Search tips
Search criteria 


Logo of schbulschizophrenia bulletinsubscriptionscontact uscurrent issuemy basketarchivemy accountsearchcontact this journaloxford journalsabout this journal
Schizophr Bull. 2007 September; 33(5): 1178–1200.
Published online 2006 December 8. doi:  10.1093/schbul/sbl065
PMCID: PMC3304082

Competing Definitions of Schizophrenia: What Can Be Learned From Polydiagnostic Studies?


The contemporary diagnoses of schizophrenia (sz)—Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition(DSM-IV) and International Classification of Diseases,10th Revision(ICD-10)—are widely considered as important scientific achievements. However, these algorithms were not a product of explicit conceptual analyses and empirical studies but defined through consensus with the purpose of improving reliability. The validity status of current definitions and of their predecessors remains unclear. The so-called “polydiagnostic approach” applies different definitions of a disorder to the same patient sample in order to compare these definitions on potential validity indicators.

We reviewed 92 polydiagnostic sz studies published since the early 1970s. Different sz definitions show a considerable variation concerning frequency, concordance, reliability, outcome, and other validity measures. The DSM-IV and the ICD-10 show moderate reliability but both definitions appear weak in terms of concurrent validity, eg, with respect to an aggregation of a priori important features. The first-rank symptoms of Schneider are not associated with family history of sz or with prediction of poor outcome. The introduction of long duration criteria and exclusion of affective syndromes tend to restrict the diagnosis to chronic stable patients. Patients fulfilling the majority of definitions (core sz patients) do not seem to constitute a strongly valid subgroup but rather a severely ill subgroup. Paradoxically, it seems that a century after the introduction of the sz concept, research is still badly needed, concerning conceptual and construct validity of sz, its essential psychopathological features, and phenotypic boundaries.

Keywords: validation, diagnosis, polydiagnostic approach, concordance, schizophrenia concept, psychopathology, review


Schizophrenia (sz) remains an elusive entity, and the history of psychiatric research is replete with the attempts at formalizing its definition and hence to distinguish it from other disorders as well as the attempts at various internal subdivisions (eg, acute—chronic or poor premorbid—good premorbid subtypes). In fact, since the introduction of the concept, psychiatry has produced not less than 40 definitions of sz.

These historical permutations naturally sink gradually into oblivion with the most recent algorithms (such as Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition [DSM-IV] and International Classification of Diseases, 10th Revision [ICD-10]) acquiring the aura of important epistemological achievements with solid empirical foundations and insidiously reified into truly existing natural entities.1, 2 Yet, it is important to realize that the operational diagnoses of today owe their shape not so much to their scientific foundations but to pragmatic needs and ensuing decisions to increase international consensus.

One possible investigative approach to the reliability and validity of sz definitions is to compare these definitions between themselves and with their historical predecessors. For example, to say that ICD-10 is superior to ICD-8/ICD-9 requires comparing these 2 algorithms with respect to some validating data of interest. The purpose of this study is to provide a review of such a polydiagnostic approach in sz research. This goal gains in urgency, given the ongoing contemplation of yet another change in the diagnostic systems.

The polydiagnostic approach35 consists of applying different sets of criteria for a given diagnostic category to the same group of patients in order to assess the degree of concordance between the diagnoses and/or to compare their validity indicators.

Materials and Method

The Medline searches were performed for all clinical and epidemiological studies published since 1970 comparing at least 2 definitions of sz. The Medline search was supplemented by screening references of the individual articles. Studies that did not indicate the numbers of patients with a given diagnosis were not included.

A preestablished scheme was used to record which and how many definitions were used, number of patients, the inclusion criteria, rating setting, the interrater reliability, the diagnostic concordance, follow-up assessments and their results, and other types of validation. Because the studies and hence the data were too heterogeneous, it was not possible to perform a systematic review, where the individual studies could enter into a meta-analytic approach.


We have identified more than 100 articles published between 1972 and 2005, referring to 92 polydiagnostic studies. Twenty-six of these were follow-up studies. An overview of all studies appears in table 1.

Table 1.
The Polydiagnostic Studies

Diagnostic Definitions

The polydiagnostic studies used approximately 40 different diagnostic definitions of sz and related disorders (2–23 in each study, median = 4). An overview of the definitions is shown in table 2. The formal criteria of these definitions differ; table 3 compares the criteria of some selected definitions.

Table 2.
Diagnostic Abbreviations
Table 3.
Comparison of the Diagnostic Criteria of Selected Schizophrenia Definitions

Inclusion Criteria of the Individual Studies

58 studies (63%) dealt primarily with psychosis, the 11 of which (12%) with first-admission or recent onset psychosis. 34 studies (37%) included broad groups of patients and population subjects.

Psychopathological Ratings

The information about the details of psychopathological rating procedures was typically inadequate, except for listing the rating scales. 45% of the studies explicitly mentioned psychiatrists as raters, a further 13% used groups of raters with varying professional backgrounds, and 42% gave no information on the education of the interviewers.

In 26% of the cases, the rating was performed solely on the basis of hospital charts, in 39% exclusively on the basis of patient interviews, and in the remainder based on composite sources of information.


The expectation of increased diagnostic reliability was what justified the introduction of operational definitions, and the DSM-III field studies did indeed present a high reliability level for sz (81%6), but the methodology was loose structured and no further field studies were presented for the later DSM revisions to clarify this issue. However, the diagnostic interrater reliability was assessed in less than half of the polydiagnostic studies, usually in the form of Cohen's kappa coefficients, which were, not surprisingly, somewhat better for the more recent (from Research Diagnostic Criteria [RDC] onward) operational definitions than for older definitions (Modestin et al,7 Kirk and Kutchins,8 cf. Kety et al9 vs Kendler et al10), generally labeled “good” or even “excellent.” Other forms of reliability checks (eg, test-retest) and other expressions of reliability (eg, symptom agreement) were rarely presented.

Before exploring the question of reliability, one should realize that there are 2 major, overlapping sources of a diagnostic disagreement: (1) criterion variance, which refers to the differences in the raters' use and interpretation of the diagnostic criteria, and (2) information variance, referring to the quality and quantity of the originally collected psychopathological information. The significance of information variance is illustrated by higher kappas found in rating live or videotaped interviews than in rating hospital charts11 and by the fact that the reliability of rating case records remained only moderate even when using structured checklists.12 Brockington13 suggested that low interrater reliability for Feighner's and New Haven definitions in the Camberwell sample was caused by their complexity, which can be seen as an effect of criterion variance. As a rule, a diagnosis based on a few simple items becomes easily reliable compared with the diagnostic algorithms defined by many and interacting features.

Unfortunately, the structure of reliability was rarely discussed, and only a few studies allowed a more detailed reliability examination. In a unique study, Strakowski14 showed that a lack of reliability between the clinical and the SCID-P (Structured Clinical Interview for DSM-II-R—Patient Version)–generated diagnoses could be partitioned into 58% caused by the information variance and 42% caused by the criterion variance. Unfortunately, such distinctions and explorations of the sources of variance are typically not performed nor discussed. Yet, if a creation or a revision of diagnostic criteria is motivated by reliability concerns, the emphasis should be focused on the criterion variance because the information variance is basically related to the comprehensiveness of the assessment.

Reliability is not an intrinsic property of the diagnostic definition. Needless to say, unreliability may be related to multiple factors, including skill and education of the interviewer. Reliability is higher in research settings but does not ensure reliability in clinical practice. Furthermore, reliability acquired through training on clinical samples cannot be unproblematically extrapolated to population studies where the majority of subjects do not suffer from any mental illness, or suffer from specific psychopathology but unaccompanied by dysfunction or distress, or where the subjects are prone to hide their symptoms. Moreover, the exact significance of quantifying reliability is not unequivocal. Thus, the magnitude of kappa coefficient may reflect differences in prevalence rates.15 Kirk and Kutchins 8 demonstrated that a kappa of the same magnitude may be presented by different adjectives (eg, good or excellent), depending on the agenda of the individual study. Finally, the conventional wisdom of low reliability precluding validity16 is not invariably true. Some authors demonstrated that diagnostic validity is possible even in the case of low reliability, if the sensitivity is low and specificity is high.17, 18

Frequencies of Specific Diagnoses

Variation in frequencies between definitions.

The studies demonstrated a wide range in the proportions of patients fulfilling the criteria for the individual definitions of sz (eg, Strauss and Gift19: 1–25%; Lewine et al20: 2–60%). Such differences in the frequency and hence in the inclusiveness of the definitions reflect the variation in the diagnostic criteria. The influence of the duration criteria and the exclusion of affective syndromes were illustrated by a shift from DSM-II (having no such criteria) to the criteria of RDC and DSM-III.21 DSM-II sz was often repartitioned as affective, schizoaffective, and schizophreniform disorders.

A DSM-IV and ICD-10 reanalysis of the Burghölzi sz sample, originally diagnosed by Eugen and Manfred Bleuler, showed that the sz diagnosis was retained in nearly in all cases as the contemporary spectrum diagnoses (sz, schizoaffective disorder, schizotypal personality disorder).7

Interstudy variation.

There was a striking interstudy variation in the proportion of patients fulfilling a given diagnosis of sz. Differences in study design and inclusion criteria were primarily responsible for this variation. The number of studies allowing an assessment of frequencies of the contemporary definitions was limited. Across 12 studies, the proportion of DSM-III-R sz varied from 24 to 100%, lowest in a group of patients with “functional psychosis22” and highest in patients with “narrowly defined schizophrenia.23” Corresponding figures are found for ICD-10 sz.

The samples composed of the patients selected because of their sz diagnosis were (tautologically) frequently diagnosed as having sz by all applied definitions.24, 25 Selection of chronic sz patients resulted in frequent sz diagnosis even by Feighner's conservative definition.11 In fact, a comparison of different samples of patients demonstrated that the proportion of Feighner sz increased with chronicity, whereas it was not the case for the frequencies of Schneider's first-rank symptom (FRS)—Berner et al26 and Lenz et al27 vs Cernovsky et al28 and Landmark et al.29 , 30

Diagnostic Concordance (47 studies)

Substantial differences in concordance between the sz definitions were demonstrated in studies comparing the various preoperational definitions.3134 Yet, between related systems, there was a considerable concordance.7, 31 Some diagnostic concentricity was seen between related definitions. Thus, in one study, almost all Feighner cases fulfilled also DSM-III criteria.33 Cases fulfilling most of the definitions of sz and, consequently, yielding the highest concordance were often named “core schizophrenia” cases. In one study,35 such cases were found to suffer from paranoid sz. The concordant group of the IPSS patients was characterized by a higher percentage of males and of single patients, a psychopathological profile with more hallucinations, delusions, and flatness of affect, fewer depressive symptoms, precipitating factors, and previous inpatient treatments.36 Uniforming the patient sample tended to increase the concordance between the definitions.

Restricting the sample to a group of patients with illness duration longer than 6 months increased the concordance kappa between definitions having different duration criteria.35 In one study, the concordance was increased by widening the sample to all first admissions and by eliminating the 3 strictest definitions.13 Definitions excluding affective symptoms were demonstrated to form a cluster with a higher kappa than the cluster formed by the definitions that permit them.37 In a sample of chronic psychotic patients, the elimination of the OPCRIT item 52, “co-occurrence of psychotic and affective symptoms,” increased the agreement of the sz spectrum disorders.38 Among all studies of the present review comparing diagnostic concordance kappas (N = 34), values above 0.80 were found exclusively in those that included chronic psychotic patients but not in first-onset psychotic patients and mixed groups of patients (Fisher exact test: P < .005).


78 studies (85%) presented validation data. The most frequently occurring measure of validation was the predictive power of diagnostic definitions. However, true concurrent validation—be it through neurobiological markers or other relevant measures that do not enter into the diagnostic definition such as family history of mental illness, psychometric measures of formal thought disorder, or subjective sense of self-dissolution39—was rare.


24 studies (28%) compared the outcome of different sz definitions. The majority of the outcome periods were longer than 5 years. The outcome variables investigated were the prediction of the course of illness, the number of readmissions, symptomatology levels, diagnostic stability, and of social and functional outcome.

Diagnostic stability as a measure of outcome (6 studies) was usually calculated as positive predictive value. Several studies showed high stability of the operational definitions, such as DSM-III-R and ICD-10.40

Conservative definitions were found to be predictors of poor outcome, but tautologically, the notion of conservatism is often dependent on the chronicity of course. This applied first of all to Feighner's criteria.4144 Broad definitions such as The New Haven Schizophrenia Index, on the other hand, did not predict the outcome.13, 31, 42, 45, 46 Such diagnoses embrace favorable as well as poor outcome cases; conservative diagnoses only include the latter group. The duration criteria of the diagnostic algorithm influence the predictive validity. Thus, the 6-month duration criterion has been demonstrated to increase predictive validity in terms of diagnostic stability.12, 47, 48 Elimination of affective components in sz tended to result in an aggregation of chronic, nonepisodic, and therefore stable forms of illness.49, 50

Schneider's FRS, playing a central part in the contemporary sz definitions, resulted in a relatively inclusive sz concept that did not predict the outcome.13, 23, 27, 31, 45, 46 In comparing DSM-II and DSM-III, the former was found to be more inclusive and indicative of a more favorable outcome. The DSM-III appeared to exclude many females with favorable outcome.51

Psychopathological Validation

In a few studies, concurrent validity was established by relating sz definitions with traditional sz symptoms or traits such as Bleuler's fundamental symptoms, Schneider's FRS, Huber's basic symptoms, and premorbid adjustment.

ICD-9 sz when compared with ICD-10 was associated with formal thought disorder39 and with self-disorders and basic symptoms (L.B.J and J.P, unpublished data from the same study).

In a comparison of 6 definitions of sz, Bleulerian fundamental symptoms were found to be more important for the diagnosis than Schneiderian FRS.26 In one study, Schneider sz was associated with better premorbid adjustment than non-Schneider sz.32 The significance of basic symptoms assessed by Frankfurt Complaint Questionnaire (FCQ)52 seemed more ambiguous,34, 50, 53 probably, because of the methodological shortcomings of the FCQ.

Cluster, Latent Class, and Factor Analyses

In the IPSS,36 a McKeon cluster analysis of the present state examination (PSE) data resulted in 10 clusters. Some ICD-8 sz subtypes tended to be concentrated in certain clusters. Some clusters were common to all centers, others only in a small number of them. Three clusters were selected to make up a sz definition for further analyses together with de ICD-8 and Catego-S diagnoses.

Latent class analysis54 was carried out in a handful of studies. In an attempt to explain test-retest reliability findings, Faraone18 estimated the sensitivity and specificity of RDC and DSM-III-R diagnoses to latent classes. Sz according to both systems had high kappas and excellent sensitivity and specificity. Kendler55 compared classes generated by a handful of OPCRIT items collected in the Roscommon Family Study with DSM-III-R diagnoses. The classes which emerged resembled well-known diagnostic categories such as classic (Kraepelinian) sz, hebephrenia, and schizophreniform disorder. Eighty-four percent of cases classified as classic sz were also so diagnosed by the DSM-III-R. The classes were validated against the familial risk of illness. The risk for sz and sz spectrum was significantly increased in relatives of all probands classes except major depression and, especially, marked in the relatives of hebephrenia-class patients (sz 16.1%, sz spectrum 45.5%).

Factor analysis of diagnostic variables of 23 sz definitions applied by Peralta56 to 660 psychotic patients yielded 3 interpretable factors (a general sz factor, a Schneiderian factor, and a Bleulerian factor) explaining 58% of the variance, which was found to support a dimensional approach to sz.

Biological Parameters

Only a few studies related biological findings to multiple diagnoses. Assuming that the prolactin-releasing potency of a drug corresponds to its antipsychotic potency, Keks57, 58 found prolactin concentration to be lower in patients fulfilling criteria precluding affective syndromes.

In measuring the growth hormone response to the injection of clonidine as an expression of α2-adrenergic receptor sensitivity, Keks59 found that most of the definitions associated with blunted response did not preclude affective symptomatology.


Heritability served as a measure of validation in a few studies.

Twin studies.

Gottesman and Shields, examining twin concordance as an expression of heritability, found both monozygotic (MZ) and dizygotic (DZ) concordance highest using the broadest definitions (among nonoperational diagnoses of 6 clinicians) but the best MZ:DZ discrimination using “middle-of-the-road” criteria.60, 61 However, the emphasis on maximizing MZ:DZ concordance ratio is only meaningful on the prior assumption of polyfactorial transmission.

Conservative definitions such as Feighner's were among those with the highest MZ twin concordance whereas FRS were among those with the lowest.62 MZ twins diagnosed by the operational definitions had higher concordance and correlation in liability compared with FRS-diagnosed twins.6264

Adoption studies.

In a sample of biological and adoptive relatives of index adoptees with sz and of control adoptees, significant differences were found in the prevalence of sz spectrum disorders in biological vs control relatives of index probands both by a Kraepelin-Bleuler-DSM-II definition9 and by DSM-III.10 The percentage of spectrum disorders was higher, though insignificantly, among the relatives of the former than of the latter.

Family history.

Few polydiagnostic studies compared the familial rates of sz. Comparing 4 definitions, Asnis65 failed to find significant differences between the familial rates of sz spectrum disorders. In a first-admission sample, ICD-9 sz was found to be significantly associated with family history of sz, whereas ICD-10 was not associated at all.39 Moreover, partitioning of ICD-10 sz39 revealed that sz selectively aggregated in the relatives probands diagnosed by the criterion 2 (an assortment of Bleulerian and second rank symptoms). Kendler's latent class analysis study,55 mentioned above, showed a dramatically increased risk for sz in the relatives of the hebephrenia-class probands.



Four studies calculated the incidence rates of sz to be within a range from 6 to 32 per 100 000 inhabitants.6669 The rates varied within each study between the diagnostic definitions. Thus, ICD-9 sz was found to be broader than DSM-III and DSM-III-R, and Feighner's definition was the most restrictive.

Examining the alleged decline in the incidence of sz, Allardyce70 found a falling rate of clinical diagnosis over time (20 years) but not the OPCRIT-generated ICD-10 and DSM-IV sz, suggesting that changes in the diagnostic habits have operated to bias the reported rates.


Lindstrom71 calculated the 1-year prevalence of sz by 4 contemporary diagnostic definitions to be within the range of 40–47 per 10 000. The prevalence found by Harvey72 was 29–31 per 10 000. The 1-year prevalence of the PSE S-class estimated by Ni Nuallain73 was as low as 10 per 10 000 as compared with the 73 of ICD-8 because of the failure of the S-class to identify patients who presented with exclusively negative symptoms. The combination of PSE and lifetime syndrome checklist data increased the PSE S-class prevalence to 39 per 10 000. Among the Iban of Sarawak, Barrett74 found rates of treated sz between 18 and 35 per 10 000—age corrected (to age 55) between 42 and 83 per 10 000, and in rural Botswana, Ben-Tovim75 found the age-adjusted 1-year prevalence of DSM-III sz to be 43 per 10 000 and of ICD-9 53 per 10 000.

Gender distribution.

40 studies inform about the gender distribution. The mean numbers of male and female patients in these particular studies were 95 and 86 (nonsignificant). Some studies allowed for a comparison of incidence rates, frequencies, and lifetime courses. The highest ratio of male to female incidence rate was produced by the narrow Feighner definition.67, 68 Other studies failed to demonstrate the incident sex ratio differences between broad and narrow definitions.66, 76 Conservative definitions yielded a significantly greater male to female prevalence ratio.20, 51, 67, 77 Patients excluded by the narrow definition were typically favorable-outcome females.51 Castle67 found the male-to-female ratio to be higher than 1 in patients with onset below age 45 and lower than 1 above age 45 in sz definitions requiring a 6-month duration.

Age of onset.

Male patients had a lower age of onset in nearly all definitions,76 but narrow definitions seemed to be associated with onset before age 25 in a greater part of the patients than the broad ones.77


The polydiagnostic studies of the past 4 decades reflect an evolution away from prototypically anchored diagnostic concepts of sz to polythetically oriented definitions, based on the so-called operational criteria. It is, however, necessary to point out that all studies reviewed here—as polydiagnostic comparisons—necessitated a certain operationalization of the examined definitions.

The principal finding of our review is that the degree of concordance between different definitions of sz varies considerably, depending, of course, on the similarity of the criteria. The number of sz cases in a given sample may vary by more than factor 3 when diagnosed by 2 different systems. This is far from trivial and not only because of psychopathological considerations. In fact, etiological research is very frequently performed through comparisons of “schizophrenias” with “nonschizophrenias,” ie, the sample is simply dichotomized into szs and the remainder of the sample. Such procedure may attenuate or otherwise obscure differences of interest because the “nonschizophrenia” group may contain spectrum cases as well as sz cases defined so by other sets of criteria.

The polydiagnostic studies do not provide sufficient validity data to justify claiming a clear superiority of any particular definition over others. In many studies, the percentage of sz cases so diagnosed by all diagnostic algorithms is remarkably low. This subgroup—usually called “core schizophrenia”—appears to us more as a product of severity and impenetrable interactions between the single criteria rather than as being reflective of a class with a particularly strong validity.

What is conspicuously lacking in the polydiagnostic studies is a serious and systematic reflection on the conceptual validity of sz, ie, what we take this illness to be in the very first place.78 Empirical phases of validation do not happen in a void but are preceded and constrained by the original typifications of what we take sz to be.7883 There are several possibilities: eg, is it an illness mainly defined by trait-like intersubjective displacement, subjective orientation with changes of the worldview (as described by Bleuler's generic term of autism84, 81), compromised unity of consciousness and self-dissolution (Kraepelin85, 86), characteristic psychotic symptoms (a view unjustly ascribed to Schneider87), a deteriorating or unremitting course (Feighner88), simply a multidimensional construct,56, 89 or something else (eg, schizotaxia90, 91)?

The issue of affective symptoms represents a special concern in the discussions of conceptual and construct validity. The exclusion of affective components from the picture of sz, despite their clinical reality as ubiquitous symptoms in all stages of sz, has also necessitated a creation of a rather convoluted category of schizoaffective psychosis.92 This evacuation of affective symptoms from sz appears as quite arbitrary, and yet as shown by Keks,5759 a stratification of sz by presence or absence of affective symptoms may be biologically meaningful. The subdivisions of sz on the basis of biological findings obtained in polydiagnostic studies are in agreement with Bleuler's claim that we deal with a group of szs rather than a single disease.84 Such a view gains currently provisional support from genetic studies. Thus, in a family study by Hallmayer et al, a mathematically identified subtype of sz, characterized by pervasive neurocognitive deficit, had a distinct genetic profile.93

Empirical validity is a multidimensional concept comprising pathogenetic and etiologic knowledge (or hypotheses), course, treatment response, etc. Although we have knowledge of a variety of etiologically relevant risk factors in sz, this knowledge has no substantive form, which could permit assessment of causal validity in a polydiagnostic context. Genetic data39 suggest that it is the Bleulerian dimension of fundamental symptoms that is associated with familial aggregation of sz. No molecular genetic studies have so far been included in the polydiagnostic designs.

Predictive validity—exploring outcome and stability of course—is examined in approximately half of the studies. Unfortunately, it is a rather equivocal type of validity. Prediction of course may serve as a validity criterion with an independent a priori assumption that, say, an unremitting course or chronic social dysfunction is constitutive of a given diagnostic entity. The recent duration criteria lead to an automatic exclusion of favorable outcome, acute psychosis. Diagnostic stability in the sense of basically unchanged psychopathological picture as a measure of validity is at odds with the well-replicated findings that 20–30% of patients with sz recover from psychosis (cf. Modestin et al,7 Hafner and an der Heiden,94 Ciompi and Muller,95 Huber et al,96 and Bleuler97). Psychopathological stability would be relevant as a validating criterion if one were interested in the persistence of the trait features of the illness, indicating structural alterations of consciousness.81 Therefore, definitions based on trait-like features (eg, Bleuler's fundamental symptoms) appear to be more stable than those based on fluctuating psychotic features (eg, FRS). In the latter case, diagnostic stability means chronic, productive psychosis. The FRS are particularly poor predictors of outcome.13, 23, 27, 31, 45, 46 Conservative definitions with inbuilt chronicity (deviant preonset personality) such as Feighner's are more likely to predict uniformly poor outcome. Unfortunately, only few studies made an attempt to examine differential validity of sz by other means than outcome prediction.

A dominating concern of contemporary psychiatry is the quest for reliability of diagnostic categories. The very rise of “operational” definitions in the 1970s was stimulated by the demonstration of alarming US-UK diagnostic disagreements.98, 99

The operational definitions seem to have modestly increased the interrater reliability (eg, Gruenberg et al100; Kety et al9 vs Kendler et al10). However, reliability is easy to achieve but “it becomes vacuous when it is a primary goal, un-associated with other concerns.101” In the quest for reliability, many domains of psychopathology of sz, once considered as taxonomically and pathogenetically crucial (eg, the notion of autism or formal thought disorder) have been either strongly simplified (converting the “fundamental” schizophrenic symptoms into behaviorally defined “negative symptoms86, 102”) or deleted altogether from the psychiatric idiom (eg, the notion of self or subjectivity103).

In conclusion, this review highlights certain steps that seem to us as urgently needed in sz research. There is a need for integrating the rapidly expanding technological means with explicit reflection constrained by phenomenological familiarity with sz. Empirical studies should increasingly lose their exploratory nature and become instead designed to answer more specific and explicit questions.


1. Maj M. Critique of the DSM-IV operational diagnostic criteria for schizophrenia. Br J Psychiatry. 1998;172:458–460. [PubMed]
2. Tucker GJ. Putting DSM-IV in perspective. Am J Psychiatry. 1998;155:159–161. [PubMed]
3. Berner P, Katschnig H, Lenz G. Poly-diagnostic approach: a method to clarify incongruences among the classification of the functional psychoses. Psychiatr J Univ Ott. 1982;7:244–248. [PubMed]
4. Berner P, Gabriel E, Katschnig H, et al. Diagnostic Criteria for Functional Psychoses. 2nd ed. Cambridge: Cambridge University Press; 1992.
5. Kendell RE. The choice of diagnostic criteria for biological research. Arch Gen Psychiatry. 1982;39:1334–1339. [PubMed]
6. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorder, 3rd ed. (DSM-III) Washington, DC: American Psychiatric Association; 1980.
7. Modestin J, Huber A, Satirli E, Malti T, Hell D. Long-term course of schizophrenic illness: Bleuler's study reconsidered. Am J Psychiatry. 2003;160:2202–2208. [PubMed]
8. Kirk SA, Kutchins H. The Selling of DSM: The Rhetoric of Science in Psychiatry. New York, NY: Aldine de Gruyter; 1992.
9. Kety SS, Wender PH, Jacobsen B, et al. Mental illness in the biological and adoptive relatives of schizophrenic adoptees. Replication of the Copenhagen Study in the rest of Denmark. Arch Gen Psychiatry. 1994;51:442–455. [PubMed]
10. Kendler KS, Gruenberg AM, Kinney DK. Independent diagnoses of adoptees and relatives as defined by DSM-III in the provincial and national samples of the Danish Adoption Study of Schizophrenia. Arch Gen Psychiatry. 1994;51:456–468. [PubMed]
11. Helmes E, Landmark J, Kazarian SS. Inter-rater reliability of twelve diagnostic systems of schizophrenia. J Nerv Ment Dis. 1983;171:307–311. [PubMed]
12. Hiller W, Dichtl G, Hecht H, Hundt W, von ZD. An empirical comparison of diagnoses and reliabilities in ICD-10 and DSM-III-R. Eur Arch Psychiatry Clin Neurosci. 1993;242:209–217. [PubMed]
13. Brockington IF, Kendell RE, Leff JP. Definitions of schizophrenia: concordance and prediction of outcome. Psychol Med. 1978;8:387–398. [PubMed]
14. Strakowski SM, Hawkins JM, Keck PE, Jr, et al. The effects of race and information variance on disagreement between psychiatric emergency service and research diagnoses in first-episode psychosis. J Clin Psychiatry. 1997;58:457–463. [PubMed]
15. Grove WM, Andreasen NC, Donald-Scott P, Keller MB, Shapiro RW. Reliability studies of psychiatric diagnosis. Theory and practice. Arch Gen Psychiatry. 1981;38:408–413. [PubMed]
16. Spitzer RL, Fleiss JL. A re-analysis of the reliability of psychiatric diagnosis. Br J Psychiatry. 1974;125:341–347. [PubMed]
17. Rice JP, Endicott J, Knesevich MA, Rochberg N. The estimation of diagnostic sensitivity using stability data: an application to major depressive disorder. J Psychiatr Res. 1987;21:337–345. [PubMed]
18. Faraone SV, Blehar M, Pepple J, et al. Diagnostic accuracy and confusability analyses: an application to the Diagnostic Interview for Genetic Studies. Psychol Med. 1996;26:401–410. [PubMed]
19. Strauss JS, Gift TE. Choosing an approach for diagnosing schizophrenia. Arch Gen Psychiatry. 1977;34:1248–1253. [PubMed]
20. Lewine R, Burbach D, Meltzer HY. Effect of diagnostic criteria on the ratio of male to female schizophrenic patients. Am J Psychiatry. 1984;141:84–87. [PubMed]
21. Silverstein ML, Warren RA, Harrow M, Grinker RR, Sr, Pawelski T. Changes in diagnosis from DSM-II to the research diagnostic criteria and DSM-III. Am J Psychiatry. 1982;139:366–368. [PubMed]
22. Forrester A, Owens DG, Johnstone EC. Diagnostic stability in subjects with multiple admissions for psychotic illness. Psychol Med. 2001;31:151–158. [PubMed]
23. Deister A, Marneros A. Prognostic value of initial subtype in schizophrenic disorders. Schizophr Res. 1994;12:145–157. [PubMed]
24. Kendler KS, Gruenberg AM, Tsuang MT. Outcome of schizophrenic subtypes defined by four diagnostic systems. Arch Gen Psychiatry. 1984;41:149–154. [PubMed]
25. Leboyer M, Jay M, D'Amato T, et al. Subtyping familial schizophrenia: reliability, concordance, and stability. Psychiatry Res. 1990;34:77–88. [PubMed]
26. Berner P, Katschnig H, Lenz G. First-rank symptoms and Bleuler's basic symptoms. New results in applying the polydiagnostic approach. Psychopathology. 1986;19:244–252. [PubMed]
27. Lenz G, Katschnig H, David H. Symptoms diagnosis and time in hospital. A polydiagnostic study of schizophrenia. Psychopathology. 1986;19:253–258. [PubMed]
28. Cernovsky Z, Landmark J, Leslie B. Social and anamnestic correlates of consensus in diagnosing schizophrenia. J Clin Psychol. 1985;41:614–619. [PubMed]
29. Landmark J, Cernovsky ZZ, Merskey H, Leslie B. Interrelationships of systems for diagnosing schizophrenia. Compr Psychiatry. 1986;27:343–350. [PubMed]
30. Landmark J, Merskey H, Cernovsky Z, Helmes E. The positive triad of schizophrenic symptoms. Its statistical properties and its relationship to 13 traditional diagnostic systems. Br J Psychiatry. 1990;156:388–394. [PubMed]
31. Stephens JH, Astrup C, Carpenter WT, Jr, Shaffer JW, Goldberg J. A comparison of nine systems to diagnose schizophrenia. Psychiatry Res. 1982;6:127–143. [PubMed]
32. Klein DN. Relation between current diagnostic criteria for schizophrenia and the dimensions of premorbid adjustment, paranoid symptomatology, and chronicity. J Abnorm Psychol. 1982;91:319–325. [PubMed]
33. McGorry PD, Singh BS, Connell S, McKenzie D, Van Riel RJ, Copolov DL. Diagnostic concordance in functional psychosis revisited: a study of inter-relationships between alternative concepts of psychotic disorder. Psychol Med. 1992;22:367–378. [PubMed]
34. Peralta V, Cuesta MJ. A polydiagnostic approach to self-perceived cognitive disorders in schizophrenia. Psychopathology. 1992;25:232–238. [PubMed]
35. Kulhara P, Mattoo SK, Chandiramani K, Bhave S, Awasthi A. Diagnostic systems for schizophrenia. A cross-sectional study of concordance from India. Acta Psychiatr Scand. 1986;74:55–61. [PubMed]
36. World Health Organization . Report of the International Pilot Study of Schizophrenia. Geneva, Switzerland: World Health Organization; 1973.
37. Copolov DL, McGorry PD, Singh BS, Proeve M, Van RR. The influence of gender on the classification of psychotic disorders—a multidiagnostic approach. Acta Psychiatr Scand. 1990;82:8–13. [PubMed]
38. Jakobsen KD, Frederiksen JN, Parnas J, Werge T. Diagnostic agreement of schizophrenia spectrum disorders among chronic patients with functional psychoses. Psychopathology. 2006;39:269–276. [PubMed]
39. Jansson L, Handest P, Nielsen J, Sæbye D, Parnas J. Exploring boundaries of schizophrenia: a comparison of ICD-10 with other diagnostic systems in first-admitted patients. World Psychiatry. 2002;1:109–114. [PubMed]
40. Amin S, Singh SP, Brewin J, Jones PB, Medley I, Harrison G. Diagnostic stability of first-episode psychosis. Comparison of ICD-10 and DSM-III-R systems. Br J Psychiatry. 1999;175:537–543. [PubMed]
41. Overall JE, Hollister LE. Comparative evaluation of research diagnostic criteria for schizophrenia. Arch Gen Psychiatry. 1979;36:1198–1205. [PubMed]
42. Bland RC, Orn H. Schizophrenia: diagnostic criteria and outcome. Br J Psychiatry. 1979;134:34–38. [PubMed]
43. Singerman B, Stoltzman RK, Robins LN, Helzer JE, Croughan JL. Diagnostic concordance between DSM-III, Feighner, and RDC. J Clin Psychiatry. 1981;42:422–466. [PubMed]
44. McGlashan TH. Testing four diagnostic systems for schizophrenia. Arch Gen Psychiatry. 1984;41:141–144. [PubMed]
45. Kendell RE, Brockington IF, Leff JP. Prognostic implications of six alternative definitions of schizophrenia. Arch Gen Psychiatry. 1979;36:25–31. [PubMed]
46. Stephens JH, Ota KY, Carpenter WT, Jr, Shaffer JW. Diagnostic criteria for schizophrenia: prognostic implications and diagnostic overlap. Psychiatry Res. 1980;2:1–12. [PubMed]
47. Helzer JE, Brockington IF, Kendell RE. Predictive validity of DSM-III and Feighner definitions of schizophrenia. A comparison with research diagnosis criteria and CATEGO. Arch Gen Psychiatry. 1981;38:791–797. [PubMed]
48. Mason P, Harrison G, Croudace T, Glazebrook C, Medley I. The predictive validity of a diagnosis of schizophrenia. A report from the International Study of Schizophrenia (ISoS) coordinated by the World Health Organization and the Department of Psychiatry, University of Nottingham. Br J Psychiatry. 1997;170:321–327. [PubMed]
49. Schanda H, Thau K, Kufferle B, Kieffer W, Berner P. Heterogeneity of delusional syndromes: diagnostic criteria and course prognosis. Psychopathology. 1984;17:280–289. [PubMed]
50. Modestin J, Spichtig L, Ryffel D. Subjektive Basissymptome und Schizophrenie-Definition. Schweiz Arch Neurol Psychiatr. 1987;138:35–41. [PubMed]
51. Westermeyer JF, Harrow M. Prognosis and outcome using broad (DSM-II) and narrow (DSM-III) concepts of schizophrenia. Schizophr Bull. 1984;10:624–637. [PubMed]
52. Süllwold L. Subjektive defizitäre Störungen bei schizophren Erkrankten. In: Brenner HD, editor. Empirische Schizophrenieforschung. Bern, Switzerland: Huber; 1983.
53. Peralta V, Cuesta MJ. Schneiderian versus Bleulerian schizophrenia and basic symptoms. Psychopathology. 1991;24:151–157. [PubMed]
54. Goodman LA. The analysis of systems of qualitative variables when some of the variables are unobservable. Am J Sociol. 1974;79:1179–1259.
55. Kendler KS, Karkowski LM, Walsh D. The structure of psychosis: latent class analysis of probands from the Roscommon Family Study. Arch Gen Psychiatry. 1998;55:492–499. [PubMed]
56. Peralta V, Cuesta MJ. The underlying structure of diagnostic systems of schizophrenia: A comprehensive polydiagnostic approach. Schizophr Res. 2005;79:217–229. [PubMed]
57. Keks NA, Copolov DL, Kulkarni J, et al. Basal and haloperidol-stimulated prolactin in neuroleptic-free men with schizophrenia defined by 11 diagnostic systems. Biol Psychiatry. 1990;27:1203–1215. [PubMed]
58. Keks NA, McKenzie DP, Low LH, et al. Multidiagnostic evaluation of prolactin response to haloperidol challenge in schizophrenia: maximal blunting in Kraepelinian patients. Biol Psychiatry. 1992;32:426–437. [PubMed]
59. Keks NA, Copolov DL, McKenzie DP, et al. Growth hormone response to clonidine in neuroleptic-free patients with multidagnostically defined schizophrenia. Psychiatry Res. 1993;48:79–90. [PubMed]
60. Shields J, Gottesman II. Cross-national diagnosis of schizophrenia in twins. The heritability and specificity of schizophrenia. Arch Gen Psychiatry. 1972;27:725–730. [PubMed]
61. Gottesman II, Shields J. Schizophrenia and Genetics: A Twin Study Vantage Point. New York, NY: Academic Press; 1972.
62. McGuffin P, Farmer AE, Gottesman II, Murray RM, Reveley AM. Twin concordance for operationally defined schizophrenia. Confirmation of familiality and heritability. Arch Gen Psychiatry. 1984;41:541–545. [PubMed]
63. Cardno AG, Marshall EJ, Coid B, et al. Heritability estimates for psychotic disorders: the Maudsley twin psychosis series. Arch Gen Psychiatry. 1999;56:162–168. [PubMed]
64. Cardno AG, Sham PC, Farmer AE, Murray RM, McGuffin P. Heritability of Schneider's first-rank symptoms. Br J Psychiatry. 2002;180:35–38. [PubMed]
65. Asnis LC, Baron M, Gruen R. Diagnostic overlap in schizophrenia research: relation to outcome predictors and family history. Psychiatry Res. 1982;6:345–353. [PubMed]
66. Cooper JE, Goodhead D, Craig T, Harris M, Howat J, Korer J. The incidence of schizophrenia in Nottingham. Br J Psychiatry. 1987;151:619–626. [PubMed]
67. Castle DJ, Wessely S, Murray RM. Sex and schizophrenia: effects of diagnostic stringency, and associations with and premorbid variables. Br J Psychiatry. 1993;162:658–664. [PubMed]
68. Iacono WG, Beiser M. Are males more likely than females to develop schizophrenia? Am J Psychiatry. 1992;149:1070–1074. [PubMed]
69. Levav I, Zilber N, Danielovich E, Aisenberg E, Turetsky N. The etiology of schizophrenia: a replication test of the social selection vs. the social causation hypotheses. Acta Psychiatr Scand. 1987;75:183–189. [PubMed]
70. Allardyce J, Morrison G, Van OJ, Kelly J, Murray RM, McCreadie RG. Schizophrenia is not disappearing in south-west Scotland. Br J Psychiatry. 2000;177:38–41. [PubMed]
71. Lindstrom E, Widerlov B, von Knorring L. The ICD-10 and DSM-IV diagnostic criteria and the prevalence of schizophrenia. Eur Psychiatry. 1997;12:217–223.
72. Harvey CA, Pantelis C, Taylor J, et al. The Camden schizophrenia surveys. II. High prevalence of schizophrenia in an inner London borough and its relationship to socio-demographic factors. Br J Psychiatry. 1996;168:418–426. [PubMed]
73. Ni Nuallain M, O'Hare A, Walsh D. The prevalence of schizophrenia in three counties in Ireland. Acta Psychiatr Scand. 1990;82:136–140. [PubMed]
74. Barrett R, Loa P, Jerah E, Nancarrow D, Chant D, Mowry B. Rates of treated schizophrenia and its clinical and cultural features in the population isolate of the Iban of Sarawak: a tri-diagnostic approach. Psychol Med. 2005;35:281–293. [PubMed]
75. Ben-Tovim DI, Cushnie JM. The prevalence of schizophrenia in a remote area of Botswana. Br J Psychiatry. 1986;148:576–580. [PubMed]
76. Katschnig H, Lenz G. Are sex differences in age of onset of schizophrenia related to phenomenological sub-types? Schizophr Res. 1988;1(special issue):111–112.
77. Berner P, Katschnig H. Approche polydiagnostique en recherche psychiatrique. Ann med psychol. 1984;142:825–831. [PubMed]
78. Kendler KS. Toward a scientific psychiatric nosology. Strengths and limitations. Arch Gen Psychiatry. 1990;47:969–973. [PubMed]
79. Schwartz MA, Wiggins OP. Diagnosis and ideal types: a contribution to psychiatric classification. Compr Psychiatry. 1987;28(4):277–291. [PubMed]
80. Parnas J, Bovet P. Research in psychopathology: epistemologic issues. Compr Psychiatry. 1995;36:167–181. [PubMed]
81. Parnas J, Bovet P, Zahavi D. Schizophrenic autism: clinical phenomenology and pathogenetic implications. World Psychiatry. 2002;1:131–136. [PubMed]
82. Parnas J, Licht D, Bovet P. The cluster A personality disorders: A review. In: Akiskal H, Maj M, editors. Personality Disorders. Chichester, England: John Wiley & Sons Ltd; 2004. pp. 1–74.
83. Parnas J, Zahavi D. The role of phenomenology in psychiatric classification and diagnosis. In: Maj M, Gaebel W, Lopez-Ibor JJ, Sartorius N, editors. Psychiatric Diagnosis and Classification. Chichester, England: John Wiley & Sons Ltd; 2002. pp. 137–162.
84. Bleuler E. Dementia Praecox or the Group of Schizophrenias. New York, NY: International Universities Press; 1950.
85. Kraepelin E. Dementia Praecox and Paraphrenia. Edinborough, Scotland: E. and S. Livingstone; 1919. p. 1919.
86. Sass LA, Parnas J. Schizophrenia, consciousness, and the self. Schizophr Bull. 2003;29:427–444. [PubMed]
87. Schneider K. Clinical Psychopathology. New York, NY: Grune & Stratton; 1959.
88. Feighner JP, Robins E, Guze SB, Woodruff RA, Jr, Winokur G, Munoz R. Diagnostic criteria for use in psychiatric research. Arch Gen Psychiatry. 1972;26:57–63. [PubMed]
89. Peralta V, Cuesta MJ. Clinical models of schizophrenia: a critical approach to competing conceptions. Psychopathology. 2000;33:252–258. [PubMed]
90. Meehl PE. Schizotaxia, schizotypy, schizophrenia. Am Psychol. 1962;17:827–838.
91. Faraone SV, Green AI, Seidman LJ, Tsuang MT. “Schizotaxia. Clinical implications and new directions for research. Schizophr Bull. 2001;27:1–18. [PubMed]
92. Vollmer-Larsen A, Jacobsen TB, Hemmingsen R, Parnas J. Schizoaffective disorder—the reliability of its clinical diagnostic use. Acta Psychiatr Scand. 2006;113:402–407. [PubMed]
93. Hallmayer JF, Kalaydjieva L, Badcock J, et al. Genetic evidence for a distinct subtype of schizophrenia characterized by pervasive cognitive deficit. Am J Hum Genet. 2005;77:468–476. [PubMed]
94. Hafner H, an der Heiden W. Course and outcome of schizophrenia. In: Hirsch SR, Weinberger DR, editors. Schizophrenia. 2nd ed. Oxford, UK: Blackwell Publishing; 2003.
95. Ciompi L, Müller C. Lebensweg und Alter der Schizophrenien. Eine katamnestische Langzeitstudie bis ins Senium. Heidelberg, Germany: Springer; 1976. [PubMed]
96. Huber G, Gross G, Schüttler R. Schizophrenie. Verlaufs- und socialpsychiatrische Langzeitundersuchungen an den 1945 bis 1959 in Bonn hospitalisierten schizophrenen Kranken. Berlin, Germany: Springer; 1979. [PubMed]
97. Bleuler M. Schizophrenic Disorders: Long-Term Patient and Family Studies. New Haven, Conn: Yale University Press; 1978.
98. Cooper JE, Kendell RE, Gurland BJ, Sharpe L, Copeland JRM, Simon R. Psychiatric diagnosis in New York and London. Oxford, UK: Oxford University Press; 1972.
99. Gurland B. Aims, organization, and initial studies of the Cross-National Project. Int J Aging Hum Dev. 1976;7:283–293. [PubMed]
100. Gruenberg AM, Kendler KS, Tsuang MT. Reliability and concordance in the subtyping of schizophrenia. Am J Psychiatry. 1985;142:1355–1358. [PubMed]
101. Faust D, Miner RA. The empiricist and his new clothes: DSM-III in perspective. Am J Psychiatry. 1986;143:962–967. [PubMed]
102. Sass L. Self-disturbance in schizophrenia: hyperreflexivity and diminished self-affection. In: Kircher T, David A, editors. The Self in Neuroscience and Psychiatry. Cambridge: Cambridge University Press; 2003.
103. Parnas J, Handest P. Phenomenology of anomalous self-experience in early schizophrenia. Compr Psychiatry. 2003;44:121–134. [PubMed]
104. World Health Organization. Schizophrenia: An International Follow-up Study. Chichester, England: JohnWiley; 1979.
105. Strauss JS, Carpenter WT., Jr Characteristic symptoms and outcome in schizophrenia. Arch Gen Psychiatry. 1974;30:429–434. [PubMed]
106. Hawk AB, Carpenter WT, Jr, Strauss JS. Diagnostic criteria and five-year outcome in schizophrenia. A report from the International Pilot Study of schizophrenia. Arch Gen Psychiatry. 1975;32:343–347. [PubMed]
107. Taylor MA, Abrams R. A critique of the St. Louis psychiatric research criteria for schizophrenia. Am J Psychiatry. 1975;132:1276–1280. [PubMed]
108. Newmark CS, Falk R, Johns N, Boren R, Forehand R. Comparing traditional clinical procedures with four systems to diagnose schizophrenia. J Abnorm Psychol. 1976;85:66–72. [PubMed]
109. Koehler K, Bruske I, Jacoby C. Kraepelin-oriented research-diagnosable schizophrenia, mania, and depression in Schneider-negative schizophrenics. Arch Psychiatr Nervenkr. 1978;225:315–324. [PubMed]
110. Bland RC, Orn H. Schizophrenia: Schneider's first-rank symptoms and outcome 9. Br J Psychiatry. 1980;137:63–68. [PubMed]
111. Endicott J, Nee J, Fleiss J, Cohen J, Williams JB, Simon R. Diagnostic criteria for schizophrenia: reliabilities and agreement between systems. Arch Gen Psychiatry. 1982;39:884–889. [PubMed]
112. Young MA, Tanner MA, Meltzer HY. Operational definitions of schizophrenia: what do they identify? J Nerv Ment Dis. 1982;170:443–447. [PubMed]
113. Burbach DJ, Lewine R, Meltzer HY. Diagnostic concordance for schizophrenia as a function of sex. J Consult Clin Psychol. 1984;52:478–479. [PubMed]
114. Rosen WG, Mohs RC, Johns CA, et al. Positive and negative symptoms in schizophrenia. Psychiatry Res. 1984;13:277–284. [PubMed]
115. Helmes E, Landmark J. Subtypes of schizophrenia: a cluster analytic approach. Can J Psychiatry. 2003;48:702–708. [PubMed]
116. Lenz G, Simhandl C, Thau K, Berner P, Gabriel E. Temporal stability of diagnostic criteria for functional psychoses. Results from the Vienna follow-up study. Psychopathology. 1991;24:328–335. [PubMed]
117. Coryell W, Zimmerman M. Progress in the classification of functional psychoses. Am J Psychiatry. 1987;144:1471–1474. [PubMed]
118. Tandon R, Greden JF. Schneiderian first rank symptoms: reconfirmation of high specificity for schizophrenia. Acta Psychiatr Scand. 1987;75:392–396. [PubMed]
119. Jorgensen A, Teasdale TW, Parnas J, Schulsinger F, Schulsinger H, Mednick SA. The Copenhagen high-risk project. The diagnosis of maternal schizophrenia and its relation to offspring diagnosis. Br J Psychiatry. 1987;151:753–757. [PubMed]
120. Fenton WS, McGlashan TH, Heinssen RK. A comparison of DSM-III and DSM-III-R schizophrenia. Am J Psychiatry. 1988;145:1446–1449. [PubMed]
121. Hwu HG, Chen CC, Strauss JS, Tan KL, Tsuang MT, Tseng WS. A comparative study on schizophrenia diagnosed by ICD-9 and DSM-III: course, family history and stability of diagnosis. Acta Psychiatr Scand. 1988;77:87–97. [PubMed]
122. Gerbaldo H, Demisch L, Bochnik HJ. Phasic and process psychoses: a polydiagnostic comparison among the Frankfurt Classification System, DSM III, RDC, Feighner criteria and ICD-9. Psychopathology. 1989;22(1):14–27. [PubMed]
123. Goodman AB. Paranoid schizophrenia: prognosis under DSM-II and DSM-III-R. Compr Psychiatry. 1989;30(3):259–266. [PubMed]
124. Moller HJ, Hohe-Schramm M, Cording-Tommel C, et al. The classification of functional psychoses and its implications for prognosis. Br J Psychiatry. 1989;154:467–472. [PubMed]
125. Report of the U.S. delegation to assess recent changes in Soviet psychiatry. Schizophr Bull. 1989;15(15 Suppl 4):1–88.
126. Wetterberg L, Farmer AE. Clinical polydiagnostic studies in a large Swedish pedigree with schizophrenia. Eur Arch Psychiatry Clin Neurosci. 1991;240:188–190. [PubMed]
127. Jablensky A, Sartorius N, Ernberg G, et al. Schizophrenia: manifestations, incidence and course in different cultures. A World Health Organization ten-country study. Psychol Med Monogr Suppl. 1992;20:1–97. [PubMed]
128. Dollfus S, Petit M, Menard JF, Lesieur P. Recherche sur la schizophrénie: nécessité d'inclure les patients selon plusieurs systèmes diagnostiques. Ann Med Psychol (Paris) 1992;150:327–331. [PubMed]
129. Farmer AE, Wessely S, Castle D, McGuffin P. Methodological issues in using a polydiagnostic approach to define psychotic illness. Br J Psychiatry. 1992;161:824–830. [PubMed]
130. Strik WK, Dierks T, Franzek E, Maurer K, Beckmann H. Differences in P300 amplitudes and topography between cycloid psychosis and schizophrenia in Leonhard's classification. Acta Psychiatr Scand. 1993;87:179–183. [PubMed]
131. Deister A, Marneros A. Long-term stability of subtypes in schizophrenic disorders: a comparison of four diagnostic systems. Eur Arch Psychiatry Clin Neurosci. 1993;242:184–190. [PubMed]
132. Dollfus S, Petit M, Menard JF, et al. Approche polydiagnostique de la schizophrénie. Validation d'une “checklist” informatisée (LIDE: Liste d'Items à visée et Evolutive) Encephale. 1994;20:91–101. [PubMed]
133. Wciorka J. Prognosis in delusional psychoses: comparison of prognostic value of schizophrenia by six diagnostic criteria. Psychiatr Pol. 1993;27:399–406. [PubMed]
134. Wciorka J, Anczewska M, Chojnowska A, Stanikowska I. Delusional psychoses during first hospitalization: age of onset and diagnosis of schizophrenia by six diagnostic criteria. Psychiatr Pol. 1993;27:385–399. [PubMed]
135. Almeida OP, Howard RJ, Levy R, David AS. Psychotic states arising in late life (late paraphrenia) psychopathology and nosology. Br J Psychiatry. 1995;166:205–214. [PubMed]
136. Davies A, McIvor RJ, Kumar RC. Impact of childbirth on a series of schizophrenic mothers: a comment on the possible influence of oestrogen on schizophrenia. Schizophr Res. 1995;16:25–31. [PubMed]
137. Craddock M, Asherson P, Owen MJ, Williams J, McGuffin P, Farmer AE. Concurrent validity of the OPCRIT diagnostic system. Comparison of OPCRIT diagnoses with consensus best-estimate lifetime diagnoses. Br J Psychiatry. 1996;169:58–63. [PubMed]
138. Hill C, Keks N, Roberts S, et al. Problem of diagnosis in postmortem brain studies of schizophrenia. Am J Psychiatry. 1996;153:533–537. [PubMed]
139. Roberts SB, Hill CA, Dean B, Keks NA, Opeskin K, Copolov DL. Confirmation of the diagnosis of schizophrenia after death using DSM-IV: a Victorian experience. Aust N Z J Psychiatry. 1998;32:73–76. [PubMed]
140. Nurnberger JI, Jr, Blehar MC, Kaufmann CA, et al. Diagnostic interview for genetic studies. Rationale, unique features, and training. NIMH Genetics Initiative. Arch Gen Psychiatry. 1994;51:849–859. [PubMed]
141. Williams J, Farmer AE, Ackenheil M, Kaufmann CA, McGuffin P. A multicentre inter-rater reliability study using the OPCRIT computerized diagnostic system. Psychol Med. 1996;26:775–783. [PubMed]
142. Harrison G, Croudace T, Mason P, Glazebrook C, Medley I. Predicting the long-term outcome of schizophrenia. Psychol Med. 1996;26:697–705. [PubMed]
143. Jeffreys SE, Harvey CA, McNaught AS, Quayle AS, King MB, Bird AS. The Hampstead Schizophrenia Survey 1991. I: prevalence and service use comparisons in an inner London health authority, 1986-1991. Br J Psychiatry. 1997;170:301–306. [PubMed]
144. Maslowski J, Jansen van RD, Mthoko N. A polydiagnostic approach to the differences in the symptoms of schizophrenia in different cultural and ethnic populations. Acta Psychiatr Scand. 1998;98:41–46. [PubMed]
145. Wciorka J, Anczewska M, Bembenek A, et al. Psychopathological profile of acute schizophrenic syndromes diagnosed according to ICD-10 and DSM-IV criteria. Psychiatr Pol. 1998;32:251–264. [PubMed]
146. Pfuhlmann B, Franzek E, Beckmann H. Absence of a subgroup of chronic schizophrenia in monozygotic twins. Consequences for considerations on the pathogenesis of schizophrenic psychoses. Eur Arch Psychiatry Clin Neurosci. 1999;249:50–54. [PubMed]
147. Azevedo MH, Soares MJ, Coelho I, et al. Using consensus OPCRIT diagnoses. An efficient procedure for best-estimate lifetime diagnoses. Br J Psychiatry. 1999;175:154–157. [PubMed]
148. Peralta V, Cuesta MJ. Diagnostic significance of Schneider's first-rank symptoms in schizophrenia. Comparative study between schizophrenic and non-schizophrenic psychotic disorders. Br J Psychiatry. 1999;174:243–248. [PubMed]
149. Peralta V, Cuesta MJ. The nosology of psychotic disorders: a comparison among competing classification systems. Schizophr Bull. 2003;29:413–425. [PubMed]
150. Hafner H. Gender differences in schizophrenia. Psychoneuroendocrinology. 2003;28(Suppl 2):17–54. [PubMed]
151. Jager M, Bottlender R, Strauss A, Moller HJ. Classification of functional psychoses and its implication for prognosis. Comparison between ICD-10 and DSM-IV. Psychopathology. 2004;18(37):110–117. [PubMed]
152. Jakobsen KD, Frederiksen JN, Hansen T, Jansson LB, Parnas J, Werge T. Reliability of clinical ICD-10 schizophrenia diagnoses. Nord J Psychiatry. 2005;59:209–212. [PubMed]
153. Stompe T, Ortwein-Swoboda G, Ritter K, Marquart B, Schanda H. The impact of diagnostic criteria on the prevalence of schizophrenic subtypes. Compr Psychiatry. 2005;46:433–439. [PubMed]
154. Tsuang MT, Dempsey M. Long term outcome of major psychoses: II. Schizoaffective disorder compared with schizophrenia, affective disorders, and a surgical control group. Arch Gen Psychiatry. 1979;36:1302–1304. [PubMed]
155. Andreasen NC, Olsen S. Negative v positive schizophrenia. Definition and validation. Arch Gen Psychiatry. 1982;39:789–794. [PubMed]
156. Astrup C, Fossum A, Holmboe R. Prognosis in Functional Psychosis. Springfield, Ill: Charles C. Thomas; 1962.
157. Wing JK, Cooper JE, Sartorius N. Measurement and Classification of Psychiatric Symptoms: An Instruction Manual for the PSE and Catego Program. London, England: Cambridge University Press; 1974.
158. Cloninger CR, Martin RL, Guze SB, Clayton PJ. Diagnosis and prognosis in schizophrenia. Arch Gen Psychiatry. 1985;42:15–25. [PubMed]
159. Crow TJ. Molecular pathology of schizophrenia: more than one disease process? Br Med J. 1980;280:66–68. [PMC free article] [PubMed]
160. Landmark J. A manual for the assessment of schizophrenia. Acta Psychiatr Scand Suppl. 1982;298:1–88. [PubMed]
161. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorder, 2nd ed (DSM-II) Washington, DC: American Psychiatric Association; 1968.
162. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorder, 3rd ed, revised (DSM-III-R) Washington, DC: American Psychiatric Association; 1987.
163. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorder, 4th ed (DSM-IV) Washington, DC: American Psychiatric Association; 1994.
164. Edwards G. Diagnosis of schizophrenia: an Anglo-American comparison. Br J Psychiatry. 1972;120:385–390. [PubMed]
165. Farmer AE, McGuffin P, Spitznagel EL. Heterogeneity in schizophrenia: a cluster-analytic approach. Psychiatry Res. 1983;8:1–12. [PubMed]
166. Bürger-Prinz H. Probleme der phasischen Psychosen. Stuttgart, NY: Enke; 1960.
167. Carpenter WT, Jr, Strauss JS, Bartko JJ. Flexible system for the diagnosis of schizophrenia: report from the WHO International Pilot Study of Schizophrenia. Science. 1973;182:1275–1278. [PubMed]
168. Forrest AD, Hay AJ. The schizophrenias: operational definitions. Br J Med Psychol. 1973;46:337–346. [PubMed]
169. Guze SB, Cloninger CR, Martin RL, Clayton PJ. A follow-up and family study of schizophrenia. Arch Gen Psychiatry. 1983;40:1273–1276. [PubMed]
170. World Health Organization. Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death, 8th ed. (ICD-8) Geneva, Switzerland: World Health Organization; 1965.
171. World Health Organization. Mental Disorders: Glossary and Guide to Their Classification in Accordance With the Ninth Revision of the International Classification of Diseases (ICD-9) Geneva, Switzerland: World Health Organization; 1978.
172. World Health Organization. The Tenth Revision of the Classification International Diseases and Related Health Problems (ICD-10) Geneva, Switzerland: World Health Organization; 1993.
173. Langfeldt G. The prognosis in schizophrenia. Acta Psychiatr Neurol Scand. 1956;37:7–66. [PubMed]
174. Leonhard K. Aufteilung der endogenen Psychosen und ihre differenzierte Ätiologie. 7. neubearbeitete und ergänzte Auflage. Stuttgart, NY: Thieme; 1995.
175. Bleuler M. Schizophrenia. In: Cancro R, editor. The Schizophrenic Syndrome. London, England: Butterworth; 1971.
176. Newmark CS, Raft D, Toomey T, Hunter W, Mazzaglia J. Diagnosis of schizophrenia: pathognomonic signs or symptom clusters. Compr Psychiatry. 1975;16:155–163. [PubMed]
177. Astrachan BM, Harrow M, Adler D, et al. A checklist for the diagnosis of schizophrenia. Br J Psychiatry. 1972;121:529–539. [PubMed]
178. Pichot PJ. The French approach to psychiatric classification. Br J Psychiatry. 1984;144:113–118. [PubMed]
179. Pull CB, Pull MC, Pichot P. L.I.C.E.T.-S: Une liste intégrée de critères d'évalution taxinomiques pour les psychoses non-affectives. J Psychiatr Biol Thérapeutique. 1981;1:33–37.
180. Pull MC, Pull CB, Pichot P. Des critères emperiques français pour les psychoses II. Consensus des psychiatres français et définitions provisoires. Encephale. 1987;13:53–57. [PubMed]
181. Spitzer RL, Endicott J, Robins E. Research diagnostic criteria. Psychopharmacol Bull. 1975;11:22–25. [PubMed]
182. Spitzer RL, Endicott J, Robins E. Research Diagnostic Criteria, Instrument Number 58. (RDC) New York, NY: New York State Psychiatric Institute; 1975.
183. Spitzer RL, Endicott J, Robins E. Research diagnostic criteria: rationale and reliability. Arch Gen Psychiatry. 1978;35:773–782. [PubMed]
184. Overall JE. Actuarial methods in the diagnosis of schizophrenia. In: Fann WE, Karacan AD, Pokorny AD, editors. Phenomenology and Treatment of Schizophrenia. New York, NY: Spectrum; 1978.
185. Overall JE. Criteria for selection of subjects for research in biological psychiatry. In: Van Pragg H, editor. Handbook of Biological Psychiatry. New York, NY: Marcel Dekker; 1979.
186. Taylor MA, Abrams R. The prevalence of schizophrenia: a reassessment using modern diagnostic criteria. Am J Psychiatry. 1978;135:945–948. [PubMed]
187. Tsuang MT, Winokor G. Criteria for subtyping schizophrenia. Clinical differentiation of hebephrenic and paranoid schizophrenia. Arch Gen Psychiatry. 1974;31:43–47. [PubMed]
188. Snezhnevsky AV. The prognosis of schizophrenia. Int J Psychiatry. 1966;2:635–638. [PubMed]
189. Holland J, Shakhmatova-Pavlova I. Concept and classification of schizophrenia in the Soviet Union. Schizophr Bull. 1977;3:277–287. [PubMed]
190. Willis JH, Bannister D. The diagnosis and treatment of schizophrenia. A questionnaire study of psychiatric opinion. Br J Psychiatry. 1965;111(481):1165–1171. [PubMed]
191. Yusin A, Nihira K, Mortashed C. Major and minor criteria in schizophrenia. Am J Psychiatry. 1974;131:688–692. [PubMed]

Articles from Schizophrenia Bulletin are provided here courtesy of Oxford University Press