Article about schizoaffective and schizotypal disorders.
- Schizoaffective disorder
- Clinical features
- Diagnosis and differential diagnosis
- Review of evidence
- Schizotypal personality disorder
- Clinical features
- Diagnosis and differential diagnosis
- Possibilities for prevention
This article focuses on schizoaffective disorder and schizotypal personality disorder, including their clinical features, classification, diagnosis, epidemiology, aetiology, course, prognosis, and possibilities for prevention. Some areas will be emphasized, to reflect controversial issues or new developments. For example, the classification of both these disorders will be stressed to consider the heterogeneity apparent in each of them. The issue is an important one, for at least two reasons.
First, it is crucial to develop reliable and valid diagnostic criteria in order to study the aetiology of the disorders and then utilize that knowledge to develop rational and testable treatment strategies. Heterogeneity adds variance to each of these steps that may reduce both the reliability of diagnosis and also the statistical power of experimental designs to detect treatment effects.
Second, the development of newer generations of psychopharmacological treatments holds the promise of matching more appropriate and efficacious medications with specific syndromes or types of symptoms. This trend underscores the importance of differential diagnosis in determining what treatment a patient will receive. Heterogeneity within a diagnostic category complicates achievement of this goal. Another area to be emphasized involves the possibility of preventative, as well as palliative, treatments in the near future, for these disorders.
In contrast, other areas such as the genetic aetiology of schizoaffective disorder and schizotypal personality disorder, and treatments for schizoaffective disorder, will receive less emphasis here, to avoid redundancies with other chapters in this volume. Each disorder will be considered separately, starting with a review of schizoaffective disorder, the more severe of the two spectrum conditions.
Schizoaffective disorder afflicts patients having schizophrenic and affective symptoms. Either they have affective symptoms of sufficient severity and chronicity to exclude an uncomplicated diagnosis of schizophrenia, or they show features of schizophrenia that are sufficient to exclude an uncomplicated diagnosis of an affective disorder. These types of symptoms may or may not occur simultaneously, which underscores the importance of viewing the illness in longitudinal as well as cross-sectional terms. That is, symptom clusters that are primarily affective or primarily schizophrenic may predominate at different times.
Compared with patients with schizophrenia, patients with schizoaffective disorder tend to demonstrate relatively high levels of premorbid function. One of the most common features of the disorder is a precipitating event, such as a life stressor. For example, Tsuang et al.(1) found a higher percentage of such events in schizoaffective disorder (60 per cent) than they did in either schizophrenia (11 per cent), mania (27 per cent), or depression (39 per cent). Marneros et al.(2) also found a higher percentage of precipitating events in schizoaffective disorder (51 per cent) than in schizophrenia (24 per cent), but did not detect a difference between schizoaffective disorder and affective disorder. The nature of the precipitating stressor may vary widely; for instance it may be either physical (e.g. recently giving birth or experiencing a head injury) or interpersonal (e.g. change in an important relationship).
The clinical course of the disorder is often characterized by a periodic rapid onset of symptoms that shows a relatively high degree of remission after several weeks or months. As Vaillant pointed out in the 1960s, many of these patients ‘recover' completely after an episode, and resume their lives at a premorbid level of function. (3) As will be considered in more detail below, the clinical features of some cases of schizoaffective disorder mainly resemble those of schizophrenia, while the features of other cases are more similar to those of an affective disorder. Regardless of the subtype or variant of the disorder, however, the mortality rate is of special concern. Rates of death, due mainly to suicide or accident, show elevations in this disorder similar to those observed in schizophrenia and in major affective disorders. (4)
In general, the disorder is more common in females than in males. (1,5) The age of onset varies, but tends to be younger than that of unipolar or bipolar disorder. Tsuang et al.(1) found the median age of onset for schizoaffective disorder was 29 years, which was significantly lower than groups with bipolar or unipolar affective disorder, but similar to a group with schizophrenia. Marneros et al.(6) also reported that a median age of onset of 29 years for schizoaffective disorder was lower than the median age for groups with affective disorders (35 years), but also reported that it was higher than a group with schizophrenia (24 years). To an extent, relative differences in the age of onset between schizoaffective and other disorders reflects differences in the diagnostic criteria employed and the heterogeneity of the disorder.
The classification of schizoaffective disorder has always been controversial. Kraepelin noted in 1919 that patients with both affective and schizophrenic symptoms complicated the differential diagnosis due to the ‘mingling of morbid symptoms of both psychoses'. Kasanin first employed the term ‘acute schizophrenic psychoses' in 1933 to describe a group of patients who experienced a rapid onset of emotional turmoil and psychotic symptoms, but who recovered after several weeks or months. (5) In other words, the symptoms appeared similar to schizophrenia during periods of exacerbation, but unlike schizophrenia, showed a greater tendency to remit between episodes. These features sparked an ongoing debate by the 1960s about the proper classification of schizoaffective disorder. Much of this discussion involved the possibility that schizoaffective disorder was conceptualized most accurately as follows:
- a type of schizophrenia (e.g. ‘remitting schizophrenia');
- a type of affective disorder;
- a unique disorder that was separate from both schizophrenia and bipolar disorder;
- an arbitrary categorization of clinical symptoms that masks a continuum of pathology between schizophrenia and affective illness;
- a heterogeneous collection of ‘interforms' between schizophrenia and affective disorder (i.e. symptoms of both disorders).
The last possibility is not mutually exclusive of the first four; for example, one or more variants of schizoaffective disorder may be related closely to schizophrenia, while another may be related more closely to an affective disorder.
Family and outcome studies provide useful ways of assessing the relative merits of each of the possibilities outlined above. These approaches are informative although interpretations of such studies are complicated at times by the use of different diagnostic criteria across studies.
Family studies provide an important tool for assessing the relationship between disorders. In particular, it is a type of genetic study that assumes that related disorders will coaggregate more frequently among biologically related individuals than they would in the general population. Thus, a disorder is concluded to be in the schizophrenia spectrum if it occurs more frequently among the relatives of schizophrenic patients, compared with suitable controls. Similarly, a disorder is considered to be in the affective spectrum if it occurs more frequently among the relatives of patients with affective disorders. Evidence for the inclusion of schizoaffective disorder in the schizophrenia spectrum is discussed in greater detail elsewhere (see Chapter 18.104.22.168). Only representative findings pertinent to the present discussion about the classification of schizoaffective disorder will be summarized here.
Bertelsen and Gottesman (7) summarized a series of seven family studies published between 1979 and 1993, using structured diagnostic criteria. Analyses of risk to the development schizophrenia, schizoaffective disorder, and affective disorder in the first-degree relatives of patients with schizoaffective disorder, were included. In all seven studies, the relatives showed a higher risk of developing an affective disorder than of developing schizoaffective disorder. In five of the seven studies the risks of developing schizophrenia was equal to or greater than the risk of developing schizoaffective disorder. Thus, the relatives of schizoaffective patients showed generally higher risks of developing disorders other than the one with which they were diagnosed.
These findings were consistent with a heterogeneous view of schizoaffective disorder, in which individual cases represented subtypes of either schizophrenia or of affective disorder. The findings were also consistent with the possibility that schizoaffective disorder represents a chance collection of ‘interforms' between schizophrenia and affective disorder.
These findings were not consistent with the view that schizoaffective disorder represented a continuum between the other two disorders, because in that case, the rate of schizoaffective disorder in first-degree relatives would have been higher, compared with the rates at which these relatives developed schizophrenia or affective disorder. The findings were also inconsistent with the possibility that schizoaffective disorder represented a unique disorder that was independent of either schizophrenia or an affective disorder. In that case, the first-degree relatives of patients with schizoaffective disorder should show relatively high rates of schizoaffective disorder itself, but relatively low rates of the other disorders. Tsuang (8) and others reported similar findings using other definitions of the disorder. (5)
In the series of studies reviewed by Bertelsen and Gottesman, (7) the morbid risk for schizoaffective disorder itself ranged from 1.8 to 6.1 per cent in first-degree relatives of patients with schizoaffective disorder, which was still higher than the rate observed in the general population (see the section on epidemiology below). These results, taken together with the higher risks for both schizophrenia and affective disorder, suggest that schizoaffective disorder is a heterogeneous condition.
The results of family studies allow for a few tentative generalizations concerning the classification of schizoaffective disorder. First, they indicate the likelihood that many cases of the disorder are related to either schizophrenia or affective illness. Results from family studies are less clear about how specific subtypes should be defined. (5) Second, the family studies leave open the possibility that schizoaffective disorder is due to the additive effects of genes for both schizophrenia and affective illness. Third, the rates of schizoaffective disorder are higher among the relatives of schizoaffective patients than would be expected in the general population.
A majority of outcome studies show that schizoaffective disorder has a better course than schizophrenia, but a poorer course than affective disorder. (9,10) For example, Samson et al.(10) reviewed 10 outcome studies reported between 1963 and 1987 that assessed patients with either schizoaffective disorder or schizophrenia. Global, marital, social, occupational, hospital course, and symptom dimensions of outcome were assessed. In each category, patients with schizophrenia showed poorer outcomes. In contrast, their review of 11 outcome studies comparing schizoaffective disorder with affective disorder showed that affective disorder was associated with equal or better outcomes on almost all dimensions. Thus, despite differences in methodology and diagnostic criteria, schizoaffective disorder was frequently associated with clinical outcomes that were intermediate between those associated with schizophrenia and those related to affective disorder.
Further evidence for this pattern was provided more recently in an epidemiological family study. (11) Schizoaffective disorder showed levels of impairment that were intermediate between schizophrenia and affective disorder on the Level of Functioning Scale (which includes nine items, such as duration of non-hospital admission, quality of social relations, symptoms, and an overall rating), and on the Scale for the Assessment of Negative Symptoms. These findings, together with family data showing increased rates of both schizophrenia and affective disorder among relatives of schizoaffective patients, were interpreted as additional evidence in favour of the (DSM-IIIR) classification of schizoaffective disorder. They were also interpreted as supportive of the hypothesis that schizoaffective disorder represents an interform of both schizophrenia and affective illness.
Marneros et al. (12) reported on outcomes in the three (modified DSM-IIIR) disorders, as part of the Cologne Longitudinal Study. The outcomes were measured by symptoms in five dimensions (psychotic symptoms, reduction of energetic potential, qualitative and quantitative disturbances of affect, and other disturbances of behaviour) that persisted for at least 3 years. Consistent with the general pattern described thus far, poor outcomes in the schizoaffective group occurred at a rate (49.5 per cent of the sample) that was intermediate between those observed in the schizophrenic (93.2 per cent) and affective groups (35.8 per cent), and differed significantly from both of them.
While these studies show schizoaffective disorder to have intermediate outcomes generally, there are some categories in which it resembles schizophrenia or affective disorder more closely. For example, Samson et al.(10) noted above that outcomes for schizoaffective disorder were equivalent to those for affective disorder in several dimensions. Marneros et al.(13) studied schizophrenic, schizoaffective, and affective subjects who were diagnosed according to narrow, modified DSM-III criteria. On some measures (e.g. psychosocial functioning, as measured by the Global Assessment Scale) the schizoaffective group performed intermediate between the affective group (which was higher) and the schizophrenic group (which was lower). On a measure of social adjustment, however, 70 per cent of the schizoaffective group was rated as good or excellent, which did not differ significantly from the 84 per cent of the affective group who received the same rating. Both groups differed significantly from the schizophrenic group, only 44 per cent of which showed a good or excellent outcome. Moreover, the schizoaffective and affective disorder groups did not differ on a rating scale of psychological impairments (e.g. body language, affect display, conversation skills, and co-operation), although both were rated as significantly less impaired than the schizophrenic group.
Both Kendler et al.(11) and Atre-Vaidya and Taylor (14) reported similarities between some types of psychotic symptoms between schizoaffective disorder and schizophrenia. The former study showed that the two groups did not differ from each other with respect to severity of delusions or positive thought disorder; the latter study showed that the two groups both demonstrated more hallucinations than did an affective disorders group, but did not differ from each other.
These overall differences in outcome further serve to validate the classification of schizoaffective disorder as a separate syndrome. Its heterogeneity, however, raises the issue of whether such intermediate outcomes might reflect the mean of a combination of mainly good and mainly poor outcomes. This in turn leads to the question of whether schizoaffective disorder can be subtyped in a useful and valid manner. If so, are better and worse outcomes associated with different variants of the syndrome?
Vaillant suggested in the 1960s that prognostic indicators, including a good premorbid level of adjustment, the presence of precipitating factors, an acute onset, confusion, the presence of affective symptoms, and a familial history of affective disorder (or the absence of a schizophrenic history), could predict remission in approximately 80 per cent of cases of ‘remitting schizophrenia'. (15,16) The inclusion of affective symptoms and a positive family history for affective illness on the list contributed (later) to hypotheses that variants of schizoaffective disorder were related to affective illness and to better outcomes. In contrast, variants associated more with schizophrenic symptoms or family history were likely to be associated with schizophrenia, and with relatively poor outcomes.
There have been a variety of attempts to subtype schizoaffective disorders, based on whether affective or schizophrenic symptoms predominate. (7,16) Tsuang and Fleming(17) also suggested an undifferentiated category. The validity of these attempts has so far remained inconclusive. For example, Bertelsen and Gottesman (7) noted that at best, relatives of individuals with affective type schizoaffective disorder, or schizophrenic type schizoaffective disorder, showed only trends towards higher rates of affective disorder or schizophrenia, respectively. Similarly, Kendler et al.(11) did not detect different rates of schizophrenia or affective illness in first-degree relatives of patients with schizoaffective disorder when the patients were subtyped into bipolar and depressive subgroups. Moreover, the subtypes did not predict differences in outcomes.
Conversely, a latent class analysis of psychotic patients from the Roscommon Study showed that most cases of DSM-IIIR schizoaffective disorder were categorized in either a bipolar schizomania class (n = 19), or in a schizodepression class (n = 13), rather than in schizophrenia (n = 1), major depression (n = 0), schizophreniform (n = 3), or hebephrenia (n = 3) classes.(18) Moreover, Winokur et al.(19) provided indirect evidence for differential outcomes based on subtypes. In that study, subjects were diagnosed with Research Diagnostic Criteria for schizophrenia, affective disorder, or schizoaffective disorder, and evaluated at intake, 1 year later, and 6 years later. Several outcome measures were employed, including 39 Schedule for Affective Disorders and Schizophrenia items. Subjects were then divided into groups that had consistent affective diagnoses (including schizoaffective disorder, affective type) or consistent schizophrenic diagnoses (including schizoaffective disorder, schizophrenic type), at each of the three assessment times. A third group had inconsistent diagnoses. The results showed that recovery from psychosis was more common in the group with consistent diagnoses of affective disorder than it was in the group with consistent diagnoses of schizophrenia. The inconsistent group was intermediate, but was closer to the consistent affective group. Together, these studies show at least some recent support for the subtyping of schizoaffective disorder into mainly affective and mainly schizophrenic variants.
Other factors that may be prognostic of poor outcomes include poor interepisode recoveries, (11) persistent psychotic symptoms in the absence of affective features, poor premorbid social adjustment, chronicity, and a higher number of schizophrenia-like symptoms. (5)
Diagnosis and differential diagnosis
The DSM-IV diagnosis of schizoaffective disorder (20) is listed in the category of ‘schizophrenia and other psychotic disorders'. The major feature of the disorder is that, in addition to meeting the clinical criteria for schizophrenia (criterion A), an individual must also experience a major depressive, manic, or mixed episode concurrently. In addition, in the same period of illness, a patient must experience symptoms of psychosis (hallucinations and/or delusions) for a period of at least 2 weeks, in the absence of mood-related symptoms (criterion B). Nevertheless, affective symptoms must comprise a substantial portion of total duration of the illness (criterion C), and symptoms may not be attributable to either substance use or to a major medical condition (criterion D). Two subtypes of the disorder, including bipolar type and depressive type, may be diagnosed.
The criteria for schizoaffective disorder in ICD-10 are similar to those in DSM-IV. The essential requirement is that prominent symptoms of affective disorder and prominent symptoms of schizophrenia are present together for at 2 weeks. Depressive, manic, and mixed subtypes are recognized as in DSM-IV.
The differential diagnosis includes, most prominently, either schizophrenia or affective disorder, which may be differentiated in part by consideration of the longitudinal criteria (criteria B and C), in addition to the cross-sectional criteria (criterion A). The presence of conditions relating to general medication and substance use should also be considered in the differential diagnosis.
The epidemiological status of schizoaffective disorder is somewhat uncertain compared with schizophrenia, largely because of dilemmas related to the diagnosis and classification of the disorder. To help in the standardization of data from different studies, representative incidence and prevalence estimates will be emphasized from recent investigations that utilized research diagnostic or DSM-IIIR criteria.
Earlier studies showed that new cases of ‘schizomanic' patients (i.e. manic patients who also demonstrated schizophrenic or paranoid symptoms) numbered approximately 1.7 per 100 000 per year.(5) This was less than the 4 per 100 000 per year shown by ‘schizodepressive' patients. The number of schizoaffective cases in this study exceeded the number of manic patients, and made up half of the number of schizophrenic cases. More recently, Tien and Eaton (21) analysed data from the Epidemiologic Catchment Area Study for three non-overlapping groups with psychotic symptoms. One of these groups comprised individuals with ‘psychotic affective syndrome', which was similar to schizoaffective disorder except that most members of the group (59 per cent) demonstrated psychotic symptoms only in conjunction with a mood disturbance (essentially DSM-IIIR mood disturbance with psychotic symptoms). The incidence of this disorder was 1.7 per 1000 per year, which was approximately equal to the rate for schizophrenia (2.0 per 1000 per year). Even if the 59 per cent of the group who met the criteria for a mood disorder with psychotic features was excluded, the remaining 41 per cent would still comprise a higher incidence rate than that detected by earlier studies. Differences in sampling procedures (treated versus non-treated samples) may have contributed to the differences observed in the rates. More importantly, however, these studies showed that schizoaffective disorder occurred at 50 to 85 per cent of the rate of schizophrenia, thus confirming that patients with this disorder comprise a clinically significant population.
There are no epidemiological studies of prevalence for schizoaffective disorder, but prevalence estimates are available, based on samples that were treated in clinics. Because a variety of factors influence the decision to enter and remain in treatment, the estimates show substantial variation. For example, Muller-Oerlinghausen et al.(22) showed that the prevalence of schizoaffective disorder assessed in lithium clinics ranged from 7 per cent in Aarhus, to 15 per cent in Berlin, 23 per cent in Vienna, and 32 per cent in Hamilton. Junginger et al.(23) found that 14 per cent of delusional patients met DSM-IIIR criteria for schizoaffective disorder, compared with 60 per cent who met the criteria for schizophrenia and 17 per cent who met the criteria for bipolar disorder. Data from the Cologne Longitudinal Study showed that 28.5 per cent of the sample with psychoses met DSM-IIIR criteria for schizoaffective disorder, which was similar to the rate for affective disorders (30 per cent), but less than the rate for schizophrenia. (24) Prevalence estimates of putative schizoaffective subtypes are subject to the same inconsistencies of diagnosis and selection factors that affect schizoaffective disorder itself. Not surprisingly, there is little consensus about whether manic or schizophrenic subtypes predominate (see also Tsuang et al.(5)).
Review of evidence
Treatments for schizoaffective disorder are the same as those for schizophrenia and affective disorders alone. As the nature and efficacy of those treatments are discussed elsewhere, they will not be considered here. Rather, this section will focus on management issues related to the need to treat symptoms of both disorders simultaneously, or sequentially.
The authors have found it useful to consider its psychopharmacological treatment in terms of its putative subtypes, including affective type schizoaffective disorder and schizophrenic type schizoaffective disorder.
Treatment of affective type schizoaffective disorder will include antipsychotic medication (e.g. clozapine, risperidone or olanzepine), particularly if psychotic symptoms are present. In addition, antidepressants, mood stabilizers (e.g. lithium), or anticonvulsants (e.g. valproate or carbamazepine) may be useful with this group. It will be necessary in such cases to weigh the potential risks of such medications, such as elevated toxicity, against the potential benefits.
In schizophrenic type schizoaffective disorder, combination treatments may also be more effective than a single treatment. We find, however, that antipsychotic treatments alone may be more efficient in many cases. This is particularly true if affective symptoms (i.e. depression) are largely secondary to the experience of having a psychotic condition, and its attendant interpersonal, social, and financial difficulties. In these cases, remediation of the psychotic symptoms may also have the effect of easing the affective problems. For other cases, which include more of a treatment-refractory depression, antipsychotic medication may be augmented with lithium (25) or antidepressant medication. Moreover, electroconvulsive therapy may reduce mortality rates in schizoaffective patients. (26)
The authors also note that clinically, it may sometimes be difficult to distinguish the affective subtype from the schizophrenic subtype. In these cases treatment decisions must rest on the presenting symptoms of the patient. Treatment during intermorbid periods is in part dependent on the presence or absence of psychotic symptoms. As noted above, psychotic episodes in this period are associated with relatively poorer outcomes, and are likely to require chronic antipsychotic therapy.
Schizotypal personality disorder
Schizotypal personality disorder is a complex and chronic condition that includes some, but not all, of the features of schizoaffective disorder and schizophrenia. Notably, persistent psychosis is not part of the syndrome, although mild forms of thought disorder may occur (e.g. magical thinking, ideas of reference). Moreover, brief episodes of psychosis may occur in times of stress.
Schizotypal patients show pervasive deficits in social and interpersonal traits. They often demonstrate aloofness, poor eye contact, affective constriction, and suspiciousness. Consequently, close interpersonal relationships are either avoided or cause discomfort and anxiety. Thus, these individuals have few friends. Not surprisingly, schizotypal patients are often deficient in accurately sensing social cues or affective signals from others. Although they can interact with people when necessary, they often prefer not to, and do not become more comfortable in social situations with time.
Schizotypal patients also show magical thinking, ideas of reference, unusual perceptions (e.g. sensing the presence of another person, or that people are talking about them), and/or perceptual illusions (e.g. often perceiving a dimly lit lamp-post as a person). Both their social deficits and these cognitive–perceptual problems contribute to an overall impression of oddness. However, this feature may occur independently of other clinical symptoms, (27) and manifest itself in odd speech or unusual appearance. The oddness or eccentricities evident in these patients are often ego syntonic (i.e. they are not experienced as problems). Moreover, schizotypal patients show deficits in attention, long-term verbal memory, and executive functions. These deficits are qualitatively similar to those seen in schizophrenia, but like many other clinical manifestations of this disorder, they are quantitatively milder.
Like schizophrenia, schizotypal personality disorder is often evident by early adulthood, but schizotypal traits may be evident in late childhood or adolescence. (28) Once it appears, the disorder tends to show a chronic course, but one that includes periodic exacerbations and attenuations of symptoms.
In contrast to the controversy surrounding the classification of schizoaffective disorder, family, twin, and adoption studies clearly support the view that schizotypal personality disorder is best classified in the schizophrenia spectrum. (29) Nevertheless, it is a complex and chronic disorder that in all likelihood, is also heterogeneous. Kendler(30) pointed out that this heterogeneity was at least partly related to the two primary methods used to study the disorder. One of these involves the ‘clinical method', which identifies patients with mild forms of schizophrenic or psychotic-like symptoms. Thaker et al. (31) for example, reported that clinical schizotypal subjects were characterized by relatively high levels of positive psychiatric symptoms (e.g. magical thinking and perceptual distortions).
In contrast, the ‘family research method' identifies relatives of patients with schizophrenia who have subtle, schizophrenia-like symptoms. Features associated more with familial than with clinical schizotypal personality disorder include a predominance of negative symptoms (e.g. social withdrawal and impairment, and higher levels of anxiety and poor rapport), cognitive impairments (e.g. impaired language comprehension, eye-tracking, and attentional dysfunctions), and elevated rates of schizophrenia and related disorders in family members. (29) Thaker et al. (31) reported that familial and clinical schizotypal personality disorders were similar on measures of physical or social anhedonia. Also, some neuropsychological deficits are associated with both groups. (32,33)
The concept of familial schizotypal disorder is particularly important because it may share a common genetic basis with schizophrenia. Meehl (34) first proposed the term ‘schizotaxia' to describe the genetic vulnerability to schizophrenia, and suggested that individuals with schizotaxia would eventually develop either schizotypal personality disorder or schizophrenia, depending on the protection or liability afforded by environmental circumstances. As the concept evolved, Meehl (35) reformulated it to allow for the possibility that some people with schizotaxia would develop neither schizophrenia nor schizotypal personality disorder. In fact, evidence now shows that the clinical symptoms observed in many non-psychotic, first-degree relatives of people with schizophrenia are similar to those observed in familial schizotypal personality disorder. (29) Psychiatric features in such relatives frequently include an aggregation of negative symptoms that are qualitatively similar to, but milder than, those often cited in schizophrenia. (36) Positive symptoms, however, are usually less evident in these relatives than they are in schizophrenia or in schizotypal personality disorder. Neuropsychological impairments in biological relatives of people with schizophrenia are also qualitatively similar to, but milder than, those seen in people with schizophrenia. (29) In particular, these neuropsychological deficits frequently include problems in working memory/attention, long-term verbal memory, and concept formation/abstraction.
Faraone et al. recently suggested a reformulation of Meehl's concept of schizotaxia that focuses on these features of negative symptoms and neuropsychological deficits.(29) Unlike schizotypal personality disorder, which occurs in less than 10 per cent of the adult relatives of patients diagnosed with schizophrenia, the basic symptoms of schizotaxia occur in 20 to 50 per cent of adult relatives, (37,38) suggesting further that the genetic liability to schizophrenia does not lead inevitably to schizophrenia, schizotypal personality disorder, or schizoid personality disorder.
Diagnosis and differential diagnosis
The DSM-IV criteria for schizotypal personality disorder (20) includes a ‘pervasive pattern of social deficits' and ‘cognitive or perceptual distortions' and behavioural ‘eccentricities' (criterion A). At least five of nine specific symptoms (e.g. ideas of reference, constricted affect, odd behaviour or appearance) must be present to satisfy this criterion. These symptoms must occur by early adulthood. They must not occur exclusively during the course of four other conditions, including schizophrenia, a mood disorder with psychotic features, any other psychotic disorder, or a pervasive developmental disorder (criterion B).
The differential diagnosis includes a variety of other disorders. A key difference between schizotypal personality disorder and schizophrenia, a psychotic mood disorder, or another psychotic condition involves the transient nature of psychotic symptoms in schizotypal personality disorder. It may be distinguished from developmental communication disorders by a lack of compensatory means (e.g. gestures) of communicating, and it may be distinguished from autistic or Asperger's disorders by the relatively greater deficits in social awareness and frequent presence of stereotyped behaviours in those disorders. Schizotypal personality disorder may be confused with several other personality disorders, but it can be distinguished. In particular, it differs from schizoid personality disorder by its pattern of cognitive–perceptual distortions, and by the odd appearance or behaviour shown frequently by schizotypal patients. The pattern of schizotypal symptoms also differs from that manifested in borderline personality disorder, although there are similarities between these conditions. Schizotypal personality disorder differs from borderline personality disorder, however, in that psychotic-like symptoms and social isolation are more likely to persist in the absence of affective turmoil, and schizotypal individuals are less likely to display the impulsive and manipulative traits often associated with borderline personality disorder.
To the authors' knowledge, there are no published incidence studies for schizotypal personality disorder.
Lyons (39) reviewed recent prevalence studies for schizotypal personality disorder. Prevalence rates in non-clinical samples ranged from 0.7 to 5.1 per cent, with a median near 3.0 per cent. Higher rates occurred in clinical samples—2.0 to 64 per cent, with a median of 17.5 per cent. The prevalence of schizotypal personality disorder among the relatives of schizophrenic index cases is as high as 10 per cent. (40)
Review of evidence
There is, unfortunately, a dearth of outcome studies involving psychotherapy, psychosocial, or psychopharmacological treatments for schizotypal personality disorder. Published studies often show methodological limitations (e.g. small samples, subjects with mixed diagnoses, inadequate controls, and problems with internal validity), or provide outcome data on only limited aspects of the disorder. Despite these caveats, it is clear that few treatment gains are evident. This is particularly true of studies that utilized psychodynamically oriented therapy, either alone or in combination with other treatments (e.g. roup therapy or art therapy) as the primary treatment modality. (41)
For example, McGlashan (42) studied former inpatients approximately 15 years after treatment, who were given retrospective DSM-III diagnoses. The study followed up former patients with a variety of diagnoses, including among others, ‘pure' schizotypal personality disorder (n = 10). Multiple outcome measures were employed. Because the main purpose of the study was to examine schizotypal personality disorder as a diagnostic entity, there was little emphasis on assessing change in the same measures, which complicates any interpretation. The results showed, however, that most subjects with pure schizotypal personality disorder functioned poorly at follow-up. On one measure of global functioning in which continuously disabled subjects scored zero and normal subjects scored 4 points, the mean score was 1.6.
Several studies investigated the usefulness of medications in treating schizotypal personality disorder, although most investigations employed small numbers of subjects and combined samples of schizotypal and borderline personality disorders. (43,44) For these reasons, conclusions about the effectiveness of treatment must be equivocal. Typical antipsychotic drugs, in particular, have been proposed to reduce positive symptoms or depressed mood in times of acute stress, but the high incidence of adverse side-effects has discouraged their widespread use at other times, including the more chronic stable (i.e. non-crisis) phases of the disorder. (43,45) Other types of medication, including fluoxetine, have shown generally non-specific effects of treatment. (43)
Amoxipine, which has antidepressant and neuroleptic effects, was administered to a small group of personality disordered patients, that included five subjects diagnosed with DSM-III schizotypal personality disorder. (46) After an average treatment duration of 39 days, significant reductions were evident in total scores on the Brief Psychiatric Rating Scale, and on the Hamilton Rating Scale for Depression.
Goldberg et al. (47) administered thiothixine (an antipsychotic medication) to a group of patients that included, among others, DSM-III schizotypal personality disorder (n = 6). The Global Assessment Scale and Hopkins Symptom Checklist-90 were among the measures used to assess treatment effects. At the end of 12 weeks of treatment, little therapeutic change was evident within the schizotypal group, but modest improvements were observed in particular areas across groups, such as the psychotic and obsessive–compulsive scales of the Hopkins Symptom Checklist-90.
Hymowitz et al. (48) administered a low dose of haloperidol to 17 outpatients with DSM-III diagnoses of schizotypal personality disorder, for 6 weeks. The initial dose of 2.0 mg was intended to rise to 12.0 mg, but side-effects prevented increases beyond a mean dose of 3.6 mg. Even with lower doses, 50 per cent of the sample withdrew from the study because of side-effects. The 17 subjects who completed 2 weeks of the protocol improved somewhat in ratings of ideas of reference, odd communications, social isolation, and overall functioning.
In summary, the available literature offers few clear indications of effective treatments. The mechanisms of those few treatments that were somewhat effective, remain unclear. Interestingly, improvements in types of symptoms (e.g. psychoticism on the Hopkins Symptom Checklist-90) across diagnoses, rather than within them, (47) suggests that medications may help at least some subgroups of patients. A review of the medications used in these studies also shows the need to find treatments that are well tolerated, and that target negative symptoms and cognitive deficits.
Patients with schizotypal personality disorder often view their worlds as odd and threatening places and may require extended courses of treatment. (45,49) Unfortunately, trust and rapport with the therapist, which are necessary for the success of any therapy, are often difficult to establish in schizotypal personality disorder. The frequent occurrence of paranoia and suspiciousness, together with social aloofness and constricted affect, make exploratory psychotherapeutic approaches less effective than supportive cognitive–behavioural therapies. (45) In fact, these patients may only seek treatment to alleviate circumscribed problems, like anxiety or somatic complaints. Approaches that emphasize concrete, interim goals, and stipulate explicit means of attaining them, thus have the best chances of success. Because individuals with this disorder are vulnerable to decompensation during times of stress and may experience transient episodes of psychosis, they may also benefit from techniques to facilitate stress reduction (e.g. relaxation techniques, exercise, yoga, and meditation). Fortunately, some people with schizotypal features are likely to seek treatment in times of stress.(50) In the short term, brief courses of antipsychotic treatment may be useful if symptoms of psychosis appear.
Cognitive problems are also frequently amenable to concrete goal-oriented approaches to treatment. Patients benefit from an understanding of their cognitive strengths and weaknesses, to help them confront and cope with long-standing difficulties in their lives. For example, problems in attention, verbal memory or organizational skills contribute to failures in educational, occupational, and social endeavours, while reinforcing negative self-images and increasing performance anxiety. Knowledge of circumscribed cognitive problems allows patients to reframe their difficulties in a more positive manner, and facilitate selection of realistic personal, educational, and occupational goals. Moreover, specific cognitive deficits are often subject to partial remediation. For example, standard procedures will attenuate deficits in the acquisition, organization, and retrieval of new information (e.g. writing information down in a ‘memory notebook', using appointment books or planners, and rehearsing new information, among others).
Possibilities for prevention
At present, most early intervention programmes involve secondary prevention, which includes the early identification and treatment of clinical (usually psychotic) symptoms. (51) While intervention is necessary to alleviate clinical symptoms at any point during the disorder, it is particularly important early on because it might alter the course of the illness. Patients treated with antipsychotic medication during their first or second hospital admission, for example, show better outcomes than those who are not treated until later in the course of the disorder. (52)
Primary prevention, which involves treatment before the disorder manifests itself clinically, is not yet available for schizoaffective disorder, schizotypal personality disorder, or other disorders in the schizophrenia spectrum. To develop such treatments, it will be necessary to predict who is most likely to develop a disorder. Here, there are some encouraging signs. These include several ongoing ‘high-risk' studies, which follow the offspring of schizophrenic parents longitudinally. Such studies help to identify traits early in life that predict which individuals are most likely to experience clinical symptoms in adulthood. In the New York High Risk Project, for instance, problems with attention in childhood predicted social deficits in adolescence and social isolation in adulthood. (53) In another study, Walker and Lewine (54) found that social and neuropsychological impairments characterized children who subsequently developed schizophrenia. This type of study is important because it facilitates formation of homogeneous high-risk groups, which in turn facilitates the development of focused prevention strategies.
With current knowledge, it is difficult to justify preventive treatments—especially medication—for people without symptoms. The authors have argued elsewhere, however, that if people in high-risk groups (like first-degree biological relatives of patients with schizophrenia) show clinically meaningful symptoms, then treatment attempts may be appropriate. (29) The authors recently proposed this course of action for people with ‘schizotaxia', and suggested preliminary guidelines for treatment. (55) Eventually, prevention will be a primary therapeutic approach for the treatment of disorders in the schizophrenia spectrum. While primary prevention has yet to occur, the authors are optimistic that high-risk studies, progress in secondary prevention, and progress in discovering the genetic aetiology of the schizophrenia spectrum, will facilitate primary prevention strategies in the near future.
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