, including proposed clinical research criteria for CTE.

Results: We will investigate the validity of these clinical criteria and sources of error by using recently validated neuropathological criteria as a gold standard for CTE diagnosis. We also will use statistical modeling to identify diagnostic features that best predict CTE pathology.

Conclusions: The UNITE study is a novel and methodologically rigorous means of assessing clinicopathological correlation in CTE. Our findings will be critical for developing future iterations of CTE clinical diagnostic criteria.
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http://dx.doi.org/10.1186/s13195-015-0148-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4601147PMC
October 2015