Download CHANGING CONCEPTS OF ADHD IN ADULTS

ADHD and
Executive Functions:
Emerging Concepts
Thomas E. Brown, PhD
Associate Director,
Yale Clinic for Attention and Related Disorders
Department of Psychiatry
Yale Medical School
Shifts in Conceptualizing ADHD
 1968
Hyperkinetic Disorder of childhood
 1980
Attention Deficit Disorder
• With or without hyperactivity
• Residual type recognized
 1987
ADHD (only combined symptoms)
 1994
AD/HD–3 types
 2000
AD/HD (impaired executive function)
Prevalence and Genetics of ADHD
 9% of children; 4.4% of adults
 Male-female: 6:1, 3:1, 1:1
 All levels of IQ
 All levels of socioeconomic status
 Family genetic transmission: 7.5 – 8.0
 Inheritance not specific to subtype
CDC 2008; Kessler, 2006; Gaub M, Carlson CL. J Am Acad Child Adolesc Psychiatry.
1997;36(8):1036-1045. Levy F, et al. J Am Acad Child Adolesc Psychiatry. 1997;36(6):737-744.
Smalley SL, et al. J Am Acad Child Adolesc Psychiatry. 2000;39(9):1135-1143.
ADHD Genetics: Heritability Coefficient
Breast cancer
Asthma
Schizophrenia
Height
Hudziak, 2000
Nadder, 1998
Levy, 1997
Sherman, 1997
Silberg, 1996
Gjone, 1996
Thapar, 1995
Schmitz, 1995
Edelbrock, 1992
Gillis, 1992
Goodman, 1989
Willerman, 1973
0
0.2
0.4
0.6
0.8
Average genetic contribution of ADHD based on twin studies
Faraone. J Am Acad Child Adolesc Psychiatry. 2000;39:1455-1457.
Hemminki. Mutat Res. 2001;25:11-21.
Palmer. Eur Resp J. 2001;17:696-702.
1
ADHD
Mean
What is ADHD?
(A Controversial Viewpoint)
ADHD (all subtypes) =
Developmental Impairment of
Executive Functions
Developmental Impairment =
(Not emerging and unfolding as expected for age)
Attention Deficit Disorder: The Unfocused Mind in Children and Adults
(T.E. Brown, Yale University Press, Sept, 2005)
Executive Functions
 Wide range of central control processes
of the brain
 Connect, prioritize, and integrate
cognitive functions–moment by moment
 Like conductor of a symphony orchestra
“Focus” and Executive Function
Impairments of ADHD
 In DSM-IV “inattention”
symptoms of ADHD
• Do not mean
• Unable to focus as in holding
the camera still to take a photo
of an unmoving object
• Do mean
• Unable to focus as in focusing
on the task of driving a car
Brown TE. In press.
Brown’s Model of Executive Functions
Impaired in ADHD
Symptom Characteristics
 Dimensional, not “all-or-nothing”
• Everyone sometimes has some impairments
in these functions; in ADHD, it is a chronic,
severe impairment
 Situational variability: “If I’m interested”
• Most persons with ADHD have a few activities
where ADHD impairments are absent
ADHD looks like a willpower problem, but it isn’t!
Brown’s Model of Executive Functions
Impaired in ADHD
Executive Functions
Organizing,
prioritizing,
and
activating
to work
Focusing,
sustaining
focus, and
shifting focus
to tasks
Regulating
alertness,
sustaining
effort, and
processing
speed
Managing
frustration
and
modulating
emotions
Utilizing
working
memory and
accessing
recall
Monitoring
and selfregulating
action
1.
Activation
2.
Focus
3.
Effort
4.
Emotion
5.
Memory
6.
Action
Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.
1. Organize, Prioritize, and Activate
 Difficulty organizing tasks,
materials
 Difficulty estimating time,
prioritizing tasks
 Trouble getting started on work
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
2. Focus, Shift, and Sustain Attention
 Loses focus when trying to listen
or plan
 Easily distracted–internal/external
 Forgets what was read, needs
to re-read
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
3. Regulating Alertness, Effort,
and Processing Speed
 Difficulty regulating sleep and alertness
 Quickly loses interest in task, especially
longer projects; doesn’t sustain effort
 Difficult to complete task on time,
especially in writing–“slow modem”
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
4. Manage Frustration,
Modulate Emotion
(Not included in DSM-IV criteria)
 Emotions impact thoughts, actions too
much
 Frustration, irritations, hurts, desires,
worries, etc., experienced “like computer
virus”
 “Can’t put it to the back of my mind”
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
5. Utilize Working Memory,
Access Recall
 Difficulty holding one or several things “on
line” while attending
to other tasks
 Difficulty “remembering to remember”
 Inadequate “search engine” for activating
stored memories, integrating these with
current info to guide current thoughts and
actions
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
6. Monitor and Self-Regulate Action
(Not just hyperactive/impulsive behavior)
 Difficulty controlling actions, slowing self
and/or speeding up as needed
for tasks
 Doesn’t size up ongoing situations
carefully
 Hard to monitor and modify own actions to
fit situation/aims
Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults;
2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents;
2001.
What Requires Executive Functions?
 Tasks that involve managing oneself
 To prioritize, start, sustain, shift, stop,
and integrate cognitive functions
 Using memory without moment-by-
moment guidance from others
Brown TE. In press.
Executive Functions:
Development and Demands
 EF capacity develops through childhood,
into adolescence, and beyond; it is not fully
present in early childhood
 Environmental demands for EF increase
with age, from preschool through adulthood
 EF impairments often are not noticeable
by age 7!
Brown TE. Emerging understandings of attention deficit disorders and comorbidities.
In: Brown TE, ed. Attention-Deficit Disorders and Comorbidities in Children, Adolescents,
and Adults; 2000:3-55.
Executive Functions and Scaffolding
 In early childhood, others perform all executive functions
for the child (parents, teachers, sibs and other caretakers)
 Scaffolding is provided by showing, directing, helping,
reminding, coaching, critiquing
(Examples: walking, getting dressed, crossing street, riding bike, driving car)
 Scaffolding is gradually withdrawn, as child becomes able
to (or is forced to) perform these functions for self
 In adolescence & adulthood scaffolding may be provided
by: friends, teachers, coaches, spouses, supervisors
How Can Executive Functions
Become Impaired?
 Developmentally, eg, ADHD
 Trauma, eg, traumatic brain injury
 Disease, eg, Alzheimer’s disease
 In trauma and disease, the
patient usually has had adequate
EF, then loses it
 In ADHD, EF has not developed
adequately
When Are ADHD
Impairments Noticeable?
 Some are obvious very early and
are noticeable in preschool years
 Some are not noticeable until
middle elementary or junior high
 Some are not apparent until child leaves
home to go to college or later
Challenges May Reveal Weaknesses
Cardiac weaknesses may not be
noticeable in EKG taken while lying quiet
on a table, but may be very noticeable
while playing basketball, shoveling snow
EF weaknesses may not be noticeable
until one’s self-management is
challenged by increased demands of
adult life
Development of Brain Structures
that Support Executive Functions
 Structures and functions that support
EF are not fully developed at birth
 Neural networks underlying effortful
control begin development at 2-4 years
old, but don’t fully develop until one’s 20s
 Development of EF capacities continues
into early adulthood
Rothbart MK, Posner MI. Mechanism and variation in the development of attentional networks.
In: Nelson CA, Luciana M, eds. Handbook of Developmental Cognitive Neuroscience; 2001.
Continuing Brain Development in
Late Childhood and Adolescence
 Between 6-15 years, extreme growth (to 80%)
occurs at the collosal isthmus that supports
associative relay, while considerable synaptic
pruning occurs
 Brain myelination increases 100% during
the teenage years
 Dopamine (DA), norepinephrine (NE), and
serotonin (5-HT) transmitter systems in the
brain continue to develop into one’s 20s
Thompson PM, et al. Nature. 2000;404(6774):190-193.
Benes FM, et al. Arch Gen Psychiatry. 1994;51(6):477-484.
Cortex Maturation in ADHD vs NC
 MRI studies of 40K cortex sites in 223
youths with ADHD vs matched controls
 Brain maturation was delayed ~3yrs in
specific regions in ADHD youths vs NC
 Frontal areas of cortex slower in ADHD
 Medial PFC developed lagged 5 yrs
(Shaw, et al, PNAS, Nov, 2007)
Emotion regulates EFs
 “All information processing is emotional …emotion is the
energy level that drives, organizes, amplifies & attenuates
cognitive activity.” (K. Dodge, 1991)
 Emotional value is automatically, uncsly assigned to stimuli
(amygdala, medial PFC)
[how threatening, important, interesting is this?]
(Damasio, 1994, 1999; LeDpux, 1996, 2002,)
 Brain imaging studies show reciprocal connections via
medial PFC between emotion and cognition,
anxiety/dysphoria & attention
(Mayberg, et al, 1999; Simpson, et al, 2001)
EFs regulate emotion
Brain imaging of NC shows “gating” of emotion to
reduce affective interference during more
valued/complex cognitive tasks.
(Pochon, Levy, et al, 2002)
Many persons with ADHD self-report chronic
impairment in their ability to modulate affective
interference in daily life. This is consistent with their
other EF impairments
(Brown, 1996, 2001)
How Can Executive Function
Impairments of ADHD Be Assessed?
 When ADHD was seen as just a disruptive
behavior disorder in childhood, diagnosis
was based on observing overt behavior
 EF impairments of ADHD are largely
cognitive, covert, and not easily observed
 Performance of complex, everyday tasks
may be a more sensitive diagnostic
indicator of EF impairments
Conflicting Models
re: How to assess EF impairments
1. Neuropsych tests of EF:
WCST, Stroop, Rey-Ost., Tower of
Hanoi, etc. (Wilcutt, et al, 2005)
2. Clinical interviews re: past/present
self-management of daily life
(Barkley, 1997, Brown, 2005)
(Brown, 2006)
How Are EF Related to ADHD?
2 Conflicting Models
 Partial overlap (~30%)
EF impairments as characteristic of
some individuals with ADHD, but not
essential
to the disorder (Willcutt, et al. 2005)
 Full overlap (100%)
-Combined subtype only (Barkley)
- All subtypes (Brown)
Brown TE. 2006.
Some assume that Executive Functions
are defined by neuropsychological
“tests of EF”
 Single neuropsychological measures are
not effective in identifying ADHD in children
or adults
 Multiple tests improved diagnosis efficiency
(high positive predictive power, modest
negative predictive power)
 Multiple tests show about 30% of those
with ADHD are impaired on EF
Doyle AE, et al. J Consult Clin Psychol. 2000;68(3):477-488.
Problems in Laboratory Measures of
Executive Functions (“Streetlamp Problem”)
 Most research tries to isolate, quantify,
and measure effects of a single variable
presumed to tax a single functional process
 This strategy is inappropriate for EF
“because an essential property of all
“executive” behavior is that, by its nature,
it involves simultaneous management of
a variety of different functional processes”1
1. Rabbitt P. Methodologies and models in the study of executive functions and DSM-IV ADHD
subtypes. In: Rabbitt P, ed. Methodology of Frontal and Executive Function; 1997.
Elements of a New Paradigm for ADHD
1. ADD = developmental impairment of
uncs self-management system of brain
2. Self-regulation of and by emotion is
impaired in ADD
3. ADD sx may be noticeable in
childhood, but often not apparent until
challenges of adolescence/adulthood
Elements of a New Paradigm for ADHD
4. ADD appears to be insufficient willpower,
but is actually a problem of chemical
dynamics in brain
5. Causes of ADD are primarily genetic, but
environmental stressors & supports modify
sx expression
6. ADD is a foundational disorder that
increases lifetime risk of other disorders.
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