Download ADHD: Comorbidity and Mimicry

ADHD: Mimicry and Comorbidity
James H. Johnson, Ph.D., ABPP
University of Florida
This presentation draws heavily on Johnson, J. H., Alvarez, H. K. and Johnson, T. A. (2009). Comorbidity & Symptom Mimicry
in ADHD: Implications for Assessment and Treatment. In B. L. Maria (Ed.) Current Management in Child Neurology 4th Ed,
Shelton, CT: B.C. Decker
ADHD Mimicry
• In assessing and diagnosing ADHD, it is
important to consider that there are a variety
of conditions that can mimic ADHD.
• These include both physical conditions and
psychological problems.
• Here, we will briefly discuss a few of these
prior to considering the issue of
comorbidity.
Conditions that Can Mimic ADHD
Symptoms
• Sensory Impairments
• Medication side effects
• Phenobarbital
• Dilantin
• Some Asthma Medications
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Seizure Disorder
RTH (Resistance to Thyroid Hormone)
PTSD
Bipolar Disorder
Anxiety Disorders
Depressive Disorders
What is Comorbidity?
• The term comorbidity first appeared in the
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psychological and psychiatric literature in the mid
1980's.
Since that time there has been a dramatic increase in
interest in this topic as reflected in the number of journal
articles containing the term comorbidity in the title.
In 1986 there were only two such articles; by 1993 the
number had increased to 243.
Since that time, work in this area has continued
unabated.
It has been suggested that, comorbidity has emerged as
perhaps the single most important concept for
psychiatric research.
What is Comorbidity?
• A variety of definitions of comorbidity have been
offered.
• From a medical epidemiology perspective, Feinstein
has defined comorbidity as any distinct additional
entity that has existed or that may occur during the
clinical course of a patient who has the index disease
under study.
• Blashfield has referred to comorbidity as the cooccurrence of different diseases in the same individual.
• Likewise, Caron and Rutter have defined comorbidity
as the simultaneous occurrence of two or more
unrelated [italics added] conditions.
What is Comorbidity?
• As can be seen from these definitions, the term
comorbidity refers to a situation in which an individual,
who has been diagnosed with one specific disorder, is
also found to meet diagnostic criteria for one or more
additional disorders
• Although the use of the concept of comorbidity seems
relatively straightforward, there has been considerable
controversy regarding the use of this term with
reference to most psychiatric disorders
• The primary reason for this concern is highlighted in
the definition of comorbidity provided by Caron and
Rutter. Here, comorbidity was defined in terms of the
co-occurrence of two or more unrelated conditions.
What is Comorbidity?
• The word unrelated is most relevant.
• It has been argued that, unlike in the medical arena,
where the etiology and pathological processes of
specific disease entities are often reasonably well
understood there is seldom a detailed understanding
of underlying causal factors in the case of psychiatric
disorders.
• Without knowledge regarding the etiology of
coexisting disorders, one cannot be certain that
individuals who meet diagnostic criteria for more
than one psychiatric disorder actually have unrelated
conditions.
What is Comorbidity?
• It has been suggested that, what appear to be
separate disorders may actually be the result of
overlapping diagnostic criteria or the result of
arbitrary diagnostic distinctions between different
syndromes that are variations on the same
underlying disorder (such as anxiety disorders).
• Increased estimates of comorbidity may also result
from the fact that, with younger children, what
looks like comorbidity may reflect relatively
nonspecific expressions of psychopathology,
associated with immature levels of cognitive and
emotional development (e. g. anxiety and
depression).
What is Comorbidity?
• As a result of these issues it has been suggested that,
while the term comorbidity may be appropriate for use
in referring to the presence of multiple medical disease
entities, it’s use is less appropriate in the psychological
arena where putative syndrome’s are defined largely in
terms of signs and symptoms, without detailed
knowledge of underlying etiological factors.
• Those who have criticized the use of the term
comorbidity with reference to child and adult
psychopathology have advocated using terms such as
diagnostic co-occurrence or diagnostic covariation as
they do not imply an association among disease
entities.
What is Comorbidity?
• While using the term comorbidity with reference to
psychopathology has been questioned the term will
be used for purposes of the present discussion.
• This term, is preferred for the following reasons;
• the term comorbidity is widely used in the
psychopathology literature to refer to instances where
individuals with one disorder also meet criteria for
another disorder,
• there are studies suggesting that comorbidity is often
found even when controlling for overlapping diagnostic
criteria
Comorbid Conditions and ADHD
• A number of studies have provided information
regarding the type and degree of comorbidity
found with children and adolescents diagnosed
with ADHD. A number of these conditions will
be considered here.
• Learning Disabilities
• Oppositional Defiant and Conduct Disorder
• Anxiety Disorders
• Mood Disorders
• Tourette’s Syndrome
• Other Related Characteristics
Learning Disabilities
• Children with ADHD often show problems
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functioning in the academic environment.
These problems include behaviors that interfere with
learning, lowered levels of school achievement, and
specific learning disabilities.
Research suggests that children with ADHD perform
more poorly in school relative to control subjects.
They show more grade repetitions and more frequent
placement in special classes.
Follow-up studies have also found that the academic
and learning problems of such children often persists
into adolescence and are associated with chronic
underachievement and school failure.
Learning Disabilities
• While academic and school related difficulties seem
ubiquitous in children with ADHD, specific learning
disabilities are somewhat less frequent.
• In reviewing comorbidity findings prior to 1991,
Biederman, et al found the degree of overlap between
ADHD and “learning disabilities” ranged from a low of
10 % to a high of 92% (??).
• Barkley (1998) has suggested that the best estimate of
comorbidity is likely to be 19 to 26 % when learning
disability is “conservatively” defined (i.e., significant
delay in reading, math, or spelling relative to IQ, with
achievement in one of these areas at or below the 7th
percentile
Learning Disabilities
• He notes that, if learning disability is defined as a
significant discrepancy between IQ and achievement,
comorbidity estimates are as high as 53%.
• With a more lax criterion, (e.g. achievement levels at
least two grades below current grade placement)
comorbidity estimates as high as 80% are found.
• Apart from general problems of school performance,
school achievement and LD, children with ADHD also
show other types of developmentally related difficulties
that can impair school functioning.
• Most prominent in this regard are speech and language
disorders which occur in as many as 30 to 64 % of
children diagnosed with ADHD.
Oppositional Defiant and Conduct
Disorder
• The finding of high levels of
comorbidity with oppositional
defiant disorder and conduct
disorder is very common, although
relatively few studies have focused
specifically on oppositional defiant
disorder.
• Available data suggests as many as
50% of clinically referred children
with ADHD also show evidence of
oppositional defiant disorder
(Johnson, Alvarez & Johnson,
2009)
Oppositional Defiant & Conduct
Disorder
• Other studies suggest that as many as 30 to 50 per
cent of children with ADHD go on to develop
more serious forms of antisocial behavior
consistent with a clinical diagnosis of conduct
disorder (Johnson, et al, 2009)
• Available research findings suggest that, not only
is comorbidity common, but that when ODD or
CD occurs with ADHD the clinical picture is one
of increased severity compared to children/
adolescents with ADHD alone.
Oppositional Defiant & Conduct
Disorder
• Children with combined ADHD and ODD seem to
represent an intermediate group in terms of
symptom severity when compared to ADHD only
children, who show less severe problems, and
children with ADHD and CD, who show more
severe problems.
• Biederman et al have noted that “ ...there is
increasing evidence that children with attention
deficit hyperactivity disorder plus conduct disorder
appear to have a particularly severe form of
attention deficit hyperactivity disorder.”
Oppositional Defiant & Conduct
Disorder
• These investigators go on to indicate that “...subgrouping
based on comorbidity with conduct disorder may be of
potential value in determining which children with
attention deficit hyperactivity disorder have a more serious
prognosis and different family-genetic risk factors and
[who may] require specialized comprehensive therapeutic
interventions.”
What are the pros and con’s of diagnostic subgrouping??
ANXIETY DISORDERS
• ADHD has not only been found to be
related to disruptive behavior disorders.
• It has also been found to be related to
internalizing problems such as anxiety
disorders and depression.
• For example, between 25 and 30 % of
clinically referred children with ADHD
show evidence of some type of anxiety
disorder (Johnson, et al, 2009).
• Rates between 23 and 58.8% have been
found in general population studies.
ANXIETY DISORDERS
• These findings, which suggest relatively high rates
of comorbidity, must be tempered by the fact that
they relate primarily to younger children;
• This link between ADHD and anxiety disorders has
been found to be markedly reduced in adolescents
(Why ??).
• It should be noted that other research suggests that
there are significant differences in comorbidity
estimates between children displaying attention
deficit disorder with and without hyperactivity.
ANXIETY DISORDERS
• Here, children with DSM III diagnosed attention
deficit disorder without hyperactivity (analogous
to DSM IV - primary inattentive type) have been
found to show the highest degree of comorbidity
with regard to anxiety disorders.
• Regarding the effects of anxiety disorder on the
clinical picture of children with ADHD, it has
been suggested that comorbid anxiety may serve
to reduce the impulsiveness often associated with
ADHD.
Mood Disorders
• While not all investigators have found
an association between ADHD and
mood disorders, studies of clinically
referred children with ADHD, suggest
that between 10 and 30% are likely to
show evidence of some sort of mood
disorder, usually major depressive or
dysthymic disorder (Johnson, et al,
2009).
• Although depressive disorders can result
from various factors (e.g. genetics),
there is speculation that some child
depressive symptoms may develop as a
result of the social, academic, and other
impairment resulting from ADHD.
• The presence of major depressive
disorder in combination with ADHD
seems to complicate the usual clinical
picture seen in children with ADHD
Mood Disorders
• Follow up studies of children with ADHD and major
depressive disorder have suggested that, while both
disorders are independently associated with significant
psychiatric morbidity, the combination of the two
disorders appears to suggest a subgroup of children
who show an especially poor long term outcome.
• Findings concerning comorbidity with bipolar disorder
are somewhat more controversial,
• The small number of studies in this area suggest that
the degree of overlap between ADHD and bipolar
disorder is in the range of 11 to 22 per-cent (Johnson,
et al , 2009)
Mood Disorders
• It has been suggested that this degree of apparent
comorbidity may be, in part, partially an artifact due
to the fact that similar symptoms (e.g., attentional
problems, poor judgment, high activity level) are
taken as diagnostic indicators of both disorders (cite
Katie’s dissertation research).
• It also seems to be the case that the relationship
between ADHD and bipolar disorder is largely
unidirectional.
• That is, the presence of bipolar disorder seems to
suggest an increased risk for ADHD, while the
presence of ADHD does not seem to suggest an
increased risk of developing bipolar disorder.
Mood Disorders
• Additional research is needed to further
investigate the precise relationship between
ADHD and bipolar disorder.
• This seems to be especially important since some
research suggests that adolescents who commit
suicide show higher rates of both bipolarity and
ADHD than do adolescents who attempt suicide
without success
• Question, is this due to ADHD or BPD – both??)
Tourette’s Disorder
• There is data to suggest that Tourette’s disorder may also be
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associated with ADHD.
Clinical studies suggest that, of those individuals with
Tourette’s disorder, somewhere between 40 and 50 % show
features of ADHD (Johnson, et al, 2009.
The number of children with ADHD who develop
Tourette’s syndrome is thought to be on the order 7%.
While such findings are of interest, it is possible that the
magnitude of overlap is in part related to referral practices.
That is, children displaying both disorders may be more
likely to be referred for assessment and/or treatment than
children who show either of the disorders alone.
Tourette’s Disorder
• It is noteworthy that the only published populationbased study suggests a much lower rate of ADHD
diagnoses (12%) in children with Tourette’s
disorder.
• While these findings support the existence of some
degree of comorbidity, they suggest that the actual
degree of comorbidity is likely to be lower than that
suggested by clinical studies.
• Additional studies in this area are necessary to more
carefully ascertain the degree of comorbidity and the
nature of the underlying relationships between
ADHD and Tourette’s Disorder.
ADHD: Associated Problems and
Correlates
• ADHD is also associated with a range of
characteristics that may need to be considered
in the medical management of these children.
• For example, children with ADHD seem to be
at increased risk for various health problems
(e.g., upper respiratory infections, allergies).
• They are also likely to show other difficulties as
well.
Intellectual Functioning
• Children with ADHD are more likely to be behind in
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intellectual development than peers or their siblings.
They tend to score on the average 7 to 15 points below
control children on standardized measures of
intelligence.
Mainly apparent in verbal intelligence
It is not clear whether these differences represent real
differences in ability or test taking behavior.
Lower scores may also be due to the fact that the child
missed out on information that other children have due
to problems of inattention and disorganized behavior
In any event functioning is lower than age related peers.
ADHD: Accident Proneness
• Children with ADHD are considerably more likely to
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experience injuries due to accidents than normal
children.
Up to 57% are accident prone, with 15% having had
at least four or more serious accidental injuries.
Studies have been conducted to determine whether
overactivity or aggressiveness are the main
contributors to accidents.
Findings suggest that both features contribute
independently to accidental injury.
Children who experience accidents are more likely to
be overactive, impulsive and defiant.
Accident Proneness
• Children injured as pedestrians or bicycle riders in
traffic accidents perform more poorly on tests of
vigilance and impulse control and receive higher
ratings from parents and teachers on measures of
hyperactive and aggressive behavior.
• This suggests that among those having serious
accidents, the children may be having a greater
number of ADHD symptoms.
• While not well studied, increased accidents may also
have to do with contextual factors in the homes of
children with ADHD.
Sleep Problems
• Studies suggest that children with ADHD have a higher
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likelihood of sleep problems than normals.
As many as 56% of children with ADHD have problems falling
asleep (compared to 23% of normal children).
Up to 39% of ADHD children show problems of nitetime
awakening.
Resistance to going to bed and fewer total hours of sleep seem to
be a major problem with many children with ADHD (and likely
add to their difficulties in school functioning).
Studies of sleep patterns do not, however, typically suggest
specific difficulties with the nature of sleep itself in these
children
Speech Difficulties
• There is a tendency for children with ADHD to be
more delayed in talking than non ADHD children.
• Studies generally suggest that ADHD children are
likely to have problems with expressive language but
not receptive language.
• Here, anywhere from 10 to 54% of children have
speech/language problems compared from 2 to 25
percent of normal children.
• Often have problems on tasks of verbal fluency.
Adaptive Behavior
• Adaptive functioning refers to the child's
development of age-appropriate motor skills,
self-help skills, personal responsibility and the
ability to function independently at an age
appropriate level.
• A number of studies suggest that, compared to
normal controls, children with ADHD show
significantly lower levels of adaptive behavior.
• Here they often are found to function in the low
average or borderline range.
Adaptive Behavior
• While children with other psychiatric disorders often
show lower levels of adaptive functioning, the
discrepancy between overall IQ and level of adaptive
functioning in children with ADHD is often found to
be greater than in most other conditions.
• ADHD may take a special toll on adaptive functioning.
• There are also findings to suggest that the greater the
degree of social or adaptive impairment the greater the
risk at follow up for the child with ADHD to show
comorbid substance abuse and psychiatric disorders.
• ??? Should impairment in adaptive behavior be
included in DSM criteria along with social,
academic and occupational impairments ???
Deficits in Rule Governed Behavior
Rule Governed Behavior has to do with difficulties
that children with ADHD have in adhering to rules
or instructions regarding behavior which is not due
to sensory handicaps, such as deafness, or
behavioral problems.
• Rule governed behavior involves behaviors that are
not simply determined by set contingencies which
follow regularly follow responses but to “language
based templates that guide and regulate behavior in
the absence of regularly occurring environmental
structure and support”
Deficits in Rule Governed Behavior
• Here it can be noted that rules assist with bridging
temporal gaps in behavioral contingencies and
contribute to the cross-temporal organization of
behavior.
• The motor execution of such verbal rules appears to be
partially dependent on the capacity to retain the rules
in working memory (to restate the rule) and to inhibit
responses that compete with the rule.
• Children with ADHD often display significant deficits
in rule governed behavior.
• They have major problems following directions and
commands.
Deficits in Rule Governed Behavior
• In experiments they have difficulty complying
with experimenter instructions (rules), particularly
if extraneous rewards are available for engaging in
other than task relevant behavior (problems with
inhibiting).
• Other findings suggest that children with ADHD
are less adequate at using general rules for
problem solving tasks and are less likely to use
organizational strategies to guide them on
memory tasks.
Deficits in Rule Governed Behavior
• The deficit in rule governed behavior in many instances
does not seem to have to do with major deficits in
knowledge.
• In many instances the rules which the child with ADHD
can use to guide his/her behavior are very clear to the
child.
• It has been suggested that the problem with children
with ADHD is “less knowing what to do and more
doing what they know (Martha Denckla )
• This statement seems to define a major problem
experienced by children with executive function deficits.
Question: Should evidence of certain executive function
deficits be included in the criteria for ADHD???
Deficits in Rule Governed Behavior
• For example, studies have found that hyperactiveimpulsive children are more prone to accidents than
normal children although they are not deficient in
their knowledge about accident prevention.
• ADHD teens and adults have significant more traffic
accidents and engage in more risky driving behaviors
than normals but are not especially deficient in their
knowledge of driving safety or accident prevention.
• Thus there seems to be a major problem in the degree
to which rules of safety as well as other types of rules
govern their behavior.
Motivational Deficits
• Children with ADHD are often characterized by their
apparent low level of sustained motivation.
• This is especially true on tasks that require repetitive
responding that involves little or no reinforcement.
• Multiple studies have documented an impairment in
persistence of effort in laboratory tasks in children
with ADHD.
• It is not clear whether this is due to the lack of
sensitivity of the ADHD child to reinforcement,
unless it is continuous, or due to some other type of
deficit
Motivational Deficits
• Barkley has suggested that the problem may relate to
the fact that, while normal children have the capacity to
bridge temporal delays across times when rewards are
sparse, children with ADHD are delayed in this ability.
• They remain more contingency bound and more
specifically under the control of immediate external
rewards.
• He suggests the problem is not that ADHD children are
not sensitive to reward or dominated by the tendency to
seek immediate rewards.
• Instead they have a diminished capacity to bridge
delays in reinforcement and permit the persistence of
goal directed acts (rule governed behavior?).
ADHD Comorbidity: Relevance
• It is clear that the issue of comorbidity has important
implications for the understanding, assessment, and
treatment of children with ADHD.
• First, the findings reported here suggest that children
with ADHD frequently show evidence of significant
comorbidity.
• Indeed, many children with ADHD display Learning
Disabilities, ODD or CD, Anxiety Disorders, and
Depressive Disorders, while still others may show
evidence of co-occurring tic disorders and perhaps bipolar disorder.
Relevance of Comorbidity
• Some show multiple comorbid disorders.
• These patterns of comorbidity have been interpreted
by Biederman, et al as suggesting that “...attention
deficit hyperactivity disorder is most likely a group of
conditions with potentially different and modifying
risk factors and different outcomes rather than a
single homogeneous clinical entity.” (multiple
conditions or ADHD with multiple comorbidities???)
• The presence of comorbid conditions likely has
significant implications for long term outcome.
Relevance of Comorbidity
• Here, children with comorbid features often
show more serious levels of impairment, are
more likely to have continuing problems, and
show a greater utilization of mental health
services than do those without evidence of
comorbidity.
• Assessing for the presence of comorbid features
that may complicate the clinical picture seems
essential in working with children with ADHD.
Relevance of Comorbidity
• Given that proper assessment should lead to
optimal treatment, it follows that treatment
programs for children with ADHD and
comorbid conditions should address the full
range of problems highlighted by assessment
findings.
• For example, in instances where a child, not
only shows features of ADHD but also meets
diagnostic criteria for Oppositional Defiant
Disorder and Learning Disability, treatment
should focus on problems associated with each of
these areas.
Relevance of Comorbidity
• This might involve pharmacological treatment for
dealing with the child’s hyperactive/impulsive and
inattentive behavior, parent oriented behavior
management approaches to modify oppositional
behavior, and specially designed educational
approaches to assist the child academically.
• Likewise, in the case of a child with ADHD and
comorbid depression, it will be necessary to treat the
child’s depression as well as the ADHD symptoms.
• With children displaying other patterns of
comorbidity, other combinations and/or approaches
to treatment may be called for.
Relevance of Comorbidity
• Simply treating symptoms of ADHD is not enough!
• Appropriate case management involves addressing the
full range of clinical problems displayed.
• Indeed, effective treatments for children with ADHD
and comorbid conditions are likely to be multimodal
and multidisciplinary in nature and necessarily more
extensive and complex that treatments for children with
“uncomplicated” ADHD.
• More research is needed to guide the treatment of
children with ADHD who display specific patterns of
comorbidity.
The End! Questions?