ADHD??!!!?!
Relationship between ADHD and EF
EF ADHD
All ADHD have some EFD but
All EFD not ADHD
ADHD and EF
The two are not the same; stem from
different descriptive systems
ADHD is a diagnosis based on cluster of
observed behaviors
EF is a neuropsychological construct
Both describe a regulatory phenomenon
Provocative Question #1
Is the traditional triad of symptoms
(Inattention, Impulsivity,
Hyperactivity) sufficient to describe
the full set of treatable
symptomatology in the syndrome
currently known as ADHD?
Provocative Question #2
Should we reconceptualize and
redefine the syndrome now known as
ADHD in terms of the
neuropsychological construct of
Executive Function?
Provocative Question #3
Should the executive function deficits
associated with ADHD be addressed
directly in educational
programming?
Attention-Deficit/Hyperactivity Disorder
(ADHD): DSM-IV Diagnostic Criteria
A. Either (1) or (2)
(1) 6 or more symptoms of Inattention have
persisted for at least 6 months:
often fails to give close attention to details or makes
careless mistakes in schoolwork, work, or other
activities
often has difficulty sustaining attention in tasks or play
activities
often does not seem to listen when spoken to directly
often does not follow-through on instructions
and fails to finish schoolwork, chores, or duties
in the workplace (not due to oppositional
behavior or failure to understand the
instructions)
often has difficulty organizing tasks and
activities
often avoids, dislikes or is reluctant to engage in
tasks that require sustained mental effort
often loses things necessary for tasks or
activities (toys, school assignments)
is often easily distracted by extraneous stimuli
is often forgetful in daily activities
Attention-Deficit/Hyperactivity Disorder
(ADHD): DSM-IV Diagnostic Criteria
(2) 6 or more symptoms of hyperactivity-impulsivity
• Hyperactivity (6)
often fidgets with hands or feet or squirms in seat
often leaves seat in classroom or in other situations in which
remaining seated is expected
often runs about or climbs excessively in situations in which it is
inappropriate
often has difficulty playing or engaging in leisure activities
quietly
is often “on the go” or acts as if “driven by a motor”
often talks excessively
• Impulsivity (3)
often blurts out answers before questions
have been completed
often has difficulty awaiting turn
often interrupts or intrudes on
(Sub)types
1. ADHD, Combined Type: A1 and A2 met
for past 6 months
2. ADHD, Predominantly Inattentive Type:
A1 met but not A2
3. ADHD, Predominantly Hyperactive-
Impulsive Type: A2 but not A1
Rule Outs
– TBI
–Epilepsy
–Language processing disorders
– Anxiety disorders including PTSD
– Depression
– Chaotic environment
–Sleep disorders
Clinical Symptoms of ADHD
Beyond the traditional triad of “not
paying attention”, “not thinking before
he acts” and “running all over the
house constantly”...
Clinical Symptoms of ADHD
Core or not?
… Reports of “Disorganization, can’t
remember 3-step instructions, poor
planning, not checking his/ her work,
difficulty accepting other strategies,
getting stuck, overemotional, locker/
notebook looks like a disaster...”
Clinical Symptoms of ADHD
Core or not?
Executive Function (EF) is largely implicit
in the DSM-IV diagnosis of ADHD.
Only Inhibit (Impulse Control) is explicit.
Should EF be formally incorporated into
theories and definitions of ADHD?
Are formal assessment and treatment of
these (core?) EF symptoms necessary?
Evolution of Diagnosis of ADHD
1st clinical description: British physician Still
(1902) - “deficit in volitional inhibition”, “defect
in moral control”
Similarities to brain-injured child syndrome
(Strauss & Lehtinen, 1947) but without evidence
of brain injury resulted in “minimal brain
damage”
“Minimal brain dysfunction”
“Hyperkinetic impulse disorder”
“Hyperactive child syndrome”
Evolution of Diagnosis of ADHD
“Hyperkinetic reaction of childhood” (DSM-II)
first mention of inattention and distractibility
“Attention-deficit disorder” (Douglas) (DSM-III)
with and without hyperactivity
“Attention-Deficit/ Hyperactivity Disorder”
(DSM-III-R) (no with or without)
“Attention-Deficit/ Hyperactivity Disorder”
(DSM-IV) (“3” subtypes)
???
Recent Conceptualizations
With a better understanding of brain-behavior
relationships, particularly the frontal lobes:
ADHD is undergoing further redefinition in
terms of a disorder of the executive
functions (EF) (Barkley, 1997, 2000;
Brown, 1999; Denckla, 1996; Pennington &
Ozonoff, 1996)
The primacy of “attention” is being
questioned.
Models of executive function in
ADHD
Pennington & Ozonoff (1996)
“frontal metaphor”: deficits in inhibition and
working memory tasks
Barkley (1997, 2000)
Inhibition as core, executive function as model
Bayliss & Roodenrys (2000)
supervisory attentional system as executive
function
Barkley (Bronowski) EF Model
Behavioral Inhibition
Working Memory Internalization of speech Self-regulation of Reconstitution (analysis,
(nonverbal) (verbal working memory) synthesis, goal-directed)
affect/ motiv./ arousal
Motor control/ fluency/syntax
Barkley (Bronowski) EF Model
Nonverbal working memory - visual imagery
and private audition; internalized resensing.
Verbal working memory - covert language that
controls self; rule-governed behavior.
Internalized emotion/ motivation - with
working memory, emotional control and
motivation can occur. Covert affective states.
Source of intrinsic motivation that drives
future behavior.
Barkley (Bronowski) EF Model
Reconstitution - analysis combining with
synthesis, allowing manipulation to
synthesize new responses. Allows flexible,
fluent, inventive goal-directed behaviors.
General Conclusions
Relationship between EF and ADHD
hypothesized by Barkley (1997, 2000) and
Pennington & Ozonoff (1996) is given
strong support by BRIEF findings
Multidimensional construct of EF appears
to define with greater specificity the
symptoms of ADHD.
General Conclusions
Multidimensionality of Executive Function
provides a more comprehensive yet more
specific model of ADHD, incorporating a
more full set of relevant symptom behaviors.
Brain Basis for the Executive Functions
Proportional size of prefrontal region
Human 29%
Chimpanzee 17%
Gibbon/Macaque 11.5%
Lemur 8.5%
Dog 7%
Cat 3.5%
Neuroanatomic Organization
Executive function & neurological development
are parallel
Development of prefrontal cortex is central
Frontal lobe damage can result in dysfunction of
various executive subdomains
BUT - Executive functions do not simply reside in
the frontal lobes
3 Neuroanatomic Axes and
Neuropsychological Function
Anterior-Posterior Axis
Anterior Systems ----- Posterior Systems
- Anticipates behavior - Receives information
- Selects Goals - Encodes
- Organizes/ Plans - Stores
- Orchestrates - Structure/ organization
- Monitors of Knowledge Base
- Modulates
Complimentary Relationship
Lateral Axis
Left Hemisphere Systems Right Hemisphere Systems
Preferentially involved with: Preferentially involved with:
Building blocks of language Spatial information
Parts of complex materials Relationship between parts
Temporal processing Configuration of complex
Processing unimodal Processing multi-modal
codable information novel information
Executive of discrete motor Emotional tone in speech
Cortical-Subcortical
Cortical (Thinking) Systems
Frontal System Modulation
Inhibition and selection
Subcortical Systems
Retic. Activ Syst Motor Control Emotions/Drive
-Arousal - Impulses
-Alertness - Emotional/Social
Drives
Neuroanatomic Organization:
Frontal lobes are densely connected with other cortical
and subcortical regions
Prefrontal system is highly, reciprocally interconnected
with the
limbic (motivational) system,
reticular activating (arousal) system
posterior association cortex (perceptual/ cognitive
processes and knowledge base)
motor (action) regions of the frontal lobes
Central neuroanatomic position underlies
regulatory control over:
Perceptual coding in posterior/temporal
isotypic regions
Conceptual processes of the posterior
association cortex
Attentional functions supported by
subcortex (reticular activating system)
Emotional functions subserved by subcortex
(limbic system)
Frontal system versus frontal lobe
Frontal system acknowledges &
incorporates interconnectedness
A disorder within any component of
the frontal system network can result in
executive dysfunction
Conditions that render the frontal systems
vulnerable include:
Connectivity disorders such as cranial radiation and
white matter development (migration errors)
Lead poisoning affecting synaptogenesis
Direct prefrontal trauma in traumatic brain injury
Dysfunctional neurotransmitters (e.g., dopamine in TS
& ADHD)
Posterior cortex disorders including LD
Arousal mechanism disorders in TBI (shearing), severe
depression.
Executive dysfunction can arise from damage to
the primary frontal regions as well as to the
densely interconnected secondary posterior or
subcortical areas. The associated cognitive
“partners” and “slave” systems must be present
in order for the executive regulatory functions
to have any operational purpose.
Neuroanatomy
“Executive Function is a convenient
shorthand that captures the problems of a
group of patients...The levels should be kept
separate; Executive function should not be
confounded with “prefrontal” except at a
hypothesis-generating level.” (Denckla,
1996)