Provided by David Satcher, M.D., Ph.D.
Surgeon General of the United States of America
Chapter 2
Diagnosis of Mental Illness
The foregoing discussion has suggested that the manifestations of mental disorders fall into a number of distinct categories such as anxiety, psychosis, mood disturbance, and cognitive deficits. These categories are broad, heterogeneous, and somewhat overlapping. Moreover, any particular patient may manifest symptoms from more than one of these categories. This is not unexpected, given the highly complex interactions that take place among the neurobiological and behavioral substrates that produce these symptoms. Despite these confounding difficulties, a systematic approach to the classification and diagnosis of mental illness has been developed. Diagnosis is essential in all areas of health for shaping treatment and supportive care, establishing a prognosis, and preventing related disability. Diagnosis also serves as shorthand to enhance communication, research, surveillance, and reimbursement.
The diagnosis of mental disorders is often believed to be more difficult than diagnosis of somatic, or general medical, disorders, since there is no definitive lesion, laboratory test, or abnormality in brain tissue that can identify the illness. The diagnosis of mental disorders must rest with the patients’ reports of the intensity and duration of symptoms, signs from their mental status examination, and clinician observation of their behavior including functional impairment. These clues are grouped together by the clinician into recognizable patterns known as syndromes. When the syndrome meets all the criteria for a diagnosis, it constitutes a mental disorder. Most mental health conditions are referred to as disorders, rather than as diseases, because diagnosis rests on clinical criteria. The term “disease” generally is reserved for conditions with known pathology (detectable physical change). The term “disorder,” on the other hand, is reserved for clusters of symptoms and signs associated with distress and disability (i.e., impairment of functioning), yet whose pathology and etiology are unknown.
The standard manual used for diagnosis of mental disorders in the United States is the Diagnostic and Statistical Manual of Mental Disorders. Most recently revised in 1994, this manual now is in its fourth edition (American Psychiatric Association, 1994, hereinafter cited in this report as DSM-IV). The first edition was published in 1952 by the American Psychiatric Association; subsequent revisions, which were made on the basis of field trials, analysis of data sets, and systematic reviews of the research literature, have sought to gain greater objectivity, diagnostic precision, and reliability. DSM-IV organizes mental disorders into 16 major diagnostic classes listed in Table 2-5. For each disorder within a diagnostic class, DSM-IV enumerates specific criteria for making the diagnosis. DSM-IV also lists diagnostic “subtypes” for some disorders. A subtype is a subgroup within a diagnosis that confers greater specificity. DSM-IV is descriptive in its listing of symptoms and does not take a position about underlying causation.
Table 2-5. Major Diagnostic Classes of Mental Disorders (DSM-IV)
| Disorders usually first diagnosed in infancy, childhood, or adolescence |
| Delerium, dementia, and amnestic and other cognitive disorders |
| Mental disorders due to a general medical condition |
| Substance-related disorders |
| Schizophrenia and other psychotic disorders |
| Mood disorders |
| Anxiety disorders |
| Somatoform disorders |
| Factitious disorders |
| Dissociative disorders |
| Sexual and gender identity disorders |
| Eating disorders |
| Sleep disorders |
| Impulse-control disorders |
| Adjustment disorders |
| Personality disorders |
DSM-IV and its predecessors2 represent a unique approach to diagnosis by a professional field. No other sphere of health care has created such an extensive compendium of all of its disorders with explicit diagnostic criteria. The World Health Organization’s International Classification of Diseases (10th edition, 1992) is a valuable compendium of all diseases. Its mental health categories are expanded upon in DSM-IV. The International Classification of Diseases (ICD) is the official classification for mortality and morbidity statistics for all signatories to the U.N. Charter establishing the World Health Organization. ICD-9CM (9th edition, Clinical Modification, 1991) is still the official classification for the Health Care Financing Administration.
Knowledge about diagnosis continues to evolve. Evolution in the diagnosis of mental disorders generally reflects greater understanding of disorders as well as the influence of social norms. Years ago, for instance, addiction to tobacco was not viewed as a disorder, but today it falls under the category of “Substance-Related Disorders.” Although DSM-IV strives to cover all populations, it is not without limitations. The difficulties encountered in diagnosing mental disorders in children, older persons, and racial and ethnic minority groups are discussed later in this chapter and throughout this report. Diagnosis rests on clinician judgment about whether clients’ symptom patterns and impairments of functioning meet diagnostic criteria. Cultural differences in emotional expression and social behavior can be misinterpreted as “impaired” if clinicians are not sensitive to the cultural context and meaning of exhibited symptoms, a topic discussed later in this chapter in Overview of Cultural Diversity and Mental Health Services.
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2 DSM-I (American Psychiatric Association, 1952),
DSM-II (American Psychiatric Association, 1968), DSM-III (American
Psychiatric Association, 1979), and DSM-III-R (American Psychiatric
Association, 1987).
3 Although addictive disorders are included as mental disorders in the DSM classification system, the ECA and NCS distinguish between addictive disorders and (all other) mental disorders. Epidemiologic data in this report follow that convention. 4 The term “serious emotional disturbance” is used in a variety of Federal statutes in reference to children under the age of 18 with a diagnosable mental health problem that severely disrupts their ability to function socially, academically, and emotionally. The term does not signify any particular diagnosis; rather, it is a legal term that triggers a host of mandated services to meet the needs of these children. |
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