PET Imaging in Chronic Traumatic Encephalopathy

* INCLUSION CRITERIA:\<TAB\> \<TAB\> * For patients: * History of head injury resulting from past or current participation in one or more contact sports (hockey, football, or boxing). Patients may have history of structural brain injury (i.e., injury accompanying abnormality on MRI or CT scan), concussion without structural injury (mild TBI), or repetitive sub-concussive injury. * Meets DMS-V criteria for Major Neurocognitive Disorder or Mild Neurocognitive Disorder * Age 18 to 60 years. * Ambulatory. * Patients unable to provide informed consent must have a surrogate decision maker. * For healthy controls: * Healthy without past or present history of brain disease. * Age 18 to 60 years. * Able to provide informed consent. EXCLUSION CRITERIA: * Past or present history of a brain disorder other than TBI. * For patients: Subjects with abnormal brain imaging findings that suggest a diagnosis other than TBI or a second lesion such as brain tumor in addition to the changes consistent with TBI. * For controls: past or present history of either a single concussion or more severe TBI, or of repetitive sub-concussive injury due to contact sport participation. * Serious medical conditions, which make study procedures of the current study unsafe. Such serious medical conditions include uncontrolled epilepsy and multiple serious injuries. The Principal Investigator of this protocol will determine whether the subject needs to be excluded. * The DSM-V criteria for Major Neurocognitive Disorder are as follows: --Evidence of significant cognitive decline from a previous level of performance in one or more cognitive domains (complex attention, executive function, learning and memory, perceptual-motor, or social cognition) based on: * Concern of the individual, a knowledgeable informant, of the clinician that there has been a significant decline in cognitive function. * A substantial impairment in cognitive performance, preferably documented by standardized neuropsychological testing, or, in its absence, another qualified clinical assessment. * The cognitive deficits interfere with independence in everyday activities (i.e. at a minimum, requiring assistance with complex instrumental activities of daily living such as paying bills or managing medications) * The cognitive deficits do not occur exclusively in the context of delirium. * The cognitive disorder is not better explained by another mental disorder (e.g. major depressive disorder, schizophrenia). * Criteria for Mild Neurocognitive Disorder are as follows: * There is evidence of modest cognitive decline from a previous level of performance in one or more of the domains outlined above based on: * Concern of the individual, a knowledgeable informant, or the clinician. * Decline in neurocognitive performance, preferably documented by standardized neuropsychological testing, or, in its absence, another qualified clinical assessment. * The cognitive deficits are insufficient to interfere with independence (eg, instrumental activities of daily living, like more complex tasks such as paying bills or managing medications, are preserved), but greater effort, compensatory strategies, or accommodation may be required to maintain independence. * The cognitive deficits do not occur exclusively in the context of a delirium. * The cognitive deficits are not primarily attributable to another mental disorder (eg, major depressive disorder, schizophrenia). There are no restrictions on medications. Since disease modifying therapy for tauopathies (including CTE and Alzheimer s disease) do not currently exist, no currently available medications, either prescribed or over-the-counter, are expected to confound the results of this study. Anti-inflammatory medications, including NSAIDs, are not expected to significantly reduce tau aggregation in CTE patients, based on the failure of these medications to prevent disease progression in Alzheimer s disease.