Assessment and Intervention for Executive Dysfunction
Executive functions are interrelated control processes involved in the selection, initiation, execution, and monitoring of cognitive functioning, as well as aspects of motor and sensory functioning. They are self-regulatory functions that organize and direct cognitive activity, emotional responses, and overt behaviors. They may also be described as the orchestration of basic cognitive processes during goal-oriented problem solving, differentiating “basic” cognitive functions from “executive” cognitive control functions. In this metaphor, the executive serves as the conductor of the orchestra by making intentional decisions regarding the final output of the music and recruiting the necessary components in reaching the intended goal. The “instruments” are the domain-specific functions, such as language, visual/nonverbal reasoning, memory, sensory inputs, and motor outputs. The specific cognitive processes subsumed under the “executive” umbrella are a matter of continued debate. Nonetheless, processes commonly considered under the rubric of executive functions include the following:
• Inhibit: Ability to not act on an impulse, stop one’s own activity at the proper time, and suppress distracting information from interfering with ongoing mental or behavioral activity
• Shift (also referred to as set shifting, mental flexibility, or cognitive flexibility): Move (p. 106) flexibly from one situation, activity, or aspect of a problem to another as the situation demands
• Emotional control: Control one’s emotional response as appropriate to the situation or stressor; maintain an optimal level of arousal
• Initiate: Begin a task or activity without requiring external prompting
• Working memory: Hold information actively in mind over time
• Sustain: Stay with or stick to an activity for an age-appropriate amount of time
• Plan: Anticipate future events, set goals, and develop appropriate steps ahead of time
• Organize: Establish or maintain order in information, an activity, or a place; carry out tasks in a systematic manner
• Self-monitor: Check on one’s own actions during or shortly after finishing a task to assure accuracy and appropriate attainment of goal; awareness of one’s cognitive, physical, and emotional abilities or state; awareness of effects of our behavior on others
• Problem solving: Ability to think abstractly and form or develop concepts necessary to achieve a goal
Individuals with executive dysfunction can exhibit a broad range of problems such as acting inappropriately due to difficulty inhibiting impulses, quickly losing track of what they are thinking or doing, making poor financial or other personal decisions, or having considerable difficulty getting started on tasks. Difficulties with executive functions are often manifested in more than one specific cognitive domain, such that inhibitory control deficits can be expressed as verbal disinhibition, behavioral impulsivity, attentional distractibility, emotional reactivity, or social inappropriateness.
Neural Basis of Executive Functions and Other Contributing Factors
Historically, executive functions have been closely associated with the integrity of the frontal lobes. Much of the evidence supporting a role for the frontal lobes in executive functions has come from studies of patients with acquired focal damage to this brain region (Stuss & Knight, 2002). More recently, studies using advanced brain imaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have shown that the frontal lobes play an intimate role in executive functions (Roth, Randolph, Koven, & Isquith, 2006). However, neuroimaging studies have also clearly shown that executive functions are not subserved by the frontal lobes alone, but rather by distributed neural circuitry that includes other cortical regions such as the temporal and parietal lobes, subcortical structures such as the hippocampus and basal ganglia, and the cerebellum. Studies of patients with acquired focal lesions in nonfrontal brain regions such as the basal ganglia have also provided further support for a distributed circuitry model of executive functions. Furthermore, there is increasing evidence that disruption of white matter pathways connecting frontal cortex to other brain regions can be associated with poor executive control. Thus, damage to any given component of this circuitry, including connectivity between certain regions, may result in executive dysfunction.
Executive functions are mediated by a number of neurochemicals, particularly dopamine, serotonin, and norepinephrine (Robbins, 2000). Roles for other neurochemicals such as glutamate, acetylcholine, and GABA are being increasingly investigated. Disruption of one or more of these neurochemical systems may in part account for executive dysfunction in conditions where there is no obvious structural brain damage.
Individual differences in executive functions have been associated with variations in age, brain structure such as volume or thickness of particular regions, genetic polymorphisms (e.g., catechol O-methyltransferase), and several personality characteristics (Braver, Cole, & Yarkoni, 2010). A variety of environmental factors such as parenting style, psychosocial stress, exercise, caffeine use, and medications (e.g., stimulants, certain anticonvulsants) have been shown to impact on the integrity of executive functions. Transient factors may also affect (p. 107) performance on tests of executive function and the ability to successfully use executive functions in everyday life, including sleep, fatigue, mood, and level of motivation among others.
It is important to note that there is no “executive function disorder.” Rather, executive dysfunction may be seen in association with a wide variety of disorders, including the following:
• Attention-deficit/hyperactivity disorder (ADHD)
• Autism spectrum disorders
• Tourette’s syndrome
• Learning disabilities
• Traumatic brain injury
• Brain tumors
• Multiple sclerosis and other disorders affecting white matter connectivity
• Parkinson’s disease, Huntington’s disease, and other movement disorders
• Alzheimer’s disease and other dementias
• Psychiatric disorders such as schizophrenia, major depressive disorder, obsessive-compulsive disorder (OCD), and bipolar disorder
• Alcoholism and substance abuse disorders
The precise nature of the executive dysfunction observed in such conditions varies. For example, some disorders have been commonly, but not exclusively, associated with deficits in inhibitory control (e.g., ADHD-Combined type, OCD), while others appear to involve prominent deficits in working memory (e.g., ADHD-Inattentive type, schizophrenia, multiple sclerosis). Residual executive dysfunction may be observed in several disorders even when other symptoms are largely resolved (e.g., major depression, bipolar disorder, schizophrenia). In addition, evidence indicates that subtle problems with executive functions may be present prior to the onset of some conditions, and are present in at least a subset of the unaffected biological relatives of persons with some disorders (e.g., schizophrenia, alcoholism). It should be noted, however, that not all individuals with a given disorder demonstrate problems with executive functions on evaluation. For example, some children and adults with ADHD may show age-appropriate executive functions on performance-based measures (i.e., putative “tests” of executive function), despite several of the symptoms of the disorder listed in well-established formal diagnostic criteria (e.g., impulsivity, difficulty with organization) corresponding relatively well with executive dysfunction.
Assessment of Executive Dysfunction
Numerous measures have been designed to assess executive function. Some of the most commonly employed performance measures are the Wisconsin Card Sorting Test, the Stroop Color-Word Interference Test, Verbal Fluency tests, Tower tasks (e.g., Tower of London, Tower of Hanoi), and Trail Making tests (Strauss, Sherman, & Spreen, 2006). Establishing that an individual has executive dysfunction usually includes not only such psychometric tests but also a clinical interview and behavioral observations, at times supplemented by reports from informants familiar with the individual. Confirming that executive dysfunction is present also requires that problems in the basic or domain-specific cognitive, sensory, and motor functions be ruled out as accounting for the appearance of executive dysfunction. These include basic attention, language, visuospatial skills, sensory inputs (e.g., hearing, vision), peripheral motor function, and learning and memory.
Assessment of executive function is thus complicated. It is difficult to tease apart deficits in executive from domain-specific functions, given that most neuropsychological instruments are multifactorial in nature. Furthermore, the highly structured testing setting may provide the organization, guidance, and cuing necessary for optimal performance on measures of executive function, which would generally not be available in naturalistic settings. Many measures of executive function are also susceptible to practice effects. That is, once a person figures out how to successfully complete the task, he or she often performs much better on repeat testing or on similar tasks. This is consistent with (p. 108) evidence that executive dysfunction is more readily observed when patients are faced with novel tasks or stimuli, rather than familiar or routine tasks. Despite these limitations, performance measures of executive function can be useful in discriminating between clinical and healthy samples, and exhibit good sensitivity but not necessarily high specificity for specific disorders (Pennington & Ozonoff, 1996).
One concern expressed with regard to more traditional performance-based measures of executive function has been their somewhat limited relationship to functioning in the everyday environment. Increased attention has therefore been devoted to the development of instruments with greater ecological validity, that is, showing a significant predictive relationship between scores on the instrument and a patient’s behavior in “real-world” settings (Gioia, Kenworthy, & Isquith, 2010). Such measures of executive function include the following:
• Performance tests that require patients to complete “real-world” type tasks in the laboratory, such as the Test of Everyday Attention (TEA), Test of Everyday Attention for Children (TEA-Ch), and the Behavioral Assessment of the Dysexecutive Syndrome (BADS)
• Structured clinician rating scales such as the Frontal Behavioral Inventory
• Patient and/or informant completed questionnaires such as the Behavior Rating Inventory of Executive Function (BRIEF), Dysexecutive Questionnaire (DEX), and Frontal Systems Behavioral Scale (FrSBe)
There is evidence suggesting that both poor performance on performance-based measures, to some extent, and rating scales of executive function are associated with outcome variables such as academic and occupational functioning. In clinical practice, an assessment approach combining performance-based measures and rating scales may be the most fruitful in providing the most comprehensive understanding of a patient’s level of functioning and factors that contribute to difficulties in everyday life.
Intervention for Executive Dysfunction
An understanding of the executive components of an individual’s functioning can lead to targeted pharmacological, behavioral, cognitive, or other therapeutic interventions. Although study findings have varied, in part due to differences in methods and study populations, improvement of executive functions may be observed with computerized training, noncomputerized games, exercise, mindfulness training, use of compensatory strategies, as well as with environmental modifications (e.g., reducing distractions). Interventions may be specifically targeted toward one area of executive functions, such as antecedent management for children with inhibitory control deficits, or may be more programmatic, such as comprehensive cognitive rehabilitation programs (Ylvisaker & Feeney, 2009). A systematic review of treatment studies for executive function deficits following brain injury found sufficient evidence from randomized clinical trials to recommend metacognitive strategy instruction (MSI) methods as a practice standard (Kennedy et al., 2008).
An executive system intervention focus is possible in many settings, including classroom and occupational settings, therapy, social/recreational milieus, and in the home. Ylvisaker and Feeney (2009) articulated key elements of collaborative problem solving interventions (e.g., MSI) in the everyday world of the individual, including the following:
• Goal setting: An initial decision about or choice of a goal to pursue (What do I need to accomplish?)
• Self-awareness of strengths/weaknesses: Recognition of one’s stronger and weaker abilities, and a decision about how easy or difficult it will be to accomplish the goal (How easy or difficult is this task/goal? Have I done this type of task before?)
• Organization/planning: Development of an organized plan (What materials do we need? Who will do what? In what order do we need to do these things? How long will it take?) (p. 109)
• Flexibility/strategy use: As complications or obstructions arise, planned (e.g., staff members ensure that problems arise) or unplanned coaching of the students in flexible problem solving/strategic thinking (e.g., When/if a problem arises, what other ways should I think about to reach the goal? Should I ask for assistance?)
• Monitoring: A review of the goal, plan, and accomplishments at the end (e.g., How did I do?)
• Summarizing: What worked and what did not; what was easy and what was difficult and why
For individuals just starting to learn executive control behaviors, young children, or individuals with extreme executive dysfunction, the focus of intervention often needs to be more externalized or environmental, such as organizing and structuring the external environment for them, and cuing strategies and behavioral routines. They often need help to know when and how to apply the appropriate problem-solving behavioral routine. Direct rewards and positive incentives may be necessary to motivate the individual to attend to and practice new behavioral routines. A scaffolding approach may be particularly helpful, whereby an individual is provided with supports (e.g., cues) to help him or her complete relatively easy tasks that then become gradually more demanding as competence and self-confidence develop. Cognitive and/or behavioral strategies (e.g., self-talk, ways to improve organization and reduce distractions) may be provided to help the individual develop independence. Supports are then gradually faded as a function of the individual’s increasing autonomy.
References and Readings
Anderson, V., Jacobs, R., & Anderson, P. J. (2008). Executive functions and the frontal lobes: A lifespan perspective. New York: Psychology Press.Find this resource:
Braver, T. S., Cole, M. W., & Yarkoni, T. (2010). Vive les differences! Individual variation in neural mechanisms of executive control. Current Opinion in Neurobiology, 20(2), 242–250.Find this resource:
Gioia, G., Kenworthy, L., & Isquith, P. K. (2010). Executive function in the real world: BRIEF lessons from Mark Ylvisaker. Journal of Head Trauma Rehabilitation, 25(6), 433–439.Find this resource:
Kennedy, M. R. T., Coelho, C., Turkstra, L., Ylvisaker, M., Moore Sohlberg, M., Yorkston, K., … Kan, P-F. (2008). Intervention for executive functions after traumatic brain injury: A systematic review, meta-analysis and clinical recommendations. Neuropsychological Rehabilitation, 18(3), 257–299.Find this resource:
Pennington, B. F., & Ozonoff, S. (1996). Executive functions and developmental psychopathology. Journal of Child Psychology and Psychiatry and Allied Disciplines, 37(1), 51–87.Find this resource:
Robbins, T. W. (2000). Chemical neuromodulation of frontal-executive functions in humans and other animals. Experimental Brain Research, 133(1), 130–138.Find this resource:
Roth, R. M., Randolph, J. J., Koven, N. S., & Isquith, P. K. (2006). Neural substrates of executive functions: Insights from functional neuroimaging. In J. R. Dupri (Ed.), Focus on neuropsychology research (pp. 1–36). New York: Nova Science.Find this resource:
Strauss, E., Sherman, E. M. S., & Spreen, O. (2006). A compendium of neuropsychological tests (3rd ed.). New York: Oxford University Press.Find this resource:
Stuss, D. T., & Knight, R. T. (2002). Principles of frontal lobe function. New York: Oxford University Press.Find this resource:
Ylvisaker, M., & Feeney, T. (2009). Apprenticeship in self-regulation: Supports and interventions for individuals with self-regulatory impairments. Developmental Neurorehabilitation, 12(5), 370–379.Find this resource:
Chapter 9, “Evaluating the Medical Components of Childhood Developmental and Behavioral Disorders”
Chapter 12, “Evaluating Dementia”
Chapter 17, “Adult Neuropsychological Assessment”
Chapter 20, “Assessing and Managing Concussion”
Chapter 58, “Practicing Psychotherapy with Adults Who Have Cognitive Impairments”