Executive Functions NOT inattention as the defining trait

 

Although called Attention Deficit Disorder, and thus many parents and teachers believe that the primary problem is distractibility or poor attention, in reality  this disorder is primarily a disorder of impaired executive function.  When an individual has ADHD, executive functions are not emerging or unfolding as expected for the child chronological age. By executive functions I refer to a wide range of central control process of the brain that temporaneously connect, prioritize and integrate cognitive functions in the same manner that a conductor directs a band.   Clearly, this does not refer to a  single task at a given point in time such as focusing on getting a hamburger when hungry, or pushing a button at a given moment in order to stop a character is a video game from going forward.   But, it does mean there is impairment in the ability to sustain concentrated focus on a task that requires constant monitoring and adjustment, as well as intermediate and long-term projection into the future such as driving a car,  following a complicate classroom lecture or interacting with others and anticipating their reactions and the long-term outcomes of my statements or actions.  In short, impaired executive functions negatively impact the real stuff of day to day life.

 

A developing brain

 

The brain structures that support these executive functions are not fully developed at birth. The neural networks underlying intentional control begin to develop between the ages of two and four, but continue to develop into the twenties.  Between the ages of six and fifteen, we see significant growth of the collosal isthus that supports associative relay, simultaneously there is a substantial amount of pruning of synaptic connections which are not routinely engaged. Dopamine, norephinephrine and serotonin transmitter systems, likewise continue to develop into young adulthood. Significantly, after puberty during adolescence brain myelination increases 100%.

 

We also know from MRI studies of normal children that cortex thickness peaks at 11 years of age for females and 12.5 years of age for males. Thereafter, gradual pruning occurs progressing caudally to rostrally to insure more efficient circuits.

 

Since executive functions physiological capacity develops throughout childhood into adolescence and young adulthood, it is clearly not fully developed t in early childhood and we cannot expect the same level of executive control from children as we would from adults.  Still, when compared to non disabled peers, executive function impairments are often noticeable by age seven or eight, though in some cases they might not be recognized until significantly later.

 

In early childhood, parents and other caregivers perform all the executive functions for children.  Support or scaffolding of executive functions is provide by adults who show, direct, help, remind, coach and critique children.  For the normal child, this scaffolding is gradually faded out as the child becomes capable of performing these functions for themselves.  In adolescence and adulthood scaffolding may be provide by friends, teacher, coaches, spouses and supervisiors when executive functions have not developed as anticipated, but for this to be arranged, everyone needs to be aware of the diagnosis, understand its practical implications and make a commitment to provide appropriate supports.

 

In fact, impaired executive function might not be observed in young children if they live in a home which is well structured and attend a school setting that is likewise well structured. When ample predictability and scaffolding support is present, it may be that no one recognizes the child’s deficits until middle school when executive challenges begin to increase. In other cases, they are obvious in preschool years.

 

So, why are executive functions important?

 

Effective Executive functions are needed to prioritize, start, sustain, shift, stop, inhibit and integrate various cognitive functions. They permit one to manage one’s own behavior and depend upon the ability to utilize memory of previous experience without continual moment by moment guidance from others.   

 

We cannot rate specific tasks for level of executive function demand because each task will have a different executive function load for each individual. This is because tasks which are unfamiliar to the individual require more executive function capacity; while well practiced tasks require less executive function capacity.  Most executive functions actual operate unconsciously.  So, if a child has  gone camping week after week for the past year, and habitually packed the same emergency equipment, being asked to pack for a camping trip on his own will not require the same level of executive function as it would of another child who had never been camping before and needed to consider each item to be packed rather than simply recall it.

 

Interestingly,  stress has a curvilinear effect on executive functions.  Too little stress is not sufficiently challenging to invoke executive functions and too much overwhelms the system. This is why the complexity of a task much be tailored to the child’s current capacity and not based on the general education curriculum.  It is also why parents walk a very fine line between setting expectations that are too low, and being perceived as nagging a child to do something they aren’t equipped to do.  The field of play where each child can function at his best is different for each child, so one parent cannot not apply another parent’s rule of thumb.

 

Specifically what does executive functioning encompass?

 

Russell Barkley has presented a model of executive function impairment that is present in the hyperactive and combined types.  From  his perspective, inhibition is the central explanatory concepts of ADHD, but there is convincing evidence to support both excitatory (activating) and inhibitory problems in ADHD.  (Gilbert, 2006) Barkley, however, focuses only upon the impact that self-regulation of affect, motivation and arousal through inhibition has upon working memory and reconstitution.

 

Thomas Brown presents a more complex model of impaired executive functions in ADHD.  He sees it as dimensional, that is, we are not looking at an “all-or-nothing” situation. The fact is that everyone sometimes evidences impairments in these functions. The key in the case of ADHD is that the impairment is both severe and chronic;  and even when they are interested in an activity or during an apparently good period, individuals with ADHD may continue to evidence impairments in executive functions.

 

Brown  (Brown, 2000) sees impaired executive functions affecting all of the following:

 

1.  Activiation or Excitation.   Here we observe problems organizing tasks and materials, as well as difficulty estimating time and task durations as well as difficulty prioritizing tasks.  There is also difficulty initiating work on new tasks.  These are problems that any parent of an ADHD child can attest to, and they may have a substantially disruptive effect upon family functioning.

 

2.  Focus, Shift and Sustained Attention.  Individuals with ADHD evidence a tendency to lose focus when trying to listen or to plan. They are easily distracted by both internal and external stimuli. Consequently, the frequently forget what they have heard and need it to be repeated or forget what they have read and need to re-read it.

 

3.  Impaired ability to regulate Alertness, Effort and Processing Speed.  Individuals evidence problems regulating sleep and alertness. They may have difficulty both falling asleep or waking up fully.  Moreover, they quickly lose interest in tasks; particularly when those tasks are lengthy and show a consistent pattern of not sustaining effort over time.

 

4.  Management of Frustration and Emotional Modulation.  Though not included in the DWM-IV diagnostic criteria,  professionals experienced in working the individuals with ADHD find that the emotional impact of their emotions upon their thoughts and actions is excessive.  They exhibit frustration, irritation, feelings of hurt, worry and desires that spread throughout their mind and persist.  In short, they are not able to set these things aside and more onto other more productive thoughts.  Often they appear more sensitive to these feelings than others and to experience them over what appears to others to be relatively minor events.

 

5.Utilizing Working Memory.  Individuals with this disorder have difficulty remembering to remember; even though others give them frequent reminders and cues. They simply have difficulty holding one or more things in their mind at the same time while attending to other tasks. So, if they are searching for the QL slot to file a file, they are not able to simultaneously keep in mind that P precedes Q and is towards the end of the alphabet,  so they begin looking under A or keep repeating the alphabet over and over to themselves until they find the correct spot.   They seem to have an inadequate “search engine” for activating stored memories when they need them to integrate with current information in order to guide their present thoughts and actions.

 

6.  Self Monitoring and Regulation  Even when individuals with ADHD are not hyperactive or impulsive they have difficulty controlling their actions. It is hard for them to slow down or speed up as appropriate for different tasks.    Living with these children is like driving a car with a broken gas pedal that goes at 50-70 miles per hour whether you are in a school zone or on the highway. These individuals do not evaluate ongoing situations carefully, and as a result respond inappropriately.  It is difficult for them to monitor and modify their own actions in order to align them with the current situation or their own goals.

 

What caused my child to have ADHD?

 

The question that parents like answered is how their child came to have impaired executive functions. Some times as in the case of ADHD it is an inherited developmental disorder  At other times, executive functions can be impaired by a mild traumatic brain injury perhaps sustained in a car accident or by diseases such as Alzheimer’s.  The difference between developmental impaired executive dysfunction and acquire dysfunction is that in the case of the developmental impaired adequate executive function capacity was never present.  In the case of acquired dysfunction the individual’s brain development normally and then some insult cause executive functions to be disrupted.

 

At one time, ADHD was assessed solely on the basis of overt behavior because it was believed to be a disruptive behavior disorder of childhood.  Now we realize that the executive function impairments of ADHD are primarily cognitive and covert.  There are two current models for assessing these executive impairments: neuropsychological evaluation and clinical interviews of past and present self-management.  In fact, neuropsychological assessment includes both tests such as the WCST, Stroop, Rey-Osterreich , Tower of Hanoi and clinical interviews and thus gives a more comprehensive picture and more accurate diagnosis. 

 

Single tests in isolation, however, are  insufficient because most tests attempt to isolate, quantify and measure effects of a single variable presumed to tax a single functional process butexecutive functions involve simultaneous management of a range of different functions.   Thus, the evaluator must look at the global view.  In short, ADHD is a developmental impairment of the self-management system of the brain wherein self-management of and by emotion is impaired.  While it may be noticeable in childhood, it may not be diagnoses until the individual experiences challenges during adolescence or young adulthood.  Although many observers believe that the individual with ADHD is exercising an insufficient amount of willpower, the fact is that there is a chemical imbalance in the brain that is manifest in terms of imbalance brainwave patterns. True the causes of ADHD are primarily genetic, but environmental supports and stressors modify the expression of the disorder.  In short, the more supports and the less stressors, the better the individual’s overall level of functioning is likely to be.

 

More to follow in future editions,

 

Presented as a Community Service by,

 

Susan Crum, B.S., M.S., Ph.D.

Special Needs Coach

Copyright August 2008

 

 

Bibliography

Brown, T. E. (2000). Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults. Washington, DC: American Psychiatric Press.

Gilbert, D. e. (2006). Comparison of the Inhibitory and Excitatory Effects of ADHD Medication Methylphemidate and Atomoxetine on Motor Cortex. Neuropsychopharmacology , 31, 442-449.