final capstone paper

Running head: EVALUATING MENTAL HEALTH OF RETIRED NFL PLAYERS

Evaluating the Impact of Concussions on the Mental Health of Retired NFL Players

Kelsey Prendergast

West Virginia University

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EVALUATING MENTAL HEALTH OF RETIRED NFL PLAYERS

Abstract

This study will examine the relationship between the repeated mild traumatic brain

injuries sustained by athletes in the National Football League with the mental health of those

football players. Current research has found evidence of numerous psychological and

physiological consequences due to concussions including personality changes, seizures, hormone

dysfunction, and cognitive impairments. Among these negative outcomes is a progressive

degenerative disease known as chronic traumatic encephalopathy, which can cause severe

symptoms such as memory loss, impaired judgment, depression, and suicidal behavior. This

study will use four neuroimaging techniques and five neuropsychological evaluations in order to

measure the cognitive abilities and mental health of 500 retired NFL players in order to further

understand the long-term consequences of concussions. Measurements will occur each year over

the course of ten years to track changes in cognitive functioning and psychological well-being.

This research will provide valuable information regarding the long-term effects of concussions

on the mental health of football players.

Introduction and Literature Review

Narrative hook

Over 1.8 million instances of traumatic brain injuries occur each year in the United States

due to a sport-related incident (Faul, Xu, Wald, & Coronado, 2010). Neurodegenerative diseases

such as chronic traumatic encephalopathy, Alzheimer disease, and dementia have been linked to

these repetitive mild traumatic brain injuries known as concussions (Casson, Viano, Powell, &

Pellman, 2010). Symptoms of these neurodegenerative diseases typically show up about ten

years after the occurrence of repetitive mild traumatic brain injury and include: short-term

memory loss, depression, anxiety, impulsivity, aggression, irritability, and a higher risk of

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suicide (Strain, et al., 2013). Research has found that 6.1% of former NFL players above the age

of 56 reported the occurrence of memory problems while only 1.2% of the general population in

this age group reported memory problems (Hart, et al., 2013). Furthermore, abnormalities in

white matter of the brain accompanied by deviations in regional cerebral blood flow that lead to

cognitive deficits and mental illness have been found to be more prevalent in retired players of

the NFL in comparison to their healthy counterparts (Diaz-Arrastia & Perl 2013).

One of the outcomes of repetitive mild traumatic brain injury is the aforementioned

progressive neurodegenerative disease called chronic traumatic encephalopathy. Chronic

traumatic encephalopathy or CTE can develop as a result of repeated hits to the head such as the

concussions endured by an NFL player throughout the game of football. The trauma endured by

NFL players after repeated concussions could cause the brain tissue to progressively degenerate,

as well as, accumulate tau, an abnormal protein in the brain tissue. Symptoms associated with

CTE include: depression, impaired judgment, irritability, aggression, memory loss, and an

increased risk of suicidal behavior. In the NFL, tight ends, running backs, defensive backs, wide

receivers, defensive linemen, offensive linemen, quarterbacks, and linebackers have all tested

positive for CTE (McKee, et al., 2013).

Related research and theory

In a research article by McKee, et al. (2013) authors examined 85 brains, each with a

history of concussions and found that 68 of them suffered from CTE. All of the subjects were

male and made up of athletes and military veterans who ranged from 17 years of age to 98. Of

the athletes diagnosed with CTE fifty were football players. Of the football players with

evidence of CTE 94% showed symptoms, with the most frequent side effects including loss of

concentration and attention, executive dysfunction and loss of short-term memory.

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Historically CTE has been associated more commonly with the sport of boxing and its

consequences were seen as mild, however, this research article proves that the neurodegenerative

disease is associated with a wider range of activities that involve repeated mild traumatic brain

injury, including football, and holds more severe consequences than previously thought. Further

research needs to be done in order to discover the specific type of head trauma that causes CTE,

as well as the quantity and frequency of the impact. Additionally, investigation into the genetics

that might predispose athletes to CTE as well as the age that players are more prone to

developing CTE needs to be researched in order to draw conclusions about the causes of this

condition.

Another research article, by Stamm et al. (2015) aimed to discuss this issue of age in

determining susceptibility to the development of cognitive impairments such as CTE. It is known

that a vital phase of cognitive development occurs during the age of 10 and 12 years old,

however, the lasting effects of concussions and head trauma during this critical time is unknown.

Thus, this study sought out to examine the connection between the age at which a child is first

exposed to head trauma in tackle football and their cognitive abilities later in life.

The study involved 42 retired players of the NFL, ranging in age from 40 to 69, all male.

Depending on the age at which he was first exposed to tackle football the group of former NFL

players were split into two different groups, those that were exposed to the sport before the age

of 12 and those exposed at the age of 12 or older. Participants were then put through a series of

tests to determine their levels of memory, cognitive ability, and executive function, including:

The 4th edition of the Wide Range Achievement Test, Neuropsychological Assessment Battery

List Learning test, Wisconsin Card Sort Test and a Reading subtest.

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On all methods of testing, the group of former NFL players that were exposed to football

before the age of 12 performed worse than those players that were exposed to football at the age

of 12 or older. These outcomes indicate more significant damage to cognitive functioning in

terms of memory recall, strategic planning, and executive function than their post-age 12

counterparts. The results of this study agree with prior research that indicates youth are more

prone to unfavorable consequences of concussions. Authors of this study offer a possible reason

for this relationship being the critical point in time that the child’s brain is developing. During

childhood aspects like cerebral blood flow, synaptic pruning, cortical thickness, and myelination

rates each play a critical role in the development of effective information processing, thus the

effect of concussions on these vital features during childhood can be devastating to cognitive

functioning later in life.

As mentioned earlier in the research article by McKee et al. (2013), depression and

suicidal behavior are common symptoms of CTE with 26% of their subjects having suicidal

tendencies and 14% completing suicide. These statistics clearly show that the psychological

health of former football players is in danger. A research article by Hart et al. (2013) further

investigates this issue of depression in former football players with a cross-sectional study aimed

to measure levels of psychological dysfunction and depression in retired NFL players.

The 34 participants in this study included both players that had a record of repeated

traumatic brain injury and those without a record. They were all recruited from the Northern area

of Texas, which is a limitation of this study. Another limitation of this study is the use of self-

report by players to ascertain their record of concussions. The players underwent neuroimaging,

clinical assessments, and neuropsychological tests in order to evaluate cognitive functioning and

abnormalities in brain matter.

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In measurements of neuroimaging researchers used Diffusion Tensor Imaging, Fluid-

Attenuated Inversion Recovery, Arterial Spin Labeling and Hemosiderin Scans to gain insight on

the neurology of the brain. Diffusion tensor imaging showed microstructural changes in the

brains of football players in comparison to the healthy control brains. Fluid-attenuated inversion

recovery (FLAIR) images allowed researchers to see lesions in white matter of the brain. Arterial

spin labeling allowed researchers to calculate blood flow of the cerebellum. Hemosiderin scans

found evidence of past bleeding in the brains of subjects with a history of concussion. In

measurements of neuropsychological testing researchers employed exams in visual learning,

verbal learning, word finding, naming, and episodic memory.

Results of this study suggest that, compared to the general public, former NFL players are

more prone to acquire deficits in cognitive functioning or depression later in life. Researchers

offer the correlation between these deficits and the abnormalities in white matter and decreased

flow of blood to certain areas of the brain. Due to limitations in the sample size of this study,

further investigation is necessary to draw conclusions on the relationship between concussions

and later-life depression and impairments in cognitive functioning.

With an overwhelming amount of studies highlighting the correlation between

concussions and cognitive dysfunction, one study sought out to test the possibility of reversing

the brain damage suffered by football players. In the research article by Amen, Wu, Taylor, and

Willeumier (2011), researchers gathered a group of 100 football players from each position of

the sport and who each played at least three years in the NFL. Prior to beginning the study all of

the participants received information on ways in which they can improve the health of their brain

including the limitation of drugs and alcohol, healthy diet, regular physical activity, and healthy

sleeping habits. Then retired NFL playing subjects subscribed to a clinical intervention that

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involved dietary supplements, weight loss for those that needed it, multi-vitamins, and fish oil in

an effort to reverse the brain damage sustained through concussions on the football field.

Researchers of this study employed a brain-imaging tool as well as a neuropsychological

test, known as the Microcog Assessment of Cognitive Functioning (MACF) to measure the

changes seen in participants after intervention. Through the use of neurological imaging,

researchers saw substantial increases in blood flow of the cerebellum in subjects after

intervention. Improvements were also seen in scores on the MACF, which indicates increases in

memory, information processing, reasoning, attention, and general cognitive functioning.

Subjects also reported decrease of symptoms linked to repetitive mild traumatic brain injury,

with a quarter of subjects sleeping better, a little less than half reporting an increase in

motivation and mood, and over half of participants noticing improvements in memory and

attention.

Findings of this study suggest hope for a reversal of impairments in football players that

have suffered from a history of concussions. Limitations of this study include its small

nonrandomized sample. This study goes beyond football players in that it can help rehabilitate

the brains of other athletes or military veteran that suffer from repeated mild traumatic brain

injury. Due to the significant devastating impairments and increased occurrence of traumatic

brain injury it is important to continue research in this topic of brain health and rehabilitation.

Among these devastating impairments are metabolic syndrome, pituitary hormone

dysfunction, and poor quality of life. All of these consequences of concussion were measured in

the prospective study performed by Kelly et al. (2014). Authors of this research article recruited

430 former players of the NFL between the ages of 30 and 65 years who played a minimum of

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one year in the league. Participants underwent various tests to measure growth hormone

deficiency, pituitary hormonal dysfunction, quality of life and metabolic syndrome.

Metabolic syndrome and pituitary dysfunction were the most common deficiencies found

amongst the subjects, which could be highly influential on their self-reported poor quality of life.

Growth hormone deficiency was another common finding in the sample with almost 20% of the

players experiencing the deficiency. Almost a quarter of the former football players were

suffering from chronic hypopituitarism. Half of the participants showed evidence of metabolic

syndrome, which can lead to cardiovascular disease and type 2 diabetes.

Results of this study highlight the correlation between hormonal dysfunction and

concussions, however further research must be performed in order to draw conclusions on the

origins of these impairments. The findings of these metabolic and hormonal dysfunctions offer

insight into the factors contributing to retired NFL players’ self-reported poor quality of life. The

limitations on the validity of this study lie in its small sample size with a greater amount of NFL

players allowing for more comparison among populations. Another limitation is the players’ self-

reporting history of concussions, which did not include severity, duration, or time between

impacts. Another limitation of this study that occurs in all previous studies mentioned above is

the factor of performance enhancing drug use. Just like the uncertainty of self-reported

concussion history, researchers can never be absolutely positive that the information provided by

retired NFL players is accurate. Thus, researchers cannot draw conclusions on the consequences

of concussions when a history of steroid use could be a contributing factor to those

consequences.

A research article by Omalu, Hamilton, Kamboh, DeKosky, and Bailes (2010) provides

further insight into the relationship between concussions and cognitive impairment with a case

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report. The case provides information on the autopsy of a former NFL player who committed

suicide at the age of 44. The athlete suffered from cognitive deficits, insomnia, chronic

depression, paranoia, and suicidal behavior.

The age of first exposure to tackle football for this athlete was 15 when he began playing

the sport in high school. He continued to play in college at a Division 2 school and ended up

playing professionally in the league for nine years. After sustaining over a dozen concussions he

stopped counting and admitted that he failed to report many of them to his team. He had a history

of depression and multiple suicide attempts after retirement. A little over a decade after he left

the NFL the subject committed suicide with a gunshot wound to the head. Autopsy findings

showed evidence of CTE with neurofibrillary tangles present in the brain tissue.

The only definitive way to diagnose an individual with CTE is through a full autopsy

post-mortem. The need for these complete autopsies on post-mortem brains of former football

players is highlighted in the findings of this case report. Furthermore, comprehensive

neuropathological examinations must be conducted on post-mortem brains of contact athletes

with a history of repeated mild traumatic brain injury in order to further knowledge on the

development of CTE. The findings also prove the need for an increased awareness by the

professionals working with NFL players in order to look for the indicators that the subject of this

case report exhibited, such as suicidal ideations, isolating behavior, and paranoia.

The limitations of this study include the fact that it is a case study on one individual.

Even more, the individual being studied is deceased which is helpful in determining the presence

of chronic traumatic encephalopathy yet researchers must rely on third parties to find

information on his life. For instance the study claimed that the player was not known to have

abused performance-enhancing drugs during his career in the NFL but players that do partake in

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utilizing performance-enhancing drugs do not usually make it known to the public anyway.

Another limitation on the validity of this case report is the athlete’s use of alcohol in the nine

years following his retirement from the NFL, which could also be a contributing factor to his

mood disorder and suicidal behavior.

Beyond the limitations of this case report, this subject serves as a wake up call to sports

medicine professionals working with contact sport athletes in that they need to be more aware of

the possible effects of concussions and the very real consequences of CTE. Further research must

be conducted in order to draw conclusions on the causes of CTE and the consequences of

repeated mild traumatic brain injury. The inclusion of more longitudinal prospective studies of

football players will aid in the advancement of knowledge on the long-term consequences of

concussions.

Purpose of this study

The purpose of this concurrent mixed methods longitudinal study is to better understand

the effect of concussions on the mental health of former players of the National Football League

by converging both quantitative and qualitative data about mental health, such as cognitive

functioning and symptoms of depression. In this longitudinal study neuroimaging techniques and

neuropsychological examinations will be used to measure the relationship between concussions

and mental health. At the same time, mental health will be explored using qualitative interviews

with former NFL players at the BrainHealth Institute for Athletes at The University of Texas at

Dallas and the Clinical Center at the National Institutes of Health in Bethesda, Maryland.

Method

Research design

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The design of this research study is based on the philosophical underpinnings of

pragmatism, which is a philosophy that evaluates assertions based solely on practical

consequences and their implications on the human condition. Following the pragmatic

philosophy, the design of this research study is a concurrent mixed methods design which will

combine the use of both quantitative and qualitative data on the mental health of retired athletes

of the National Football League. This longitudinal study will be comprised of neuroimaging,

neuropsychological assessments and neurological measures that will gather information

necessary to better understand the effects of concussions on psychological health.

Participants and setting

Participants of this study will be recruited across the United States of America through an

email sent out to members of the National Football League Players Association and the National

Football League Alumni Association. All 500 of the participants of this study will be male and

have played professionally in the NFL for at least one full season. Participants of this study will

range in age and vary in race and ethnicity. This study will include players from various

positions including offensive linemen, defensive linemen, quarterbacks, running backs, tight

ends, linebackers, wide receivers, and defensive backs. Every player will be above the age of 18

years old with at least one year of experience playing for the NFL. Players will be included

regardless if they have or have not reported complaints of psychological symptoms.

Procedures

The gathering of cognitive data will take place at the BrainHealth Institute for Athletes at

the University of Texas at Dallas and also at the Clinical Center at the National Institutes of

Health located in Bethesda, Maryland. The BrainHealth Institute for Athletes is one of the

nation’s leading centers for research in mental health with over twenty years of study in brain

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injury with a concentration in head injuries in sports. The Clinical Center at the National

Institutes of Health is the largest hospital in the United States devoted completely to clinical

research and will contribute to the collection of cognitive data. Data will be obtained through a

number of instruments described in more detail below: neuroimaging, neuropsychological

assessments and neurological measures.

Participants will complete the following neuropsychological examinations as a means of

testing their cognitive functioning: the Wechsler Adult Scale of Intelligence, the Wisconsin Card

Sorting Test, the California Verbal Learning Test, the Beck Depression Inventory, and the

Neuropsychological Assessment Battery List Learning test.

This longitudinal study will take place over the course of a ten-year period while

measurements will be acquired from participants on a yearly basis. Due to the high rate of retired

players with careers that still depend on the happenings of the National Football League the

collection of this data will take place during the off season of the NFL, in the months of May and

June. In an attempt to keep the conditions surrounding these measurements uniform each

participant will be tested during the months of May and June, regardless of career.

The procedures and equipment utilized in this study are identical at both the BrainHealth

Institute for Athletes and the Clinical Center at the National Institutes of Health locations, thus

participants have the option of either site for data collection. This element of convenience will

hopefully increase participants’ likelihood to continue with this ten-year study.

Researchers at both the Maryland and Texas data collection sites are trained to administer

all of the neuropsychological examinations and hold the equipment necessary for neuroimaging

measurements. Data will be obtained over the course of two consecutive days during the months

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of May or June depending on availability of the participants. All participants will undergo testing

in the same order.

Testing will begin at 11:00 a.m. eastern standard time where participants will first

complete the self-administered second edition of the Beck Depression Inventory, which takes

approximately five minutes. At 11:30 a.m. EST participants will complete a computerized

version of the Wisconsin Card Sort Test that takes approximately 20 to 30 minutes. At 12:30

a.m. EST participants will complete a computerized version of the second edition of the

California Verbal Learning Test, which takes approximately 30 minutes. At 3:00 p.m. EST

researchers will perform brain scans on participants by utilizing the GE Signa HDxt 1.5T

magnetic resonance scanner. The neuroimaging techniques performed by researchers using GE’s

Signa HDxt 1.5T magnetic resonance scanner will occur in the following order: diffusion tensor

imaging, hemosiderin scans, arterial spin labeling and fluid-attenuated inversion recovery. This

brain scan portion of cognitive data collection process will take about 45 minutes.

The second day of data collection is composed of the final two neuropsychological

examinations. At 11:00 a.m. EST participants will have 90 minutes to complete the fourth

edition of the Weschler Adult Scale of Intelligence. Participants will have a two and a half hour

break before researchers will administer the List Learning Test of Neuropsychological

Assessment Battery at 3:00 p.m. EST, which takes approximately 45 minutes.

Measures (Outcomes)

Mental health will be measured through a variety of instruments in neuroimaging,

neuropsychological assessments and neurological measures. Neuroimaging techniques in

magnetic resonance imaging that will be utilized for this study include: diffusion tensor imaging,

hemosiderin scans, arterial spin labeling and fluid-attenuated inversion recovery.

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Self-Report Surveys

Participants will complete the following neuropsychological examinations as a means of

measuring their cognitive functioning: the Wechsler Adult Scale of Intelligence, the Wisconsin

Card Sort Test, the California Verbal Learning Test, the Beck Depression Inventory, and the

Neuropsychological Assessment Battery List Learning test.

Wechsler’s (2008) fourth edition is the most current edition of the Wechsler Adult Scale

of Intelligence and is comprised of ten subtests that make up the measurement of the subject’s

intelligence quotient. The ten subtests that make up the exam measure working memory,

perceptual reasoning, processing speed, and verbal comprehension. Working memory involves

letter-number sequencing, digit span, and arithmetic to measure the concentration, attention, and

mental control abilities of the subject. The perceptual reasoning portion includes matrix

reasoning, block design, visual puzzles, and picture completion to examine participants’

reasoning abilities like spatial perception, visual abstract processing, problem solving and

inductive reasoning. Another portion of the Wechsler Adult Scale of Intelligence test measures

processing speed through coding, cancellation, and symbol search that measures the subjects’

visual-perceptual speed, scanning speed, visual working memory, and motor and mental speed.

The final portion of the exam deals with verbal comprehension, which is made up of vocabulary,

information, and similarities sections that test subjects’ abilities in abstract verbal (Wechsler,

2008).

The Wechsler Adult Scale of Intelligence is a neuropsychological exam that will measure

the intelligence of this study’s subjects. The fourth edition of this exam has been standardized

based on a group of 2,200 Americans that ranged in age from sixteen years old to ninety years

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old. The test-retest reliability for this exam ranged between 0.70 to 0.90 and validity it is further

seen in inter-scorer coefficients which all scored above 0.90 (Wechsler, 2008).

Upon completion of the exam subjects will receive four variable scores that indicate

substantial aspects of intelligence including: processing speed index, working memory index,

verbal comprehension index, and perceptual reasoning index. The sum of the scaled scores of all

subtests generates the participant’s Full Scale Intelligence Quotient (FSIQ), which can range

from 40 to 160. An IQ score of 130 and above is considered very superior, 120-129 considered

superior, 110-119 considered high average, 90-109 considered average, 80-89 considered below

average, 70-79 considered well below average, and 69 and lower considered extremely low

(Wechsler, 2008).

Grant and Berg’s (1948) Wisconsin Card Sorting Test is a widely used

neuropsychological test that will measure executive function in the brains of participants by

testing skills like organized searching, strategic planning, impulse control, behavioral direction,

and cognitive set shifting. Researchers of this study will administer the most recent computerized

form of the Wisconsin Card Sorting Test, the Microsoft Windows-compatible version 4.0.

Participants’ ability to recognize patterns and adapt to changing rules will be tested as they are

given a set of four cards on the computer screen and asked to classify them according to different

criteria such as color, size, shape, or number.

According to Grant and Berg (1948) criterion-related validity of the Wisconsin Card

Sorting Test is well established based on subject selection and comparison to summary

neuropsychological assessments. Construct validity is considered established based on

correlations of Wisconsin Card Sorting Test scores to Halstead-Reitan Category Test and

Wechsler Intelligence measures.

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The overall score of Grant and Berg’s (1948) test is accumulated from the number of sets

correctly sorted by the participant. The test also offers further quantitative data in more specific

scoring categories that include the numbers and percentages of trials, errors, and categories

achieved. Scores also include numbers and percentages of perseverative errors, which are

mistakes that would have been considered correct in the previous set of cards.

The second edition of the California Verbal Learning Test will be used to measure

participants’ verbal memory and learning abilities (Delis, Kramer, Kaplan, & Ober, 1987). This

computerized test utilizes two lists of words to test participants’ abilities in cued recall, free

recall, recognition memory, and rate of learning. The participant is first presented with a list of

sixteen items and then asked to recall them for a series of five trials. The participant is then

presented with a second list of sixteen new items to recall, eight of which are from the first list

and eight new items. After a twenty-minute break, free recall, immediate recall, recognition

memory and cued recall of the first list are tested again. The computer-scoring program of the

California Verbal Learning Test will provide each subject with a score as well as a standard

score that compares that subject to a normative group with similar age and educational

background (Delis et al., 1987).

Internal validity of the California Verbal Learning Test II ranges from .78 to .94, which

would make it an acceptable measurement of verbal learning. The second edition of this

assessment also has high test-retest correlation coefficients ranging from 0.80 to 0.84 (Delis et

al., 1987).

The Beck Depression Inventory will serve as the measurement for mood and diagnoses of

depression in participants of this study (Beck, Steer, & Brown, 1996). This self-report

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questionnaire is composed of twenty-one questions that measure both physical and psychological

symptoms, like weight loss, lack of sex drive, and feelings of guilt or hopelessness.

This exam has high test-retest reliability with a Pearson product-moment correlation

coefficient of 0.93 and a positive correlation with the Hamilton Depression Rating Scale with

Pearson product-moment correlation coefficient of 0.71 (Beck et al., 1996).

This questionnaire is filled out by the subjects themselves who rate each question on a

scale of zero to three. The scores of each of the twenty-one questions in this inventory are then

added up to determine one’s severity of depressive symptoms. Subjects that obtain a score

between zero and thirteen are considered to have minimal depression, those who receive a score

between fourteen and nineteen are considered to have mild depression. Scores that range

between twenty and twenty-eight are considered to show symptoms of moderate depression and

scores ranging from twenty-nine to sixty-three are considered to show symptoms of severe

depression (Beck et al., 1996).

Stern and White’s (2003) List Learning test in the Neuropsychological Assessment

Battery will measure participants’ verbal episodic memory. This measurement is of particular

interest because of its sensitivity to deficiencies that are a result of traumatic brain injury and

neurodegenerative disease. The variables that will be utilized in this study include long delay

recall, short delay recall, and immediate recall to evaluate each participant’s levels of learning

and memory in terms of verbal abilities.

In terms of construct validity, the NAB List Learning Test scores upheld many important

relationships with other neuropsychological exams that evaluate cognitive functioning and

memory. The total Index scores for the reliability of the NAB List Learning Test suggests high

reliability with a score of .96. There is also high correlation in the studies done on the interrater

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reliability of the NAB List Learning Test that involve more subjective scoring (Stern & White,

2003).

The scores of this examination have been normalized on the sample of 1,448 Americans

with variations in age, sex, and education. Participants will receive raw scores that indicate their

degree of verbal episodic memory, which will then be converted into a score relative to the group

that is similar to them in terms of demographics (Stern & White, 2003).

Image and Scanning Measures

Various measures of neuroimaging will be conducted on the participants to evaluate the

health of the brain. These images will be obtained through diffusion tensor imaging, hemosiderin

scans, arterial spin labeling and fluid-attenuated inversion recovery.

Microstructural changes in brain tissue will be visible through the utilization of diffusion

tensor imaging. This measurement works by showing the pattern of water molecule diffusion in

the brain tissue, more specifically the areas of restriction. This method of imaging works by

collecting data from images in 32 different directions of the brain and sums up all the

information on the location of water diffusion in each voxel with a parametric map (Bammer,

2003). These parametric images will be compared over time to establish changes in brain tissue

through the flow of water diffusion. Measurements from diffusion tensor imaging are shown in

an ellipsoid, which is an elongated sphere. Very good diffusion of water along the axis of the

brain is shown in a long thin ellipsoid, while a sphere represents even levels of diffusion in all

directions throughout the brain (Shenton, Hamoda, Schneiderman, Bouix, Pasternak, Rathi, et

al., 2012).

This observation is used as a common method for predicting the formation of

encephalopathy in the brains of subjects with histories of concussion. A study done on the

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reliability of diffusion tensor imaging found that upon applying a standard diffusion encoding

scheme of 30/32 gradient directions, invariant scalar measures can be estimated within the brain

with very little variation at a coefficient of variation of less than 0.5% (Magnotta, Matsui, Liu,

Johnson, Long, Bolster, … Paulsen, 2012).

Researchers will be able to acquire evidence of past bleeding in brain tissue with

hemosiderin scans of football players’ brains. After the brain bleeds from a traumatic injury to

the head a bloodstain is left behind on the white tissue of the brain called hemosiderin, which

represents shear injury to the white matter of the brain. MRI scans for hemosiderin will detect

the presence of previous hemorrhaged blood in the brain tissue (Barbosa, Santos, & Salmon,

2015).

Measurements of the hemosiderin scan will be obtained through axial T2 weighted

images which will highlight areas of past brain hemorrhages. Each cerebral hemisphere will be

divided into five areas: the sylvian fissure, parietal, frontal, occipital, and temporal. Then the

numbers of regions displaying hemosiderin deposits are calculated and the size of deposits will

be recorded (Thulborn, Sorensen, Kowall, McKee, Lai, McKinstry, Moore, Rosen, & Brady,

1990). These measurements will be taken each year over the ten-year study to determine

presence and growth of past hemosiderin. Research has found hemosiderin scans to have positive

predictive value of 96% with a 95% confidence interval in the range of 86% to 100% and a

diagnostic accuracy of 95% confidence interval in the range of 86% to 99% (Zamboni, Izzo,

Fogato, Carandina & Lanzara, 2003).

Arterial spin labeling is a non-invasive technique in magnetic resonance imaging that will

allow researchers to track blood flow in the brain. This subtype of magnetic resonance imaging

highlights the flow of blood through arteries and capillaries throughout various parts of the brain

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including the cerebellum by labeling the water molecules in the arterial blood magnetically. The

tracer in the arterial blood flows into the cerebellum or portion of interest in the brain and

reduces total tissue magnetization during which time the tag image is taken. This process is

repeated without the use of the tracer to create the control image. The tag image is subtracted

from the control image to create a perfusion image, which represents the amount of arterial blood

delivered to each voxel in the brain (Petcharunpaisan, Ramalho, & Castillo, 2010). This

observation will measure the blood flow in the cerebellum, which can be a predictor of future

neurodegenerative diseases in the brain.

Research done on the test-retest reliability of arterial spin labeling has found that arterial

spin labeling demonstrates high within-session reproducibility and high within-subject

coefficient variables with a 95% confidence interval (Chen, Wang, & Detre, 2011).

Fluid-attenuated inversion recovery is a technique in magnetic resonance imaging used to

identify lesions and tumors in the structure of the brain. These images are obtained through a

type of inversion recovery, which suppresses certain fluids in the brain in order to show any

changes in the structure of the brain tissues, such as lesions or tumors (White, Hajnal, Young, &

Bydder, 1992). This measurement will allow researchers to record any changes in lesions or

growth of tumors over the course of this longitudinal study.

A study that used the fluid-attenuated inversion recovery technique to assess lesions in

patients with multiple sclerosis found that the reliability of this method of atrophy rating to be

very good. The intraobserver agreement has a mean of 0.9 in the range of 0.8 to 1.0 and the

interobserver agreement has a mean of 0.8 in the range of 0.6 to 1.0, which are both high

correlation scores (Bakshi, Ariyaratana, Benedict, & Jacobs, 2001).

Justification of outcomes being evaluated

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There are over 4,000 players currently suing the NFL in federal court over allegations

regarding the league’s denial of the connection between brain damage and the sport of football.

In response to lawsuits and increased media attention on the mental health of football players the

NFL has amended rules, altered protective headgear and donated over thirty million dollars to

research foundations in efforts to decrease the occurrence of concussions in the league, however,

concussions remain to be an inevitable part of the sport (Amen, Wu, Taylor, & Willeumier,

2011). The long-term health consequences of concussions have proven to be life altering and, in

more severe cases, life ending. Therefore it is imperative that further investigation be performed

to analyze the origins of these impairments and the growth of neurodegenerative diseases. The

results of this study will provide practical implications for those involved in the NFL as well as

any individuals participating in sports that include repeated trauma to the head.

Data Analysis

The measurements collected from participants of this study will occur each year for the

duration of ten years. The variables tested will be analyzed over time in order to decipher

differences within each year. A repeated measures analysis of variance will be used to determine

changes from baseline in the first year of data collection, each year until the tenth and final year

of data collection. This analysis of variance will be used to determine whether there are any

significant differences between the means of the variables being measured each year and provide

insight on the deviations in measurements.

21


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final capstone paper

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