As simple background, according to the DSM-IV, the basic diagnostic distinction between autism and Asperger’s disorder is absence of clinically significant delays in language, cognitive development, and adaptive functioning in the Asperger’s group. The rest of the diagnostic criteria (impairments in social interactions, restricted repetitive and stereotype patterns of behaviors) between autism and Asperger’s is identical. This makes it difficult to differentiate children with Asperger’s from those with High Functioning Autism (HFA; i.e., those who meet the diagnosis of autism but perform in the average to above average rage in intellectual tests). Therefore, two teens with otherwise identical clinical profiles would be diagnosed differently if they differ on their history of language and cognitive delays. The child with a history of language/cognitive delays would be diagnosed with HFA and the child without a history of language/cognitive delays would be diagnosed with Aspeger’s. I mention this because any discussion about the science of the possible differences between these two categories is limited by the fact that both groups have been selected, by definition, to be different. Thus, the question is not whether these two groups are different – they are different because we have defined them differently. The question is whether these two groups actually represent two distinct typologies that go beyond the distinction of language/cognitive delay vs. no delay.

So what would drive the DSM-V to propose the merger between Asperger’s and Autism? In essence, the questions are 1) whether these two conditions represent two different disorders or are simply variations within a larger spectrum, and 2) whether having two categories, as defined today, is clinically useful. If Asperger’s and Autism are simply the same disorder separated by an arbitrary distinction (language/cognitive delays), having two categories would not help us in our understanding or treatment of the conditions, and keeping them as separate categories may be an obstacle for research because it encourages researchers to focus on a domain that may not be relevant or informative. However, if the language/cognitive delay distinction reflects differences between two truly distinct categories, the existence of two categories rather than one should help us make more effective interventions, inform our clinical decisions, or help us better understand the phenomenology of both conditions. Has this been the case?

Let me address the clinical impact of these two conditions from the perception of clinicians (Note: although I am basing these statements on my experience as a clinician interacting at academic/training settings, I admit that this may not represent the experience and practice of all clinicians). I interact weekly with graduate students who are learning how to conduct neuropsychological evaluations for children and adolescents. Often these students have already developed a schema, or prototype, of the child or adolescent with Asperger’s. They would describe such a child as someone who has intense and unusual interests, maybe superior skills in some area such as music or art, rigidity in behaviors and interests, and social and communication ‘deficits’ leading to difficulties interacting and relating to others. The problems begin when we start seeing actual assessment cases. For example, recently a doctoral intern and I sat in supervision to discuss a case of a teenage boy who could be described as having a “perfect” Asperger’s profile, fitting both the student’s schema and the DSM-IV criteria; except for one thing: the client had a documented history of language delays. There was no question about the diagnosis: If the teen had a history of “language delays’ the diagnosis is autism. My student then asked me, so if this is HFA, how does Asperger’s look like? I replied, just like this.

Therefore, in clinical settings, HFA and Aspeger’s disorder look mostly identical, assuming the clinician follows DSM guidelines. But the most important question is whether the current diagnostic difference is clinically useful.  When debating the Autism vs. Asperger’s diagnostic question, I have always asked my students and supervisors whether the diagnostic difference would change anything regarding our approach to the case. This is the most critical question: would our recommendations or conclusions change based on the final diagnosis that we provide (autism vs. Asperger’s)? The answer is usually, if not always, no. Given identical clinical profiles, the recommendation for treatment, school accommodations, parental interventions, and so forth, would be the same for two adolescents who only differ on the presence or absence of language delays in early childhood. The provision of a diagnosis of autism vs. Asperger’s may lead to different political/personal/social consequences, but clinically, the current DSM-IV distinction between these two conditions, and the research that has come out of this distinction, has not informed or improved our clinical practice (e.g., selection of treatment, assessment, prognosis, etc). This is likely one of the main reasons that led the DSM committee to suggest the merger of Asperger’s and Autism.

But why has the DSM-IV distinction failed to improve clinical services or lead to a greater understanding of these conditions? One possibility is that these two conditions are variations of a greater spectrum and that the language/cognitive delay difference is arbitrary (see for example Bennett et al., 2008 for a study showing identical clinical outcomes between HFA and Asperger’s). In such a case, the merger of the two conditions would better reflect the true nature of the conditions as a variations within a single spectrum. However, another possibility is that the DSM-IV criteria is simply wrong. Under that hypothesis, research has failed to find utility for this classification because of an erroneous diagnostic criteria which led to the incorrect classification of people. Some support for this later position was provided by the research team of Fred Volkmar at the Yale University Child Study Center (Klin et al., 2005). They proposed a new diagnostic criteria for Asperger’s disorder that was more inline Asperger’s original 1944 observation of his cases. Under this system HFA and Asperger’s would differ on 3 specific domains:

1. Nature of social impairments: HFA would be characterized by self-isolation and lack of interest while Aspeger’s would be characterized by interest in social relations and ‘seeking others’ (social motivation) but in a socially insensitive or atypical manner.

2. Nature of language impairment: HFA would be characterized by delayed, echolalic and stereotyped language while Asperger’s would be characterized by adequate or precocious language but with difficulties in the use of language (pragmatics).

3. In addition, the Asperger’s diagnosis would include one-sided verbosity and the presence of factual, circumscribed interest that interferes with the person’s functioning (e.g., education and social interactions).

Interestingly, some research has shown differences between HFA and Asperger’s when using the Klin criteria above (see for example Mazefsky and Oswald. 2006). Thus, it is possible that the lack of clinical utility of the current DSM-IV diagnostic distinction between HFA and Asperger’s is due to a lack of validity of the DSM-IV criteria rather than the lack of validity of the constructs of HFA and Asperger’s as two distinct syndromes. So why did the DSM-V committee recommend the merger of these two conditions rather than a redefinition of the Asperger’s criteria? It appears that their interpretation of the totality of the data is that there is no sufficient evidence to validate these two conditions as two separate syndromes regardless of diagnostic criteria used, and that the differences observed are better accounted for by differences in language, IQ, and severity, rather than features of the disorder.

From the DSM-V committee:

Differentiation of autism spectrum disorder from typical development and other “nonspectrum” disorders is done reliably and with validity; while distinctions among disorders have been found to be inconsistent over time, variable across sites and often associated with severity, language level or intelligence rather than features of the disorder.

Update: I just noticed that Dr. Mohammad Ghaziuddin, an accomplished autism and Asperger’s researcher and clinician working at the University of Michigan, just published an opinion piece on the Journal of Autism and Developmental Disorders arguing for a redefinition of Asperger’s rather than its merger with Autism. He argues that the current DSM-IV definition is incorrect and a new updated definition (following the Klin’s criteria outlined above) would be more accurate and clinically useful. He states:

…what is needed is a revision of its criteria taking into account, its quality of social impairment (active but oddrather than aloof and passive); idiosyncratic interests (oftensophisticated and intellectual); communication style (oftenpedantic and verbose); and age of onset/emergence of symptoms (often around 7–8 years). In addition, effortsshould continue to establish its validity not only from autism but also from other conditions.

References:

Klin, A., Pauls, D., Schultz, R., & Volkmar, F. (2005). Three Diagnostic Approaches to Asperger Syndrome: Implications for Research Journal of Autism and Developmental Disorders, 35 (2), 221-234 DOI: 10.1007/s10803-004-2001-y

Bennett, T., Szatmari, P., Bryson, S., Volden, J., Zwaigenbaum, L., Vaccarella, L., et al. (2008). Differentiating Autism and Asperger Syndrome on the Basis of Language Delay or Impairment. Journal of Autism and Developmental Disorders, 38(4), 616-625. doi: 10.1007/s10803-007-0428-7

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Let me start by explaining that the creation of TDD does NOT deny the existence of classic bipolar disorder in childhood. That is, although extremely rare, bipolar disorder can occur in children and adolescents, and it looks very much like adult bipolar.  Instead, TDD was created to capture a valid syndrome with characteristics and outcomes that are different than those of bipolar disorder. The available scientific data supports the position that the TDD syndrome is NOT simply the manifestation of bipolar disorder in childhood. This means that thousands of children that have been diagnosed with childhood bipolar disorder may not have bipolar and instead have a completely different syndrome now called Temper Dysregulation Disorder with Dysphoria.

So what is TDD?

Here is the proposed criteria for TDD:

A. The disorder is characterized by severe recurrent temper outbursts in response to common stressors.

1.  The temper outbursts are manifest verbally and/or behaviorally, such as in the form of verbal rages, or physical aggression towards people or property.

2.  The reaction is grossly out of proportion in intensity or duration to the situation or provocation.

3.  The responses are inconsistent with developmental level.

B. Frequency: The temper outbursts occur, on average, three or more times per week.

C. Mood between temper outbursts:

1.  Nearly every day, the mood between temper outbursts is persistently negative (irritable, angry, and/or sad).

2.  The negative mood is observable by others (e.g., parents, teachers, peers).

D. Duration: Criteria A-C have been present for at least 12 months.  Throughout that time, the person has never been without the symptoms of Criteria A-C for more than 3 months at a time.

E. The temper outbursts and/or negative mood are present in at least two settings (at home, at school, or with peers) and must be severe in at least in one setting.

F.  Chronological age is at least 6 years (or equivalent developmental level).

G. The onset is before age 10 years.

H. In the past year, there has never been a distinct period lasting more than one day during which abnormally elevated or expansive mood was present most of the day for most days, and the abnormally elevated or expansive mood was accompanied by the onset, or worsening, of three of the “B” criteria of mania (i.e., grandiosity or inflated self esteem, decreased need for sleep, pressured speech, flight of ideas, distractibility, increase in goal directed activity, or excessive involvement in activities with a high potential for painful consequences; see pp. XX). Abnormally elevated mood should be differentiated from developmentally appropriate mood elevation, such as occurs in the context of a highly positive event or its anticipation.

I.  The behaviors do not occur exclusively during the course of a Psychotic or Mood Disorder (e.g., Major Depressive Disorder, Dysthymic Disorder, Bipolar Disorder) and are not better accounted for by another mental disorder (e.g., Pervasive Developmental Disorder, post-traumatic stress disorder, separation anxiety disorder). (Note: This diagnosis can co-exist with Oppositional Defiant Disorder, ADHD, Conduct Disorder, and Substance Use Disorders.) The symptoms are not due to the direct physiological effects of a drug of abuse, or to a general medical or neurological condition.

The syndrome captured by section A-C (frequent and intense temper outbursts, happening several times per week in the context of negative emotionality) is the core of the symptoms that has been incorrectly interpreted as indicative of childhood bipolar disorder.  Section H is very interesting. It states that this diagnosis is not appropriate if the person has experienced classic mania (e.g., bnormally elevated or expansive mood), as in such a case the diagnosis of bipolar is likely more accurate.

So why did the DSM-V decide that this syndrome is not simply bipolar disorder of childhood?

1. Lack of continuity to bipolar.

If TDD is simply the expression of bipolar disorder during childhood, then children diagnosed with this condition would eventually develop symptoms of classic bipolar disorder as they reach adulthood. The data do not support this hypothesis. That is, children who display the TDD syndrome in childhood (and are often incorrectly diagnosed as bipolar) are not more likely to develop classic bipolar disorder later in life as their peers (see Brotman et al., 2006; Leibenluft et al, 2006; Stringaris et al, 2009).  Instead, these children are more likely to develop depression, not bipolar!

2. Different Biological Markets.

Youth who are diagnosed with classic bipolar differ significantly from those who have a TDD-like syndrome (see Brotman et al, 2010; Guyer et al, 2007; Rich et al, 2008).  If TDD is simply bipolar, then the biomarkers of TDD should be similar to those of bipolar, but this is not the case.

3. Different Demographic Factors.

If TDD is simply bipolar, then the gender distribution of TDD should be similar to that of bipolar. This does not appear to be the case. Specifically, there is no gender differences in the rate of classic bipolar; male and females are equally likely to develop the condition. However, the TDD-like syndrome is disproportionately observed in boys rather than girls.

4. A need for a new category that would impact treatment and research.

In theory, the presence of TDD will educate clinicians, researchers, and the public that this syndrome is not simply a version of bipolar disorder. This would facilitate research on the causes, features, and treatments for this condition. This has major implications for treatment. For example, the standard treatment for bipolar disorder does NOT seem to work in children that have the TDD syndrome (Dickstein et al, 2009). By explicitly stating that TDD is not bipolar, researchers would be less likely to approach the search for treatments from a “bipolar framework”, which would potentially facilitate the discovery of more effective interventions.

I am actually glad about this change as it will have a clear impact on clinical practice and research that will most likely benefit the children affected with this condition.

References:

Brotman MA, Schmajuk M, Rich BA, Dickstein DP, Guyer AE, Costello EJ, Egger HL, Angold A, Pine DS, & Leibenluft E (2006). Prevalence, clinical correlates, and longitudinal course of severe mood dysregulation in children. Biological psychiatry, 60 (9), 991-7 PMID: 17056393

Dickstein DP, Towbin KE, Van Der Veen JW, Rich BA, Brotman MA, Knopf L, Onelio L, Pine DS, Leibenluft E (2009): Randomized double-blind placebo-controlled trial of lithium in youth with severe mood dysregulation. J Child Adolesc Psychopharm 19: 61-73

Guyer AE, McClure EB, Adler AD, Brotman MA, Rich BA, Kimes AS, Pine DS, Ernst M, Leibenluft E (2007): Specificity of face emotion labeling deficits in childhood psychopathology. Journal of Child Psychiatry and Psychology, 48:863-71

Leibenluft E, Charney DS, Towbin KE, Bhangoo RK, Pine DS (2003): Defining clinical phenotypes of juvenile mania. Am J Psychiatry 160: 430-437

Rich BA, Grimley ME, Schmajuk M, Blair KS, Blair RJR, Leibenluft E (2008): Face emotion labeling deficits in children with bipolar disorder and severe mood dysregulation. Development and Psychopathology 20: 529-546

Stringaris A, Cohen P, Pine DS, Leibenluft E (2009): Adult outcomes of adolescent irritabilty: A 20-year community follow-up. Am J Psychiatry 166: 1048-54

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So today I want to touch on a topic raised by renowned child psychologist Dr. Thomas Achenbach in a recent issue of the journal Psychology Clinical Science and Practice. This topic, the role of “functional impairment” as a component of the diagnostic process, will likely become the elephant in the room, and a source of much tension and debate.

There are many extensive resources about the history of the DSM and the process of the DSM-V (I invite readers to visit the DSM-V official page). So here I provide you a very simplistic background of the issues:

In 1980, the American Psychiatric Association, published the DSM-III, which at the time represented a paradigm shift in Psychiatry. The system was based on the basic concept that psychiatric disorders, just like other medical disorders, where organized in discrete categories. You had depression or you didn’t. You had schizophrenia or you didn’t. The decision as to whether you had or did not have a disorder was based on a threshold consensus of how many symptoms you experienced: 4 symptoms? You have the disorder. 3 symptoms? You don’t have the disorder. etc, etc, etc. This system was kept relatively intact in the next version of the DSM (DSM-IV) published in 1994.

So for almost 30 years our field has followed a categorical diagnostic classification system. But the problem is that such a system is actually not well supported by the science in at least in two key issues: 1) Research has consistently shown that there is significant fluidity between diagnostic categories. That is, the line between depression and anxiety, for example, is more of an imaginary line than an actual wall. So clinical phenomena (depression, anxiety, phobias, delusions, compulsions, etc) occur on integrated dimensions that are not as easily separated as the DSM-IV categorical system suggests. And 2) Research is also consistent in showing that the degree of severity of each symptom and each overall condition also fall on a continuum or dimension. Unlike the assumption of the categorical system, we don’t really have an “all or nothing” situation, a “you have it or you don’t”. Instead, the story is much more complex. Therefore, as clinical phenomena occur in a continuum, clinical decisions should also occur in a continuum. Thus, a dimensional view of these clinical conditions may facilitate research on how different thresholds may lead to more effective clinical decisions (for example, at what level of depression is hospitalization the best option, or at what level does SSRI is recommended?).

Now, when I talk to colleagues about these issues, some mistakenly believe that the change in DSM-V is mostly about adopting a dimensional approach to functional impairment. This is due to the erroneous view that severity of a disorder = severity of impairment. In the Psychology Clinical Science and Practice article, Dr. Achenbach argues that impairment should be separated from diagnoses. He states:

Although impairment should certainly be considered when deciding whether to treat, how to treat, and with what dose level, inclusion of impairment criteria for diagnoses implies that disorders are present only when they cause significant impairment. If impairment were required for diagnoses such as HIV and cancer, epidemiological studies would exclude many people who have the diseases but are not yet impaired. Worse yet, treatment could not be justified until impairment occurred, when it may be too late. Quantification of the number and/or severity of symptoms could help us evaluate the certainty and severity of disorders without confusing the existence of disorders with the important but separate issue of impairment.

Why do I think this is the big elephant in the room? Because for many decades the concept of impairment has been embedded into our conceptualization of disorders, and, with a few rare exceptions, all DSM-IV diagnostic criteria require the presence of impairment. Impairment has been central to the field’s attempt to deal with issues of culture, normalcy, and the notion of disease vs. disorder. Yet, Dr. Achembach presents what some could argue to be a medical model that separates impairment as an implicit requirement of the diagnostic process.

Does a person with asthma only have the condition when he or she is functionally impaired? What about diabetes, infections, viruses, tumors… do they require the person to be functionally impaired before they are illegible to receive a diagnosis and treatment? Then why would schizophrenia, depression, and anxiety be any different? Why would a person with depression need to wait until the depression affects her work, personal life, and/or education before he/she is able to receive treatment and a proper diagnosis?

UPDATE: In my original post I incorrectly mentioned Asperger’s as one disorder that does not have an explicit requirement of impairment in the current DSM-IV-TR.  One of our readers correctly mentioned that it is autism, not asperger’s, that doesn’t include the explicit impairment requirement. I deleted the example from the main post as it was not directly related to the core issues I wanted to discuss but I’m including this update to provide context to some of the comments below.

Achenbach, T. (2009). Some Needed Changes in DSM-V: But What About Children? Clinical Psychology: Science and Practice, 16 (1), 50-53 DOI: 10.1111/j.1468-2850.2009.01142.x

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