FDDNP Protocol for Visualizing Brain Proteinopathies to Assist in the Diagnosis of Persons With Suspected CTE and AD

Inclusion criteria for all participants Participants enrolling in the trial must meet all of the following criteria: * Participant may be male or female and of any race/ethnicity * Age 18 to 80 years at the time of study drug dosing * Female participants must be either surgically sterilized or post-menopausal, defined as at least one-year without menses as reported by the participant or have a negative serum pregnancy test * Participant or participant's legally acceptable representative (when appropriate) provides informed consent * Participant is capable of complying with study procedures * Participant is capable of communicating with study personnel * Participant is willing to undergo longitudinal follow-up at 1 and 2 years after the Imaging Visit * All participants will meet criteria for mild cognitive impairment (Petersen et al, 2014) or Mild Neurocognitive Disorder (APA, 2013): * Patient awareness of a memory problem, preferably confirmed by another person who knows the patient * Memory impairment detected with standard assessment tests * Ability to perform normal daily activities * For a broad definition of mild cognitive impairment, we also use guidelines to identify those with other mild cognitive impairment subtypes, including those with memory impairment and/or additional cognitive deficits (Winblad et al, 2004). The diagnosis will be corroborated by clinical judgment and include participants who score 1 standard deviation or more below the age-corrected norms because this threshold for impairment yields high sensitivity for predicting dementia (de Jager et al, 2005). To balance increased sensitivity with specificity, impairment on at least 2 neuropsychological tests will be required (Jak et al., 2009). Inclusion criteria for participants with suspected CTE Participants with suspected CTE enrolling in the trial must meet all of the following criteria: • Participant must meet the most recently proposed clinical criteria for suspected CTE (termed possible traumatic encephalopathy syndrome or TES; Reams et al, 2016). These proposed diagnostic criteria for possible TES include the following features: Required Features: * Persistence of symptoms for longer than 2 years; no other neurologic disorder that is more likely to account for all the clinical features; history of head trauma exposure; progressive course; and at least 1 supportive feature * History of head trauma exposure, typically associated with history of concussion, although may be limited to subconcussive trauma * Head trauma exposure is repetitive in nature * Demonstrated progressive course * Delayed symptom onset * Self-report or observer report of cognitive dysfunction, confirmed with objective cognitive decline documented by results of formal neuropsychological testing. Cognitive decline typically affects more than 1 domain (executive, visuospatial, memory, and language). * Supportive Features (only 1 required): * Emotional dysregulation: including depression, anxiety, agitation, aggression, paranoid ideation, deterioration of interpersonal relationships, and suicidality * Behavioral change: including violence, poor impulse control, socially inappropriate behavior, avolition, apathy, change in personality, and comorbid substance abuse * Motor disturbance: including bradykinesia, tremor, rigidity, gait instability, dysarthria, dysphagia, and ataxia Inclusion criteria for participants with suspected AD Participants with suspected AD enrolling in the trial must meet all of the following criteria: * Cognitive deficits do not occur exclusively in the context of a delirium. * Cognitive deficits are not better explained by another mental disorder (e.g., major depressive disorder, schizophrenia). * There is insidious onset and gradual progression of impairment in one or more cognitive domains. * The participant has documented memory problems in one or more other cognitive domains, such as language, visual-spatial functioning, executive functioning, etc. (Busse et al., 2006). Exclusion criteria for all participants Participants meeting any of the following criteria will not be enrolled in the study: * Participant is pregnant or nursing * Phone screen of Telephone Interview for Cognitive Status-modified (TICS-M) ≥ 33 * Participant unable to remain still for duration of imaging procedure or has an inability to tolerate neuropsychological, clinical, or PET scan studies (e.g., head tremor that may cause head motion artifact, uncontrollable psychosis, acute suicidality) * Participant has prior history of stroke or other condition of the head or neck that, in the investigator's opinion, might affect circulation to the head or image interpretation * Preexisting major neurologic or other physical illness that could confound results (e.g., multiple sclerosis, diabetes, cancer) * Participant has a major psychiatric disorder such as mania or schizophrenia, which might interfere with completing study procedures (APA, 2013) * Participant has a psychiatric disorder, such as anxiety or depression, severe enough to interfere with completing study procedures * Participant has a condition or personal circumstance that, in the judgment of the investigator, might interfere with the collection of complete accurate quality data * Participant has a history of significant prescription drug, non-prescription drug, or alcohol abuse, including but not limited to marijuana, cocaine, heroin or derivatives * Participant has previously received \[F-18\]FDDNP at any time, or any other investigational product within the past thirty days * Participant has a history of allergic reactions to albumin * Participant has severe anemia in which case the use of albumin would be medically contraindicated * Participant has cardiac failure in which case the use of albumin would be contraindicated * Participant has unstable cardiac disease or uncontrolled hypertension (systolic BP \> 170 or diastolic BP \> 100) * Participants taking ibuprofen or naproxen will be asked to stop taking the medication for five days before the PET scan since these medicines may affect \[F-18\]FDDNP-PET scan results. Other anti-inflammatory medicines, such as diclofenac or aspirin, can be substituted during that period. If the participant cannot temporarily discontinue the medicine, that participant will be excluded from the study * Participant has used of any investigational drugs within the previous month or has participated in imaging or other clinical research protocols that might confound study results