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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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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EVALUATING MENTAL HEALTH OF RETIRED NFL PLAYERS
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.
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EVALUATING MENTAL HEALTH OF RETIRED NFL PLAYERS
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