Executive Functions by Thomas Brown

7/29/2019 Executive Functions by Thomas Brown

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by Thomas E. Brown, PhD

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13February 2008

Functions

Until we know much more about underlying neural processes,any descriptive model is likely to be a bit arbitrary. But regardless

o how the clusters are arranged, these executive unctions tend

to operate in an integrated way. Most persons diagnosed with

ADHD report signicant chronic diculties in at least some as-pect o each o these six clusters. Impairments in these clusters o

cognitive unctions tend to show up together; they appear clini-

cally to be related.

When an individual with ADD is treated with appropriate

medication and shows signicant improvement in one o these sixclusters, some signicant improvement is usually seen in aspects

o the other ve clusters as well.

Since these clusters o symptoms oten appear together inpersons diagnosed with ADD and oten respond together to

treatment, it seems reasonable to think o these symptoms o

impairment as a syndrome. Because this syndrome consists

primarily, though not exclusively, o symptoms associated withthe disorder currently classied as attention-decit hyperactivity

disorder, I reer to it as ADD syndrome. Taken together, the six

clusters in this model describe my understanding o the execu-

tive unctions o the brain.

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Although many people associate ADD with impulsive and hyper-

active behavior where aected individuals are too quick to speak or

act, diculties in getting started on tasks are a primary complainto many individuals with ADD syndrome. Though they may be

impulsive in some domains o activity, those with this syndrome

oten complain that procrastination is a major problem, particu-

larly when they are aced with tasks that are not intrinsically in-

teresting. Oten these individuals lament that they keep puttingo important tasks until the task has become an emergency. Only

when aced with dire consequences in the very immediate uture

are they able to get themselves motivated enough to begin.Many persons with ADD report that they oten are aware o

specic tasks they need, want, and intend to do, but are unable

to get themselves to begin the necessary actions. Oten these are

routine tasks such as completing homework assignments, laun-dering clothes, or submitting invoices or expense account reports

to obtain reimbursement. Or they may be important, less com-

mon tasks like completing a thesis or a degree, asking or a raise

or promotion, or ling income tax returns on time.

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Persons with ADD syndrome oten complain that they have much

more diculty than most others in sorting out and assigning priori-

ties to various tasks. Many routines o our daily lie involve organiz-ing, prioritizing, and sequencing jobs according to their importance,

their urgency, and the availability o resources. Usually, but not always,

critical variables include time or money, which cause very practical

constraints to quickly come into play.When they describe specics o their diculties with organizing

themselves, persons with ADD syndrome oten indicate a recurrent

ailure to notice critical details. Oten these diculties involve ailures

to estimate time properly or to calculate the relationship betweenexpenditures and income. A similar tendency to ignore realistic limi-

tations is oten seen in the to do lists kept by some persons with

ADD syndrome. Though they may be very intelligent about other

things, many seem clueless about how many tasks they can actuallyaccomplish within a single day or week. Many create lists with thirty

or more items or a single day, some o which are time-consuming

projects that no one could actually accomplish in a month. They seem

to have great diculty guring out how long a task will take and thenprioritizing by putting some items ahead o others, deerring some to

another day, or simply recognizing some as currently not possible.

cLustER 2: Fg, sag, ad shfg Ae

takOne o the most common complaints o persons with ADD syndrome

is that they cannot ocus their attention on a task and keep ocusing as

long as necessary. Sometimes their problem is one o selection. Theynd it very hard to ocus on the particular stimulus that requires atten-

tion: the voice on the telephone or the words printed on the page.

Another acet o the problem o not being able to ocus on an

intended task is excessive distractibility. Even when they have ocusedon a task, whether reading, listening, or trying to do some other work,

persons with ADD syndrome oten eel themselves drawn away by dis-

tractions. Like anyone else they see and hear things going on around

them and they have many thoughts continually going through their

head. But unlike most others, who readily block out distractions inorder to do what needs to be done, persons with ADD syndrome have

chronic and severe diculty screening out those distracting stimuli.

They cannot ignore the myriad thoughts, background noises, andperceptions in the surrounding environment.

This is not simply a problem o immaturity. Children and adoles-

cents have no monopoly on excessive distractibility, and the problem

is not limited to students sitting in boring classrooms. Many adultswith ADD syndrome report persistence o this problem, which can

cause trouble in their jobs, driving, and social relationships.

The same individuals who have chronic diculty with getting dis-

tracted and driting o task report that they sometimes have the oppo-

site problem: they are unable to stop ocusing on one thing and redirect

their ocus to another when they need to. Some call this hyperocus.They describe it as locking on to some task, sight, or sound they are

interested in while totally ignoring or losing track o everything else,

including some things they ought to attend to, like looking ahead while

driving the car or answering someone who has directly spoken to them.Many persons with ADD syndrome report that they get stuck in this way

while using their computer. Sometimes it occurs in conversation. Some

persons with ADD syndrome report similar problems in writing.

Maintaining eective attention requires the ability to select themost important o countless external and internal stimuliand

screen out those that intrude on awareness. Yet it also requires the

ability to shit ones ocus o attention as needed, to attend to other

words, images, sounds, eelings, topics, and matters. People with ADDsyndrome oten report chronic diculty in ocusing their attention,

in sustaining their ocus o attention, and in shiting their ocus o

attention as needed to meet the demands o learning, work, social in-

teractions, and the countless tasks o daily lie. As in the other clusters

o symptoms described here, these diculties occur occasionally oreveryone. But or persons with ADD syndrome they seem to be more

persistent, pervasive, and problematic.

cLustER 3: Reglag Alere, sag Effr,

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Many with ADD syndrome report that they requently become very

drowsyto the point where they can hardly keep their eyes openwhen they have to sit still and be quiet. Some describe themselves as

borderline narcoleptic. Usually this is not a problem when they are

physically active or actively engaged in conversation. But it can pose seri-

ous diculties when they are trying to listen to a lecture or proceedings

o a meeting. Getting drowsy is especially problematic when they try toread, particularly i what they are reading is not especially interesting to

them. Similar diculties occur or many when they sit down to write an

essay or report. Some report the same drowsiness when they are driv-ing long distances on a highway, without the stimulation o having to

negotiate heavy trac or the possibility o observing many people.

From clinical descriptions, it appears that this problem o drowsi-

ness when sitting still and being quiet is related not to being over-tired, but rather to chronic diculties in sustaining alertness. It is

as though individuals with ADD syndrome cannot stay alert unless

they are engaged actively in a behavior that provides steady motoric,

social, or cognitive eedback.

The continuous process of attention involves organizing and setting

priorities, focusing and shifting focus, regulating alertness, sustaining

effort, and regulating the minds processing speed and output. It also

involves managing frustration and other emotions, recalling facts,

using short-term memory, and monitoring and self-regulating action.


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15ChADD does not endorse products, services, publications, medications or treatments, including tose advertised in tis magazine. February 2008

Though the problem o daytime drowsiness aficts many

with ADD syndrome even when they are not tired, heavy eye-

lids sometimes appear or a dierent reason. Many with ADDsyndrome report that they are oten tired during the day be-

cause they have chronic and severe diculties in settling into

sleep, even when they are very tired and want to all asleep.

This is the opposite pole o the same problem: diculty inregulating alertness.

Even when they do expend signicant eort, many persons

with ADD syndrome report that they require an extraordi-

narily long time to complete certain types o tasks because oa tediously slow processing speed. They oten complain that it

takes them a particularly long time to read and write. Some-

times slow processing time in reading results rom the need to

reread repeatedly. In writing, the problem o excessive slownessmay be due to the getting-stuck problem (also known as sticky

perseveration). But or many with ADD syndrome, there is

a chronic problem with slow processing speed that is dier-

ent rom these earlier described diculties. Mel Levine (2003)has described this output problem in written expression; he

laments that many with such diculties are seen as lazy, when

they actually are impaired in their ability to coordinate and

integrate the multiple skills required or writing.

Although individuals with ADHD oten have a slow pro-cessing speed or certain tasks, in other situations many have

trouble slowing themselves down enough to minimize errors.

Boys with ADHD studied by Virginia Douglas (1999) were bothtoo slow and too ast. Their reaction times or some cognitive

tasks were too slow, but on other, more demanding tasks they

had diculty slowing themselves down enough to perorm

careully. They were unable to regulate their processing speedappropriately or changing task demands.

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The diagnostic criteria or attention-decit hyperactivity disor-der in the DSM-IV do not include any items reerring to emo-

tions. Yet many clinicians report that patients with ADHD strug-

gle with managing their emotions. My own clinical research onchildren, adolescents, and adults has led to similar conclusions.

ADD symptom rating scales I have developed rom studying

each o these age groups include a cluster o symptoms related

to managing rustration and modulating emotions. In analyz-ing reports rom patients with ADHD, I have ound that their

problems with emotions seem to all into two closely related

types: a very low threshold or rustration, and chronic diculty

in regulating subjective emotional experience and expression.


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Many with ADD syndrome report disproportionate emotional

reactions to rustration: a short use, a low threshold or irritability.

Many with ADD syndrome describe the ollowing aspect o emotionalexperience: a eeling that an emotion foods ones mind, taking up all

available space. This overwhelming intensity o eeling then can cause

one to lose perspective and become, or a ew moments or much longer,

so preoccupied with that particular eeling that other relevant thoughtsand eelings are displaced, ignored, or overlooked. The immediacy o

the emotion then can have too much infuence on thought and action,

causing one to speak or act in ways that dont adequately take account

o other eelings, ideas, or inormation that may also be important.Many with ADD syndrome describe themselves as overly sensi-

tive and reacting too intensely to even minor slights or criticism.

Some others report that they oten have diculty modulating eelings

o sadness, discouragement, or depression.Some with ADD syndrome also meet ull criteria or another

disorder that more directly refects problems with managing one or

more emotions, or example, an anxiety, depressive, or bipolar mood

disorder. At issue with these various examples is simply that personswith ADD syndrome, with or without any additional psychiatric dis-

order, tend to suer rom chronic problems in managing rustration

and other emotions. These chronic problems appear to be an integral

aspect o ADD syndrome and not just overlap with other disorders. In

addition, like other symptoms o ADD syndrome, they oten respondto treatment with stimulants.

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Chronic diculties with memory appear to be a core problem in ADD

syndrome, but the impairments are not generally with long-term stor-

age memory; instead they involve working memory, a term that hasbeen used in many dierent ways, most o which are unrelated to the

older term short-term memory. Working memory has several unc-

tions. An important one is to hold one bit o inormation active while

working with another. One patient described his impairment o this

essential unction as lacking a hold button in his memory.Working memory is like a very active computational unit that

not only holds inormation, but also actively processes this current

inormation in connection with the vast les o longer-term memory.In other words, working memory might be compared to the RAM o

a computer combined with its le manager and search engine.

Impairments o working memory can interere with both recep-

tive and expressive aspects o communication between individualsand within groups. Maintaining reciprocal communication is di-

cult when working memory unction is impaired, and is a common

complaint among persons with ADD syndrome.

Another aspect o working memory involves the retrieval o inor-

mation rom the les o longer-term memory. Deective retrieval o

learned inormation is a distinct type o memory problem. Persons

with ADD syndrome oten complain that they have chronic dicultypulling up rom the les o longer-term memory the inormation

needed to do a task at hand. Sometimes the problem is recalling the

name o someone whose ace has just been recognized as amiliar.

Sometimes the problem lies in retrieving inormation or proceduresneeded to answer a question or solve a problem.

Many aspects o academic work depend heavily on the eective unc-

tioning o working memory. When reading, one needs to hold in mind

the sounds symbolized by the rst part o a word while decoding thesound o later syllables to recognize the word as a whole. One then has to

retrieve rom memory the meanings associated with that word and hold

those in mind while linking them to meanings o other words to get the

ull meaning and context o the entire sentence. This process happensautomatically or fuent readers as they rapidly link up and absorb layers

o meaning built on words, sentences, paragraphs, chapters, and so on.

Persons whose working memory is signicantly impaired, however, may

experience great diculty in understanding an entire text, even i theyare quite competent in decoding each word. Reading comprehension

is built on the eective unctioning o working memory in conjunction

with an active, sustained attention to the text.

Working memory is also essential or doing math, even simple

arithmetic. I one cannot keep in mind what quantities have been bor-rowed or need to be carried rom one column to another in calcula-

tions, ones answers are not likely to be correct. And i one cannot keep

in mind the sequence o operations, then much o algebra, geometry,and higher math becomes incomprehensible.Written expression also

places strong demands on working memory. There has not been much

research on students who have problems with written expression, but

preliminary studies indicate that persons with ADHD demonstrate adisproportionately high incidence o impairment in this respect.

Working memory is involved not only in academic tasks, but also

in countless aspects o everyday lie, as one holds briefy in mind the

continuing fow o perceptions o current external eventssounds

just heard, images just observed, impressions just ormed. Problemswith integrating internal and external inormation can have a sub-

stantial infuence on ones ability to link new inormation being ac-

quired with other inormation already in mind.The dierence between problems o working memory and problems

o insucient attention has been a matter o debate among research-

ers. Neuroscientists studying memory unctions have argued that what

is currently reerred to as working memory is not simply a memoryunit o the mind, but a complex system that involves both working

attention and working memory serving together to manage the con-

tinuous fow o inormation in the mind. Chronic impairments in this

complex system are an important aspect o the ADD syndrome.

Most persons diagnosed with ADHD report

significant chronic difficulties in at least some aspect of each of these six clusters.

Impairments in these clusters of cognitive functions tend to show up together;

they appear clinically to be related.


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17ChADD does not endorse products, services, publications, medications or treatments, including tose advertised in tis magazine. February 2008

cLustER 6: Mrg ad self-Reglag

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Most descriptions o the disorder now known as ADHD emphasizeproblems with hyperactive and impulsive behavior. Many persons

identied with this disorder tend to act without sucient orethought,

or are chronically restless and hyperactive, nding it very dicult to

slow down and accurately control their actions. Children with ADHDhave oten been seen as wild, restless, and impulsive, unable suciently

to control their words and bodies and so needing much more supervi-

sion rom teachers and parents than others o the same age.

Researchers have identied impaired ability to inhibit as a coreproblem in these hyperactive and impulsive symptoms o ADHD.

Russell Barkley (1997) has argued that impairment o the ability to

inhibit is the primary problem o persons with ADHD, and, o all the

executive unctions impaired in the disorder, is the one on which thedevelopment and eective unctioning o all other executive unc-

tions depends.

Yet to overemphasize inhibition as the central problem o ADHD

is to ignore the essential connection between holding back actionsand engaging in actions. It is to overlook the need to go, which is as

important as the need to hold back or stop. Certainly it is important

or a person to be able to stop at the curb rather than impulsively run-

ning across a busy street. But it is also important or that person to be

able to monitor the trac on the street, to determine when it is saeto cross, and then to actually cross. Indeed, most behaviors require

the ability to act, to do it, as well as the ability to inhibit, to rerain

rom acting. And essential to ones success in this regard is the abilityto monitor the context o action, in this case, the trac, so that one

can decide when to wait and when to cross the street.

Social situations are oten among the most challenging or those

with diculties monitoring and sel-regulating their actions. In thosecircumstances, one must quickly assess the expectations and percep-

tions o other persons in order to behave appropriately. When is it okay

to tell this joke, or to complain about an injustice, or to conront ones

boss, teacher, coworker, customer, parent, spouse, child, or riend? Be-

cause persons with ADD syndrome nd it harder to monitor eectivelythe context in which they are operating, they report that they tend to be

too random in what they notice, attending too much to some details

and too little to others that may be equally or more important. Espe-cially dicult or these persons are those situations where one has to

monitor and gauge the emotions and intentions o other people with

whom one is interacting. Indeed, oten persons with ADD syndrome

complain that they have gotten into trouble because they have ailedto notice how others were reacting to them, or have been insuciently

aware o how they themselves were coming across to others. This moni-

toring is made even more dicult when one is simultaneously holding

in check ones own reactions while interacting with others.

Some other persons with ADD syndrome have a dierent prob-

lem. They tend to be excessively ocused on how others are reacting

and are excessively sel-conscious. They tend to be too constricted, tooshy, too inhibited in their social actions. These persons oten cannot

bring themselves to act eectively in a group.

Although there are a variety o ways in which individuals experi-

ence diculty in monitoring and regulating their actions, most withADD syndrome report chronic diculties in one or more aspects o

inhibiting action, monitoring ones sel, monitoring ones context,

and taking action in an appropriate way. This cluster o ADD-related

impairments extends ar beyond simple excesses o hyperactive orimpulsive behavior: these problems hamper ones ability to perorm

well in a wide variety o everyday tasks. A

thma E. br, PhD, is assistant clinical professor of psychiatry at the

Yale University School of Medicine and associate director of the Yale Clinic

for Attention and Related Disorders. He is a former member of CHADDs

professional advisory board.

the extracts in this adaptation w w t bw

k,Attention Defcit Disorder: The Unocused Mind in Children and Adults(y uv p,

2005). Attention k, .., add adhd, ,

w ad/hd.

Executive Functions by Thomas Brown

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