itself. It too is an invocation for further research on etiology, pathology, course, and treatment (Kety, 1974).

As even more knowledge unfolds about etiology and pathology, an established syndrome can rise to the level of a disease. The term “disease” is often, but not always, reserved for abnormalities in body structure or function with known etiology (e.g., virus, abnormal gene, toxin, physical or psychosocial trauma) and/or pathology (detectable lesion). Diseases are considered mutually exclusive categories (WHO, 1992). Each disease is presumed to have a unique pathophysiology, but complete knowledge rarely exists (Scadding, 1996). According to the International Nomenclature of Diseases, the name of the disease should be specific, unambiguous, and self-descriptive and, if possible, should reflect the cause (WHO, 1992). In practice, the label acts as a shorthand description of the characteristic features of a disease that confer a biological disadvantage3 and deviate from the norm (Scadding, 1996).

A syndrome can ascend the nosological hierarchy to a “disorder” even if there are only clinical manifestations (i.e., symptoms and/or signs) yet no known lesion. In contrast to a syndrome, the term “disorder” conveys that more is known about diagnostic reliability and validity, natural history, and impact on functioning (Goldman and Foreman, 1994). Impairment of functioning—social, educational, or occupational—is considered one of the quintessential criteria for a mental disorder. In its standard manual used for the classification and diagnosis of mental disorders in the United States, the American Psychiatric Association defines a mental disorder as a behavioral or psychological syndrome associated with distress and disability (i.e., impairment of functioning) (APA, 1994). Disorder is thus a more rigorous label than syndrome, but not as rigorous a label as disease, because the disorder’s pathology or etiology are, by definition, not yet known. Yet there are always exceptions in deference to current or historical usage.

The advent of AIDS offers a recent illustration of how a new disease comes to be defined and labeled. The condition was entitled a “syndrome,” according to an early case definition4 promulgated by the Centers for Disease Control and Prevention (CDC) in 1982, before the cause was found. The syndrome was defined by the unusual combination of opportunistic infections and cancer (Kaposi’s sarcoma) first detected in young male homosexuals (CDC, 1982). The rare combination of symptoms, signs, diagnoses, and young age bolstered the hypothesis that this was indeed a new syndrome. CDC’s case definition for AIDS was modified several times within the first few years of the epidemic as research uncovered other populations affected (e.g., hemophiliacs), the mode of


The “disadvantage” may also carry social components (Wakefield, 1992).


The first unofficial label given to AIDS in 1981 was gay-related immunodeficiency syndrome or GRID (to signify the first known patient population), but this term disappeared as more cases appeared in different patient populations (Garrett, 1994). The first official case definition promulgated by CDC was “Kaposi’s sarcoma and opportunistic infections in previously healthy persons” (CDC, 1982). Soon thereafter, the case definition was entitled AIDS (Garrett, 1994).

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement