ADHD: Mimicry and Comorbidity

1. 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

2. 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.

3. Conditions that Can Mimic ADHD Symptoms • Sensory Impairments • Medication side effects • Phenobarbital • Dilantin • Some Asthma Medications • Seizure Disorder • RTH (Resistance to Thyroid Hormone) • PTSD • Bipolar Disorder • Anxiety Disorders • Depressive Disorders

4. What is Comorbidity? • The term comorbidity first appeared in the 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.

5. 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 co-occurrence 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.

6. 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 unrelatedconditions.

7. 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.

8. 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).

9. 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.

10. 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

11. 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

12. Learning Disabilities • Children with ADHD often show problems 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.

13. 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

14. 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.

15. 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)

16. 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.

17. 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.”

18. 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??

19. 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.

20. 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.

21. 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.

22. 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

23. 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)

24. 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 largelyunidirectional. • 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.

25. 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??)

26. Tourette’s Disorder • There is data to suggest that Tourette’s disorder may also be 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.

27. Tourette’s Disorder • It is noteworthy that the only published population-based 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.

28. 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.

29. Intellectual Functioning • Children with ADHD are more likely to be behind in intellectual developmentthan 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.

30. ADHD: Accident Proneness • Children with ADHD are considerably more likely to 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.

31. 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.

32. Sleep Problems • Studies suggest that children with ADHD have a higher 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

33. 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.

34. 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.

35. 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 ???

36. Deficits in Rule Governed Behavior Rule Governed Behavior has to do with difficulties that children with ADHD have inadhering 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 arenot 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”

37. 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.

38. 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.

39. 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???

40. Deficits in Rule Governed Behavior • For example, studies have found that hyperactive-impulsive 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.

41. 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

42. 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?).

43. 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 bi-polar disorder.

44. 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 conditionswith 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.

45. 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.

46. 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.

47. 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.

48. Relevance of Comorbidity • Simply treating symptoms of ADHD is not enough! • Appropriate case management involvesaddressing 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.

49. The End! Questions?