Diagnosis in Schizophrenia and Manic-Depressive Illness A Reassessment of the

in the

Light

Specificity

of

'Schizophrenic' Symptoms

of Current Research

Harrison G. Pope, Jr, MD,

Joseph

F.

Lipinski, Jr,

MD

\s=b\ Present clinical and research methods of differential diagnosis of schizophrenia and affective psychoses rely very heavily on presenting symptoms and signs, especially in acute psychosis. We have reviewed studies bearing on this issue, including studies of the phenomenology of psychotic illness, outcome, family history, response to treatment with lithium carbonate, and cross-national and historical diagnostic comparisons. We conclude that most so-called schizophrenic symptoms, taken alone and in cross section, have remarkably little, if any, demonstrated validity in determining diagnosis, prognosis, or treatment response in psychosis. In the United States, particularly, overreliance on such symptoms alone results in overdiagnosis of schizophrenia and underdiagnosis of affective illnesses,

mania. This compromises both clinical treatment and research. (Arch Gen Psychiatry 35:811-828, 1978)

particularly

years have seen a striking reawakening of interest in the differential diagnosis of psychotic disorders. Specifically, several lines of evidence have converged to indicate that many acutely psychotic

Recent

patients, currently diagnosed as schizophrenic, are more likely to be suffering manic-depressive illness (MDI), especially mania. ("Manic-depressive illness" will be used here interchangeably with "primary affective disorder" as Accepted

for publication Nov 1, 1977. From the Laboratories for Psychiatric Research, Mailman Research Center, McLean Hospital, Belmont, Mass, and the Department of Psychiatry, Harvard Medical School, Boston. Reprint requests to Mailman Research Center, McLean Hospital, 115 Mill St, Belmont, MA 02178 (Dr Lipinski).

defined by Peighner et al.1) This same evidence, further¬ more, has called into question the practice of using present¬ ing psychotic symptoms, taken in cross-section, as primary differential diagnostic criteria. The material reviewed below will suggest that overreliance on presenting psychotic symptoms, and consequent overdiagnosis of schizophrenia and underdiagnosis of affective disorder, are particularly widespread in contem¬ porary American diagnostic practice. With the advent of more efficacious and selective pharmacological treatments, especially lithium carbonate, such diagnostic bias is becom¬ ing increasingly serious, since it may compromise patient treatment. In addition, research exploring the etiology or the treatment of the psychoses requires homogeneous populations of patients, and can be jeopardized or even rendered invalid by misdiagnosis. Thus it seems timely to review the state of knowledge in this area. THE CURRENT DIAGNOSTIC USE of 'Schizophrenic' Symptoms

Before reviewing specific diagnostic studies, it will be helpful to illustrate the degree to which psychiatrists, past and present, have relied on "schizophrenic" symptoms as differential diagnostic criteria. Although Kraepelin- emphasized the course of illness as a major distinction between dementia praecox and MDI, subsequent influential writers have focused more on symp¬ toms. Bleuler,' introducing the term "schizophrenia," enumerated what he believed to be its primary and second¬ ary symptoms, and explicitly stated that a diagnosis of MDI should be made only by elimination of the diagnosis of

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schizophrenia. Schneider placed further emphasis on symp¬ by listing 11 "first-rank" symptoms (the Schneiderian FRSs) about which he wrote," When any of these modes of experience is undeniably present, and no somatic

toms

illness

can

be

found,

we

may make the decisive clinical

diagnosis of schizophrenia."5""341 Widespread use of Bleuler's and Schneider's "schizophrenic" symptoms* as diag¬ nostic criteria helped to widen the definition of schizophre¬ nia and narrow that of MDI, the latter diagnosis becoming reserved only for those patients who displayed "pure" affective states with no "schizophrenic" symptoms. One of the clearest expressions of this philosophy was the asser¬ tion by Lewis and Piotrowski that "even a trace of schizophrenia is schizophrenia."6 The net effect of such writers was to encourage the frequent diagnosis of schizo¬ phrenia of the basis of the presence of even a single symptom, or clusters of symptoms presumed to be "schizo¬ phrenic." Conversely, the diagnosis of MDI was discour¬ aged until one had clearly established the absence of "schizophrenic" symptoms. Abundant evidence suggests that this practice continues today. For example, the American Psychiatric Associa¬ tion's Diagnostic and Statistical Manual of Mental Disor¬ ders (DSM-II), used throughout this country since 1968, defines schizophrenia almost exclusively by symptoms, including delusions, hallucinations, ideas of reference, and hebephrenic and catatonic behavior. Conversely, although DSM-II allows that some psychotic phenomena may occur in MDI, it allows only that these be secondary to the dominant mood disorder: "When illusions, hallucinations, and delusions (usually of guilt or of hypochondriacal or paranoid ideas) occur, they are attributable to the domi¬ nant mood disorder."7