Which is an advantage of having a diagnostic system for classifying Mental Disorders?

Uses of Mental Health Classifications

Classification of mental disorders has traditionally started from practical efforts to seek similarities and differences among patient groups. Today its greatest use is for administrative and reimbursement purposes. In addition, researchers use mental disorder classifications to identify homogeneous groups of patient populations so as to explore their characteristics and possible determinants of mental illness such as the cause, treatment response, and outcome. Use of mental disorder classifications has also gained importance as a guide in teaching and clinical practice. Earlier practice of psychiatry and behavioral medicine was mainly based on clinical judgment and speculative theories about etiology; the introduction of operational diagnostics has demystified aspects of various practices: identification of a clinical feature should be defined, observed, and if possible measured in a similar way independent of the assessor. One of the greatest achievements of mental disorder classifications so far has been understanding that mental illnesses could be explained as brain dysfunctions. For example, schizophrenia, which was seen as a myth or a societal label, was defined as an integration of mental functions originating in the brain: Errors in thought processing, for example, result in this mental disorder.

4.03.2.1 Purposes of Classification According to DSM-5 and ICD-11

A classification of mental disorders has to serve multiple purposes. Understanding these purposes can help elucidate the choices made by developers of the DSM-5 and ICD-11, especially when it comes to differences between the two systems. It is worth noting that the various purposes of a classification for mental disorders are not mutually exclusive; indeed, they often overlap in complicated ways. The manner in which we present them here is oversimplified in order to illuminate and highlight clearly some of the most important components of how a classification is used (see Table 1).

Table 1. Major purposes of a diagnostic system for mental disorders

(1)

Allows professionals to recognize patterns among the symptoms that people present (i.e., syndromes).

Serves as an agreed upon authority that determines a threshold for impairment and/or distress that warrants a diagnosis as well as recovery from the diagnosis.

Provides a set of nouns, which may aid quick and efficient communication among professionals, patients, families, insurance companies, public health officials, researchers, and the general public.

Organizes mental health conditions and disorders into groups and structures that allow users of the diagnostic manual to find a disorder for which they are looking.

Aids public health care in the identification of individuals in need of service, make informed choices about how best to allocate the system's resources, and decide of who qualifies for service (e.g., insurance reimbursement and universal health care).

Informs treatment planning, target of treatment, and clinical management of people with mental health conditions.

Defines which behaviors a society is willing to accept and which are not tolerated (e.g., antisocial behavior).

According to WHO's vision for the ICD-11 (for all diseases, conditions, and disorders), the most superior purpose of assigning a diagnosis is to ease suffering.

At face value, a classification exists to describe the various conditions that mental health professionals treat and manage. The alternative would be for clinicians to describe every person from “scratch”, based on their particular symptoms, which is not only inefficient as it would take an inordinate amount of time and effort, but likely unreliable and subject to the personal and professional biases of the diagnostician. Disorder descriptions in a classification form the basis of how professionals recognize patterns among the symptoms that people present. As such, a classification is successful to the degree that it describes patterns of covariation in people's symptoms that repeat across people and across time. Such patterns are typically termed syndromes, and imply nothing more than certain symptoms are likely to occur in the presence of certain other symptoms. Once the field starts to make claims that the pattern of symptoms is linked to external factors, like neural pathways, psychological mechanisms, or demographic factors, then the condition is more properly termed a disorder (Kazdin, 1983). The term “disease” is reserved for conditions where the etiology and prognosis of the condition is well established and clearly understood. To date, very few if any conditions classified in the DSM or ICD would qualify as a disease. A possible exception might be Alzheimer's dementia, where the pathogenesis of the condition arising from a genetic predisposition resulting in neurofibrillary tangles and amyloid plaques in the brain leads to a well-defined profile of symptoms and progressive cognitive decline (Robinson et al., 2017).

Diagnostic classifications exist as a tool to aid communication among professionals, patients, families, insurance companies, public health officials, researchers, and the general public. The classification provides a set of nouns that people can use to quickly and efficiently communicate a set of information about a person's condition. If a clinician had to describe a patient's full history every time she wanted to talk to another provider, the process would be burdensome to say the least. The conditions described in a classification system give various parties a short-hand for communicating about particular conditions. However, like any short-hand system, some information is lost along the way.

Another purpose of a classification system comes from its organizational value. There are hundreds of conditions listed in the DSM and ICD. The limits of human memory place a cap on how much any single person could remember about them. As such, a classification serves as a system for organizing information about different mental health conditions. At one level, the classification arranges disorders into groups and structures that allow users of the manual to find a disorder for which they are looking. Essentially, this structure is the table of contents. Both the DSM-5 and ICD-11 have paid explicit attention to placing disorders together that seem similar or may even be confused for one another (Andrews et al., 2009). At another level, a classification organizes information about mental disorders by providing a quick and ready reference for relevant information, like possible causes, known genetic influences, gender differences, cultural presentations, conditions that should be considered as part of differential diagnosis, and so on. This organizational structure helps clinicians avoid relying too much on memory, which can lead to diagnostic errors resulting from which cases come most easily to mind (i.e., the representativeness heuristic) or which cases a clinician most often sees (i.e., the availability heuristic).

Classifications also serve a vital public health service. Public health systems are predicated on being able to identify individuals in need of service and decide who qualifies for service, either through insurance reimbursement or universal health care. A vital component of public health services is being able to track individuals over time, determine who no longer needs services, and thereby make informed choices about how best to allocate the system's resources. A classification system is integral to that function by determining the threshold for disorder(s).

A classification system of mental disorders is also successful to the degree that it serves as a general guide for the treatment and management of people with mental health conditions. Society has decided that certain states of being are undesirable (either from the perspective of the person suffering or the needs of society) and thus there is an impetus to do something to improve that person's condition. Thus, the degree that the classification is useful for a clinician selecting a treatment or making decisions about the management of a person's condition is important. However, if the conditions in the classification are not associated with meaningful differences in treatment approach or other aspects of clinical care, then—at least from a practical perspective—it is worth questioning if the distinctions among disorders are necessary.

Finally, a classification of mental disorders serves, unwittingly or even wittingly a variety of sociopolitical functions. In a fundamental way, a classification of mental disorders defines which behaviors a society is willing to accept and which it will not tolerate, and in that sense are culturally defined. It draws a separate but parallel line to that of a legal system, defining a more lenient threshold that does not necessitate legal punishment but nonetheless holds an expectation for changing or controlling the person's behavior. Historically, classifications of mental disorder have been used to justify marginalizing a minority group by claiming that their behavior is pathological (Kutchins and Kirk, 1997). A salient example is the pathologizing of homosexuality, which due to cultural (predominantly religious) values used to be considered a mental disorder. Its disorder status was then used to justify attempts to alter the person's sexual orientation. Homosexuality was removed from the DSM-II and ICD-9 in recognition that the distress experienced by these individuals was due to stigma from society rather than something inherent to the person.

The international classifications

International classifications of mental disorders have existed for over one hundred years but were poorly developed and had little influence before the late 1960s. Successive revisions of ICD have provided some improvements despite the inherent problems associated with an international classification. There was a constant tendency for the classification to expand by incorporating alternative and sometimes incompatible concepts. ICD-9 (WHO 1978) contained no less than 13 categories for patients with depressive symptoms, because in effect several different ways of classifying depressions were included alongside one another.

The text of ICD-10 was published in 1992 and came into use in the UK and most other countries in 1993. It had a new title – the International Statistical Classification of Diseases and Related Health Problems – and a new alphanumeric format (WHO 1992). The principle of this was to provide more categories and so leave space for future expansion without the whole classification having to be changed. The general format of the section entitled ‘Mental, behavioural and developmental disorders’ (F00–F99) is very similar to that of the APA's recent classifications because it incorporates many of the innovations introduced in DSM-III. The traditional distinction between psychoses and neuroses has been laid aside, though the terms themselves are retained, and all mood (affective) disorders are brought together in a single grouping (F3). All disorders due to the use of psychoactive substances, including alcohol, have also been brought together under a common format (F1). There is also an operationalised version of ICD-10 for research (WHO 1993) although very few researchers use them.

INTERNATIONAL PSYCHIATRIC CLASSIFICATIONS

The classification of mental and behavioral disorders recommended by the World Health Organization11 is a part of the overall international classification. Categories have been established with an eye to agreement with the layout of the Diagnostic and Statistical Manual, Fourth Edition (DSM-IV) of the American Psychiatric Association (APA),12 which is well known in many countries. The ICD-10 classification of mental and behavioral disorders preserves parallel categories to those used in DSM-IV, although the descriptions are often different. However the ICD-10 classification does not use the “checklist approach” but rather gives a general description and major criteria required. The APA DSM-IV and DSM-IV TR (in which the explanatory text changed but not the codes) retain the same criteria as each other.

With respect to pain, the options in both systems are as follows. First, any particular diagnosis such as schizophrenia or depression of some sort may be made and indicated as a cause of the patient's pain, where it is understood that the diagnosis applies and pain may be accepted as resulting from such conditions. Then, the ICD-10 classification provides a category of Pain Disorder, Somatoform Persistent (F45.44). This category in essence corresponds to what DSM-IV now calls Persistent Somatoform Pain Disorder as well. In the ICD-10, the predominant complaint is of persistent, severe, and distressing pain that cannot be explained fully by a physiologic process or a physical disorder. It is presumed to be of psychological origin but pain occurring during the course of depressive disorder or schizophrenia is not included. Pain due to known or inferred psychophysiologic mechanisms such as muscle tension pain or migraine, but which is still believed to have a psychogenic cause, is coded under Psychological or Behavioral Factors Associated with Disorders or Diseases Classified Elsewhere (e.g., muscle tension pain or migraine). In ICD-10, the most common problem is to differentiate this disorder from the histrionic elaboration of organically caused pain. Thus this category essentially is meant to deal with pain that serves an unconscious motive. For a number of practical reasons, that is an extremely difficult proposition to prove clinically.

Under DSM-IV the criteria are similarly stringent but the diagnosis is made much more frequently, both in the United States and Canada. According to the description of chronic pain disorder in the DSM-IV, the word somatoform was dropped from the title. Pain disorder is the predominant focus of the clinical presentation, and it must cause significant stress or impairment in social, occupational, or other important areas of functioning. Psychological factors must be judged to have an important role in the onset, severity, exacerbation, or maintenance of the pain, and the symptom or deficit is not intentionally produced. This condition is not to be diagnosed if the pain is better accounted for by a mood, anxiety, or psychotic disorder or if it meets criteria for dyspareunia.

These criteria have the effect of limiting the condition to one that is not associated with significant depression or anxiety or that results from a physical illness. Within DSM-IV, two versions of pain disorder were allowed. One is “pain disorder associated with psychological factors” wherein the necessary criteria are met as above without psychologic illness being present. The other is “pain disorder associated with both psychological factors and a general medical condition.” In this case the same rules apply as for pain disorder on its own, but it is thought that a physical condition may be present but not sufficient to account for a large part of the syndrome. It is stated as follows: “Both psychological factors and a general medical condition are judged to have important roles in the onset, severity, exacerbation, or maintenance of the pain.” The associated general medical condition or anatomic site of the pain is coded separately.

In my observation, many diagnosticians who are sincerely interested in the patient's welfare welcome this category as a means for diagnosing a distressing psychological state to which they do not see an adequate physiologic or general medical explanation. In my view, that is not the way it should be used. It would only logically be justifiable having regard to the criteria for the cognate diagnoses, if it could be demonstrated that there was some psychological cause that was unconsciously producing the symptom at the same time as producing anxiety or depression; in other words, what used to be called hysteria. For reasons discussed elsewhere,13 the diagnosis of pain as “a conversion disorder” can rarely be adequately made. Persons with doubts should try to imagine whether they could produce, by thinking about it, a physical symptom such as paralysis that they would maintain consciously and whether they could produce a state of feeling of chronic pain in themselves by reflecting on it, and then ask how is it possible that pain could be produced unconsciously if it cannot even be done consciously? Overall then, psychological diagnoses as causes of pain are not favored by this writer except in very limited situations. Occasional patients with classic depressive illness develop severe headache that goes away when the depression is better. Occasional patients with postherpetic neuralgia have much worse pain when they become depressed and much less pain when the depression is treated, but these are relatively rare and do not reflect the bulk either of general medical, neurologic, or psychiatric practice.

International Psychiatric Classifications

The classification of mental and behavioral disorders recommended by the World Health Organization11 is a part of the overall international classification. Categories have been established with an eye to agreement with the layout of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), of the American Psychiatric Association (APA),12 which is well known in many countries. The ICD-10 classification of mental and behavioral disorders preserves categories parallel to those used in DSM-IV, although the descriptions are often different. However, the ICD-10 classification does not use the “checklist approach” but rather gives a general description and the major criteria required. The APA DSM-IV and DSM-IV TR (in which the explanatory text changed but not the codes) retain the same criteria as each other.

With respect to pain, the options in both systems are as follows: First, any particular diagnosis such as schizophrenia or depression of some sort may be made and indicated as a cause of the patient’s pain in cases in which it is understood that the diagnosis applies and pain may be accepted as resulting from such conditions. Then, the ICD-10 classification provides a category of Pain Disorder, Somatoform Persistent (F45.44). This category in essence corresponds to what the DSM-IV now calls Persistent Somatoform Pain Disorder. In the ICD-10 classification, the predominant complaint is persistent, severe, and distressing pain that cannot be explained fully by a physiologic process or a physical disorder. It is presumed to be of psychological origin, but pain occurring during the course of a depressive disorder or schizophrenia is not included. Pain that is due to known or inferred psychophysiologic mechanisms such as muscle tension pain or migraine but is still believed to have a psychogenic cause is coded under Psychological or Behavioral Factors Associated with Disorders or Diseases Classified Elsewhere (e.g., muscle tension pain or migraine). In ICD-10, the most common problem is to differentiate this disorder from the histrionic elaboration of organically caused pain. Thus, this category is essentially meant to deal with pain that serves an unconscious motive. For a number of practical reasons this is an extremely difficult proposition to prove clinically.

Under DSM-IV the criteria are similarly stringent but the diagnosis is made much more frequently, both in the United States and in Canada. According to the description of chronic pain disorder in DSM-IV, the word somatoform was dropped from the title. Pain disorder is the predominant focus of the clinical manifestation, and it must cause significant stress or impairment in social, occupational, or other important areas of functioning. Psychological factors must be judged to have an important role in the onset, severity, exacerbation, or maintenance of the pain, and the symptom or deficit must not be intentionally produced. This condition is not to be diagnosed if the pain is better accounted for by a mood, anxiety, or psychotic disorder or if it meets the criteria for dyspareunia.

These criteria have the effect of limiting the condition to one that is not associated with significant depression or anxiety or that results from a physical illness. Within DSM-IV, two versions of pain disorder were allowed. One is “pain disorder associated with psychological factors,” wherein the necessary criteria are met as above but psychological illness is not present. The other is “pain disorder associated with both psychological factors and a general medical condition.” In this case the same rules apply as for pain disorder on its own, but it is thought that a physical condition may be present but not sufficient to account for a large part of the syndrome. It is stated as follows: “Both psychological factors and a general medical condition are judged to have important roles in the onset, severity, exacerbation, or maintenance of the pain.” The associated general medical condition or anatomic site of the pain is coded separately.

In my observation, many diagnosticians who are sincerely interested in the patient’s welfare welcome this category as a means of diagnosing a distressing psychological state for which they do not see an adequate physiologic or general medical explanation. In my view, however, this is not the way it should be used. It would only logically be justifiable with respect to the criteria for cognate diagnoses if it could be demonstrated that there was some psychological cause that was unconsciously producing the symptom at the same time as producing anxiety or depression—in other words, what used to be called hysteria. For reasons discussed elsewhere,13 the diagnosis of pain as “a conversion disorder” can rarely be made adequately. Persons with doubts should try to imagine whether they could produce, by thinking about it, a physical symptom such as paralysis that they would maintain consciously and whether they could produce a state of feeling of chronic pain in themselves by reflecting on it and then ask how is it possible that pain could be produced unconsciously if it cannot even be produced consciously? Overall then, psychological diagnoses as causes of pain are not favored by this writer except in very limited situations. Occasionally, patients with classic depressive illness suffer from severe headaches that go away when the depression is better. Occasionally, patients with post-herpetic neuralgia have much worse pain when they become depressed and much less pain when the depression is treated, but this situation is relatively rare and does not reflect the bulk of either general medical, neurologic, or psychiatric practice.

The diagnosis of chronic pain related to psychiatry is, at present, a controversial issue with respect to DSM-V, which has the category Pain Disorder. The current proposal of the APA is that there will be substantial changes in the pain disorder criteria involving both Pain Disorder and other so-called “Somatoform Disorders.” It appears that the “Somatic Symptom Disorder Work Group” is proposing radical changes in this category and will (or may) rename the Somatoform Disorders section as “Somatic Symptom Disorders,” eliminate four existing DSM-IV categories (Somatization Disorder, Hypochondriasis, Pain Disorder, and Undifferentiated Somatoform Disorder), replace these discrete categories and their criteria with a single new category (“[Complex] Somatoform Symptom Disorder”), and apply new criteria.

To receive a diagnosis of complex somatic symptom disorder, patients must complain of at least one somatic symptom that is distressing or disruptive of their daily lives. Also, patients must have at least one of the following from the E type criteria: “emotional/cognitive/behavioural disturbances: high levels of health anxiety, disproportionate and persistent concerns about the medical seriousness of the ‘symptoms,’ and an excessive amount of time and energy devoted to the symptoms and health concerns. Finally, the symptoms and later concerns must have lasted for at least six months.” There are some further qualifications, and the development of the system has been vigorously criticized by Dr. Allen Frances, the principal architect and editor in chief of DSM-IV, which has been widely used and officially adopted by various bodies.

The diagnosis of “Pain Disorder” in DSM-IV was not entirely satisfactory in this author’s view, and reasons have been given for not using it. Nonetheless (for reasons connected with funding the diagnosis on insurance claims from either side of the fence), many expert witnesses have tended to rely on the DSM-IV diagnoses. Some have also relied on the DSM-IV grading systems with respect to functional abilities. Others, like myself, who have treated pain—entirely—as a physical disorder for medicolegal purposes have made use of whichever version of the American Medical Association Guides to the Evaluation of Impairment was relevant in their particular jurisdiction. For psychiatric purposes in evaluating the disability caused by pain, one can reasonably apply the criteria for disability of the Somatoform Disorders Scale as published in DSM-IV by reference to the Global Assessment of Functioning scale. In jurisdictions outside the United States the same scale can also reasonably be used for both physical and psychological illness. Thus, rather than the questionable diagnosis of “Pain Disorder,” the Global Assessment of Functioning scale may be used independent of the diagnosis simply on the basis of what the patient can and cannot do—without necessarily applying a psychiatric diagnosis.

In my experience to date, similar situations have been interpreted in the medicolegal situation more often to the benefit of the defense than to the benefit of the injured party in compensation disputes. However, on a fair presentation it should work equally well for both sides of the argument and better than any arbitrary scaling unrelated to the life experience of the individual.

6.02.2 Classifying and Treating Psychological Disorders

The dawn of the classification of mental disorders dates back to the early 1950s, with the development of the DSM. The DSM was developed with its Task Force to serve as a tool to classify mental disorders, in order to best understand a person's psychological experience and to seek out the etiology, course, and response to treatment of characteristic forms of mental suffering. An influential and longstanding definition of mental disorders was described by Wakefield (1992) as harmful dysfunction. The DSM-5, and its associated ICD-11, emphasize symptoms that are thought to reflect underlying psychobiological dysfunction, leading to clinically significant distress or disability. Both diagnostic tools were established around the principle that the primary causes of mental disorders are dysfunctions in biological, genetic, psychological and developmental processes (Hayes and Hofmann, 2018). The DSM-5 emphasizes the importance of having diagnoses to help clinicians determine prognosis, treatment plans, and outcomes (American Psychiatric Association, 2013). However, research on syndromes has not been able to find identifiable linked diseases, and the high prevalence of comorbidity suggests that clusters of signs and symptoms do not appear to be highly correlated with discrete underlying mechanisms (Kupfer et al., 2002).

Critics of the DSM have argued that disorders are arbitrary labels used to describe typical human experiences that are deemed abnormal (Deacon, 2013; Hofmann and Hayes, 2019). An example of this concept is that different countries have varied expectations and views of norms, values, and belief systems (Bredström, 2019). Many researchers and psychologists have argued that the DSM is based on a cluster of symptoms and thus, research and practice should address underlying symptoms rather than focus on predetermined objective measures. In response to criticisms of the DSM-5, the NIMH establish Research Domain Criteria (RDoC) which aims to classify mental disorders based on dimensions of observable behavior and neurobiological measures (Insel et al., 2010). The RDoC framework proposes that underlying psychobiological abnormalities lead to observable patterns that overlap in various psychopathologies. Furthermore, the initiative uses different levels of analyses-including molecular, brain circuit, symptom level and behavioral-to define constructs that are proposed to be core symptoms of mental disorders.

Although RDoC is lauded as a hybrid between the shifting DSM and movement toward a focus on underlying processes, some argue that RDoC is overly reductionistic by mostly focusing on biological processes and equating psychiatric problems with brain disorders (Deacon, 2013; Hofmann and Hayes, 2019). Others have argued that RDoC deemphasizes the centrality of an individual and his or her cultural and biopsychosocial contexts (Hayes et al., 2019). Even though the DSM remains the primary diagnostic tool, both classification systems share the same view that psychological distress is caused by a latent disease. Whereas in the DSM, the belief is that latent constructs are measured through clinical impressions and symptom reports, with RDoC, the view is that latent diseases can be measured with biological and behavioral tests. Given the substantial criticism of both systems and the continued rising rates of psychological disorders despite evidence-based treatments, it appears imperative to shift focus from a latent disease approach to a symptom- and change-process based approach to measuring and treating psychopathology.

Conclusion

Although still found in the major classifications of mental disorders, given the continuing controversy over the validity of the DID diagnosis and the reliability of methods to assess it, there is still much skepticism within the mental health professions. Some regard is as a spurious diagnosis largely due to iatrogenic factors. Others make the diagnosis frequently and argue that critics are blind to the frequent occurrence of the disorder. It is therefore not surprising that the legal system has difficulty coming to terms with the alleged phenomenon and there is consequently no consensus, at least in the United States where most of the cases have been heard, concerning the degree to which those who supposedly have DID are able to be held accountable for their actions.

Categorical and Dimensional Approaches

Although the DSM system relies largely on the categorical classification of mental disorders, growing recognition of common neurobiological mechanisms underlying symptom clusters has led to greater recognition of the value of dimensional approaches. This is reflected in the NIMH Research Domain Criteria initiative and in the inclusion of an alternative, dimensional model of personality disorders in section III of the DSM-5. Categorical and dimensional approaches to psychiatric diagnosis can be viewed as having complementary roles. It is useful to distinguish different disorders from one another using categorical approaches. Dimensional models, on the other hand, are useful in capturing clinical phenomena falling on a spectrum (i.e., impulsivity) that is shared across several disorders and may have neurobiological implications for prognosis and treatment.

Many models of anxiety disorders have been proposed. The tripartite model of anxiety symptoms (Clark and Watson) is one influential dimensional approach to the symptoms of anxiety and depression. The relevant dimensions are (1) negative affect – general distress such as worry, tension, and irritability; (2) positive affect – the level of pleasurable agreement with the environment; and (3) autonomic hyperarousal. The Tripartite model proposes that negative affect is shared by both anxiety and mood disorders, while autonomic hyperarousal is peculiar to anxiety. An absence of positive affect (mainly, anhedonia) differentiates mood disorder from anxiety disorders.

8 Conclusion

The past two decades have witnessed tremendous advances in the classification of mental and behavioral disorders with regard to increased reliability, validity, clinical and research utility, comprehensiveness, and improved communication. The current available systems, however, are far from being satisfactory. More research is clearly needed not only to improve further the reliability of explicit criteria and to clarify the boundaries of disorders, but, in particular, to explain more effectively the complex etiology and pathogenesis of mental disorders on neurobiological, psychological, and social-behavioral levels. Such research will result, hopefully, in the identification of common and disorder-specific core psychopathological processes that might provide more valid and comprehensive criteria for a sharper and more satisfactory classification system.