Former NFL players with low cognitive function and medium concussion history will be included in this group.

Former NFL Players with medium cognitive functioning and low concussion history with be included in this group.

Former NFL Players with medium cognitive functioning and medium concussion history with be included in this group.

Former NFL Players with medium cognitive functioning and high concussion history with be included in this group.

Former NFL Players with high cognitive functioning and high concussion history with be included in this group.

Per study protocol static PET images will be acquired after IV infusion of F-PBR111 to generate standard uptake values (SUVs). PET imaging is necessary in order to address the primary and secondary outcome measures as a component of neurological health (i.e., presence of proteinopathies empirically associated with neurodegenerative disease, cognitive decline, and neurological signs/symptoms). All groups will participate in this portion of the protocol.

Per study protocol static PET images will be acquired after IV infusion of F-T807 to generate standard uptake values (SUVs). PET imaging is necessary in order to address the primary and secondary outcome measures as a component of neurological health (i.e., presence of proteinopathies empirically associated with neurodegenerative disease, cognitive decline, and neurological signs/symptoms). All groups will participate in this portion of the protocol.

The stability-sensory organization test is an index obtained by the NeuroCom Balance System. The minimum score is 0 and there is no specified maximum value. A lower score indicates better postural stability. Postural stability is measured utilizing a dynamic force plate to quantify the vertical forces exerted through the patient's feet to measure center of gravity position and postural control.

A 75 true-or-false item measures that assesses malingering psychopathology and neuropsychological symptoms. The measure provides an overall score for probably malingering, as well as five subscales; including Psychosis, Low Intelligence, Neurologic Impairment, Affective Disorders, and Amnestic Disorders Endorsement of highly atypical symptoms and endorsement pattern profiles, this measure has demonstrated efficacy in differentiating malingerers from true clinical populations.

The MSVT is measure typically used in the detection of suboptimal effort. The test consists of a process in which participants are asked to learn 10 word pairs and later recall the word pairs. The minimum score is 0% and the maximum value is 100%.

A computerized measure of cognitive functioning across several domains of cognition developed by the NIH. The Toolbox Cognition measure is comprised of several subtests assessing various domains of cognitive functioning. The minimum score is 0 and there is no maximum score.

The RAVLT is a measure of auditory verbal learning, which is commonly affected among individuals with memory and other related cognitive disorders. Subjects are asked the learn and immediately recall a 15-word list across 5 different trials. They are asked to do the same for second, intrusion list, and then they are asked to recall the first list immediately after. Following a 30 minute delay, participants are asked to spontaneously recall the word list. Immediately following the delay recall trial, recognition memory is tested in a yes/no format where subjects are asked to discriminate words from the original list from novel distractors. The minimum score is 0 and the maximum score is 15.

The Dot Counting Test is a measure effort and validity of session results. Within the measure, subjects are essentially asked to count the number of dots on various stimuli pages. Each specific page has a maximum ranging from 7-28 and the minimum score is 0.

The DKEFS is a measure that is associated with integrity and functioning of the frontal system of the brain, or executive functioning. Verbal fluency involves administration of 3 trials in which participants generate words based on letter prompts. The minimum score is 0 and there is no maximum. Two additional trials involving generation of word lists based on categories is also included. The DKEFS TMT is a test of speeded sequencing and set-shifting with sensitivity to sport-related concussion. There are 4 trials consisting of psychomotor speed, number sequencing, letter sequencing, and letter-number sequencing/shifting. The minimum is 0 and there is no maximum. DKEFS Color-Word consists of 4 trials in which participants are timed on (1) colors on the page, (2) read words on the page, (3) inhibit responses of words and state colors that items are printed in, and (4) set-shift in their ability to perform number 3 based on different principles. The minimum is 0 and there is no maximum.

Satisfaction with Life Scale is a short 5-item instrument designed to measure global cognitive judgments of satisfaction with one's life. Questions are responded to on a 7-point Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). Total scores can be classified at extremely satisfied (31-35), satisfied (26-30), slightly satisfied (21-25), neutral (20), slightly dissatisfied (15-19), dissatisfied (10-14), and extremely dissatisfied (5-9).

Alcohol Use Disorders Identification Test consists of three domains: Hazardous alcohol use (items 1-3), dependence symptoms (items 4-6), and harmful alcohol use (items 7-10). Participants respond to items on a scale between 0 to 4, and a total score can be calculated based on individual items.

The PROMIS Cognitive Function is a self-reported measure that assesses patient-perceived cognitive deficits and the extent to which cognitive impairments interfere with daily functioning. The short-form consists of 4-itens that are scored on a 5-point Likert scale (5-never) to 1 (very often). Raw scores are converted into T-score for each participant. A T-score rescales the raw score into a standardized score with a mean of 50 and a standard deviation (SD) of 10.

The Coding and Symbol Search subtests of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) are two subtests that make up the Processing Speed Index of the WAIS-IV. Each subtest requires two minutes to complete and ultimately, reflect the participants ability to complete as many items correctly as possible within the time limit. The minimum score is 0 and the maximum is 60 for Symbol Search and 135 for Coding.

This is an eight-item measure from the Neuro-QOL set of tools, which assesses various symptoms and behaviors associated with frontal lobe dysfunction, particularly as it relates to disinhibited actions or behaviors. Items are scored on a five-point Likert scale, ranging from 1 (never) to 5 (always). A T-score rescales the raw score into a standardized score with a mean of 50 and a standard deviation (SD) of 10.

The FrSBe is a 46-item self-report measure of various symptoms and behaviors commonly associated with executive dysfunction. On a 5-point Likert scale ranging from 1 to 5, participants endorse the degree to which they experience the symptom/behavior before and after the present illness/injury. A total frontal systems score can be calculated for before and after the injury/illness, as well as three subscales of frontal lobe symptoms or behaviors, including apathy, disinhibition, and executive dysfunction. Raw scores are converted into T-score for each participant. The T-score rescales the raw score into a standardized score with a mean of 50 and a standard deviation (SD) of 10.

This measure is intended to be used as a measure of behaviors typically associated with forgetfulness and other cognitive difficulties. This will aid in identifying neurological health difficulties (i.e., cognitive decline) among those individuals who have limited insight on self-report cognitive functioning measures. The ECog Assessment is comprised of 12-items that are rated on a 4-point Likert scale ranging from 1 (better or no change compared to 10 years earlier) to 4 (consistently much worse). Total scores from the measure are calculated by summing responses on all items and dividing by the number of questions answered.

The cognitive complaints scale is a subscale of the derived from the full MMPI-2-RF. As part of the full instrument, the Cognitive Complaints Scale has been used as an embedded measure of symptom validity. In order to avoid administering the full over 500 item instrument, only the 13-itmes from the Cognitive Complaints Scale are administered in isolation for the current study. Items are presented in a true-false format. This method of administration has been performed in a number of studies in the published literature. A T-score rescales the raw score into a standardized score with a mean of 50 and a standard deviation (SD) of 10.

A self-report 29-itme measure of overall functioning. Participants respond on a Likert scale ranging from 5 (without any difficulty) to 1 (unable to do). The measure generates an overall score of functioning, as well as subscales of physical function, anxiety, depression, fatigue, sleep disturbance, able to participate in social roles/activities, pain interference, and pain intensity. Raw scores are converted into T-score for each participant. The T-score rescales the raw score into a standardized score with a mean of 50 and a standard deviation (SD) of 10.

A 21-item measure inquiring about common symptoms of depression. Each item is measured on a scale from 0-3, with higher numbers reflecting a higher-degree of symptomology over the last 2 weeks for that item. Raw scores can be classified into severity categories, including normal (0-13), mild (14-19), moderate (20-28), and severe (29-63).

A 21-item measure of common physiological and worry-related symptoms associated with anxiety. Responses are recorded on a 4-point Likert scale ranging from 0 (not at all) to 3 (severely). Raw scores can be classified into severity categories, including minimal anxiety (0-7), mild anxiety (8-15), moderate (16-25), and severe (26-63).

A measure of common dementia-related behavioral symptoms among older adults. Within the measure 12 domains of these symptoms are recorded, including delusions, hallucinations, agitation/aggression, dysphoria, anxiety, euphoria, apathy, disinhibition, irritability/lability, and aberrant motor activity night-time behavioral disturbances and appetite, and eating abnormalities. A screening question is asked about each sub-domain. If the responses to these questions indicate that the patient has problems with a particular sub-domain of behavior, the caregiver is only then asked all the questions about that domain, rating the frequency of the symptoms on a 4-point scale, their severity on a 3-point scale, and the distress the symptom causes them on a 5-point scale.

This 43-item measure quantifies stress associated with common life events (life changing unit), with a unique value associated with each event over a 12-month period. For example, death of a spouse garners a score of 100 and major holidays equals 11 points. The total number of points is summed and a higher score is representative of a greater degree of life-event related distress. A score of 150 life units or less suggests a 30% change of suffering from stress, 150-299 is associated with a 50% chance of suffering from stress, and over 300 life units suggests that the person has an 8% chance of developing a stress related illness.

This is a 14-item measure used to assess resilience in individuals following stressful events. Items are scored on a 4 point Likert Scale ranging from 1-Does not Apply at All, 2-Applies Slightly, 3-Applies Somewhat, and 4- Applies Very Strongly; and scores for each item are summed to obtain a total score. Higher scores indicate a more favorable outcome

This questionnaire has been adapted from the previously established "Athletic Identity Measurement Scale" for currently active athletes (not retired). Items are scored on a 7 point Likert Scale ranging from 1-Strongly Disagree to 7-Strongly Agree.

This is a 33-item questionnaire that was developed from previous work to give insight into childhood experiences, socioeconomic stability, and other important environmental factors that may influence later-life socioeconomic factors, health, and well-being. The questionnaire contains items pertaining to Social and Community Context (1 item), Economic Stability (4 items), Education Access and Quality (1 item), Health Care Access and Quality (2 items), Neighborhood and Built Environment (3 items), and Adverse Childhood Experiences (Emotional Neglect [6 items], Financial Need [2 items], Parental Intimidation [4 items], Parental Violence [2 items], and Family Problems and Separation [4 items]).

This is a 4-item questionnaire intended to obtain data on health-related physical activity. It was developed for both research studies and patient monitoring. Each of the 4 items asks about the number of days per week, and the duration of time in each day participating in different physical activities: vigorous; moderate; walking; and sitting. Answers to these questions will be used to compare to activity recommendations put forth by organizations such as the American College of Sports Medicine.

This is a 16-item questionnaire about the individuals' behaviors regarding food consumption. Participants respond to the first 13 items by selecting from the following options: "Usually/often"; "Sometimes"; "Rarely/Never"; or, when appropriate, a selection that the item does not apply to them. Responses from these first 13 items are then scored and summed into a diet quality score, where the total range of values falls between "13" (lowest quality diet) and "39" (highest quality diet). Items 14 and 15 request "Yes" or "No" responses: 14. "You or a member of your family usually shops and cooks rather than eating sit-down or take-out restaurant food?"; and 15. "Usually feel well enough to shop or cook." The 16th item is answered on a 5-point Likert scale from "1" (Very willing) to "5" (Not at all willing).