Diagnosis of Schizophrenia: Pathognomonic Signs or Symptom Clusters Charles S. Newmark, William

Hunter,

David Raft, Timothy and Joseph

Toomey.

Mazzaglia

A

LTHOUGH it has long been a focus for professional concern, psychiatric diagnosis remains the greatest impediment to investigative work in schizophrenia. Feighner et al.’ l discussed the difficulties involved in arriving at a research definition of schizophrenia, while the unreliability of the psychiatric diagnosis of schizophrenics has been documented thoroughly.8*‘7 DS M-II,2 revised to alleviate some of the vagueness and ambiguity of DSM-I,’ has led to even more controversy regarding objective criteria for the diagnosis of schizophrenia.32 The inadequacies of DSM-II, especially with regard to its lack of specificity in the definition of terms used to define schizophrenia and its inadequacy as a nomenclature, have been discussed extensively.1s.17 Many investigators beginning with Kraepelin”’ have attempted to establish pathognomonic criteria that brought together patients with varied phenomenology under the same diagnostic class. For example, Bleuler5 described four general primary symptoms of schizophrenia which included loose associations, flat affect, autism and ambivalence as well as secondary symptoms called ego functions. However, this system has been considered inadequate since it uses imprecise terminology, mixes theoretical concepts with observations and because such symptoms also are prevalent to some degree in other physical and psychiatric disorders.32 While initially considered to have some basic validity and explanatory power, Bleuler’s concepts now receive little support.12 The most impressive effort to date in describing pathognomonic symptoms of schizophrenia has been described by Schneider. 27This phenomenologic system includes 11 first rank order symptoms (FRS) which include three forms of auditory hallucinations, delusions, somatic passivity, thought insertion, thought withdrawal, thought broadcasting, and affect impulses or motor activity experienced as imposed and controlled from the outside. A detailed explanation of each symptom can be found elsewhere. g These FRSs are regarded as pathognomonic of schizophrenia when one is present in the absence of somatic illness. While the FRSs were chosen pragmatically according to their ease of identification, with no relation to theory, no empirical tests of the predictive validity of these concepts were conducted until recently. Mellor2’ found that 72% of 166 newly admitted schizophrenics demonstrated From the University of North Carolina School of Medicine. Chapel Hill, N.C. Charles S. Newmark, Ph.D.: Assistant Professor of Psychology; Timothy C. Toomey, Ph.D.: Assistant Professor of Psychology; David Raft, M.D.: Assistant Prof&sor of Psychiarrv; Joe Mazzaglia, M.D.: Residenf in Psychiatry; William Hunter, M.D.: Assisfanr Professor of Psychiafrr; University of North Carolina School of Medicine, Chapel Hill, N.C. Requests for reprints should be addressed to Charles S. Newmark. Ph.D., Department of Ps.vchiatry. University of North Carolina School of Medicine, Division of Health Affairs, Chapel Hill. N.C. 27514. o 1975 bv Grune & Srratton, Inc.

Comprehensive Psychiatry, Vol. 16. No. 2 (March/April).

1975

155

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ET AL.

at least one FRS. However, contamination and bias with regard to diagnosis could have occurred if the criteria used for identifying schizophrenia was based on the British Glossary of Mental Disorders’ where FRSs are considered symptoms of schizophrenia. Unfortunately, Mellor only reported that the consultants’ final diagnosis was schizophrenia. Carpenter and Strausslo analyzed diagnostic data collected in nine countries in order to assess the clinical utility of these 11 FRSs. The results suggested that FRSs did occur with sufficient frequency in schizophrenics (53%) to have potential diagnostic usefulness and that 9 of the FRSs analyzed were highly discriminating for this group. However, FRSs were not pathognomonic since they were reported in patients receiving other psychiatric diagnoses. For example, 23% of manic psychoses patients exhibited one or more FRSs, with the specific number of symptoms not reported. Thus Schneider’s rule that the presence of any one FRS is sufficient to diagnose schizophrenia, while highly discriminating, leads to significant diagnostic errors if FRSs are considered pathognomonic. Several other investigators as summarized by Lehmann20 also have postulated numerous arrays of primary symptoms of schizophrenia. However, subsequent investigations by Robins & Guze2s, Carpenter, Strauss and Mulechg and Carpenter & Strauss lo failed to support the existence of pathognomonic symptoms of schizophrenia. As yet, no diagnostic criteria for schizophrenia have received universal support. Yusin, Nihira, and Mortashed35 discouraged with the apparent inability to find pathognomonic symptoms of schizophrenia, attempted to delineate the schizophrenic syndrome by identifying symptom combinations or clusters. Using a symptom assessment questionnaire consisting of 27 operationally defined textbook symptoms associated with schizophrenia, 6 major symptoms were found that significantly discriminated schizophrenics from nonschizophrenics. These six symptoms, namely loose associations, ambivalence, withdrawal, loss of ego boundaries, hallucinations and delusions were present in 35%7 1% (M = 50%) of all schizophrenics, but were present in only 3%28% (M = 9%) of nonschizophrenics. These investigators therefore proposed that the presence of at least 5 of the 6 major symptoms was necessary before an accurate diagnosis of schizophrenia could be made. However, Yusin et al.35 criticized their own investigation due to the limited number of symptoms evaluated and the potential of idiosyncratic diagnostic bias of schizophrenia based solely on subjective interviews with emergency room cases. This latter bias is especially critical in view of recent findings by Taylor, Gaztanaga, and Abrams31 that a significant majority of patients with an admitting diagnosis of acute schizophrenic reaction actually suffer from affective psychoses. Another methodological difficulty concerned interrater agreement which was only periodically checked by having all 8 raters use the symptom assessment questionnaire to assess one patient. Additionally, considerable variability in rater experience, which has been shown to be a crucial variable in reliability studies,lg was evident. The raters were 3 first-year psychiatric residents, 4 staff psychiatrists and 1 staff psychologist. The data analysis employed was incomplete, as only phi correlations were obtained to determine the degree of correlation between each symptom and the diagnosis of schizophrenia. An arbitrary

DIAGNOSIS

157

OF SCHIZOPHRENIA

0.4 correlation coefficient was used as a cutoff point to delineate major symptoms. Simple chi-squares should have been computed from the phi coefficients to establish whether the variables are related. Also, 3 of the 6 primary symptoms occurred with less than 47% frequency in schizophrenics which limits the potential usefulness of these criteria. The present investigation is an extension of the study of Yusin et al., incorporating numerous methodological modifications in an attempt to formalize the apparent commonality of clinical features which combined may establish a diagnosis of schizophrenia through the development of a reliable checklist of symptoms. Attempts to identify reliable clinical criteria for recognition of the schizophrenic syndrome should not be abandoned since this approach promises to yield clues for differential diagnosis.

METHOD

Subjects The sample consisted of 157 women and 115 men from chiatric Inpatient and Outpatient Clinics whose ages ranged significant age differences outpatients.

as a function

the University of North Carolina Psyfrom 16-72 (M = 38.6). There were no

of sex. Of these 272 subjects,

184 were inpatients

while 88 were

Procedure An extension of the 27-item symptom assessment questionnaire of schizophrenia of Yusin et al. was developed by obtaining additional symptoms of schizophrenia which were available in the psychiatric literature. This revised questionnaire now contains 43 operationally defined textbook symptoms associated with schizophrenia (Table 1). A precise definition of each symptom is available elsewhere.“~‘“~24 While definitions can never be rigorous or complete except in mathematics, they nevertheless serve to demarcate a concept even though its boundaries remain somewhat blurred.jR Before administration of the symptom assessment questionnaires, the raters, consisting of 3 Ph.D. clinical psychologists, 2 psychiatrists and 1 psychiatric nurse discussed all of the symptom definitions to insure that no idiosyncratic biases were evident. All raters had at least 3 years of diagnostic experience. This procedure was necessary since Kreitman Is demonstrated that variables relating to nomenclature and degree of experience are the greatest impediments to reliability in psychiatric diagnoses. Clearly definable terms and equivalent diagnostic experience are essential. Each subject in the sample was interviewed immediately following admission to one of the psychiatric clinics in the hospital by one of the raters. All interviews were conducted with either another rater present in the room or observing behind a one-way mirror. Reliability is definitely enhanced if 2 raters observe the same interview rather than each rater observing a separate interview.Z’ Thus, each subject was rated each time by 2 raters so that interrater reliability was assessed for each subject. Immediately following the interview, each rater recorded his observations independent of his colleague’s rating. Few previous investigations have rater reliability measures for each subject and several only used data obtained from the charts following discharge.3.30 A symptom was not considered as present unless both raters agreed upon its presence. The percent of agreement between raters ranged from 75%100% (Md = 0.94). Phi coefficients were used to determine the degree of correlation between each symptom and the diagnosis of schizophrenia. Simple chi-squares then were computed to establish whether the variables were related. Those symptoms which occurred significantly more frequently (phi L 0.50) and with sufficient frequency (at least 50%) in schizophrenic patients were called major symptoms. A discriminate function analysis then was conducted to assess if any symptom clusters were highly discriminating of schizophrenia. The criterion diagnoses were established during the first week of admission to the hospital by a

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Table 1. Percentages of Schizophrenics

and Nonschizophrenics

ET AL.

Rated as Exhibiting

Each Symptom

Symptom

Schizophrenics (n = 112)

Nonschizophrenic (n = 160)

Correlation Coefficient

X2

P

Anxiety

79

70

.09

Flat affect

68

34

.33

29.4

t

Loose association

84

8

.76

155.4

t

Ambivalence

88

47

.42

47.5

t

Autism

73

7

.68

126.0

t

2.0

Symbolism

22

2

.32

27.6

t

Social withdrawal

89

32

.56

85.6

t

Sensitivity

69

31

.36

35.7

t

Loss of ego boundaries

62

5

.61

101.2

t

Variability

38

17

.23

14.8

t

Hallucinations

40

7

.40

42.7

t

Delusions

67

11

.57

88.4

t

Archaic

17

2

.26

18.2

t

13.9

t

or magical thinking

Agitation

39

18

.23

Depressjon

76

78

.02

Depersonalization

10

3

.12

4.2

l

Incoherent

33

9

.30

23.9

t

Overinclusion

31

7

.31

26.1

t

Confabulation

4

2

.03

0.23

14

11

.03

0.31

3

6

.07

1.2

52

6

.51

70.5

3

0

.09

2.2

Echoialia

0

Verbigeration

2

0 0

Stilted

2

Tangential Retardation Concrete

of speech

thinking

Neologisms Mutism

language

0.08

.oo

0.0

.oo

0.0

.06

0.95

.Ol

0.02

t

Echopraxia

0

0

.oo

0.0

Negativism

26

4

.32

26.8

t

14

6

.I2

4.0

*

6

7

.oo

0.01

5

0

.16

6.5

18

12

.07

1.5

Stereotyped

behavior

Perseveration Oneiric

state

Disorientation

to place

Disorientation

to person

Disorientation

to time

Inappropriate

affect

7

3

.07

1.5

16

9

.lO

2.7

.04

0.34

25

21

Labile

28

Blocking

16

‘9 7

Amnesia

4

.

.09

2.5

.13

4.9

.06

0.94

l

l

Circumstantial

15

6

.13

4.9

*

Paralogia

29

5

.32

27.3

t

.33

29.9

t

38

37.8

t

Paleologic thinking

19

Regression

40

lp

9

=z 0.05.

tp < 0.001.

review of all available clinical information, social history and interview behavior. Those patients diagnosed as schizophrenia were then administered psychological tests consisting of the MMPI and Rorschach in order to substantiate the diagnosis. If the diagnosis of schizophrenia was not supported by the test data, the patient was eliminated from the sample. Of the 142 potential schizophrenics requiring psychological testing, the test data supported the initial diagnosis in 79% of the cases.

DIAGNOSIS

159

OF SCHIZOPHRENIA

RESULTS

One hundred sixty nonschizophrenics and 112 schizophrenics comprised the sample. The nonschizophrenic population encompassed diagnostic categories described in DSM-II. These categories included: psychoses due to organic factors (n = 9); affective psychoses, including involutional melancholia and manicdepressive (n = 14); other psychoses, including paranoid states and psychotic depression (n = 10); neurosis, including anxiety, hysterical, obsessive-compulsive, depressive, and hypochondriacal (n = 62); personality disorders, including paranoid, schizoid, hysterical, antisocial, passive-aggressive, sexual deviate, alcoholism, and drug dependent (n = 43); psychophysiological disorders, including gastrointestinal and musculoskeletal (n = 9); and transient situational disturbance, including adjustment reactions of adolescence and late life (n = 13). No diagnostic category was eliminated from the study in order to expedite the identifications of the number and kinds of symptoms found in all categories describing other psychiatric entities as well as schizophrenia. The schizophrenic population consisted of 7 diagnostic categories described in DSM-II. These categories included simple, paranoid type, acute, latent, residual, affective, and chronic undifferentiated. That no catatonic or hebephrenic schizophrenia was diagnosed is consistent with the findings of a recent study by Morrisonz3 revealing that the diagnosis of these two schizophrenic entities has decreased significantly over the past 47 years. The decreases appear due to changes in definitions and hospital admission practices. The percentages of schizophrenics and nonschizophrenics rated as exhibiting each symptom are presented in Table 1. Pathognomonic symptoms of schizophrenia were neologisms, verbigeration, and oneric states. However, the prevalence of each of these symptoms was 5% or less suggesting that their usefulness as pathognomonic symptoms in the diagnosis of schizophrenia is quite limited. The pathognomonic signs of schizophrenia obtained in Yusin’s investigation, namely stilted language, neologisms, and echopraxia, also occurred with a significantly low frequency to have minimal utility. Furthermore, Bowers6 found that many symptoms thought to be pathognomonic of schizophrenia also occur in patients with acute psychoses induced by psychotomimetic drug abuse. Twenty-five of the 43 symptoms evaluated were found with significantly greater frequency in schizophrenics than nonschizophrenics. This is not surprising in view of the criterion for inclusion on the symptom questionnaire, namely potential association with schizophrenia. However, 6 of these 25 symptoms were present in at least 50% of the schizophrenics and obtained phicorrelation of L 0.50. Using a phi correlation of 2 0.50 is consistent with the literature on factor analytic studies where numerous high correlations were obtained and 0.50 is generally arbitrarily chosen as a cutoff point for discussion purposes. The 6 major symptoms found in this study, which included loose associations, autism, social withdrawal, loss of ego boundaries, delusions and concrete thinking, were present in 52%89% (M = 71%) of schizophrenics and were present in only 5%32% (M = 11%) of nonschizophrenics. Five of the 6 major symptoms present in Yusin’s investigation were corroborated here. Only the

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Table 2.

Coefficients

of the Discriminant

Symptoms Symptom

Functions

for the Four Major

Used to Classify Schizophrenics Schizophrenic

Nonschizophrenic

Loose associations

6.85035

0.65298

Autism

4.69684

0.45912

Loss of ego boundaries

4.94757

1.88828

Delusions

4.25569

0.52454

Constant

ET AL.

-8.81648

- 1.06585

presence of hallucinations in Yusin’s study and concrete thinking in the present study were different. Thus, even though more stringent criteria for inclusion as a major symptom of schizophrenia were used here, the results are markedly similar to those obtained by Yusin et al. Using a discriminant function analysis, the 6 major symptoms in decreasing order of discriminating ability were loose associations (F = 361.44), autism (F = 222.98), loss of ego boundaries (F = 145.06), delusions (F = 141.27), social withdrawal (F = 125.20) and concrete thinking (F = 98.78). None of these symptoms had sufficient discriminating power to be used independently. For example, using only the coefficients of the discriminant function for using loose associations to diagnose schizophrenia would still result in 15% of the schizophrenic sample and 10% of the nonschizophrenic sample being misclassified using this dichotomy. Therefore, combinations of the discriminative values of these six major symptoms were varied until almost total diagnostic classification accuracy was obtained. Using the coefficients of the discrimination functions of four of the six major symptoms to predict schizophrenia, namely loose associations, autism, loss of ego boundaries and delusions, would correctly classify 97% of the total sample of 272 subjects. The coefficients of the discriminant functions for these 4 symptoms used to classify subjects as schizophrenics or non-schizophrenics are presented in Table 2. Only by using 16 symptom variables was the classification accuracy increased to 100%. However while using the 4 major symptoms listed above as discriminative of schizophrenia would result in 3% less accuracy, using fewer symptom variables usually increases the reliability of the system, making this approach the more parsimonious and practical. DISCUSSION

This investigation provided further evidence that any pathognomonic symptoms of schizophrenia occur with such limited frequency that their diagnostic utility is nil. Thus, it appears that the approach taken by the present investigators, namely using discriminant function analyses with 4 major symptoms which significantly differentiate (97% accuracy) a schizophrenic from other psychiatric entities, is the most reliable and practical approach. Using such a statistical approach provides different discriminating power to each symptom so that in some cases only 2 and in many cases only 3 of the 4 major symptoms need be present to accurately diagnose schizophrenia. In each instance however, the coefficients of the discriminant functions for the 4 major symptoms as presented in Table 2 must be utilized for accurate diagnosis for schizophrenia. Such

DIAGNOSIS

OF SCHIZOPHRENIA

161

calculations require little time and effort. For example, if patient A exhibits loose associations, autism and delusions, but not loss of ego boundaries, the discriminant function equation using Table 2 would be 6.85035 (1) + 4.69684 (1) + 4.94757 (0) + 4.25569 (1) - 8.81648 = 6.9864 and 0.65298 (0) + 0.45912 (0) + 1.88828 (1) + 0.52454 (0) - 1.06585 = 0.82273. Since the value obtained using coefficients for schizophrenia is greater than the value obtained using coefficients for nonschizophrenia, the patient is classified as schizophrenic. Note, that the number 1 is used as the multiplier with the coefficients for schizophrenia if the symptom is present while 0 is used as the multiplier with the coefficients for schizophrenia if the symptom is absent. Whatever multiplier, namely 0 or 1, is not used with the symptom coefficient of schizophrenia is then used as the multiplier with the corresponding symptom coefficient for nonschizophrenia. One potential application of the frequency data obtained from the present sample is to assist computer models for psychiatric diagnosis. Many computer models, such as the Bayes method, are based on probability theory and therefore require estimates of the relative frequency or base rates of occurrence of symptoms in each diagnostic group. I3 That such an approach based on probability theory is feasible and practical is supported by the widespread use and acceptance of the Minnesota Multiphasic Personality Inventory (MMPI) as an objective personality assessment technique. Furthermore, using estimates of the relative frequencies of significant descriptive symptoms has resulted in computerbased models for advocating a treatment of choice with psychiatric patients.22 The search for redefinition and new understanding of schizophrenia through a more scientific methodology has brought objective data to the fore. These are purported to be more significant than data which reflect and arise from patientclinician interactions. These new methods were initially proposed to add quantitative data to clinical impressions, but because of the enthusiasm of their proponents, these techniques have encroached upon clinical methods.2g The present investigators realize the need for skilled observation and increasing expertise that arises from professional training, personal maturation, attention to affective responses both from clinician and patient, and intuition, which is rationalized according to the concept of a particular theory of personality development and behavior. Symptom check lists or questionnaires, such as the one used in the present investigation, should only be used as an adjunct to assist the clinicians in diagnostic decisions. In the field of behavioral disorders, a classification system attempts to organize the population of those suffering from behavioral disorders into diagnostic subgroups according to curtain common signs, symptoms and other identifying characteristics. It is important to define a schizophrenic syndrome since most clinicians agree that specific objective diagnostic criteria are needed to provide a common ground for different research groups so that diagnostic definition can be amended constructively as further studies are completed.” The use of formal diagnostic criteria, especially for schizophrenia, by a number of investigators regardless of their area of interests could result in a solution of the problem of whether patients described by different investigators are comparable. This would allow for examining prognosis across institutions and demographically distinct populations and by establishing diagnosis that is independent of institutional bias,

162

NEWMARK ET AL.

different treatment modalities could be compared both within and cross culturally.” In addition to the obvious significance for research, the diagnosis of schizophrenia is a vital prerequisite for psychiatric prognosis,15 therapeutic treatment modality and epidemiology,lg and to facilitate communication among psychiatrists as well as between psychiatrists and other physicians.” Thus, the importance of the findings of this investigation are in relation to diagnosis in psychiatry. Presently, many clinicians are extremely ambivalent about the notion of psychiatric diagnosis in general and schizophrenia in particular,” and a plethora of suggestions exist for either abolishing or revising diagnostic classification.25 However, while the area of diagnosis is in grave danger of becoming a fetid quagmire of anecdotalism based on purely suggestive appraisal and without the benefits of objective terminology of what constitutes the schizophrenic syndrome, many clinicians agree with SmithZ* that reliable diagnostic categories can be attained using traditional psychiatric nosology provided the basic phenomena of psychopathology are operationally defined and combined in a systematic manner, The use of probability data and discriminant function analyses appears to be a step in this direction. The next step is to evaluate the reliability and validity of the system proposed. REFERENCES 1. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, (ed 1). Washington DC, 1952 2. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, (ed 2). Washington DC, 1968 3. Abrams R, Taylor M: First rank symptoms, severity of illness, and treatment response in schizophrenia. Compr Psychiatry 14:353-355, 1973 4. Astrachan BM, Harrow M, Adler D, et al: A checklist for the diagnosis of schizophrenia. Br J Psychiatry 121529-539, 1972 5. Bleuler E: Dementia Praecox (1908). Translated by Zinkin J: New York, International Universities Press, 1950 6. Bowers MB Jr: Acute psychosis induced by psychotomimetic drug abuse: I. Clinical findings. Arch Gen Psychiatry 27:437-439, 1972 7. British Glossary of Mental Disorders Based on the International Statistical Classification of Diseases: Injuries and Causes of Death (8th Revision, 1965). London, Her Majesty’s Stationery Office, 1968 8. Cancro R: A classificatory principle in schizophrenia. Am J Psychiatry 126:131-136, 1970 9. Carpenter WT Jr, Strauss JS, Muleh S: Are there pathognomonic symptoms in schizophrenia? An empirical investigation of Kurt Schneider’s first-rank symptoms. Arch Gen Psychiatry 28:847-852, 1972

10. Carpenter WT Jr, Strauss JS: Crosscultural evaluation of Schneider’s first-rank symptoms of schizophrenia: a report from the international pilot study of schizophrenia. Am J Psychiatry 131:682-687,1974 11. Feighner JP, Robins E, Guze SB, et al: Diagnostic criteria for use in psychiatric research. Arch Gen Psychiatry 26:57-63, 1972 12. Fitzgibbons DI, Shearn CR: Concepts of schizophrenia among mental health professions. J Consult Clin Psycho1 38:288-295,1972 13. Hirschfeld R, Spitzer RL, Miller RG: Computer diagnosis in psychiatry: a Bayes approach. J Nerv Ment Dis 158:399-407, 1974 14. Hoch PH: Differential Diagnosis in Clinical Psychiatry. New York, Science House, 1972, pp 60-648 15. Ianzito BM, Cadoret RJ, Pugh DD: A research technique for organizing multiple psychiatric diagnoses. Compr Psychiatry 13:73-78, 1972 16. Jackson B: Reflections on DSM-II. Int J Psychiat 7:385-392, 1969 17. Jackson 8: The revised diagnostic and statistical manual of the American Psychiatric Association. Am J Psychiatry 127:65-73, 1970 18. Kraepelin E: Dementia Praecox and Paraphrenia. Translated by Barclay RM: Edinburgh, Livingston, 1919 19. Kreitman N: The reliability of psychiatric diagnosis. J Ment Sci 107~876-886, 1961 20. Lehmann HE: Schizophrenia, IV: Clinical

DIAGNOSIS

OF SCHIZOPHRENIA

features, in Freedman AF, Kaplan HI (eds): Comprehensive Textbook of Psychiatry. Baltimore, Williams & Wilkins, 1967, pp 621-648 21. Mellor CS: First-rank symptoms of schizophrenia. Br J Psychiatry 117:15~23, 1970 22. Mirabile C, Houck J, Glueck, B: Computer prediction of treatment success. Comp Psychiatry 12:48%53,1971 23. Morrison JR: Changes in subtype diagnosis of schizophrenia: 1920-1966. Am J Psychiatry 131:674--677, 1974 24. Noyes AP, Kolb LC: Modern Clinical Psychiatry (ed 6). Philadelphia, WB Saunders, 1967, pp %92 25. Phillips L, Dragon JG: Classification of the behavior disorders. Ann Rev Psycho1 22:447-m 472, 197I 26. Robins E, Guze SB: Establishment of diagnostic validity in psychiatric illness: its application to schizophrenia. Am J Psychiatry 126:983-987, 1970 27. Schneider K: Clinical Psychopathology. Translated by Hamilton MW: New York, Grune & Stratton, 1959 28. Smith WG: A model for psychiatric diagnosis. Arch Gen Psychiatry 14:521&529,1966

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29. Straker M: Schizophrenia and psychiatric diagnosis. Am J Psychiatry 131:693--694, 1974 30. Taylor MA: Schneiderian first-rank symptoms and clinical prognostic features in schizophrenia. Arch Gen Psychiatry 26:64--67, 1972 31. Taylor MA, Gaztanaga P, Abrams R: Manic-depressive illness and acute schizophrenia: a clinical, family history, and treatmentresponse study. Am J Psychiatry 131:678 -681. 1974 32. Taylor MA, Heisler J: Phenomenology: an alternative approach to diagnosis of mental disease. Comp Psychiatry 12:48&486. 1971 33. Wender PL: The role of genetics in the etiology of schizophrenias. Am J Orthopsychiatry 39:447-458, 1969 34. Wittenborn JR: Reliability. validity, and objectivity of symptom-rating scales. J Nerv Ment Dis 154:79-87, 1972 35. Yusin A. Nihira K, Mortashed C: Major and minor criteria in schizophrenia. Am J Psychiatry 131:688 ~690, 1974 36. Zubin J: Classification of the behavior disorders. Ann Rev Psycho1 18:373-403, 1967

Diagnosis of schizophrenia: pathognomonic signs or symptom clusters.

Diagnosis of Schizophrenia: Pathognomonic Signs or Symptom Clusters Charles S. Newmark, William Hunter, David Raft, Timothy and Joseph Toomey. Maz...
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