Ahmed Aboraya, MD, DrPH

Just as  hybrid cars with engines that use both electricity and gasoline become more  common, do not be surprised to hear more about hybrid models of psychiatric  diagnoses included in DSM-5. Psychiatric diagnoses are conceptualized using a  top-down approach and a bottom-up approach. Using the top-down approach (ie, a  categorical or disease model), expert clinicians use their own experience, the  existing literature, and new data in order to define diagnostic criteria for a  specific mental disorder. The DSM system is based on the categorical model  approach with the main assumption that psychiatric disorders are separate  disease entities.

In contrast,  a bottom-up approach (ie, a dimensional model) is driven primarily by symptoms  collected from patients’ reports, and statistical analyses are used to  determine which symptoms cluster together into syndromes. In reality, the  categorical and dimensional model approaches are 2 sides of the same coin as  you look at the same patient from 2 different angles.

Both  categorical and dimensional approaches have benefits and drawbacks. Categorical  models have been widely used in psychiatry since the publication of DSM-III in  1980 and have improved the reliability of psychiatric diagnoses. The  categorical approach in DSM has fostered progress in basic, epidemiological,  and clinical research, as well as treatment.

Categorical  models are commonly used in other specialties and put psychiatry in line with  the rest of medicine. Generally, categorical models are preferred to  dimensional models by clinicians because they are parsimonious and useful. One  diagnostic label can convey a considerable amount of useful clinical information  in a vivid, succinct manner. Categorical models facilitate decisions making  (eg, whether a patient has a disorder, whether a patient needs a certain  medication, whether a patient needs to be hospitalized). Overall, communication  among clinicians is easier using categorical models.

 have several problems, such as the  questionable validity of DSM categories. Using categorical models can result in  loss of important information. Categorical models evaluate the presence versus  the absence of a disorder and do not allow for evaluation of the severity of  the disorder in question.

By  themselves, categorical models do not necessarily tell the clinician how severe  the condition is. For example, a patient diagnosed with 

, may be stable on one antipsychotic medication and live in the community  with outpatient follow-up. Another patient diagnosed with schizophrenia,  paranoid type, may have delusions and hallucinations in spite of treatment with  1 or 2 antipsychotic medications and may spend a significant amount of time in  the hospital. Because of the artificial boundaries of disorders, many patients  do not fit any one category. Consequently, diagnoses of Not Otherwise Specified  (NOS) are popular in many clinical settings. Many patients present with  symptoms that meet criteria for several conditions. Finally, some researchers  posit that the slavish adoption of DSM criteria may have hindered research on  the etiology of mental disorders.

In  comparison to categorical approaches, 

 start and build on the  symptoms and therefore reflect clinical reality. In psychiatry, we treat the  totality of symptoms and signs. A patient with depressive symptoms receives  antidepressant medication, a patient with delusions receives antipsychotic  medication, and so on. Dimensional models provide a greater amount of  information and allow measuring of the severity of psychiatric disorders.  Furthermore, dimensional models display a higher degree of validity, reliability,  and stability over time. Finally, dimensional models are preferred for  hypothesis generation and testing, and they provide greater utility in research  contexts.

However,  dimensional models are more complex and more difficult to use than categorical  models. Providing too much information can be a hindrance rather than help to  clinicians, especially if the information is not clinically relevant. For  example, the 

 (PANSS) uses a 7-point scale  (absent, minimal, mild, moderate, moderate severe, severe and extreme).

Most of the  time, minimal and mild symptoms are not clinically significant and do not  affect the clinician’s decisions. Similarly, the difference between moderate  and moderate-severe or severe and extreme do not affect clinicians’ decisions  in general. That explains why psychiatrists do not use the PANSS in clinical  settings. In general, clinicians do not have the time, training, or inclination  to use dimensional ratings.

 readers show that most respondents  did not use any of the 4 clinical rating scales routinely used in clinical  trials, which are required for FDA approval of psychiatric medications.

  Lack of time was the most common reason cited for not using these tools.

Moreover, no  dimensional model has achieved wide acceptance. The clinical utility of  dimensional models is yet to be determined. Therefore, efforts to empirically  demonstrate the clinical utility of dimensional models should be a prerequisite  for their future implementation, in order to establish that their advantages  outweigh the disadvantages.

 Finally, communication among clinicians  using the dimensional model is more difficult than with the categorical model.

Historically  speaking, after the introduction of DSM-III in 1980, the categorical approach  gained ground and DSM diagnoses have been used worldwide in clinical and  research contexts. Advocates of the categorical models hoped and assumed that  it was only a matter of time until scientists discovered the etiology of  psychiatric disorders as categorized by DSM. To the disappointment of  categorical model advocates, more than 30 years after the publication of  DSM-III, the goal of validating psychiatric disorders by discovering common  etiologies remains elusive.The case for schizophrenia is especially alarming;  after decades and millions of dollars spent on research, biological markers or  specifics for schizophrenia as a distinct disease have yet to be identified.

As the DSM-5  Work Groups began to work on the DSM-5 revision, a decision was made to  incorporate the dimensional models into DSM-5. All researchers agreed to keep  the disorders categorical (with new changes) and add dimensional measures along  with DSM categories, hence, the concept of hybrid models was born. Common sense  indicates that if you have a hybrid model, then you have the best of both  categorical and dimensional approaches. The challenge for the DSM-5 is to “find  ways to create dimensional measures that are compatible with categorical definitions  and not overly disruptive to clinical practice.”

The DSM-5  Task Force decision to include a dimensional component to DSM categories seems  reasonable but ambitious. In a recent publication, the DSM-5 Task Force  declared “one of the major-if not the major-differences between the DSM-IV and  DSM-5 will be more prominent use of the dimensional measures in DSM-5.”

  Because the DSM-5 Task Force put all or most of their eggs into the basket of  dimensional measures, you would expect the DSM-5 Task Force to allocate all  available resources to make sure that the major part of DSM-5 changes are  successful.

The DSM-5  Task Force recommends a group of dimensional scales to be used with DSM-5 and  expects clinicians to use them. The proposed measures are vague, complicated,  not designed for clinical applications, not useful to clinicians’ work, and not  researched adequately to justify their use. It would require another article’s  worth of space to explain in detail why this is the case. The most that the  DSM-5 Task Force can hope for with the proposed measures is to find researchers  who can solicit funding and use the proposed measures in the funded project.  When the project is over and the funds dry out, the measures will be placed on  the shelves, along with many other devised and unused measures.

 It takes many years to develop, test, refine, and  retest new scales and structured interviews. It took more than 10 years for the  developers of SCAN (Schedule for Clinical Assessment in Neuropsychiatry), SCID  (Structured Clinical Interview for DSM Disorders), MINI (Mini International  Neuropsychiatric Interview), and other instruments to develop and test these  tools.

After I  finished my psychiatry residency, my main research interest was the use of  psychiatric scales and structured interviews in clinical settings. Even with  the plethora of structured interviews and psychiatric scales available, I could  not find a single tool that was applicable to the daily work of psychiatrists  in real 

. None of the existing instruments was really designed  for working psychiatrists in real clinical settings. Therefore, I took upon  myself to develop a new instrument-the Standard for Clinicians’ Interview in  Psychiatry (SCIP).

I envisioned  the SCIP as an instrument that would capture the dimensional component of  psychopathology, in addition to the categorical component of psychiatric  disorders-a hybrid model. More than 50 colleagues in 4 countries (USA, Canada,  Egypt, and England) took part in the SCIP project for 10 years and data were  collected on 1010 subjects-making this the largest validity and reliability  study of a structured instrument. The SCIP was designed to yield dimensional measures and scores for obsessions,  compulsions, depression, mania, suicide, delusions, hallucination, agitation,  disorganized behavior, negative symptoms, catatonia, attention, hyperactivity  and drug addiction, in addition to psychiatric diagnoses according to DSM and  ICD criteria.

Any  classification system has to be useful to clinicians to entice them to use  it. If the classification system is not used by clinicians, no matter how good  the system is, the system is a waste and will end up filed away in the bottom  drawer or on the shelves of history. At the end of the day, a disease  classification has to be useful and used by clinicians to serve its major  purpose.

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Dimensional Appoaches in Diagnostic Classification: Refining the Research Agenda for DSM-V.

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 Aboraya A. The Schedules for Clinicians’ Interview in Psychiatry (SCIP): A New Instrument With Categorical and Dimensional Models for Substance Use Disorders. Presented at the 10th Annual Meeting for International Society of Addiction Medicine. Cape Town, South Africa; 2009.


Aboraya A, Rankin E, France C, et al. The reliability of psychiatric diagnosis revisited: the clinician’s guide to improve the reliability of psychiatric diagnosis. 

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Articles

Do not be surprised if you hear more about hybrid models of psychiatric diagnoses included in DSM-5. The categorical and dimensional model approaches are 2 sides of the same coin as you look at the same patient from 2 different angles.

Coming Along With the DSM-5: Hybrid Models of Psychiatric Diagnosis

As I was driving to work on February 10, 2010, I listened to the National Public Radio host Melissa Block talking about how children labeled “bipolar” may get a new diagnosis.

 I was shocked that the chair of one of the DSM5 work groups, David Shaffer, MD, would discuss a controversial diagnostic topic with the media. The impetus for writing this commentary is my empathy for millions of parents who have children with a mental disorder-whether experts call it “bipolar disorder” or the newly manufactured “temper dysregulation disorder” (TDD) proposed by the DSM5 work group. The parents of afflicted children need all the help and education they can get from experts in child psychiatry, and the last thing they need is confusion and extra stress in their lives.

Let me set the record straight. . . . I am not a child psychiatrist or an expert on childhood ailments, but I know enough to say that neither Dr Shaffer nor the work group has any scientific evidence to back up the newly manufactured TDD. Dr Shaffer went even further and declared that temper dysregulation disorder will be seen as a brain or a biological dysfunction, but not necessarily as a lifelong condition like bipolar. I would like the DSM5 experts to share with the psychiatric community their scientific evidence regarding the biological nature of TDD.

The interview with Dr Shaffer reminded me of the wrong and unproven schizophrenogenic mother hypothesis of Fromm-Reichmann in the 40s as a cause of schizophrenia.

 In the case of TDD, the situation is made worse because of the creation of an entirely new, scientifically unproven disorder. If TDD turns out to be a false disorder, every theory and all the research related to the TDD will be a waste.

The science of classification (taxonomy) has the following 9 important functions as described in textbooks and papers

:
• Economizing memory, meaning that describing a group of individuals subsumes the description of each individual in the group
• Summarizing the information and attaching a convenient label to it
• Easing the manipulation and retrieval of information
• Conceptualizing clinical diagnostic entities for human illnesses and using them in clinical practice
• Identifying and assigning previously unallocated entities to their appropriate categories and assigning individual patients to an appropriate diagnosis
• Communicating clinical information (diagnoses) to other health care providers, families, and health care systems administrators
• Describing and simplifying the attributes and relationships of subjects in different diagnostic entities • Generating and testing hypotheses (eg, testing and choosing effective interventions to improve the clinical outcomes of different diagnostic entities)
• Assessing the clinical needs of diagnostic entities and predicting their course and outcomes

None of the functions of classification includes manufacturing and selling of new mental disorders to the public as the DSM5 work group is doing with the TDD.

Mental disorders can be classified using-a categorical model or a dimensional model.

 The categorical model used in DSM assumes discrete disease entities of mental disorders; these entities do not cover the heterogeneity of patients seen in clinical practice. This limitation has resulted in the overuse of the not otherwise specified (NOS) category by clinicians.

 In an attempt to solve this problem, each new DSM edition has expanded and added new disorders and new subtypes. A good example is the addition of bipolar II disorder in DSM-IV to capture patients with hypomanic episodes and major depression.

Advocates of the dimensional model argue that their model may solve this and other problems inherent in the categorical model.

 The DSM5 Task Force decided to include a dimensional component in DSM5.22,23 I wonder if Dr Shaffer and his colleagues have developed (or are developing) a mood spectrum dimension that can be the scientific solution to misdiagnosis.

Did the DSM5 work group think about the basic expected consequences of creating a new mental disorder? Did they consider the possibility of creating a false epidemic of a new mental disorder? Will the TDD cause unnecessary panic and confusion for the public? What guidelines do child psychiatrists and clinicians need to use to diagnose and treat the new TDD? How about the disruption of research efforts such as meta-analyses? Concerning the unintended consequences of making new DSM changes, Allen Frances, MD, has elaborated on them in his criticism of the DSM5 process.

Dr Shaffer argues that many children who have received a diagnosis of bipolar disorder do not meet the essential diagnostic criteria-namely a discrete weeklong episode of mania or a 2-week-long episode of depression. If this is the case, the problem appears to be that clinicians do not apply DSM criteria correctly. As Verheul

 said, “a classification system can be theoretically sound, valid and provide perfect coverage, yet be completely worthless when it is not used at all or when it is not used correctly.”

Maybe we need to educate and train clinicians to use the DSM system correctly. If the DSM5 Task Force approves TDD, what will the DSM experts do when clinicians do not use the new criteria of TDD correctly? Dr Shaffer admits that he does not know whether psychiatrists or psychologists will actually change their ways with the new TDD. I have to agree with him on this one.

 In today’s era of evidence-based medicine, clinical research and scientific evidence is the solid ground of medicine and psychiatry.

 If the DSM5 work group embarks on the road of “pseudoscience” and the creation and selling of mental disorders to the public, this may signal the decline of the DSM classification system. I would like to remind the DSM5 experts of a historical lesson: psychoanalysis and psychoanalysts enjoyed more than half a century of hegemony in the United States and ended up bankrupt because they did not back up their theories with scientific research.

Since the experts in the field do not agree on the diagnosis, why do we need to confuse the public and parents by going to the mass media? Do not take me wrong. . . . I am a proponent of free speech and free media. However, I implore the DSM5 work group to do their homework at home. The true home for scientific discussions on psychiatric nosology belongs to research proposals, field trials, scientific journals, and conferences.References
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As I was driving to work on February 10, 2010, I listened to the National Public Radio host Melissa Block talking about how children labeled “bipolar” may get a new diagnosis. I was shocked that the chair of one of the DSM5 work groups, David Shaffer, MD, would discuss a controversial diagnostic topic with the media.

Ahmed Aboraya, MD, DrPH

Articles

Coming Along With the DSM-5: Hybrid Models of Psychiatric Diagnosis

DSM5 Task Force: Do Not Go to the Mass Media-Do Your Homework