Cognitive Research Unit, University Department of Psychiatry, Hvidovre Hospital
Cognitive Research Unit, University Department of Psychiatry, Hvidovre Hospital and Danish National Research Foundation, Centre for Subjectivity Research, University of Copenhagen, Denmark
Correspondence: Dr Peter Handest, University Department of Psychiatry, Hvidovre Hospital, Brøndby stervej 160, 2605 Brønby, Denmark. E-mail: handest{at}dadlnet.dk
* Paper presented at the Third International Early Psychosis Conference,
Copenhagen, Denmark, September 2002.
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ABSTRACT |
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Aims To describe psychopathological profiles of patients with ICD10 schizotypal disorder.
Method A total of 151 first-admitted patients (with affective and somatic disorders excluded) were given a comprehensive psychopathological evaluation, including the Bonn Scale for the Assessment of Basic Symptoms. Patients with schizotypal disorder (n=50) were compared with those with psychosis (n=51) and those outside the schizophrenia spectrum (otherdiagnoses, n=50) on a number of psychopathological scales.
Results Patients with schizotypal disorder scored intermediately between patients with psychosis and other diagnoses on scales related to positive and negative symptoms, disorders of emotional contact and formal thought disorder, but had the same scores as patients with schizophrenia for subtle aberrations of subjective experience. Schizotypal criteria were not normally distributed with an excess of patients between 2 and 6 criteria. Family history of schizophrenia was equally elevated among those with schizotypal disorder and those with psychosis.
Conclusions ICD10 schizotypy represents a milder, less psychotic, variant of schizophrenia but there is no clear-cut division between the two disorders.
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INTRODUCTION |
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Schizotypy is located on Axis I in the ICD10 as a syndrome listed immediately after somatic disorders and schizophrenia. In the DSMIV (American Psychiatric Association, 1994), it is a personality disorder, and as such, it may in principle be associated with any syndromatic diagnosis (with the exception of schizophrenia).
The purpose of this article is twofold: (a) to present a detailed psychopathological description of patients diagnosed as having the ICD10 schizotypal disorder in a consecutive series of first hospital admissions; (b) to discuss the bearing of these findings on the epidemiology and the taxonomic status of schizotypy.
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METHOD |
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All the individuals were assessed with a semi-structured interview lasting 35 h, consisting of the Operational Criteria for Psychotic Illness (OPCRIT) checklist (McGuffin et al, 1991) expanded with several items used in the Copenhagen High Risk Study (Parnas et al, 1993), the Danish version of the Bonn Scale for the Assessment of Basic Symptoms (BSABS; Gross et al, 1987), the Positive and Negative Syndrome Scale (PANSS; Kay et al, 1987), the Premorbid Adustment Scale (PAS; Cannon-Spoor et al, 1982) and the DSMIV Global Assessment of Functioning scale (GAFF; Endicott et al, 1976). All interviews were carried out by the first author (P.H.). Each diagnosis was allocated following agreement between P.H. and the second author (J.P.). Another clinician collected family history data with the Family History Method (Andreasen et al, 1977). All patients were also assessed using the standardised Danish version of the National Adult Reading Test (NART; Nelson & OConnell, 1978), a measure of premorbid IQ.
In order to condense the extensive psychopathological data, a number of
rational a priori scales were constructed. The content of these
scales was selected to reflect essential aspects of schizophrenia-spectrum
psychopathology, i.e. disorder of emotional contact and formal thought
disorder. Moreover, five scales (predominantly derived from the BSABS) were
specifically created to measure several domains of anomalous subjective
experience believed to be pertinent to the schizophrenia-spectrum disorders
(Parnas & Handest, 2003):
perplexity (loss of meaning), cognitive disorders, subjective disorders
(anomalies in subjective experience), perceptual disorders and cenesthesias
(anomalous bodily experience). In addition, a scale targeting affective
symptoms was created. Details of the scales as well as their
-coefficients (Cronbach,
1951) are shown in the Appendix. In addition, the PANSS positive
and negative symptoms scales were included for comparative purposes.
P values were calculated with non-parametric tests
(KruskallWallisANOVA, MannWhitney test, logistic
regression and multivariate logistic regression) because the data were mainly
ordinal in nature and usually not normally distributed. Two-tailed P
values <0.05 were considered statistically significant.
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RESULTS |
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The group with psychosis comprised 41 patients with schizophrenia; the remainder comprised individuals with various acute psychoses, one case of delusional disorder and one case of schizoaffective psychosis. The other diagnoses group had a range of diagnoses (affective illness, obsessivecompulsive disorder, anxiety, eating disorder and personality disorder). There were no statistically significant gender differences, but the categories of schizotypy and other diagnoses had more females than males (which is caused by a bias operating through exclusion criteria, especially substance misuse and aggression). There were no significant age differences. Patients with psychosis had the lowest global level of functioning (GAFF=35.1, s.d.=11.5). This was statistically significant compared with the group with schizotypy (GAFF=51.7, s.d.=9.07) and with the group with other diagnoses (GAFF=59.8, s.d.=8.1). Patients with schizotypy had a significantly lower GAFF than the group with other diagnoses (P <0.001 for all these comparisons). Patients with schizotypy had a longer duration of untreated illness (DUI) than those with psychosis but this difference disappeared if they were only compared with the patients with schizophrenia from the group with psychosis. The duration of social and work dysfunction tended to be longer among patients with psychosis. There were no significant correlations between several duration variables (e.g. DUI) and the concurrent GAFF or severity measures of psychopathology. There were no significant IQ differences between the groups or differences in educational levels. Family history of schizophrenia was similar in groups with psychosis and schizotypy and more frequent than among other diagnoses (Table 2).
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Of the patients with schizotypy, 92% had had at least one psychiatric treatment contact prior to admission (median number of treatment attempts was three) compared with 67% of patients with psychosis and 92% of patients from the group with other diagnoses. The variable pre-admission management included several psychiatric therapies provided by the general practitioner, psychologist or psychiatrist, high-school or university psychological counselling facilities, etc. The vast majority of those treated pre-admission in all groups received antidepressant drugs, perhaps because of a diagnostic possibility of affective illness. We have no systematic data on the efficacy of these treatments but they did not prevent subsequent hospitalisation.
Schizotypal criteria
Among the 50 patients with schizotypy diagnosis (4 of a possible 9
criteria), there were 47 combinations of criteria. All schizotypal criteria
also occurred among patients in the category of other diagnoses with a
frequency ranging between 10% and 50%. Among the patients with schizotypy, the
least frequent symptoms were eccentricity and suspiciousness/paranoid ideation
(3638%) and the most frequent symptoms were odd speech and perceptual
disorder (7678%). The number of schizotypal criteria across the
combined patient groups with schizotypy and other diagnoses (n=100)
was not normally distributed but displayed a surplus aggregation of patients
in the range of 26 criteria (KolmogorovSmirnoff test). If the
ICD10 diagnostic threshold for schizotypy were lowered to 2 criteria or
elevated to 6 criteria, these changes would have correspondingly resulted in
86 or 14 patients receiving a diagnosis of schizotypy. Factor analysis (with
VARIMAX rotation) of the ICD10 schizotypy criteria in the 100 patients
with no psychosis resulted in four factors (criteria loading highly on the
factors are given in parentheses) with eigenvalues >1:
interpersonal/negative (isolation, constricted/inadequate affect),
disorganised (eccentric, odd speech), perceptual/positive
(micropsychosis, perceptual disorders) and paranoid
(suspiciousness, paranoid ideation).
Patterns of psychopathology
Symptom profiles are shown in Table
3 and provide the scores on all scales across the diagnostic
groups. It should be noted that for the PANSS positive and negative symptom
scales as well as for the a priori scales targeting contact disorder
and formal thought disorder, the distribution of scores is linear: psychosis
scores significantly more than schizotypy, which in turn scores higher than
other diagnoses. On all scales targeting anomalies of subjective experience
(e.g. perplexity, cognitive and perceptual disorders), patients with psychosis
and schizotypal disorders had the same scores which were significantly higher
than other diagnoses. Because the psychosis and schizotypy scales were
positively intercorrelated, we compared all the scales using a multivariate
logistic regression model with a binary outcome (schizotypy v. other
diagnoses). The self-disorders and cognitive disorders remained significant at
P <0.01 in separating the outcome. Affective symptoms were less
pronounced in psychosis than in schizotypy and other diagnoses, whereas the
last two did not differ from each other.
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Prodromal symptoms in psychosis and schizotypy
We examined the diagnostic values on 16 prodromal symptoms reported
retrospectively, which are frequently cited as being typical prodromal
features of schizophrenia (Häfner
& Novotny, 1995). We compared psychosis and schizotypy with
logistic regression and odds ratio (OR) statistics. There were five
significant differences: patients with schizotypy scored higher on depression
(OR=6.65, 95% CI 2.5217.60) and sleep disturbances (OR=4.91, 95% CI
1.6514.57) and lower on suspiciousness (OR=0.28, 95% CI
0.120.63), loss of role functioning (OR=0.17, 95% CI 0.060.44)
and odd behaviour (OR=0.42, 95% 0.190.95). The remaining symptoms
(anxiety, hypochondria, neurosis-like symptoms, irritability,
isolation/withdrawal, lack of initiative, neglect, emotional indifference,
perceptual disturbances, magical thinking, poverty of speech) were equally
frequent in the history of patients with psychosis and schizotypy.
Polydiagnostic assessment: ICD10 v.ICD8/9
The entire sample of 151 patients has undergone a polydiagnostic assessment
reported elsewhere (Jansson et
al, 2002). It is of interest to note in this context that a
computer-based operationalised algorithm for the ICD8/9 schizophrenia
diagnosis resulted in ICD8/9 schizophrenia among 37 out of 50 patients
with schizotypy (74%). These 37 patients diagnosed with schizotypal disorder
scored numerically higher on all scales listed in
Table 3 than the 13 with
schizotypy who were not diagnosed with ICD8 schizophrenia (the
difference was statistically significant for emotional contact and formal
thought disorders and perplexity and the PANSS negative symptom scale). The
corresponding rates for ICD8/9 schizophrenia in the remaining sample
were n=48 (94%) among patients with psychosis and n=4 (8%)
among other diagnoses. In other words, the ICD8/9 concept of
schizophrenia corresponds quite well to the ICD10 concept of
schizophrenia spectrum (psychosis and schizotypy).
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DISCUSSION |
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The notion of a spectrum of disorders
The present study seems to support the spectrum concept of schizophrenic
disorders as it is presented in the ICD10. There is a gradation of
schizophreniform symptomatology with its fading out in the category of other
diagnoses. The schizotypal disorderespecially in the dimensions clearly
reflective of the ICD10 diagnostic criteria of schizophrenia (contact
and formal thought disorder and PANSS positive and negative
symptoms)occupies a tautologically intermediate position between
non-effective psychosis and other diagnoses. However, a strong similarity
observed between patients with psychosis and those with schizotypal disorders
(Table 3) on the scales
measuring qualitative alterations of subjective experience (perplexity,
cognitive, self-disorders and perceptual disorders) provides additional and
independent validation of schizotypy as a part of the schizophrenic spectrum
of disorders.
Anomalies of subjective experience have already been described in the classical literature as characteristic of schizophrenia and were considered of paramount diagnostic significance (Berze, 1914; Minkowski, 1927; Berze & Gruhle, 1929; Conrad, 1958; Huber, 1966). More recent empirical work has rediscovered these phenomena. Thus, it seems that certain anomalies of subjective experience (Blankenburg, 1971; Cutting & Dunne, 1989; Parnas et al, 1998, 2003; Möller & Husby, 2000; Meehl, 2001), especially anomalies of self-awareness (Parnas & Handest, 2003; Sass & Parnas, 2003), represent a fundamental nucleus of schizophreniform symptomatology. These symptoms may be the most sensitive and specific clinical phenotypes currently available in the context of early detection (Klosterkötter et al, 2001). The frequency of typical prodromal symptoms in the history of patients with schizophrenia and those with schizotypal disorder is mainly suggestive of psychopathological similarity.
The distribution of family history of schizophrenia across the diagnostic groups (Table 2) supports the categorical affinity of schizophrenia and schizotypy, as does the fact that 76% of patients with schizotypy were diagnosed with ICD8/9 schizophrenia.
In summary, the data point to an overall psychopathological similarity of schizophrenia and schizotypy. Elevated levels of Bleulerian fundamental symptoms (Bleuler, 1911) and anomalies of subjective experience characterise both groups. It is mainly the severity of psychosis (a diagnostic requirement for an ICD10 diagnosis of schizophrenia) that marks the distinction of schizophrenia from schizotypy (in the latter group only micro-psychotic experiences are allowed).
Affective symptoms and schizotypy
Population studies suggest that compensated patients with schizotypal
disorder are rarely treated (Parnas et
al, 1993) and those who are display apparently affective
symptoms, substance misuse and actingout behaviour
(Parnas & Teasdale, 1987).
This may explain the findings of elevated levels of affective symptoms among
the patients with schizotypy in this sample
(Table 3), as well as the
frequent reporting of depression as a pre-admission symptom in the history of
illness. It points perhaps to a relative preservation of affectivity in
patients with schizotypy as opposed to patients with schizophrenia, although
the clinical overlap between schizotypal or schizophrenic anhedonia (and other
so-called negative symptoms) and genuine depressiveaffective complaints
makes any such interpretation quite tentative (see
Parnas & Handest, 2003,
and Sass & Parnas, 2003,
for a phenomenological analysis of initial complaints in schizophrenia). None
the less, it is striking that most pre-admission treatments
involved antidepressant medication. It appears that clinicians become quickly
impressed by the affective complaints of their
patients.
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Schizotypal criteria
The study shows the arbitrary nature of the four criteria needed for the
ICD10 schizotypy diagnosis. The distribution of criteria among 100
patients with no psychosis follows a steep symmetrical curve, where any number
of criteria between 2 and 6 might be chosen as an appropriate cut-off level
for schizotypy. Moreover, a dimensionality of schizotypy, as demonstrated
through the factor analysis (and in agreement with the results from many other
studies, e.g. Vollema & van den Bosch,
1995; Venables & Rector,
2000; Fossati et al,
2001) suggests a methodological inaccuracy of a purely polythetic
diagnostic approach with each criterion possessing equivalent diagnostic
value. Such an approach becomes highly problematic when the criteria are not
independent but are correlated in sets.
Relevance for early detection of schizophrenia
The ICD10 schizotypy, as it appears in this study, can be considered
as being a diluted schizophrenia, and as such not a pre-onset
condition. Thus, the gradual transition of the ICD10
schizophrenia-spectrum criteria complicates the issue of pre-onset diagnosis
and early intervention in schizophrenia, because it challenges the concept of
schizophrenia as a clearly demarcated condition. As also demonstrated by the
polydiagnostic studies, schizophrenia has variable borders, changing with the
diagnostic perspective (Jansson et
al, 2002). Thus, despite a widely held illusion of a
tremendous recent progress in psychiatric classification
(Parnas & Zahavi, 2002), there is still an acute need for serious work on the conceptual validity (also
called non-empirical validity,
Kendler, 1990) of such
categories as schizophrenia or psychosis (see also
Parnas, this issue). From a more optimistic perspective, we may conclude that
schizophrenia and schizotypy are associated with certain characteristic
anomalies of subjective experience (the so-called basic symptoms in German
terminology) which may be potentially useful for early clinical detection of
individuals at risk for schizophrenia-spectrum disorders. We are now
conducting a 4-year follow-up of this particular sample, expecting additional
schizophrenia cases to emerge mainly, but not only, from the schizotypal
group. These longitudinal data will shed more light on the diagnostic
significance of anomalies of subjective experience.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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