Putting Executive Performance in a Theoretical Context Lisa Tabor Connor, Adina Maeir key words: executive function, occupational performance, cognition ABSTRACT This article provides a theoretical context to understand the role of executive functions in occupational performance. The authors provide definitions of the components of executive functions and their occupational significance. Assessment and intervention strategies for individuals with executive function deficits are discussed.
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xecutive functions are the skills that underlie our ability to complete complex tasks in daily life, such as making a meal, completing a school assignment, managing a family, and completing essential job functions (Burgess, 2000; Shallice & Burgess, 1991). Executive functions are often more evident when they are disordered or absent than when intact. Components of executive function include the ability to formulate and maintain goals and strategies, to hold information in mind for further processing, and to inhibit irrelevant information. Executive functions are evident any time multi-tasking is required, when goals need to be formulated to accomplish a task, when tasks have a particular sequence of activities that must be performed for successful completion, when competing stimuli must be ignored to maintain goal-directed activities, or when there is a conflict between what one needs to do and what one would prefer to do (Burgess & Shallice, 1996; Kaplan & Berman, 2010; Shallice & Burgess, 1991). Individuals across a wide-range of diagnoses and ages exhibit disorders of executive functions. Executive functions are often delayed during atypical development and are disrupted by disease or trauma in
both children and adults. Several theories have been put forward regarding the components of executive functions. These theoretical frameworks are useful for occupational therapists to guide them in assessment, goal-setting, and treatment planning. One of the most difficult tasks is determining whether component skills of executive functions are affecting performance or whether “putting it all together” is the primary difficulty for a client. An understanding of the underlying theory of executive abilities makes this task much more manageable. Using an executive function theoretical framework to guide assessment will also help clinicians work with their clients to manage impairments of executive function that translate to difficulties in their occupational performance.
Definitions In reviewing the literature, three abilities emerge with empirical support as the major subdivisions of executive function: (1) inhibition, (2) working memory, and (3) strategic processing/planning (Braver, Cohen, & Barch, 2002; Diamond, 2002; GoldmanRakic, 1996; Shallice, Levin, Eisenberg & Benton,
Lisa Tabor Connor, PhD, is Assistant Professor, Program in Occupational Therapy and Departments of Radiology & Neurology, Washington University School of Medicine, St. Louis, Missouri. Adina Maeir, PhD, is Occupational Therapist and Lecturer, School of Occupational Therapy, Hadassah and the Faculty of Medicine Hebrew University, Jerusalem, Israel. Originally submitted July 15, 2010. Accepted for publication July 25, 2010. The authors have no financial or proprietary interest in the materials presented herein. Address correspondence to Lisa Tabor Connor at [email protected]. doi: 10.3928/15394492-20101108-02
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1991; Smith & Jonides, 1999). Each of these subdivisions has several theoretical models; for instance, Baddeley has developed an extensive model of the components of working memory (see Repovš & Baddeley [2006] for a review). Some investigators further divide these executive abilities into sub-processes or skills. For example, working memory has been parceled into set shifting, switching, monitoring, and updating (Baddeley, 1996; Jonides & Smith, 1997; Miyake et al., 2000; Norman & Shallice, 1986). Because the field has less consensus regarding these finer distinctions than for the broader executive constructs, we focus on the three agreed-upon primary components of executive function. Inhibition is the ability to suppress irrelevant information. For example, a person may receive a telephone call during a critical time in a cooking task. Inhibition would come into play if the person was able to ignore the distracting telephone ring to complete the time-critical cooking task. Working memory is the ability to both hold information in a short-term storage buffer and to mentally manipulate that information. An example of working memory in action is calculating a tip on a restaurant bill. One must hold the total in mind, multiply the total by a percentage (maybe in a multi-step process), retrieve the total, and add the tip, arriving at the final amount to be paid. Strategic processing is the ability to formulate a plan and to monitor the success of a strategy. For instance, given a list of words to memorize, a strategy that one may employ is to group the items into categories such as “items of clothing” or “fruits” to aid in retrieval. During recall of that list, people who properly use categorization as a strategy will retrieve the members of the list within a category sequentially and may even prompt themselves with the category label “clothing” to help retrieve more items. People with impairments of executive abilities may have difficulties performing tasks that rely on specific ones of these component processes or may have multiple problems that affect their performance. In addition to these components, some executive function models include an “overseer” or “glue” that aids in coordinating the component activities. Shallice (2001) proposed a Supervisory System that influences lower level processes. However, Duncan and colleagues (Duncan, 2005; Roca et al., 2010) proposed that executive skills are equivalent to fluid intelligence, that a supervisory system does not exist, and that frontal executive functions are not truly dissociable. Stuss and Alexander (2007) proposed an intermediate position, that the component processes are attentionally based and dissociable but are not overseen by a supervisory system.
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Although cognitive models of executive abilities include inhibition, working memory, and strategic processing, these constructs do not have a oneto-one correspondence to brain structures. Recent work, moreover, has indicated that not all of the brain structures involved in executive abilities reside in the frontal lobes (Alvarez & Emory, 2006; Tamez et al., 2010). Although traditional neuropsychological tests of executive abilities are sensitive to frontal lobe damage, they are not specific. Therefore, one may expect to see impairments of executive abilities in people with lesions throughout the brain in gray or white matter and in those with degenerative diseases such as Alzheimer’s disease, Parkinson disease, or multiple sclerosis.
Occupational Significance Executive functioning supports occupational engagement, particularly in novel, complex, and unstructured activities (Gillen, 2009; Katz, 2005). Routinely performed activities in familiar context provide minimal challenges to the executive functions, but even a minimal alteration in activity demands or context will require the activation of the executive functions (e.g., inhibiting automatic responses, selecting, implementing, and monitoring an alternative plan of action). Instrumental activities of daily living (IADLs), by definition, are complex and continuously changing, and therefore considered a classic focus for occupational therapy intervention (assessment and treatment) for populations with suspected executive function deficits. The need for executive functions in productivity and leisure occupational areas vary, depending on the complexity of the task, the degree of familiarity, and the amount of structure provided. Social participation is one of the more complex occupational areas. Because engagement in social interactions entails perceiving and interpreting multiple cues, selecting adequate behavioral responses, and monitoring their effectiveness, it is inherently linked with executive functioning. The multiple contexts of our lives frequently undergo change, requiring us to devise new ways to perform activities that we want or need to do. The contextual novelty in our lives ranges from the profound changes that occur with age, moving to a new residence, changing workplace, transitory social networks, political and legal reforms, and technological innovations, to a simple detour in traffic due to road repair. Such novelty requires that we identify the need for making changes and suppress our habitual performance mode, come up with new plans, execute, and monitor our performance accordingly.
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Thus, the nature of the dynamic environment we live in challenges our executive functioning on a daily basis. The unique Person-Environment-OccupationPerformance (PEOP) (Baum, Bass-Haugen, & Christiansen, 2005) perspective reveals a highly significant role for the executive functions in living with the complexity and novelty posed by the dynamic demands of daily life. Even a mild deficit in executive functions could have serious implications for a person’s occupational performance. The adaptive path of an individual with deficits in executive function who encounters difficulty in performing an activity involves the recruitment of resources (within the person or environment) and use of strategies that enable successful performance. When an individual is not able to recruit such resources (due to lack of awareness or availability of resources) and he or she experiences repeated failure in desired activities, a maladaptive cycle may begin. This disabling cycle, triggered by negative occupational experiences due to executive function deficit, may have broad implications for overall health and well-being, including reduced self-efficacy, occupational withdrawal, social isolation, and deterioration in mental and physical health (Christiansen, Baum, & Bass-Haugen, 2005). The objectives of occupational therapy intervention for individuals with executive function deficit are to enable participation and to prevent the harmful consequences of these deficits.
Assessment Recently, the assessment of executive functions has evolved from a neuropsychological-psychometric approach toward a performance-based clinimetric approach. Historically, clients have been assessed with tabletop tools such as the Wisconsin Card Sorting Test (Heaton, Chelune, Talley, Kay, & Curtiss, 1993), the Stroop Color-Word Interference task (Stroop, 1935), the Trailmaking Test (Reitan & Wolfson, 1993), the Digit Span Task (especially the Digits Backward condition, Wechsler, 1997), the Controlled Oral Word Association Test (Benton & Hamsher, 1976), and the Delis–Kaplan Executive Function System (Delis, Kaplan, & Kramer, 2001). The client’s performance on all of these paper-and-pencil tests is presumed to extrapolate to performance in everyday tasks requiring these executive skills. However, the nature of the relationship between performance on these measures of executive abilities and performance in everyday tasks is unclear. Burgess et al. (2006), in particular, have criticized these tools as having dubious ecological validity and limitations
in their ability to generalize to real-world functioning. Due to the limitations of the neuropsychological tools in predicting performance in everyday problem-solving tasks, Burgess et al. (2006) have urged the development of tools that simulate the conditions of everyday task performance to evaluate a client’s ability to function in the real world. This performance-based clinimetric approach is particularly germane to occupational therapists because it focuses on what a person is able and unable to do. Several instruments have been developed to accomplish this goal: the Multiple Errands Test and its variants (Alderman, Burgess, Knight, & Henman, 2003; Dawson et al., 2009; Shallice & Burgess, 1991); the Executive Function Performance Test (EFPT; Baum, Morrison, Hahn, & Edwards, 2003); the Cognitive Performance Test (Burns, 2006); the Assessment of Motor and Process Skills (Fisher, 2006a, 2006b); and the Kettle Test (Hartman-Maeir, Harel, & Katz, 2009). These tools have been developed to detect clinically meaningful deviation on a task that will have relevance to performance in real-world functioning. Two of these instruments, the EFPT and Kettle Test, were developed specifically with the component processes of executive abilities in mind. The EFPT measures performance on four IADLs—preparing food, making a telephone call, paying bills, and taking medications— all IADLS required for independent living. The test measures the amount of cueing that a client needs to be successful in each of the tasks and scores cueing levels required in domains of executive functioning—initiation, organization, sequencing, completion, and judgment and safety. Relating this to our theoretical conception of executive abilities, initiation, organization, and completion requires strategic processing; sequencing requires working memory and inhibitory control; and judgment and safety requires strategic processing and inhibitory control. The Kettle Test was designed to require these same executive components, working memory, strategic processing (problem-solving in their scheme), and inhibitory control. Careful examination of the manner in which clients exhibit difficulty with the tasks in the EFPT, or steps in the Kettle Test, reveals the source of the underlying executive impairment. For instance, if the client selectively and consistently requires cueing in the sequencing component of tasks in the EFPT or if the client is overwhelmed by the additional kitchen utensils placed on a tray as distracters in the Kettle Test, one may infer that the client has difficulty with inhibitory control. Moreover, one may expect that other tasks requiring inhibitory control, such as ignoring a telephone call while cooking, may present challenges to occupational performance. The Cog-
OTJR: Occupation, Participation and Health • Vol. 31, No. 1 (Suppl.), 2011 Downloaded from otj.sagepub.com at UCSF LIBRARY & CKM on March 15, 2015
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nitive Functional Evaluation (Hartman-Maeir, Katz, & Baum, 2009) conceptualizes the evaluation process for individuals with suspected cognitive disabilities and is recommended as the basis for intervention decisions.
dence-based interventions that will enable participation and improve the health and well-being of these individuals.
Intervention
Alderman, N., Burgess, P. W., Knight, C., & Henman, C. (2003). Ecological validity of a simplified version of the multiple errands shopping test. Journal of the International Neuropsychological Society, 9, 31-44.
Interventions for individuals with executive function deficit rely on the occupational therapy models for rehabilitation of individuals with cognitive disabilities (Katz, 2005) and include metacognitive strategy training, functional task training, and environmental adaptations. These models differ in their requirements (declarative learning, procedural learning, and environmental resources) and hence can be tailored to the individual profile of the client. The metacognitive model requires declarative learning processes to acquire executive strategies (e.g., defining realistic goals, planning templates, time management, and self-monitoring), whereas the functional training approach focuses on specific task training and relies primarily on procedural learning mechanisms. The value of strategy training lies in the potential transfer of executive strategies to multiple activities and contexts, thus offering valuable tools to foster a broad impact on occupational performance, whereas the value of functional training lies in its high probability of achieving rapid success in a meaningful activity. The adaptive model delineates the type of support that will enable participation for individuals with executive function deficit (e.g., providing a structured plan for achieving a goal, reducing complexity, and mediated social interactions) and relies on the availability of environmental resources (i.e., individuals in the client’s environment who are able and willing to provide such supports). The unique value of this model lies in the minimal emotional and cognitive resources it requires from the client. The model enables participation as long as the supports are in place. The primary factors that contribute to clinical reasoning in the choice of models include severity of deficit, awareness of disability, the emotional state of the client, and environmental resources. Furthermore, an integrative approach that uses these assessment tools and intervention models, coupled with sound clinical reasoning, can provide a powerful change agent, targeting the maladaptive occupational functioning due to executive function deficit. Given the impact of executive functions on so many aspects of participation, and the vulnerability of executive functions in a wide variety of health conditions, occupational therapy is faced with the challenge of providing theoretically driven, evi-
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References
Alvarez, J. A., & Emory, E. (2006). Executive function and the frontal lobes: A meta-analytic review. Neuropsychology Review, 16, 17-42. Baddeley, A. (1996). Exploring the central executive. Quarterly Journal of Experimental Psychology, 49, 5-28. Baum, C. M., Bass-Haugen, J., & Christiansen, C. (2005). A model for planning interventions for individuals and organizations. In C. Christiansen & C. M. Baum (Eds.), Occupational Therapy: Performance, Participation and Well-Being (pp. 372-385). Thorofare, NJ: SLACK Incorporated. Baum, C. M., Morrison, T., Hahn, M., & Edwards, D. F. (2003). Test manual: Executive Function Performance Test. St. Louis, MO: Washington University. Benton, A. L., & Hamsher, K. (1976). Multilingual aphasia examination. Iowa City, IA: University of Iowa Press. Braver, T. S., Cohen, J. D., & Barch, D. M. (2002). The role of the prefrontal cortex in normal and disordered cognitive control: A cognitive neuroscience perspective. In D. T. Stuss & R. T. Knight (Eds.), Principles of frontal lobe function (pp. 428-448). Oxford: Oxford University Press. Burgess, P. W. (2000). Strategy application disorder: The role of the frontal lobes in human multitasking. Psychological Research, 63, 279-288. Burgess, P. W., Alderman, N., Forbes, C., Costello, A., Coates, L. M-A., Dawson, D. R., et al. (2006). The case for the development and use of “ecologically valid” measures of executive function in experimental and clinical neuropsychology. Journal of the International Neuropsychological Society, 12, 194-209. Burgess, P. W., & Shallice, T. (1996). Response suppression, initiation and strategy use following frontal lobe lesions. Neuropsychologia, 34, 263-273. Burns, T. (2006). Cognitive Performance Test (CPT). Pequannock, NJ: Maddak. Christiansen, C. H., Baum, C. M., & Bass-Haugen, J. (2005). Occupational therapy: Performance, participation, and well-being. Thorofare, NJ: SLACK Incorporated. Dawson, D. R., Anderson, N. D., Burgess, P., Cooper, E., Krpan, K. M., & Stuss, D. T. (2009). Further development of the Multiple Errands Test: Standardized scoring, reliability, and ecological validity for the Baycrest version. Archives of Physical Medicine and Rehabilitation, 90(Suppl. 1), S41-S51. Delis, D. C., Kaplan, E., & Kramer, J. H. (2001). Delis Kaplan Executive Function System. San Antonio, TX: The Psychological Corporation, Harcourt Assessment Company. Diamond, A. (2002). Normal development of prefrontal cortex from birth to young adulthood: Cognitive functions, anatomy, and biochemistry. In D. T. Stuss & R. T. Knight (Eds.), Principles of frontal lobe function (pp. 466-503). Oxford: Oxford University Press. Duncan, J. (2005). Frontal lobe function and general intelligence:
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Why it matters. Cortex, 41, 215-217. Fisher, A. G. (2006a). Assessment of motor and process skills. Vol 1: Development, standardization, and administration manual (6th ed.). Fort Collins, CO: Three Star Press. Fisher, A. G. (2006b). Assessment of motor and process skills. Vol 2: User manual (6th ed.). Fort Collins, CO: Three Star Press. Gillen, G. (2009). Cognitive and perceptual rehabilitation: Optimizing function. St. Louis, MO: Mosby, Elsevier. Goldman-Rakic, P. S. (1996). The prefrontal landscape: Implications of functional architecture for understanding human mentation and the central executive. In A. C. Roberts, T. W. Robbins, & L. Weiskrantz (Eds.), The prefrontal cortex: Executive and cognitive functions (pp. 87-103). Oxford: Oxford University Press. Hartman-Maeir, A., Harel, H., & Katz, N. (2009). Kettle Test – A brief measure of cognitive functional performance: Reliability and validity in stroke rehabilitation. American Journal of Occupational Therapy, 63, 592-599. Hartman-Maeir, A., Katz, N., & Baum, C. (2009). Cognitive Functional Evaluation (CFE) process for individuals with suspected cognitive disabilities. Occupational Therapy in Health Care, 23(1), 1-23. Heaton, R. K., Chelune, G. J., Talley, J. L., Kay G. G., & Curtiss, G. (1993). Wisconsin Card Sorting Test Manual: Revised and Expanded. Odessa, FL: Psychological Assessment Resources. Jonides, J., & Smith, E. E. (1997). The architecture of working memory. In M. D. Rugg (Ed.), Cognitive neuroscience. Cambridge, MA: The MIT Press. Kaplan, S., & Berman, M. G. (2010). Directed attention as a common resource for executive functioning and self-regulation. Perspectives on Psychological Science, 5(1), 43-57. Katz, N. (2005). Cognition and occupation across the life span: Models for intervention in occupational therapy. Bethesda, MD: American Occupational Therapy Association Press. 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 “fron-
tal lobe” tasks: A latent variable analysis. Cognitive Psychology, 41, 49-100. Norman, D. A., & Shallice, T. (1986). Attention to action: Willed and automatic control of behavior. In R. J. Davidson, G. E. Schwartz, & D. Shapiro (Eds.), Consciousness and self-regulation (Vol. 4, pp. 1-18). New York: Plenum Press. Reitan, R. M., & Wolfson, D. (1993). The Halstead-Reitan neuropsychological test battery: Theory and clinical interpretation (2nd ed.). South Tucson, AZ: Neuropsychology Press. Repovš, G., & Baddeley, A. (2006). The multi-component model of working memory: Explorations in experimental cognitive psychology. Neuroscience, 139, 5-21. Roca, M., Parr, A., Thompson, R., Woolgar, A., Torralva, T., Antoun, N., et al. (2010). Executive function and fluid intelligence after frontal lobe lesions. Brain, 133, 234-247. Shallice, T. (2001). Fractionating the supervisory system. Brain and Cognition, 47, 30. Shallice, T., Levin, H. S., Eisenberg, H. M., & Benton, A. L. (Eds.). (1991). Frontal lobe function and dysfunction. Oxford: Oxford University Press. Shallice, T., & Burgess, P. W. (1991). Deficits in strategy application following frontal lobe damage in man. Brain, 114, 727-741. Smith, E. E., & Jonides, J. (1999). Storage and executive processes in the frontal lobes. Science, 283, 1657-1661. Stroop, J. R. (1935). Studies of interference in serial verbal reaction. Journal of Experimental Psychology, 18, 643-662. Stuss, D. T., & Alexander, M. P. (2007). Is there a dysexecutive syndrome? Philosophical Transactions of the Royal Society B, 362, 901-915. Tamez, E., Myerson, J., Morris, L., White, D. A., Baum, C., & Connor, L. T. (2010). Assessing executive abilities following acute stroke with the Trail Making Test and Digit Span. Manuscript submitted for publication. Wechsler, D. (1997). Wechsler Memory Scale-III. Manual. New York: Psychological Corporation.
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E
xecutive functions are the skills that underlie our ability to complete complex tasks in daily life, such as making a meal, completing a school assignment, managing a family, and completing essential job functions (Burgess, 2000; Shallice & Burgess, 1991). Executive functions are often more evident when they are disordered or absent than when intact. Components of executive function include the ability to formulate and maintain goals and strategies, to hold information in mind for further processing, and to inhibit irrelevant information. Executive functions are evident any time multi-tasking is required, when goals need to be formulated to accomplish a task, when tasks have a particular sequence of activities that must be performed for successful completion, when competing stimuli must be ignored to maintain goal-directed activities, or when there is a conflict between what one needs to do and what one would prefer to do (Burgess & Shallice, 1996; Kaplan & Berman, 2010; Shallice & Burgess, 1991). Individuals across a wide-range of diagnoses and ages exhibit disorders of executive functions. Executive functions are often delayed during atypical development and are disrupted by disease or trauma in
both children and adults. Several theories have been put forward regarding the components of executive functions. These theoretical frameworks are useful for occupational therapists to guide them in assessment, goal-setting, and treatment planning. One of the most difficult tasks is determining whether component skills of executive functions are affecting performance or whether “putting it all together” is the primary difficulty for a client. An understanding of the underlying theory of executive abilities makes this task much more manageable. Using an executive function theoretical framework to guide assessment will also help clinicians work with their clients to manage impairments of executive function that translate to difficulties in their occupational performance.
Definitions In reviewing the literature, three abilities emerge with empirical support as the major subdivisions of executive function: (1) inhibition, (2) working memory, and (3) strategic processing/planning (Braver, Cohen, & Barch, 2002; Diamond, 2002; GoldmanRakic, 1996; Shallice, Levin, Eisenberg & Benton,
Lisa Tabor Connor, PhD, is Assistant Professor, Program in Occupational Therapy and Departments of Radiology & Neurology, Washington University School of Medicine, St. Louis, Missouri. Adina Maeir, PhD, is Occupational Therapist and Lecturer, School of Occupational Therapy, Hadassah and the Faculty of Medicine Hebrew University, Jerusalem, Israel. Originally submitted July 15, 2010. Accepted for publication July 25, 2010. The authors have no financial or proprietary interest in the materials presented herein. Address correspondence to Lisa Tabor Connor at [email protected]. doi: 10.3928/15394492-20101108-02
OTJR: Occupation, Participation and Health • Vol. 31, No. 1 (Suppl.), 2011 Downloaded from otj.sagepub.com at UCSF LIBRARY & CKM on March 15, 2015
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1991; Smith & Jonides, 1999). Each of these subdivisions has several theoretical models; for instance, Baddeley has developed an extensive model of the components of working memory (see Repovš & Baddeley [2006] for a review). Some investigators further divide these executive abilities into sub-processes or skills. For example, working memory has been parceled into set shifting, switching, monitoring, and updating (Baddeley, 1996; Jonides & Smith, 1997; Miyake et al., 2000; Norman & Shallice, 1986). Because the field has less consensus regarding these finer distinctions than for the broader executive constructs, we focus on the three agreed-upon primary components of executive function. Inhibition is the ability to suppress irrelevant information. For example, a person may receive a telephone call during a critical time in a cooking task. Inhibition would come into play if the person was able to ignore the distracting telephone ring to complete the time-critical cooking task. Working memory is the ability to both hold information in a short-term storage buffer and to mentally manipulate that information. An example of working memory in action is calculating a tip on a restaurant bill. One must hold the total in mind, multiply the total by a percentage (maybe in a multi-step process), retrieve the total, and add the tip, arriving at the final amount to be paid. Strategic processing is the ability to formulate a plan and to monitor the success of a strategy. For instance, given a list of words to memorize, a strategy that one may employ is to group the items into categories such as “items of clothing” or “fruits” to aid in retrieval. During recall of that list, people who properly use categorization as a strategy will retrieve the members of the list within a category sequentially and may even prompt themselves with the category label “clothing” to help retrieve more items. People with impairments of executive abilities may have difficulties performing tasks that rely on specific ones of these component processes or may have multiple problems that affect their performance. In addition to these components, some executive function models include an “overseer” or “glue” that aids in coordinating the component activities. Shallice (2001) proposed a Supervisory System that influences lower level processes. However, Duncan and colleagues (Duncan, 2005; Roca et al., 2010) proposed that executive skills are equivalent to fluid intelligence, that a supervisory system does not exist, and that frontal executive functions are not truly dissociable. Stuss and Alexander (2007) proposed an intermediate position, that the component processes are attentionally based and dissociable but are not overseen by a supervisory system.
S4
Although cognitive models of executive abilities include inhibition, working memory, and strategic processing, these constructs do not have a oneto-one correspondence to brain structures. Recent work, moreover, has indicated that not all of the brain structures involved in executive abilities reside in the frontal lobes (Alvarez & Emory, 2006; Tamez et al., 2010). Although traditional neuropsychological tests of executive abilities are sensitive to frontal lobe damage, they are not specific. Therefore, one may expect to see impairments of executive abilities in people with lesions throughout the brain in gray or white matter and in those with degenerative diseases such as Alzheimer’s disease, Parkinson disease, or multiple sclerosis.
Occupational Significance Executive functioning supports occupational engagement, particularly in novel, complex, and unstructured activities (Gillen, 2009; Katz, 2005). Routinely performed activities in familiar context provide minimal challenges to the executive functions, but even a minimal alteration in activity demands or context will require the activation of the executive functions (e.g., inhibiting automatic responses, selecting, implementing, and monitoring an alternative plan of action). Instrumental activities of daily living (IADLs), by definition, are complex and continuously changing, and therefore considered a classic focus for occupational therapy intervention (assessment and treatment) for populations with suspected executive function deficits. The need for executive functions in productivity and leisure occupational areas vary, depending on the complexity of the task, the degree of familiarity, and the amount of structure provided. Social participation is one of the more complex occupational areas. Because engagement in social interactions entails perceiving and interpreting multiple cues, selecting adequate behavioral responses, and monitoring their effectiveness, it is inherently linked with executive functioning. The multiple contexts of our lives frequently undergo change, requiring us to devise new ways to perform activities that we want or need to do. The contextual novelty in our lives ranges from the profound changes that occur with age, moving to a new residence, changing workplace, transitory social networks, political and legal reforms, and technological innovations, to a simple detour in traffic due to road repair. Such novelty requires that we identify the need for making changes and suppress our habitual performance mode, come up with new plans, execute, and monitor our performance accordingly.
Copyright © American Occupational Therapy Foundation Downloaded from otj.sagepub.com at UCSF LIBRARY & CKM on March 15, 2015
Thus, the nature of the dynamic environment we live in challenges our executive functioning on a daily basis. The unique Person-Environment-OccupationPerformance (PEOP) (Baum, Bass-Haugen, & Christiansen, 2005) perspective reveals a highly significant role for the executive functions in living with the complexity and novelty posed by the dynamic demands of daily life. Even a mild deficit in executive functions could have serious implications for a person’s occupational performance. The adaptive path of an individual with deficits in executive function who encounters difficulty in performing an activity involves the recruitment of resources (within the person or environment) and use of strategies that enable successful performance. When an individual is not able to recruit such resources (due to lack of awareness or availability of resources) and he or she experiences repeated failure in desired activities, a maladaptive cycle may begin. This disabling cycle, triggered by negative occupational experiences due to executive function deficit, may have broad implications for overall health and well-being, including reduced self-efficacy, occupational withdrawal, social isolation, and deterioration in mental and physical health (Christiansen, Baum, & Bass-Haugen, 2005). The objectives of occupational therapy intervention for individuals with executive function deficit are to enable participation and to prevent the harmful consequences of these deficits.
Assessment Recently, the assessment of executive functions has evolved from a neuropsychological-psychometric approach toward a performance-based clinimetric approach. Historically, clients have been assessed with tabletop tools such as the Wisconsin Card Sorting Test (Heaton, Chelune, Talley, Kay, & Curtiss, 1993), the Stroop Color-Word Interference task (Stroop, 1935), the Trailmaking Test (Reitan & Wolfson, 1993), the Digit Span Task (especially the Digits Backward condition, Wechsler, 1997), the Controlled Oral Word Association Test (Benton & Hamsher, 1976), and the Delis–Kaplan Executive Function System (Delis, Kaplan, & Kramer, 2001). The client’s performance on all of these paper-and-pencil tests is presumed to extrapolate to performance in everyday tasks requiring these executive skills. However, the nature of the relationship between performance on these measures of executive abilities and performance in everyday tasks is unclear. Burgess et al. (2006), in particular, have criticized these tools as having dubious ecological validity and limitations
in their ability to generalize to real-world functioning. Due to the limitations of the neuropsychological tools in predicting performance in everyday problem-solving tasks, Burgess et al. (2006) have urged the development of tools that simulate the conditions of everyday task performance to evaluate a client’s ability to function in the real world. This performance-based clinimetric approach is particularly germane to occupational therapists because it focuses on what a person is able and unable to do. Several instruments have been developed to accomplish this goal: the Multiple Errands Test and its variants (Alderman, Burgess, Knight, & Henman, 2003; Dawson et al., 2009; Shallice & Burgess, 1991); the Executive Function Performance Test (EFPT; Baum, Morrison, Hahn, & Edwards, 2003); the Cognitive Performance Test (Burns, 2006); the Assessment of Motor and Process Skills (Fisher, 2006a, 2006b); and the Kettle Test (Hartman-Maeir, Harel, & Katz, 2009). These tools have been developed to detect clinically meaningful deviation on a task that will have relevance to performance in real-world functioning. Two of these instruments, the EFPT and Kettle Test, were developed specifically with the component processes of executive abilities in mind. The EFPT measures performance on four IADLs—preparing food, making a telephone call, paying bills, and taking medications— all IADLS required for independent living. The test measures the amount of cueing that a client needs to be successful in each of the tasks and scores cueing levels required in domains of executive functioning—initiation, organization, sequencing, completion, and judgment and safety. Relating this to our theoretical conception of executive abilities, initiation, organization, and completion requires strategic processing; sequencing requires working memory and inhibitory control; and judgment and safety requires strategic processing and inhibitory control. The Kettle Test was designed to require these same executive components, working memory, strategic processing (problem-solving in their scheme), and inhibitory control. Careful examination of the manner in which clients exhibit difficulty with the tasks in the EFPT, or steps in the Kettle Test, reveals the source of the underlying executive impairment. For instance, if the client selectively and consistently requires cueing in the sequencing component of tasks in the EFPT or if the client is overwhelmed by the additional kitchen utensils placed on a tray as distracters in the Kettle Test, one may infer that the client has difficulty with inhibitory control. Moreover, one may expect that other tasks requiring inhibitory control, such as ignoring a telephone call while cooking, may present challenges to occupational performance. The Cog-
OTJR: Occupation, Participation and Health • Vol. 31, No. 1 (Suppl.), 2011 Downloaded from otj.sagepub.com at UCSF LIBRARY & CKM on March 15, 2015
S5
nitive Functional Evaluation (Hartman-Maeir, Katz, & Baum, 2009) conceptualizes the evaluation process for individuals with suspected cognitive disabilities and is recommended as the basis for intervention decisions.
dence-based interventions that will enable participation and improve the health and well-being of these individuals.
Intervention
Alderman, N., Burgess, P. W., Knight, C., & Henman, C. (2003). Ecological validity of a simplified version of the multiple errands shopping test. Journal of the International Neuropsychological Society, 9, 31-44.
Interventions for individuals with executive function deficit rely on the occupational therapy models for rehabilitation of individuals with cognitive disabilities (Katz, 2005) and include metacognitive strategy training, functional task training, and environmental adaptations. These models differ in their requirements (declarative learning, procedural learning, and environmental resources) and hence can be tailored to the individual profile of the client. The metacognitive model requires declarative learning processes to acquire executive strategies (e.g., defining realistic goals, planning templates, time management, and self-monitoring), whereas the functional training approach focuses on specific task training and relies primarily on procedural learning mechanisms. The value of strategy training lies in the potential transfer of executive strategies to multiple activities and contexts, thus offering valuable tools to foster a broad impact on occupational performance, whereas the value of functional training lies in its high probability of achieving rapid success in a meaningful activity. The adaptive model delineates the type of support that will enable participation for individuals with executive function deficit (e.g., providing a structured plan for achieving a goal, reducing complexity, and mediated social interactions) and relies on the availability of environmental resources (i.e., individuals in the client’s environment who are able and willing to provide such supports). The unique value of this model lies in the minimal emotional and cognitive resources it requires from the client. The model enables participation as long as the supports are in place. The primary factors that contribute to clinical reasoning in the choice of models include severity of deficit, awareness of disability, the emotional state of the client, and environmental resources. Furthermore, an integrative approach that uses these assessment tools and intervention models, coupled with sound clinical reasoning, can provide a powerful change agent, targeting the maladaptive occupational functioning due to executive function deficit. Given the impact of executive functions on so many aspects of participation, and the vulnerability of executive functions in a wide variety of health conditions, occupational therapy is faced with the challenge of providing theoretically driven, evi-
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References
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