Fair Mile Hospital, Cholsey
Prince of Wales International Centre for Research on Schizophrenia and Depression, University of Oxford, UK
Correspondence: Professor T. J. Crow, POWIC, University Department of Psychiatry, Warneford Hospital, Oxford OX37JX, UK. Tel: 01865226474; fax: 01865244990; e-mail: tim.crow{at}psychiatry.oxford.ac.uk
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ABSTRACT |
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Aims To examine the relationships between linguistic deviations and symptoms in patients with acute psychosis.
Method We assessed language disturbances and first-rank symptoms with the Clinical Language Disorder Rating Scale (CLANG) in 30 consecutive patients with acute psychosis, selected for the presence of at least one active first-rank symptom, and 15 control participants with depression but no psychotic symptoms.
Results Strong positive correlations were found between the CLANG factor poverty (of speech) and first-rank delusions of control and (delusional perceptions) between semantic/phonemic paraphasias and verbal auditory hallucinations. Language disturbances were superior to nuclear symptoms in discriminating ICD-10 schizophrenia from other psychoses.
Conclusions Evaluating the features of psychosis as deviations in the cerebral organisation of language paves the way to a concept of psychosis that supersedes these traditional but competing categorical concepts.
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INTRODUCTION |
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In this study we investigated the relationship of language abnormalities to Schneiderian first-rank symptoms in acute psychosis, and compared the predictive diagnostic validity of language disturbances and first-rank symptoms for an ICD-10 diagnosis.
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METHOD |
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Table 1 shows the demographic characteristics of the analysed sample. The three diagnostic subgroups, defined using ICD-10 criteria, did not differ significantly from one another in current age, age at onset of illness, duration of illness, gender, ethnicity and mean severity of illness. All patients had experienced a new episode or an exacerbation of existing illness just prior to enrolment into this study. All patients with first-rank symptoms had been receiving antipsychotic medication for periods varying from a few days to several years.
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Schneiderian first-rank symptoms
First-rank symptoms were rated as absent or borderline (0) or definitely
present (1) using the definitions proposed by Mellor
(1970) and revised by Sims
(1995). Clinical information
was collected with a semi-structured interview which was largely based on the
Present State Examination (PSE; Wing
et al, 1974) with the addition of more-detailed questions
focusing on first-rank symptoms. Symptoms were recorded as currently active if
patients had experienced them within the week before the interview. In reality
the great majority of enrolled patients had experienced first-rank symptoms in
the few hours before or were still experiencing them during the clinical
inteview.
Language abnormalities
The characteristics of language were assessed with the Clinical Language
Disorder Rating Scale (CLANG; Chen et
al, 1996). This consists of 17 observer-rated items anchored
on a four-point severity scale (see Appendix).
Stratification into diagnostic groups
Based on the patients' ICD-10 diagnoses
(Table 1), patient groups were
compared as follows:
Data analysis
The data were analysed as follows. Factor analysis (principal component
analysis with varimax rotation) was applied to the 17 CLANG and 11
Schneiderian First-Rank Symptom (SFRS) Scale individual items (sample
n=30; only patients with first-rank symptoms were analysed).
Cronbach's coefficient was computed for the CLANG and SFRS factors to
assess the internal reliability of the whole scales and their sub-scales.
Non-parametric correlation coefficients (Spearman's
) were computed
between CLANG and SFRS factors and total scales (sample n=45, all
patients). All these analyses were completed using the Statistical Package for
the Social Sciences statistical software SPSS for Windows, Release 10.1.0.
Odds ratios and 95% confidence intervals were computed for selected CLANG items associated with first-rank symptoms. If one or more cells of 2 x 2 contingency were equal to zero, 0.5 was added to all cells. Fisher's exact test (two-tailed) was used to test the null hypothesis that there is no relationship between the CLANG and the SFRS items.
The abilities of the CLANG and SFRS scales to discriminate disease cases from control cases were evaluated using receiver operating characteristic (ROC) analysis. Sensitivity, specificity, positive likelihood ratios, the area under the ROC curve and their relative 95% confidence intervals were computed using Confidence Interval Analysis for Windows (Altman & Machin, 2000). The comparison of areas under the ROC curve using different diagnostic tests was computed with AccuROC for Windows, version 2.3, which uses a non-parametric approach.
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RESULTS |
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Internal reliability of CLANG
The internal consistency of the CLANG and the relative contribution of
individual items were characterised by applying Cronbach's coefficient
to the data-set (n=30). The internal reliability for the first two
sub-scales was high (
=0.92 for semantic disorders,
=0.77 for poverty), but less good for the third sub-scale
(
=0.61) and the entire scale (
=0.52)
(Table 2).
Factorial structure of psychotic symptoms rated by the SFRS
Scale
Five factors were extracted using an eigen-value > 1 as the criterion
for interpretation, accounting for 81% of total variance. Most of the variance
(63%) was accounted for by the first three factors, which we labelled
voices, passivity and hearing
thoughts (Table 3). A
fourth factor accounted for 9% of variance and was tentatively labelled
possessed. Delusional perception was extracted as a separate
factor, accounting for a further 9% of variance.
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Internal reliability of the SFRS Scale
The internal reliability for the first two sub-scales was high
(=0.93 for voices,
=0.81 for
passivity) and just adequate for the remaining two (
=0.69
for hearing thoughts,
=0.64 for possessed).
The full-scale
was 0.73, but
could be enhanced to 0.77 if item
1 (delusional perception) was removed.
Convergent validity
Convergent validity (Table
4) was assessed by analysing the correlation (non-parametric
Spearman's ) of CLANG ratings with SFRS ratings in all patients
(n=45), assuming correlations with
>0.5 and
P<0.001 (with Bonferroni correction:
=0.05/336=0.00015) to
be of interest. Positive correlations were found only between the sub-scale
scores CLANG poverty and SFRS passivity
(
=0.61, 95% CI 0.38-0.77) and between CLANG total score and both SFRS
hearing thoughts (
=0.52, 95% CI 0.27-0.71) and SFRS total
score (
=0.63, 95% CI 0.41-0.78). A few individual items of the CLANG
scale were positively correlated with SFRS items: SFRS item 3 (voices
arguing or discussing) correlated with two items of the CLANG semantic
sub-scale 1, excess phonetic association (
=0.52,
95% CI 0.26-0.70), and 17, paraphasic error (
=0.52, 95% CI
0.26-0.70). The SFRS item 10 passivity of volition correlated
with two items of the CLANG poverty sub-scale: 8, lack of
details (
=0.63, 95% CI 0.41-0.78) and 14, poverty of
speech (
=0.58, 95% CI 0.35-0.75). Finally, SFRS item 6
thought insertion correlated with CLANG item 8 lack of
details (
=0.53, 95% CI 0.28-0.71), and SFRS item 8
passivity of affect with CLANG item 14 poverty of
speech (
=0.54, 95% CI 0.29-0.72).
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The association between poverty of speech and passivity phenomena was also confirmed by a 2 x 2 contingency table. Thirty patients (67%) scored positive for the presence of CLANG factor 2 (poverty), of whom 15 (50%) also scored positive for SFRS factor 2 (passivity). Only two further patients scored positive on SFRS factor 2, while scoring negative on CLANG factor 2. The odds ratio of passivity phenomena in patients with or without poverty of speech was 6.5 (95% CI 1.25-33.91) and the null hypothesis of no association between the two variables could be rejected (two-tailed Fisher's exact test, P=0.023). Also confirmed was the association between SFRS item 3 voices arguing or discussing (present in 12 patients) and the presence of either CLANG item 1 (excess phonetic association) or item 17 (paraphasic error), which was observed in 6 patients with SFRS item 3 and in no patient without. The approximated odds ratio of paraphasic errors in patients with or without the symptom of voices arguing was 67 (95% CI 3.35-1341) and the null hypothesis of no association between the two variables could be rejected (two tailed Fisher's exact test, P=0.00011).
Diagnostic significance
The distribution of language abnormalities (CLANG items) was examined
across the three main study groups: SFRS schizophrenia, SFRS other
diagnoses and depression without first-rank symptoms (further details
available from the authors upon request). Only two items of the CLANG scale
11, pragmatic disorder (defective knowledge of the
world, which is difficult to assess) and 15, pressure of speech
were not scored in at least one member of the SFRS groups. Conversely,
only three CLANG items were scored as present in the depression
control group: 8, lack of details, 9, aprosodic
speech, and 14, poverty of speech. All language
disturbances measured by CLANG, except abnormal prosody, were more frequently
observed in the SFRS schizophrenia group. The largest differences in
proportions between the SFRS schizophrenia and SFRS other
diagnoses groups were observed for CLANG items 5 referential
failures (difference 35%, 95% CI 6-59%; two-tailed Fisher's exact test,
P=0.02) and 6, discourse failure (difference 41%, 95%
CI 11-64%; two-tailed Fisher's exact test, P=0.01). The first and
third CLANG sub-scales (semantic disorder and excess of speech) received a
zero score in all patients in the depression group. Scores on the
semantic disorders sub-scale were higher in the schizophrenia
group (mean 2.76, 95% CI 0.59-4.93) than in the SFRS other
diagnoses group (mean 0.08, 95% CI 0-0.24); P=0.003 on
two-tailed KruskalWallis test.
Several items (further information available from the authors upon request) and sub-scales (Table 5) of CLANG were shown to be highly specific (up to 1, 95% CI 0.77-1) for the diagnosis of schizophrenia and other non-affective psychoses. This high specificity was obtained at the expense of a lower sensitivity: the highest figure was obtained for item 8, lack of details (0.71, 95% CI 0.47-0.87). Detailed criteria for interpreting positive likelihood ratios have been described elsewhere (Geddes et al, 1996; Peralta & Cuesta, 1999). Briefly, a clinical test, in order to be considered of some usefulness, should have a positive likelihood ratio in excess of 4. As detailed in Table 5, CLANG factor 1 (semantic disorder), the sum score of the first three CLANG factors and the CLANG total score satisfied this minimum criterion in one or more diagnostic contrasts. The very wide spread of 95% confidence intervals seen here was the result of the small sample size of this study.
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Table 5 reports the areas under the ROC curve for CLANG and SFRS sub-scales using different diagnostic definitions for positive and negative groups. At least in our small sample, only CLANG factor 1 and CLANG sum scales showed adequate diagnostic performance (the confidence interval included the 0.5 value) in all diagnostic contrasts. The SFRS dimensions proved to have adequate diagnostic performance only in separating non-affective psychoses from affective disorders.
Figure 1 compares ROC curves (a graph that plots the true positive rate as a function of the false positive rate at different cut-off points) for the sum of the scores of first three CLANG factors, and the first four SFRS factors, defining as positive cases SFRS schizophrenia and as negative cases SFRS other diagnoses. The difference between areas under the ROC curve was 0.30 (95% CI 0.02-0.59; Z=2.09, two-tailed P=0.037).
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DISCUSSION |
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CLANG structure
We attempted to replicate the original validation study of the CLANG scale
(Chen et al, 1996).
The factor structure found in our study three main factors:
semantic, poverty and excess of
speech partially matched the structure observed by Chen, whose three
main factors were syntactic, semantic and
production. Most of the items composing Chen's first two factors
(including paraphasias, abnormal syntax and neologisms in his first factor)
were grouped to form our first factor. Chen's production factor
was made up of three of the four items characterising our
poverty factor. The most appealing aspect of our very simple
factor structure is its close resemblance to the main factors found by
Andreasen & Grove (1986) as
well as to Bleuler's classification of thought disorders. Andreasen &
Grove observed three main components on factor analysis. At least their first
two factors closely resemble our first two. The first factor, which they
called fluent disorganisation, was marked by high positive
loadings on pressure of speech, derailment, incoherence, illogicality, loss of
goal, and perseveration, and high negative loading on poverty of speech; this
includes components of our first factor. The second factor, called
emptiness, had high positive loadings on poverty of speech,
poverty of content and tangentiality, and a negative loading on pressure of
speech and circumstantiality, clearly resembling our second factor
poverty.
Bleuler's classification of thought disorder
Bleuler's classification is even more similar to the factors extracted in
our analysis. He described one main group of thought disorders, which he named
loose associations, and suggested the presence of two other
types of disturbance with opposite time relationships (positive
and negative), which he believed could respectively resemble the manic flight
and the depressive slowing of ideas. The contrasting disorders observed by
Bleuler in schizophrenia were impulsive ideation at one extreme
and thought block/withdrawal at the other of this time-dependent
spectrum. It is evident that our second and third factors,
poverty and excess, closely resemble the two
time-related dimensions of Bleuler's construct.
Our second CLANG factor, poverty, correlated highly
(=0.61) with the second SFRS factor, passivity.
This positive correlation was confirmed by associations between individual
items forming the two factors in a 2 x 2 contingency table analysis. We
interpret these findings as indicating that a primary negative psychomotor
syndrome, which affects predominantly speech (poverty), is
sometimes associated with a delusional interpretation by the patient of being
controlled. In summary, our first factor (semantic) encompasses
Bleuler's fundamental symptom of loosening of association and Andreasen &
Grove's (1986) fluent
disorganisation and relates them to failures of discourse and reference, to
excess phonetic associations and, in symptomatology, to verbal hallucinations;
our second factor (poverty) incorporates poverty and aprosody of
speech and relates to Bleuler's negative time factor, to Andreasen &
Grove's emptiness factor and to passivity phenomena; our third factor
(excess) comprising excess details and constraints, may relate
to Bleuler's positive time factor, but its definition and clinical correlates
are less clear.
Diagnostic validity of CLANG
A significant but unexpected finding is the superior diagnostic validity of
various dimensions of the CLANG (positive likelihood ratios >4) compared
with the SFRS scale in differentiating ICD10 schizophrenia from other
diagnostic categories, including ICD10 non-schizophrenic psychoses with
nuclear symptoms. We had thought that the CLANG would not fare much better
than the SFRS for the following reasons: Chen did not devise the CLANG for
diagnostic purposes (Chen et al,
1996); Andreasen's Thought, Language and Communication scale had
shown only a weak diagnostic validity in differentiating schizophrenias from
schizo-affective disorders (Andreasen &
Grove, 1986); the ICD10 diagnostic criteria for
schizophrenia give more prominence to Schneider's first-rank symptoms than to
Bleuler's loose associations, and the methods of our study (excluding patients
with schizophrenia but without first-rank symptoms) were biased in favour of
the diagnostic relevance of first-rank symptoms. Therefore, our finding that
the application of ICD10 criteria leads to the selection of cases more
consistent with Bleuler's views than with Schneider's is a paradox that
requires explanation. The reason why our 13 patients with at least one
first-rank symptom were not classified as suffering from schizophrenia was
either that first-rank symptoms and other qualifying symptoms had not been
documented before the onset of a disturbance of mood (10 patients) or that
they had been present for less than 1 month (3 patients). From our data one
could conclude that in the application of the ICD10 criteria, the
presence of first-rank symptoms was useful as a screen (on account of its
sensitivity), and then, by the exclusion of patients who were predominantly
mood-disordered and with short-lasting first-rank symptoms, a
group of patients characterised by a more profound disruption of thought
processes (independently recognised by the CLANG) was defined.
A new nosological perspective
If the diagnostic process proposed by ICD10 (and similarly by
DSMIV) reflects current clinical practice, it is clear that an
alternative and more rational procedure is possible. We do not propose that
Schneiderian first-rank symptoms should be substituted by language
abnormalities in the diagnosis of schizophrenia, as the CLANG requires
extensive training in its use, and it is not clear how easily it could be
adopted in practice. In contrast, first-rank symptoms have become popular in
diagnosis because they are easy to recognise. However, the popularity of
first-rank symptoms as a diagnostic tool may also represent a drawback, since
these symptoms can be feigned or concealed by patients as easily as they can
be recognised by clinicians; simulation and concealment of CLANG abnormalities
would require much more skill and initiative from a less-collaborative
patient. Therefore, at least in a forensic setting, CLANG could prove to be
useful in defining the core group of psychoses.
From the viewpoint of nosological theory our observations can be interpreted as a challenge to the categorical and disease-entity-related concepts of both Bleuler and Schneider (and their precursor in the original Kraepelinian dichotomy). It has been argued that the phenomena of psychosis and the human capacity for language share an origin in the genetic changes that defined the species and that these changes were critically related to differentiation of function of the two hemispheres (Crow, 1995, 1997). Thus, delusions can be considered as deviations in the capacity to attach significance to the phonological representations that are the primary building blocks of words, and Schneider's nuclear symptoms can be conceived as disorders of the transitions from thought to speech, and from perceived speech to meaning, within a reference frame that distinguishes the self of the speaker from that of interlocutors in the outside world (Crow, 1998, 2000).
This view has the merit that it relates the phenomena of psychosis to the components of a specific capacity (language) and to its neural basis in the differentiation of function of the two hemispheres. The prospect that emerges is the possibility of relating a dimensional description of the phenomena of psychosis, various versions of which have been widely discussed (Crow, 1980; Andreasen & Olsen, 1982; Liddle, 1987) but which sit uneasily within the classical Kraepelinian categories (with which they may actually be in conflict), to disturbances of the components of the core function of the human brain, which is the capacity for language (DeLisi, 2001).
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Clinical Implications and Limitations |
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LIMITATIONS
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APPENDIX |
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ACKNOWLEDGMENTS |
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REFERENCES |
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American Psychiatric Association (1980) Diagnostic and Statistical Manual of Mental Disorders (3rd edn) (DSMIII). Washington, DC: APA.
American Psychiatric Association (1994) Diagnostic and Statistical Manual of Mental Disorders (4th edn) (DSMIV). Washington, DC: APA.
Andreasen, N. C. (1979a) Thought, language, and communication disorders. I. Clinical assessment, definition of terms, and evaluation of their reliability. Archives of General Psychiatry, 36, 1315-1321.[Abstract]
Andreasen, N. C. (1979b) Thought, language, and communication disorders. II. Diagnostic significance. Archives of General Psychiatry, 36, 1325-1330.[Abstract]
Andreasen, N. C. & Grove, W. M. (1986) Thought, language, and communication in schizophrenia: diagnosis and prognosis. Schizophrenia Bulletin, 12, 348-359.[Medline]
Andreasen, N. C. & Olsen, S. (1982) Negative vs positive schizophrenia: definition and validation. Archives of General Psychiatry, 39, 789-794.[Abstract]
Bleuler, E. (1911) Dementia Praecox or the Group of Schizophrenias. Reprinted 1950 (trans. and ed. J. Zinkin). New York: International University Press.
Carpenter, W. T., Jr, McGuffin, P., Mellor, C. S., et al (1996) Commentaries on first-rank symptoms or rank-and-file symptoms? British Journal of Psychiatry, 169, 541-550 (see the commentaries by Geddes, Christolfi and Sackett).
Chen, E. Y. H., Lam, L. C. W., Kan, C. S., et al (1996) Language disorganisation in schizophrenia: validation and assessment with a new clinical rating instrument. Hong Kong Journal of Psychiatry, 6, 4-13.
Crow, T. J. (1980) Molecular pathology of schizophrenia: more than one disease process? BMJ, 280, 66-68.[Medline]
Crow, T. J. (1995) Constraints on concepts of pathogenesis: language and the speciation process as the key to the etiology of schizophrenia. Archives of General Psychiatry, 52, 1011-1014.[CrossRef][Medline]
Crow, T. J. (1997) Is schizophrenia the price that Homo sapiens pays for language? Schizophrenia Research, 28, 127-141.[CrossRef][Medline]
Crow, T. J. (1998) Nuclear schizophrenic symptoms as a window on the relationship between thought and speech. British Journal of Psychiatry, 173, 303-309.[Abstract]
Crow, T. J. (2000) Schizophrenia as the price that Homo sapiens pays for language: a resolution of the central paradox in the origin of the species. Brain Research Reviews, 31, 118-129.[CrossRef][Medline]
DeLisi, L. E. (2001) Speech disorder in schizophrenia: review of the literature and exploration of its relation to the uniquely human capacity for language. Schizophrenia Bulletin, 27, 481-496.[Medline]
Liddle, P. F. (1987) The symptoms of schizophrenia: a re-examination of the positivenegative dichotomy. British Journal of Psychiatry, 151, 145-151.[Abstract]
Mellor, C. S. (1970) First rank symptoms of schizophrenia. I. The frequency in schizophrenics on admission to hospital. II. Differences between individual first rank symptoms. British Journal Psychiatry, 117, 15-23.[Medline]
Peralta, V. & Cuesta, M. J. (1999) Diagnostic significance of Schneider's first-rank symptoms in schizophrenia. Comparative study between schizophrenic and non-schizophrenic psychotic disorders. British Journal of Psychiatry, 174, 243-248.[Abstract]
Schneider, K. (1957) Primary and secondary symptoms in schizophrenia. English translation (1974) in Themes and Variations in European Psychiatry. An Anthology (eds S. R. Hirsch & M. Shepherd), pp. 40-44. Bristol: John Wright.
Sims, A. (1995) Symptoms in the Mind An Introduction to Descriptive Psychopathology (2nd edn). London: Saunders.
Wing, J. K., Cooper, J. E. & Sartorius, N. (1974) Measurement and Classification of Psychiatric Symptoms: An Instruction Manual for the PSE and Catego Program. Cambridge: Cambridge University Press.
World Health Organization (1992) Tenth Revision of the International Classification of Diseases and Related Health Problems (ICD10). Geneva: WHO.
Received for publication April 15, 2002. Revision received August 21, 2002. Accepted for publication August 30, 2002.
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