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Jacob Wisnoski
Professor: Antonio E. Puente, Ph.D.
INVESTIGATING THE RELATIONSHIP BETWEEN BLAST-RELATED TRAUMATIC BRAIN INJURY AND
EXECUTIVE FUNCTION PERFORMANCE IN A MILITARY SAMPLE
ACKNOWLEDGEMENTS
• I would like to thank the following individuals who, without their advice and support, this project would not have been possible:
• My mentor, Dr. Puente
• My committee members, Dr. MacKain & Dr. Pond
• The UNCW Neuropsychology Lab
• My family and my girlfriend, Julie
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
WHAT IS A TRAUMATIC BRAIN INJURY (TBI)?
• There are many different examples of what falls under the category of “TBI”
• The definition often varies depending on the guidelines of a particular organization (e.g., ICD-9, DVBIC)
WHAT IS A TBI? (CONT.)
INTRACRANIAL INJURY, EXCLUDING THOSE WITH SKULL FRACTURE (850-854)
• 850 Concussion
• Includes:
• commotio cerebri
• 851 Cerebral laceration and contusion
• 852 Subarachnoid, subdural, and extradural hemorrhage, following injury
• 853 Other and unspecified intracranial hemorrhage following injury
• 854 Intracranial injury of other and unspecified nature
• Includes:
• injury:
• brain NOS
• cavernous sinus
• Intracranial
• (Taken from the International Classification of Diseases (ICD-9))
WHAT IS A TBI? (CONT.)
• TBI in military operational settings is defined as an injury to the brain resulting from an external force and/or acceleration/deceleration mechanism from an event such as a blast, fall, direct impact, or motor vehicle accident which causes an alteration in mental status
• Typically resulting in the temporally related onset of symptoms such as:
• headache
• nausea
• vomiting
• dizziness/balance problems
• fatigue
• insomnia/sleep disturbances
• drowsiness
• sensitivity to light/ noise
• blurred vision
• difficulty remembering
• and/or difficulty concentrating
• (Defense and Veterans Brain Injury Center (DVBIC) , 2006)
A BRIEF HISTORY OF BLAST-RELATED TRAUMATIC BRAIN INJURY (bTBI)
• During World War I, soldiers were exposed to more potent explosives and, as a result of advances in medicine/protective gear, were able to survive these injuries.
• Soldiers also began demonstrating a new host of psychophysiological symptoms that would give rise to the term, “shell shock”.
• “It was soon recognized that one type of case was due to the explosion of big shells in the immediate vicinity of the patient, who did not himself receive any detectable physical injury or bodily wound” (Turner, 1915, p.833)
A BRIEF HISTORY OF bTBI(CONT.)
• Turner’s description of the symptoms seen in “shell shock”:
• “In the first group, there is a definite type of mental shock in which the symptoms are essentially of psychical character.
• In the second group there is a spinal type characterized by a limitation of the symptoms to the extremities, and usually to the lower limbs.
• In a third group the symptoms are referred more particularly to the special senses.
• More specialized symptoms, such as stammering or hesitation of speech, local palsies and tic-like movements, have been included in a fourth group.” (Turner, 1915, p.833)
HISTORY OF bTBI (CONT.)
• By World War II, the term “postconcussion syndrome” replaced “shell shock” as it took into account the number of blasts, the time since injury, and reported symptoms.
• Wittenbrook (1941) describes the symptoms of this syndrome as followed:
• “The most common symptoms form a triad of headache, dizziness, and nervousness.
• Many show a fatigability similar to that seen in neurasthenics.
• Certain of the cases with tinnitus, impairment of memory, poor concentration…character changes, emotional instability, and antisocial behavior belong in this syndrome.” (Wittenbrook, 1941, p.170)
BLAST-RELATED TBI TODAY
• Since 2000, the Department of Defense estimates that 294,172 new diagnoses of TBI have occurred.
BLAST-RELATED TBI TODAY (CONT.)
• The increased use of improvised explosive devices and advances in medicine and protective equipment have contributed to this high prevalence of TBI (McCrea et al., 2011; Taber et al., 2007).
• While more U.S. warfighters are surviving blast injuries, these same individuals are now dealing with a host of neuropsychological problems.
MECHANISM OF bTBI DAMAGE
• “Primary blast injury results from blast wave-induced changes in atmospheric pressure (barotrauma). Organs and tissues of different densities are accelerated at different relative rates, resulting in displacement, stretching and shearing forces.”
• (Taber, Warden, & Hurley, 2006, p. 142-143)
MECHANISM OF bTBI DAMAGE (CONT.)
• “Secondary blast injury results from objects put in motion by the blast wind impacting a person (ballistic trauma). This category includes both injuries due to flying debris and due to collapse of structures.
• Tertiary blast injury results from a person being blown into solid objects by the blast wind.”
• (Taber, Warden, & Hurley, 2006, p. 142-143)
• The secondary/tertiary injuries brought about by the primary mechanism of injury damage the brain through a process known as “coup/contrecoup injury”.
MECHANISM OF bTBI DAMAGE (CONT.)
• This process means that the brain will injure itself against a surface/object as a product of the blast mechanism (coup).
• Contrecoup damage is caused when the brain bounces back against the back of the skull in response to the impact of the coup injury.
• The damage done to the brain after being exposed to a blast is described as follows:
• “Impact mechanisms associated with secondary injury result primarily in cortical injury, affecting the anterior and inferolateral temporal lobes, orbitofrontal regions, and frontal poles. Acceleration and deceleration associated with tertiary injury lead to diffuse traumatic injury to white matter in the brain” (Bogdanova & Verfaellie, 2012, p.6)
THE EFFECTS OF TBI ON THE FRONTAL LOBES: A HISTORICAL EXAMPLE
• “He is fitful, irreverent, indulging at times in the grossest profanity…impatient of restraint or advice when it conflicts with his desires…devising many plans of future operation, which are no sooner arranged than they are abandoned in turn for others appearing more feasible.” (Harlow, 1868, p.340-341)
THE FRONTAL LOBES
The orbitofrontal cortex is divided into ventromedial (reddish) and the lateral orbitofrontal cortex (green)
Pictures presented with permission of Toth, J.
PREFRONTAL CORTEX (PFC) CONNECTIVITY IN THE HUMAN BRAIN
Figure presented with permission of Toth, J.
NEUROANATOMY & EXECUTIVE FUNCTIONS
• Luria (1966)
• Luria’s model of frontal lobe functions is a three-stage, hierarchical model with the first two stages being primarily focused on motor activity
• The tertiary stage is much more closely related to the PFC and EFs
• “The higher development and perfection of the whole sphere of voluntary, goal-directed acts was associated with the formation of the tertiary fields of the frontal region proper…These fields, occupying in man about one quarter of the entire surface of the cortex, belong to the phylogenetically youngest divisions of the neocortex” (Luria, 1962/1966, p.57).
NEUROANATOMY & EXECUTIVE FUNCTIONS (CONT.)
• Stuss & Benson (1986)
• “The executive function represents many of the important activities that are almost universally attributed to the frontal lobes which become active in nonroutine, novel situations that require new solutions” (Stuss & Benson, 1986, p. 244)
• Additionally, Stuss and Benson emphasize that, similar to Luria, “the prefrontal cortex is the anatomical basis for the function of control” (Stuss & Benson, 1986, p.244).
WHAT ARE EXECUTIVE FUNCTIONS?
• Baddely & Hitch (1974)
• Working memory research conducted by the team incorporated a “central executive” component in their theory.
• “Responsible for coordinating and monitoring the many and complex subroutines that are responsible for both acquiring new material and retrieving old” (Baddeley & Hitch, 1974, p.47).
• Lezak (1982)
• “Those mental capacities necessary for formulating goals, planning how to achieve them, and carrying out the plans effectively” (Lezak, 1982, p.281).
• Lezak described EFs are necessary for an individual to perform activities that are considered creative, productive, and socially and personally fulfilling.
WHAT ARE EXECUTIVE FUNCTIONS? (CONT.)
• Miyake et. al (2000)
• “General-purpose mechanisms that modulate the operations of various cognitive subprocesses and thereby regulate the dynamics of human cognition” (Miyake et al., 2000, p.50).
• Additionally, Miyake et al have placed emphasis on the “unity/diversity” of EFs
• Alvarez & Emory (2006)
• “higher-level cognitive functions involved in the control and regulation of “lower-level” cognitive processes and goal-directed, future-oriented behavior.” (Alvarez & Emory, 2006, p.17)
• Gilbert & Burgess (2008)
• “the high-level cognitive processes that facilitate new ways of behaving, and optimize one’s approach to unfamiliar circumstances” (Gilbert & Burgess, 2008, p. R110).
WHAT ARE EXECUTIVE FUNCTIONS? (CONT.)• While there is no singularly agreed upon definition of the term ‘executive function’ (EF), it is
often thought as an umbrella term which looks at the following variables:
• planning
• cognitive flexibility
• inhibition of behavior
• creating goals/goal-oriented behavior
• problem solving
• verbal fluency/reasoning
• adapting to novel situations and stimuli
• decision-making
• multitasking
• working memory
• switching between tasks
• filtering out interference
• (Banich, 2009; Chan, Shum, Toulopoulou, & Chen, 2008; Gilbert & Burgess, 2008; Jurado & Rosselli, 2007; Lezak, 1982)
TRAUMATIC BRAIN INJURY & EXECUTIVE FUNCTIONS
• Among issues related to EF, TBI, and frontal lobe damage, is an ailment known as dysexecutive syndrome.
• This syndrome is categorized by, “complex cluster of executive function concerns (i.e., cognition, behavior, and emotion) that arose as a result of damage to the brain” (Wilson, Evans, Emslie, Alderman, & Burgess, 1998).
• The team of Wilson et. al (1998) defined this syndrome to better capture EF deficits rather than the term previously used describe these clusters of issues, frontal lobe syndrome.
• Researchers have found that the following EFs have had deficits as a result of TBI damage: working memory, attention (and divided attention aka multi-tasking), cognitive flexibility, rule attainment, and decision-making.
• Fonseca, Zimmermann, Cotrena, Cardoso, Kristensen, Grassi-Oliveira, 2012; Hartikainen et. al, 2010; Serino, Ciaramelli, Santantonio, Malagù, Servadei, & Làdavas, 2006.
ISSUES IN TBI & EF RESEARCH
• Issues in Measurement
• There have been many critiques raised against the ability for neuropsychological tests to predict “real-world” outcomes this is an issue of ecological validity.
• There is a fair amount of literature that has shown that there is poor ecological validity in EF measures with particular emphasis on populations with both mild and severe TBI (Douglas, 2010; Wood & Liossi, 2006)
• As the previous slides have illustrated, there is issues in the operationalization of EF and frontal lobe functions which creates discrepancy in what is truly being measured.
ISSUES IN TBI & EF RESEARCH (CONT.)
• Issues in Generalizability
• While the research that has discussed the deficits of EF in varying clinical populations has been important, there is limited generalizability of findings to a “neurotypical” population (Busch, McBride, Curtiss, Vanderploeg, 2005; Schieser, Delis, Filoteo, Delano-Wood, Han Jak, Drake, & Bondi, 2011)
• Issues in Experimental Design
• Studies looking at the relationship between EFs and TBIs often have some variation of the following issues: small n value, limited number of EF measures, low level statistical processes.
• As will be discussed later, the issue of “unity/diversity” also presents a problem when discussing EF testing.
ISSUES IN TBI & EF RESEARCH (CONT.)
• Examples of TBI & EF studies with the issues discussed in the previous slide
• Brenner et al. (2010)
• N=45
• Number of EF tests: 3 (Stroop, Trail Making Test, and Wisconsin Card Sorting Task)
• Findings show a decline in executive function performance in TBI group
• Procedures used: t-tests
• Verfaellie, Lafleche, Spiro, & Bosquet (2013)
• N=127
• Number of EF tests: 3 (Delis-Kaplan: Stroop, Trail Making Test, and Verbal Fluency Test)
• Findings show a mild impairment of executive functioning
• Procedures used: multiple regression analyses
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
OBJECTIVE• The prospective study will contribute to the present body
of literature discussing the relationship between blast-related TBIs’ and EFs in the following ways:
• Analyze a larger sample size (N=735)
• Incorporate more EF measures (4)
• Utilize more advanced statistical techniques (e.g., latent variable analysis)
• Investigate the influence of the EF measures against one another
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
METHODS: PARTICIPANTS
• The prospective study will utilize a large electronic data set consisting of evaluations from Marines and sailors.
• The following exclusion criteria will be applied to these data:
• Unspecified demographic information (n=165)
• Sub-optimal performance (score of less than 45) on the Test of Memory Malingering (n=156)
• Based on these exclusion criteria, the prospective study will analyze data of 735 Marines and sailors
DEMOGRAPHIC INFORMATION• Gender
• 721 Male
• 14 Female
• Age
• Mean: 25.85 Years
• SD: 5.6 Years
• Education
• Mean: 12.5 Years
• SD: 1.1 Years
• Handedness
• Right-Hand: 498 participants
• Left-Hand: 191 participants
• Ambidextrous: 46 participants
METHODS: PROCEDURE
• Evaluation Procedure
• Psychodiagnostic Interview
• Neuropsychological Testing
• Follow-up Session
• Data Collection
• Jacksonville Trips
• Data Input
METHODS: MATERIALS
• The dataset collected from Camp Lejeune includes four measures of EF that will be used for the proposed study:
• The Hayling Sentence Completion Test & Brixton Spatial Anticipation Test (Burgess & Shallice, 1997)
• The Controlled Oral Word Association (COWA) Test
• The Trail Making Test (Reitan & Wolfson, 1993)
• The Stroop Test (Stroop, 1935 & Golden, 1978)
THE HAYLING & BRIXTON TESTS
• The Hayling Sentence Completion Task
• Consists of two, 15 sentence completion tasks where the final word of each sentence is missing.
• The first round of 15 sentences has participants filling in the missing word as quickly as possible.
• The second round tasks participants with completing the sentence with a nonsensical answer thus, challenging them to inhibit automatic, logical responses.
THE HAYLING AND BRIXTON TESTS (CONT.)
• The Brixton Spatial Anticipation Task
• Consists of a 56 page stimulus book where each page has ten circles aligned in a two by five line up. Each circle is numbered one through ten.
• On each page, one of the circles is blue and the blue coloring will change from page to page.
• How the changes occur depends on a series of simple rules and the participant is tasked with determining this rule and figuring out where the blue circle will be next.
• Together, these tests are supposed to measure the following EF variables: initiation speed, response suppression, and rule attainment.
CONTROLLED ORAL WORD ASSOCIATION TEST (COWAT)
• The COWA Test is a two component neuropsychological test which is intended to measure the EF variable, verbal fluency
• Letter Fluency
• The letter fluency component of the COWA is commonly referred as the “FAS test” since the participant is asked to produce as many unique words beginning with the letters F, A, and S as they can in one minute (per letter).
• The participant cannot give the names of proper nouns (e.g. names) or repeat words with a different ending (e.g., fish, fishing, fishes, etc.)
• Semantic Fluency
• The procedures for the semantic fluency task are essentially the same as the letter fluency task except participants are now tasked with naming as many animals, fruits, and vegetables as they can in one minute per category.
THE TRAIL MAKING TEST (TMT)
• Trail A
• Trail A contains 25 circles with numbers in them and tasks the participant with connecting the dots in numerical order as quickly as possible.
• Trail B
• Trail B of the TMT is uses a similar form as Trail A but, instead of numbers alone being in the circles, the 25 circles contain both numbers and letters.
• The goal of Trail B is to have participants alternate between numbers and letters (e.g., 1-A, 2-B, 3-C, 4-D,and so on) as quickly as possible
• Research conducted using the TMT has shown that the following EF variables are measured with this test: cognitive flexibility, ability to maintain set, and ability to switch between sets (in the case of Trail B) (Arbuthnott & Frank, 2000; Kortte, Horner, & Windham, 2002).
THE STROOP TEST
• The Stroop task typically consists of three sections:
• The Neutral Task: Participants are asked to read aloud various color names printed in black ink and name as many as possible in a pre-determined amount of time (usually 45 seconds-1 minute).
• The Color Task: Participants are then asked to read aloud color names (or a neutral series of letters such as “xxxxx”) printed in inked whose color is congruent to the color name being red (e.g., ‘red’ being printed in red ink).
• The Color-Word Task: Participants are then presented with color names printed in ink incongruent to the actual word given (e.g., the word ‘green’ printed in blue ink). Participants must inhibit their natural tendency towards language processing and name the color of the ink instead.
• The EF measures that are tapped by the Stroop task include: goal-oriented behavior and behavior inhibition.
METHODS: PROPOSED PROCEDURE
• The proposed research project will consist of two main studies, each focusing on a different series of research questions.
• Study 1 will be more clinically oriented and investigate the relationship between mechanism of injury (MOI), number of times blasted, and EF performance.
• Study 2 will be more experimental and exploratory in nature as it will probe deeper into the question of what an executive function is and how to measure them.
METHODS: STUDY 1 PROCEDURE
• Study 1 will begin by comparing two different categories of blast injured groups (single v.s. multiple) to see if there are significant differences in EF performance between the groups.
• Single-Blast Group (n = 136)
• Multiple-Blast Group (n = 303)
• This will be accomplished through the use of a two-tailed, dependent samples t-test.
• This will inform whether or not a single “blast” group can be used for statistical analyses in Study 1 or if two separate groups must be compared.
METHODS: STUDY 1 PROCEDURE (CONT.)
• Study 1 also aims to compare EF performance using a three (or four) factor one-way ANOVA in three different MOIs:
• A bTBI group (n = 439)
• Single-blast (n = 136)
• Multiple-blast (n = 303)
• A TBI group whose injury was not blast-related (n = 107)
• A no TBI group (n = 22)
• Post-hoc pairwise comparisons will also be conducted to examine specific differences amongst the groups.
METHODS: STUDY 2 PROCEDURE
• Study 2 is organized into three levels of analyses which range from low to high complexity in terms of the depth of analysis.
• The first level is intended to examine the “unity/diversity” issue through the use of ANOVA and regression.
• Specifically, a repeated measures ANOVA and post-hoc analyses will be used to probe for significant differences between EF measures (diversity).
• Multiple regression will analyze the correlation between EF measures and how well each measure predicts values of other EF tests (unity).
METHODS: STUDY 2 PROCEDURE (CONT.)
• The next level of analysis is intended to build off of the regression analyses by looking at possible third variables that may affect the statistical relationships between EF measures.
• This will be accomplished through the use of moderation analyses which will analyze:
• Categorical variables (e.g., gender, ethnicity, MOI, and loss of consciousness)
• Continuous variables (e.g., age, number of blasts, time since last injury, education, and, most importantly, EF scores)
METHODS: STUDY 2 PROCEDURE (CONT.)
• Phase II will probe for these interactions between EF measures and additional variables using the moderation procedure developed by Preacher, Curran, & Bauer (2006)
METHODS: STUDY 2 PROCEDURE (CONT.)• The final level of analysis will utilize the methodology
developed by Miyake et al. (2000) to study the “unity/diversity” issue which is conducted as followed:
• “One selects multiple exemplar tasks that seem different on the surface but still capture the target ability.
• If exemplar tasks are chosen that share little systematic non-EF variance, one can statistically extract what is common across those tasks (using multivariate statistical techniques such as structural equation modeling and exploratory factor analysis).
• Use the resulting “purer” latent variable as the measure of EF.” (Miyake et al., 2000, p 8-9)
Hayling & Brixton
Stroop Task
Trail Making Test
COWAT
Common Executive Function Construct
Rule Attainment
Inhibition
Cognitive Flexibility
Verbal Fluency
Response Suppression
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
STUDY 1 PREDICTIONS
• It is hypothesized that the initial t-test will reveal that there is no significant difference between individuals who experienced a single blast when compared to those who experienced multiple blasts on any of the executive function measures.
• This hypothesis is supported by a number of studies (Ivins, Kane, & Schwab, 2009; Luethecke, Bryan, Morrow, & Isler, 2011; Verfaellie, Lafleche, Spiro, & Bousquet, 2013) which have demonstrated that the number of TBIs experienced has no significant effect on the outcomes of neuropsychological test performance.
STUDY 1 PREDICTIONS (CONT.)
• It is predicted that the ANOVA will yield a statistically significant F-value and thus, there will be a significant difference present between the three MOI groups on all four EF tests.
• It is likely that this prediction will come about due to the mere differences in the sample sizes of each MOI group rather than an actual effect.
• A Levene’s test will be conducted to reduce the violation of assumed heterogeneity of variance (HOV) as the size of the dataset may be overpower findings and will produce significant findings.
• Therefore, the subsequent pairwise comparisons will also yield significant differences between MOI groups on each EF test.
STUDY 2 PREDICTIONS
• In regards to the first level of analyses, it is hypothesized that each repeated measure ANOVA will produce a statistically significant result which suggests that there are significant differences present amongst the four EF measures.
• Subsequent pairwise comparisons will further yield significant results and illustrate where those differences lie between each EF measure when compared to one another.
• The purpose of this series of analyses is to begin to examine the diversity of EF measures as that will likely be more apparent.
STUDY 2 PREDICTIONS (CONT.)
• Furthermore, while discussing the first level of analyses, it is predicted that the multiple regression experiments will yield statistically significant results.
• It is hypothesized that the relationship between each measure of EF (when compared with one another) will be low to moderately strong and positively directed.
• Significant findings in the regression analyses will being to empirically support the notion that there is a unity amongst the EF measures.
STUDY 2 PREDICTIONS (CONT.)
• In regards to the second round of analyses in Study 2, there has been little information published that looks at moderators of interest.
• However, there are previous studies that have demonstrated differences in EF measures based on the following categorical variables:
• gender (Niemeier, Marwitz, Lesher, Walker, & Bushnik, 2007)
• ethnicity (Proctor & Zhang, 2008)
• loss of consciousness
• mechanism of injury
STUDY 2 PREDICTIONS (CONT.)
• There also a number of continuous variables which have previously shown demonstrated differences that will also be probed:
• time since last injury (Belanger, Curtiss, Demery, Lebowitz, & Vanderploeg, 2005)
• age (Bryan & Luszcz, 2000)
• number of blasts
• education
• scores on the four measures of EF
• As little research has been done looking at moderation on this type of sample with these variables (both continuous and categorical), it is predicted that interactions between each EF measure to one another will be dependent on each of these variables.
STUDY 2 PREDICTIONS (CONT.)
• In regards to the third level of analysis, the individual EF measures appear to be quite diverse in terms of the constructs being measured.
• A latent variable analysis needs to be conducted in order to determine if there is an underlying all of the tests.
• It is likely that since all of the measures in this study are considered EF measures, there should be a minor portion of the variance that can be explained by this underlying EF component.
Hayling & Brixton
Stroop Task
Trail Making Test
COWAT
Common Executive Function Construct
Rule Attainment
Inhibition
Cognitive Flexibility
Verbal Fluency
Response Suppression
PRESENTATION OVERVIEW
• Introduction
• Objective
• Methods
• Expected Results
• Discussion
STUDY 1 DISCUSSION
• In Study 1, the intended goal was to begin evaluating the relationship between certain variables (e.g., # of blasts, MOI) that may affect EF performance within the sample.
• If the expected results of study one are found to be as predicted, then this will add support to the literature that states that factor such as MOI (Belanger et al. 2009) and number of blasts (Ivins et al., 2009; Luethecke, et al., 2011; Verfaellie et al., 2013) may not be the most salient when evaluating a client.
• That is not to imply that these variable do not have an important role to play in the evaluation of the client but, perhaps, that other variables such as the presence of depression or PTSD may have greater impact on neuropsychological performance.
STUDY 2 DISCUSSION
• The findings of the first level of analysis of Study 2 will demonstrate whether or not it is possible to statistically illustrate the unity/diversity framework using lower level mathematical functions.
• The findings of the post-hoc tests will be very important in determining what conclusions can be drawn from these statistical procedures as there must also be a way to compensate for overpowered data due to the large sample size.
• The second level of analysis is an investigation into whether or not there are additional variables that may be impacting the regression analyses from the prior analyses.
• This level will operate as a screening for third variable moderators that may not have been considered by previous research or considered at all.
• The majority of these variables may also, to some small degree, act as manifest variables and thus, the variance attributed to these variables needs to be explained before probing the possible latent variable(s) within the dataset.
STUDY 2 DISCUSSION (CONT.)
• The third level of analysis is the major portion of Study 2 as it is the most statistically sophisticated and has the most implications associated with its findings.
• If it is indeed found that there is unity underlying all of the EF measures in this project, then it would mean that it may be necessary to re-evaluate the tests themselves to ensure that future forms of these measures accommodate the effects of other EF measures on each individual test.
• Additionally, a latent variable analysis demonstrating unity within the model will also prove that the methods discussed by Miyake et al (2000) can be completed with more dissimilar tests and with fewer tests.
GENERAL DISCUSSION
• As this study utilizes data from a military sample (which has often been considered to have different cultural habits/attitudes than civilian populations) and this sample has been exposed to bTBIs, this project may also inform how this sort of sample differs from civilian samples.
• Further, it may be possible to start learning how bTBIs affect the common EF construct as well as the individual EF constructs captured by each test.
• As this is a military sample being measured, the findings of this research may even be able to modify EF measures to better reflect the conditions and conditioning that a military sample would be exposed to while in training, in combat and as a veteran sample.
LIMITATIONS
• This is a retrospective analysis rather than a prospective analysis.
• Testing procedure relied on the subjective knowledge and opinion of a clinician, additional error may have been factored in without report or inter-rater reliability procedures being carried out.
• Alvarez & Emory (2006) found in their review of EF and frontal lobe studies that, contradictory to what they considered the historical neuropsychological approach of localization, that “both frontal and non-frontal brain regions are necessary for intact executive functions” (Alvarez & Emory, 2006, p.33).
FUTURE DIRECTIONS
• Utilize a broader range of EF measures to better capture key functions such as decision-making and working memory and developer a more powerful argument in the “unity/diversity” framework.
• It is important to note that the proposed study is, arguably, only investigating half of what may be considered an executive function.
• In Ardila’s (2008) discussion on the possible evolutionary origins of EFs, two types of EF are brought up: metacognitive and emotional. Ardila describes a second type of EF, emotional (or “hot” cognition), which is supposed to deal with motivation as well as the frontal lobe serving as an emotional impulse control for limbic system activity.
• To further enhance this procedure, the inclusion of neuroimaging would be an important addition to provide clear structural/functional relationships between EFs and their neuroanatomical correlates.
QUESTIONS?
REFERENCES
Brenner, L.A., Terrio, H., Homaifar, B.Y., Gutierrez, P.M., Staves, P.J., Harwood, J.E.F., Reeves, D., Adler, L.E., Ivins, B.J., Helmick, K., & Warden, D. (2010). Neuropsychological test performance in soldiers with blast-related mild TBI. Neuropsychology, 24 (2), 160-167.
Burgess, P.W. & Shallice, T. (1997). The Hayling and Brixton tests. Thurston, Suffolk: Thames Valley Test Company.
Burgess, P.W., Alderman, N., Evans, J., Emslie, H., & Wilson, B.A. (1998). The ecological validity of tests of executive function. Journal of the International Neuropsychological Society, 4, 547-558.
Busch, R.M., McBride, A., Curtiss, G., & Vanderploeg, R.D. (2005). The components of executive functioning in traumatic brain injury. Journal of Clinical and Experimental Neuropsychology, 27, 1022-1032.
Bryan, J. & Luszcz, M.A. (2000). Measurement of executive function: Considerations for detecting adult age differences. Journal of Clinical and Experimental Neuropsychology, 22(1), 40-55.
Chan, R.C.K., Shum, D., Toulopoulou, T., & Chen, E.Y.H. (2008). Assessment of executive functions: Review of instruments and identification of critical issues. Archives of Clinical Neuropsychology, 23, 201-216.
Chaytor, N., Schmitter-Edgecombe, M., & Burr, R. (2006). Improving the ecological validity of executive function assessment. Archives of Clinical Neuropsychology, 21, 217-227.
Cohen, J., Cohen, P., West, S.G., & Aiken, L. S., (2003). Applied multiple regression/correlation analysis for the behavioral sciences . Hillsdale, N.J.: L. Erlbaum Associates.
Damasio, A.R. (1994) Descartes’s error: Emotion, reason, and the human brain. New York: G.P. Putnam’s Sons.
Demakis, G.J. (2004). Frontal lobe damage and tests of executive processing: A meta-analysis of the Category Test, Stroop Test, and Trail Making Test. Journal of Clinical and Experimental Neuropsychology, 26 (3), 441-450.
Douglas, J.A. (2010). Relation of executive functioning to pragmatic outcome following severe traumatic brain injury. Journal of Speech, Language, and Hearing Research, 53, 365-382.
DVBIC (2006). Defense and veterans brain injury center working group on the acute management of mild traumatic brain injury in military operational settings. Washington, DC: Defense and Veterans Brain Injury Center.
REFERENCES (CONT.)
• Faul, F., Erdfelder, E., Buchner, A., & Lang, A-G (2009). Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behavior Research Methods, 41(4), 1149-1160.
• Faul, F., Erdfelder, E., Lang, A-G, & Buchner, A. (2007) G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior Research Methods, 39 (2), 175-191.
• Fonseca, R.P., Zimmermann, N., Cotrena, C., Cardoso, C., Kristensen, C.H., & Grassi-Oliveira, Rodrigo. (2012). Neuropsychological assessment of executive functions in traumatic brain injury: Hot and cold components. Psychology & Neuroscience, 5 (2), 183-190.
• Gioia, G.A. & Isquith, P.K. (2004). Ecological assessment of executive function in traumatic brain injury. Developmental Neuropsychology, 25 (1&2), 135-158.
• Gilbert, S. J. & Burgess, P. W. (2008). Executive function. Current Biology, 18, R110–R114.
• Grafman, J. & Litvan, I. (1999) Importance of deficits in executive functions. The Lancet, 354, 1921-1923.
• Harlow, J.M. (1868). Recovery from the passage of an iron bar through the head. Bulletin of the Massachusetts Medical Society, 2, 327-347.
• Hartikainen, K.M., Wäljas, M., Isoviita, T., Dastidar, P., Limatainen, S., Solbakk, A.K., Ogawa, K.H., Soimakallio, S., Ylinen, A., & Öhman, J. (2010). Persistent symptoms in mild to moderate traumatic brain injury associated with executive dysfunction. Journal of Clinical and Experimental Neuropsychology, 32 (7), 767-774.
• Hicks, R.R., Fertig, S.J., Desrocher, R.E., Koroshetz, W.J., & Pancrazio, J.J. (2010). Neurological effects of blast injury. J Trauma, 68 (5), 1257-1263.
• Hoge, C.W., McGurk, D., Thomas, J.L., Cox, A.L., Engel, C.C., & Castro, C.A. (2008). Mild traumatic brain injury in U.S. soldiers returning from Iraq. The New England Journal of Medicine, 358 (5), 453-463.
• Ivins, B. J., Kane, R., & Schwab, K. A. (2009). Performance on the Automated Neuropsychological Assessment Metrics in a nonclinical sample of soldiers screened for mild TBI after returning from Iraq and Afghanistan: A descriptive analysis. Journal of Head Trauma Rehabilitation, 24, 24–31.
• Jones, E., Fear, N.T., & Wessely, S. (2007). Shell shock and mild traumatic brain injury: A historical perspective. The American Journal of Psychiatry, 164, 1641-1645.
• Jurado, M.B. & Rosselli, M. (2007). The elusive nature of executive functions: A review of our current understanding . Neuropsychology Review, 17 (3), 213-233.
• Kortte, K.B., Horner, M.D., & Windham, W.K. (2002). The Trail Making Test, Part B: Cognitive flexibility or ability to maintain set? Applied Neuropsychology, 9 (2), 106-109.
• Lezak, M.D. (1982). The problem of assessing executive functions. International Journal of Psychology, 17, 281-297.
• Luethecke, C.A., Bryan, C.J., Morrow, C.E., & Isler, W.C. (2011). Comparison of concussive symptoms, cognitive performance, and psychological symptoms between acute blast-versus nonblast-induced mild traumatic brain injury. Journal of the International Neuropsychological Society, 17, 36-45.
• Luria, A.R. (1966) Higher cortical functions in man. (Haigh, B., Trans.). New York: Basic Books, Inc. & Consultants Bureau Enterprises, Inc. (Original work published 1962)
• McCrea, M., Pliskin, N., Barth, J., Cox, D., Fink, J., French, L., Hammeke, T., Hess, D., Hopewell, A., Orme, D., Powell, M., Ruff, R., Schrock, B., Terryberry-Spohr, L., Vanderploeg, R., & Yoash-Gantz, R. (2008). Official position of the military TBI task force on the role of neuropsychology and rehabilitation psychology in the evaluation, management, and research of military veterans with traumatic brain injury. The Clinical Neuropsychologist, 22 (1), 10-26.
• Miyake, A. & Friedman, N.P. (2012). The nature and organization of individual differences in executive functions: Four general conclusions. Current Directions in Psychological Science, 21 (1), 8-14.
• Miyake, A., Friedman, N.P., Emerson, M.J., Witzki, A.H., Howerter, A, & Wager, T.D. (2000). The unity and diversity of executive functions and their contributions to complex “frontal lobe” tasks: A latent variable analysis. Cognitive Psychology, 41, 49-100.
• Mooney, G., Speed, J., & Sheppard, S. (2005). Factors related to recovery after mild traumatic brain injury. Brain Injury, 19 (12), 975-987.
• Niemeier, J.P., Marwitz, J.H., Lesher, K., Walker, W.C., & Bushnik, T. (2007). Gender differences in executive functions following traumatic brain injury. Neuropsychological Rehabilitation, 17 (3), 293-313.
• Odhuba, R.A., van der Broek, M.D., & Johns, L.C. (2005). Ecological validity of measures of executive functioning. British Journal of Clinical Psychology, 44, 269-278.
• O’Reilly, R.C. (2010) The what and how of prefrontal cortical organization. Trends in Neuroscience, 33 (8), 355-361.
• Preacher, K.J., Curran, P.J., & Bauer, D.J. (2006). Computational tools for probing interactions in multiple linear regression, multilevel modeling, and latent curve analysis. Journal of Educational and Behavioral Statistics, 31 (4), 437-448.
REFERENCES (CONT.)
• Proctor, A. & Zhang, J. (2008). Performance of three racial/ethnic groups on two tests of executive function: Clinical implications for traumatic brain injury. NeuroRehabilitation, 23, 529-536.
• Rao, V. & Lyketsos, C. (2000). Neuropsychiatric sequelae of traumatic brain injury. Psychosomatics, 41, 95-103
• Raskin, S.A. & Rearick, E. (1996). Verbal fluency in individuals with mild traumatic brain injury. Neuropsychology, 10 (3), 416-422.
• Reitan, R.M. (1955). The relation of the Trail Making Test to organic brain damage. Journal of Consulting Psychology, 19 (5), 393-394.
• Reitan, R. M. (1958). Validity of the Trail Making Test as an indicator of organic brain damage Perceptual and Motor Skills, 8, 271–276.
• Reitan, R. M., & Wolfson, D. (1993). The Halstead-Reitan Neuropsychological Test Battery: Theory and clinical interpretation (2nd ed.) . Tucson, AZ: Neuropsychology Press.
• Salthouse, T.A. (2005). Relations between cognitive functioning and measures of executive functioning. Neuropsychology, 19 (4), 532-545.
• Sbordone, R.J. (2001). Limitations of neuropsychological testing to predict the cognitive and behavioral functioning of persons with brain injury in real-world settings. NeuroRehabilitation, 16(4), 199-201.
• Sbordone, R.J., Seyranian, G.D., & Ruff, R.M. (1998). Are the subjective complaints of traumatically brain injured patients reliable? Brain Injury, 12(6), 505-515.
• Schiehser, D.M., Delis, D.C., Filoteo, J. V., Delano-Wood, L., Han, D.S., Jak, A.J., Drake, A.I., & Bondi, M.W. (2011). Are self-reported symptoms of executive dysfunction associated with objective executive function performance following mild to moderate traumatic brain injury? Journal of Clinical and Experimental Neuropsychology, 33(6), 704-714.
• Schwarzbold, M.L., Rial, D., Bem, T.D., Machado, D.G., Cunha, M.P., dos Santos, A.A., dos Santos, D.B., Figueiredo, C.P., Farina, M., Goldfelder, E.M., Rodrigues, A.L.S., Prediger, R.D.S., & Walz, R. (2010). Effects of traumatic brain injury of different severities on emotional, cognitive, and oxidative stress-related parameters in mice. Journal of Neurotrauma, 27, 1883-1893
• Serino, A., Ciaramelli, E., Santantonio, A.D., Malagù, S., Servadei, F., & Làdavas, E. (2006). Central executive system impairment in traumatic brain injury. Brain Injury, 20 (1), 23-32.
• Stroop, J.R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18 (6), 643-662.
• Stuss, D.T. & Benson, D. F. (1986). The frontal lobes. New York: Raven Press.
• Taber, K.H., Warden, D.L., & Hurley, R.A. (2006). Blast-related traumatic brain injury: What is known? The Journal of Neuropsychiatry and Clinical Neurosciences, 18 (2), 141-145.
• Teuber, H.-L. (1972). Unity and diversity of frontal lobe functions. Acta Neurobiologiae Experimentalis, 32, 615-656.
• Tombaugh, T.N. (2004) Trail Making Test A and B: Normative data stratified by age and education. Archives of Clinical Neuropsychology, 19, 203-214.
• Turner, W.A. (1915). Remarks on cases of nervous and mental shock observed in the base hospitals in France. The British Medical Journal, 1(2837), 833-835.
• Vasterling, J.J., Proctor, S.P., Amoroso, P., Kane, R., Heeren, T., White, R.F. (2006). Neuropsychological outcomes of army personnel following deployment to the Iraq war. Journal of the American Medical Association, 296 (5), 519-529.
• Verfaellie, M., Lafleche, G., Spiro, A., & Bousquet, K. (2013). Neuropsychological outcomes in OEF/OIF veterans with self-report of blast exposure: Associations with mental health, but not mTBI. Neuropsychology. 1-10.
• Warden, D. (2006). Military TBI during the Iraq and Afghanistan wars. Journal of Head Trauma Rehabilitation, 21 (5), 398-402.
• Williamson, V. & Mulhall, E. (2009) Invisible wounds: Psychological and neurological injuries confront a new generation of veterans. New York: Iraq and Afghanistan Veterans of America , 7, 291-310.
•
• Wilson, B.A., Evans, J.J., Emslie, H., Alderman, N., & Burgess, P. (1998). "The development of an ecologically valid test for assessing patients with a dysexecutive syndrome." Neuropsychological Rehabilitation, 8, 213-228.
•
• Wittenbrook, J.M. (1941). The post-concussion syndrome: A clinical entity. Journal of Nervous and Mental Disease, 94(2), 170-176.
• Wood, R.L. & Liossi, C. (2006) The ecological validity of executive tests in a several brain injured sample. Archives of Clinical Neuropsychology, 21, 429-437.
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