What is Executive Function?

Executive Function (EF) refers to brain functions that activate, organize, integrate and manage other functions. It enables individuals to account for short and long term consequences of their actions and to plan for those results. It also allows individuals to make real time evaluations of their actions, and make necessary adjustments if those actions are not achieving the desired result.There are differing models of executive function put forth by different researchers, but the above statements cover the basics that are common to most. Two of the major ADHD researchers involved in studying EF are Russell Barkley, PhD, and Tom Brown, PhD.
Barkley breaks executive functions down into four areas:

1. Nonverbal working memory
2. Internalization of Speech (verbal working memory)
3. Self-regulation of affect/motivation/arousal
4. Reconstitution (planning and generativity)

Barkley's model is based on the idea that inabilities to self-regulate lie at the root of many challenges faced by individuals with ADHD. He puts forth that they are unable to delay responses, thus acting impulsively, and without adequate consideration of future consequences -- beneficial or negative.1

Brown breaks executive functions down into six different "clusters."

1. Organizing, prioritizing and activating for tasks
2. Focusing, sustaining and shifting attention to task
3. Regulating alertness, sustaining effort and processing speed
4. Managing frustration and modulating emotions
5. Utilizing working memory and accessing recall
6. Monitoring and self-regulating action

According to Brown, these clusters operate in an integrated way, and people with ADHD tend to suffer impairments in at least some aspects of each cluster. Because these impairments seem to show up together much of the time, Brown believes they are clinically related.

Under Brown's model, difficulties in these clusters lead to attentional deficits, as individuals have difficulty organizing tasks, getting started, remaining engaged, remaining alert, maintaining a level emotional state, applying working memory and recall, and self-monitoring and regulating actions.2

It is clear that executive function impairments have an adverse effect on an individual's ability to begin, work on and complete tasks. It is also commonly thought that deficits in executive functions are highly interrelated to symptoms associated with ADHD.

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1. Barkley, Russell A., Murphy, Kevin R., Fischer, Mariellen (2008). ADHD in Adults: What the Science Says (pp 171 - 175). New York, Guilford Press.

2. Brown, Thomas E. (2005). Attention Deficit Disorder: The Unfocused Mind in Children and Adults (pp 20 - 58). New Haven, CT, Yale University Press Health and Wellness.